Human evolution: man is the wolf of man

Discussions unearthing human history including cultural anthropology, linguistics, etc.

Human evolution: man is the wolf of man

Postby Paralith on April 26th, 2014, 5:58 pm 

Starting a new thread to pursue the conversation that started as follows:

Obvious Leo wrote:
Paralith wrote:
Obvious Leo wrote:An even more gruesome thought. Very likely for a large part of our evolutionary history a non-trivial proportion of our meat protein intake would have been sourced from our less fortunate homo sapiens brethren. We got smarter by eating the dumb ones, after all.


Sorry Leo, I'm pretty skeptical that cannibalism was a non-trivial aspect of hominin diets, at any point in time, at least from a species-wide view. Meat eating, especially meat eating with tools, leaves distinctive marks on the bones of the prey items. We don't really find many hominin bones with those kinds of marks on them. Once you get into the Homo genus, like us humans, there is more cultural variation between social groups and like in modern humans you can get some groups that practice a certain amount of cannibalism or ritual defleshing of the dead. There are some Neandertal bones with marks that suggest both of these things as well, but it certainly doesn't appear to be a widespread, species typical mode of supplementing protein. Neandertals hunted large ice age game like mammoths, after all - I don't think they were that desperate for extra meat.

If man is the wolf of man, it's not so he can eat man for breakfast. It's so he can take man's food and resources for himself. That's plenty enough motivation for killing each other.


I was really only being facetious, Paralith, as far as the dietary comments were concerned. The real point I was driving at was that human evolution was primarily driven by this self-reinforcing evolutionary loop where homo was both predator and prey of his own kind. Evolution is driven by death and human brain size trebled in about 100,000 generations, a mere blink of an evolutionary eye for such a massive phenotypic change in a higher order mammal. That means intelligence was being powerfully selected for, which means that the homos were dropping like flies. What could possibly have been killing off the homos in such extraordinary numbers while they were steadily getting smarter and smarter? It doesn't look like rocket science to me.

Particularly persuasive to this notion is our unique talent for long distance running. I'm not sure how many mammals could beat a bloke over the marathon distance of 42km but it wouldn't be many and I'd be willing to bet that the few who could would be short-haired herbivores, not top-order predators. Homo getting smarter was clearly a top-order predator and his behaviour should therefore be compared with that of other top-order predators. If the lion doesn't get the antelope within the first few hundred yards then he'll have to look for an alternative lunch. He's a sprinter, not a stayer. You only need ten yards start on a crocodile and he won't get you. The top order predators give up quickly and wait for a better opportunity, whereas it's the prey that has the skills to get away.

Aside from our intelligence almost all of the phenotypic changes which distinguish homo from the other great apes seem to be associated with this talent for running away so "homo hominis lupus est" resonates quite logically with me. I realise that your knowledge of primate evolution is far superior to mine and I'm truly not trying to step on your toes. I've written quite extensively on this but only in a conceptual way and not in a learned scientific sort of way. I can't see how human intelligence could possibly have evolved to the extraordinary level that it has in the absence of such a self-reinforcing loop. We are our own genetic engineers.

"The survival value of human intelligence has never been satisfactorily demonstrated"... Michael Crichton.

I would respectfully suggest that this hypothesis of mine confirms Crichton's gloomy world-view and I have a great deal more that I could say on the subject. However I don't want to derail this valuable thread about the insects and such commentary would be more appropriate in a separate discussion.
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Re: Human evolution: man is the wolf of man

Postby Paralith on April 26th, 2014, 6:29 pm 

Leo,

No need to worry about stepping on my toes. I enjoy having the opportunity to have these kinds of discussions as they don't seem to come up too often on the forum these days.

What animal is most dangerous to a human? Another human. You will not find me arguing with that. I'm just not sure I can get with you on all the details for how and why this statement is true.

Let me begin by saying that many people do feel that between-group competition played an important role in our evolution. Some people feel quite certain that direct violent attack on other groups must have been a part of this competition. Recently I've been having my reservations about how important this kind of selective force was, or at least how certain we can be that this kind of hypothesis is the only sufficient explanation for our current state. But I can't deny the evidence that supports the existence of this competition, and for me some of the strongest evidence is the ease with which we humans make us-vs-them assignations.

So with that said, let me get to some of the difficulties I have with your position.

Firstly, I'm not so sure about your "eyeblink" judgement. Assuming the evolution of our lineage began with Ardipithecus at over 4 million years ago, which a brain size like a modern chimp and presumably like our common ancestor with chimps, and leading up to modern human brain sizes at around 500,000 years ago, that gives an evolutionary time span of at least 3.5 million years. Using a very conservative generation time of 20 years (which is surely an overestimate for most of the hominin lineage), that gave me 175,000 generations. Relatively short, sure. An eyeblink? I think that's an extreme label. I don't think this is something that stands out as especially odd in the history of evolution on this planet.

Secondly, it is not necessary that every less-fit hominin individual died before reproducing. They need only reproduce less successfully than their more-fit compatriots. They regularly had less children, or less surviving children, etc. It doesn't take an excessive number of generations for a consistent difference in reproductive success to drive a certain gene lineage into extinction. That being said I'm sure many hominins did die before accomplishing much reproduction, but much of this need not have been from direct violent attack by their compatriots. Disease (be it bacterial, viral, or parasitic), malnutrition, starvation, and for the million or so years that our ancestors were still very chimp-like, predation probably still played a serious role.

Finally, I guess I'm still not clear on what you're trying to say about the long distance running adaptation. To me, the overarching story of hominin locomotive physiology is one of increasing efficiency. No longer were were chimp-like creatures living our whole lives in a few square miles; we had to move from food patch to food patch, we had to increasingly follow our resources and our prey as they ranged across the continent. A hunter may have to spend days and days away from his group's current camp pursuing prey; to be able to efficiently follow that prey and efficiently bring it back home is a strong selective force. If this ability is, as you suggest, a method for getting away from other humans, well - if we as a species are all good runners, what real advantage is running in getting away from another good runner?

I feel that there is plenty survival value in our intelligence. But I also feel that this post is quite long enough already!
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 26th, 2014, 6:57 pm 

Thank you for your thoughtful response. You raise a number of points which I feel I can respond to without actually contradicting what you're saying. However I've got a number of things on my plate today and this will have to wait. I'd also be interested to see if anybody else wants to buy into this conversation.

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Re: Human evolution: man is the wolf of man

Postby Forest_Dump on April 27th, 2014, 9:39 am 

Not too many years ago there was (heated) debate on the prevalence of cannibalism starting with some of the work of Marvin Harris and his attempts to explain it in terms of functionalism (cultural materialism) and then reignited by the book "Man Corn" which led to interest by people such as Tim White (yes, he of A, afarensis and Ardi fame, etc.).

It seems likely that cannibalism was a relatively casual addition to diet early on in the evolution of hominins since many scavengers, etc., will display this behaviour if given the opportunity. But I doubt it would have been a common addition to diet if for no other reason than the same reason why carnivores rarely are more than a rare or casual addition to diet - the pool of prey is rare and potentially dangerous making it too "expensive" to count on. So when any member of a species at or near the top of the food chain is eaten, it is treated as special and usually wrapped up in religion of some form. So, of course there is cannibalism within our species but there is a very wide range of contexts ranging from enemies in some cases to just immediate family on others or admirable individuals in still other cases (the latter of which survives symbolically in Christendom in the symbolism of the Holy Communion.)
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Re: Human evolution: man is the wolf of man

Postby rchrdstvr77 on April 27th, 2014, 1:13 pm 

The only way cannibalism will be accepted is to keep the process secret like the did in Soylent Green

“What we think, or what we know, or what we believe is, in the end, of little consequence.
The only consequence is WHAT WE DO.” John Ruskin (1819 - 1900)
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 27th, 2014, 4:27 pm 

Paralith wrote:Firstly, I'm not so sure about your "eyeblink" judgement.


Guilty as charged, your honour, of the crime of hyperbole. Nevertheless the phenotypic changes which distinguish homo from our common great ape ancestors have come about unusually rapidly for a higher order mammal. The most radical change is in brain size and brain complexity, where not only did our brains get a lot bigger, they also evolved more complex structures not seen in our nearest primate kin or any other mammal. Intelligence was clearly being selected for in a big way. Can you think of a comparable example in any other primates?

I'd go along with the more general logic that cannibalism in the hominins was more opportunistic than goal-driven and that the major selection factors for self-predation would have been access to resources, as you suggest. For that reason the importance of self-predation would have been a rather haphazard selection factor depending on the availability of such resources. Provided that the early hunter-gatherer tribes were able to establish themselves in sustainable niches I very much doubt that they would have gone looking for a fight, for the reasons that Forest gave. It would have been too expensive in overall reproductive terms.

I think our notion of human "courage" is an entirely cultural construct and not hard-wired at all. 9 times out of 10 our instincts will be telling us to turn and flee rather than stand and fight, but this doesn't mean that some tribal groups wouldn't have been more aggressive than others. Bear in mind that I'm speaking here mostly of the pre-homo hominins with the smaller brains to see how self-predation gradually emerged to become a major selection factor later on. Some hominin species and sub-species would have been naturally more aggressive than others and for most of hominin history many such sub-species would have co-existed, essentially competing for the same resources. At times of environmental stress it's not hard to imagine them at each others throats and it's safe to conclude that the more aggressive group would statistically come out on top and the better runners are also favoured. That means this argument doesn't wash.

Paralith wrote: If this ability is, as you suggest, a method for getting away from other humans, well - if we as a species are all good runners, what real advantage is running in getting away from another good runner?


When regarded in the pre-homo context today's bully becomes tomorrows victim. No matter how tough and smart we think we are there's always someone tougher and smarter, so in times of stress a given tribal group is not only on the lookout for more powerful enemies to flee from, it is also keeping an opportunistic eye out for less powerful groups to chase after, in order to dislodge them from their niche. The notion of "us" and "them" is born, which the later homos managed to develop into a high art form.

It's a very long story, this one, which has its origins in complexity modelling in self-organising information systems, but following this line of argument cannot be done with brevity so I'll just give the bullet points. Over the long haul the survival of the fittest becomes the survival of the smartest and the survival of the best runners is better regarded as a collateral consequence. I'm not attracted to the idea of a top-order predator chasing his lunch for marathon distances across the tropical savannah on the grounds of common sense. This would have got them laughed out of the predator's guild. Predators are successful because they're smarter than their prey, not because they've got greater endurance. Thus we see the beginnings of a self-reinforcing evolutionary loop where intelligence effectively selects for itself. In complexity modelling we would say that the entire system becomes more informationally complex. Biological systems are typical examples of self-organising information systems and such systems are mandated to evolve from the simple towards the complex. Once such a self-reinforcing selection loop gains a toehold in such a system then the complexity of the overall system increases at exponential speed.

To put this notion back into the context of hominin evolution, complexity theory requires that in the best case scenario a single predator will come out on top by vanquishing all its rivals. It does this by becoming more informationally complex. Once the homos acquired language it was a no contest. We clawed our way to the top and there we stand asking ourselves the only useful question. Now what?

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Re: Human evolution: man is the wolf of man

Postby Paralith on April 27th, 2014, 6:38 pm 

Obvious Leo » Sun Apr 27, 2014 2:27 pm wrote:
Guilty as charged, your honour, of the crime of hyperbole. Nevertheless the phenotypic changes which distinguish homo from our common great ape ancestors have come about unusually rapidly for a higher order mammal. The most radical change is in brain size and brain complexity, where not only did our brains get a lot bigger, they also evolved more complex structures not seen in our nearest primate kin or any other mammal. Intelligence was clearly being selected for in a big way. Can you think of a comparable example in any other primates?


Sorry Leo, I just don't see where you're getting "unusually rapid" from. I don't have another solid example off the top of my head, but I do know that the primate family is full of significant and complex changes. Any animal family is. With the right selective pressure, considerable change can happen fairly quickly, especially if the underlying genetic architecture of a trait allows for relatively easy change. And more traits are like this than you probably realize. We know from comparing our genome to that of chimpanzees that they are not hugely different, and that many of the key differences are not in actual protein-coding genes, but in the regulatory regions, the genes that say how much of different proteins to make. A few tweaks in the level of gene expression for the right developmental genes and very simply you can grow a new finger, or even a whole new limb where there wasn't one before. A few tweaks in the level of gene expression for the right brain genes is probably all it took for the major changes in overall brain size and size of specific brain regions between humans and our chimp-like ancestors. The question is not how hard is it to build a brain like that, but are the right selective pressures in place to maintain these mutations when they arise? That this happened in a few million years once the right selective pressures were in place is not particularly remarkable to me.

If there is something remarkable here, it's the fact that intelligence of this level has not, as far as we can see, been selected for before in the history of life on this planet, at least not consistently enough to result in a species like us. The selection pressures and our evolutionary history have apparently come together in a fairly unique combination, and that is interesting and remarkable. The amount of time that passed just isn't, not to me. Certainly the speed isn't remarkable enough for me to assume a priori that an uncommon amount of death must have been involved in the evolution of human intelligence.

I think our notion of human "courage" is an entirely cultural construct and not hard-wired at all. 9 times out of 10 our instincts will be telling us to turn and flee rather than stand and fight, but this doesn't mean that some tribal groups wouldn't have been more aggressive than others. Bear in mind that I'm speaking here mostly of the pre-homo hominins with the smaller brains to see how self-predation gradually emerged to become a major selection factor later on. Some hominin species and sub-species would have been naturally more aggressive than others and for most of hominin history many such sub-species would have co-existed, essentially competing for the same resources. At times of environmental stress it's not hard to imagine them at each others throats and it's safe to conclude that the more aggressive group would statistically come out on top and the better runners are also favoured. That means this argument doesn't wash.

Paralith wrote: If this ability is, as you suggest, a method for getting away from other humans, well - if we as a species are all good runners, what real advantage is running in getting away from another good runner?


When regarded in the pre-homo context today's bully becomes tomorrows victim. No matter how tough and smart we think we are there's always someone tougher and smarter, so in times of stress a given tribal group is not only on the lookout for more powerful enemies to flee from, it is also keeping an opportunistic eye out for less powerful groups to chase after, in order to dislodge them from their niche. The notion of "us" and "them" is born, which the later homos managed to develop into a high art form.


I don't really follow your logic here. Sometimes groups would attack each other so therefore everyone needs to become a hardcore long distance runner? I'm not seeing the necessity that one leads to the other.

I'm not attracted to the idea of a top-order predator chasing his lunch for marathon distances across the tropical savannah on the grounds of common sense. This would have got them laughed out of the predator's guild. Predators are successful because they're smarter than their prey, not because they've got greater endurance.


This is very strange way of looking at it, Leo. There is no one right way to be a predator. Just because one animal does it differently than others doesn't mean it's wrong - if in the end they successfully catch enough food to support themselves, that's all that matters. And we humans are coming from a very different evolutionary history than most other predators. We are not from a long line of animals that were carnivores - we are from a long line of arboreal fruit eaters. The fact that we hunt in ways differently than other carnivores is not especially surprising, and certainly not reason enough to laugh a hypothesis about human hunting off the table.

Let me tell you something about these top predators you keep lauding. The success rate of many of these predators, like lions, is only around 25%. Three times out of four, they try to make a kill and they fail. What about non-dedicated carnivores that hunt? Like chimpanzees hunting monkeys? Their success rate, compared to top predators, is kind of incredible. It's around 80 to 90%. Most of the time, when they go after some monkeys, they're coming home with some meat. By this measure it would appear that chimpanzees are better hunters than your top predators! What's the difference? Chimpanzees don't hunt every chance they get. They wait to hunt at times when they know they are likely to be successful - in particular when a large number of their fellow males are all in the same place at once.

If a human hunter knows that there aren't many prey items in the area, and he sees an antelope, and he knows he can just chase that poor thing, tracking it even when he can't physically see it, until it just collapses from exhaustion and he can trot up and kill it at his leisure, what difference does it make that he's not doing it the way a lion would do it?

To put this notion back into the context of hominin evolution, complexity theory requires that in the best case scenario a single predator will come out on top by vanquishing all its rivals. It does this by becoming more informationally complex. Once the homos acquired language it was a no contest. We clawed our way to the top and there we stand asking ourselves the only useful question. Now what?


Well, Leo, if I know more than you about primates, you know more than me about complexity theory. I'm not following how complexity theory requires that a predator becomes more informationally complex. More complex than what? Must it be constantly getting more and more complex?

I'm also not sure how endurance running plays into this. You said to think of it as more of a side-effect of intelligence, but I'm not really seeing it. I think just turning tail and running from your attackers, letting them have whatever resource you're leaving behind, is definitely a "stupider" approach than forming a complex coalitionary relationship with other members of your group and mounting a cooperative defense of your resources.

To put my personal perspective in a nutshell, I don't think we're smarter than chimps because we chased each other around the savannas trying to kill each other. I think we're smarter than chimps because we work together better. My programmer fiancé phrased it very well - probably the most computationally complex thing one intelligence can do is to model the behavior of another intelligence. An individual human depends intensely on other individual humans for many reasons - for help with raising their offspring, for help with hunting prey, for help with complex food gathering tasks, for gifts of food when their own food gathering trips were unsuccessful that day - a real risk in the human dietary niche! An individual human must work cooperatively with other humans to be successful. To be a good cooperator you need to understand your cooperative partner, you need to communicate with them, you need to understand when you're pissing them off or when they're pleased with what you've done. This need to work well with others is no doubt enhanced when you need to work together to fight off other attackers who are also working together; but the need to cooperate exists in absence of direct violent attack, too.
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 27th, 2014, 8:20 pm 

You raise a host of interesting points about the value of co-operative behaviour in predatory success which could easily set me off on a long digression about Dunbar's number and the optimum size of social groupings. I might leave that for another time.

Your arguments about large phenotypic change resulting from minor changes in gene expression are very persuasive, and so you've already got me shifting my position somewhat on my regrettable eyeblink metaphor. Such is the value of discussions such as this. I think we're basically agreeing with each other that such changes are driven by selective pressures which are inevitably multi-factorial and the stronger these selective pressures are the more quickly these changes can come about. I assume this is the point you were making and since it makes perfect sense to me I'm more than willing to go along with it. In that sense all I'm really saying is that the selective pressure for greater intelligence was a strong pressure which became self-reinforcing. Smart begat smarter, if you like.

Paralith wrote:If there is something remarkable here, it's the fact that intelligence of this level has not, as far as we can see, been selected for before in the history of life on this planet, at least not consistently enough to result in a species like us.


To a complexity theorist this is unremarkable, which is not to say that I'm not struck with awe at the sheer scale of this event or the staggering potential of human intelligence, which I regard as practically infinite. Our planet has now evolved the Uber-predator who is the master of all that he surveys. He is his own genetic engineer and will determine the future evolutionary direction of all future life on his host planet, whether he likes the idea or not. That is until he engineers his own destruction and Darwinian chaos takes her job back. Complexity theory is a rather dry and arcane subject which only really gets interesting when applied to real-world situations. It basically applies to all chaotic systems and incorporates notions such as negative entropy and so forth, which are not for the faint-hearted. Living systems are the epitome of chaos and thus lend themselves very well to studying questions of informational complexity and this is very much my angle of approach, which makes this statement particularly pertinent.

Paralith wrote:This is very strange way of looking at it, Leo.


This could well be engraved onto my tombstone because it's the story of my life. When I see that the history of physical reality from the Big Bang onwards is one of a punctuated evolution towards informational complexity, culminating in the observer that can comprehend it, I don't resort to an assumption of coincidence. Unlike Stephen Hawking I don't regard life as a random chemical smear but rather as the point of the whole cosmic story. As an atheist I have no room in my philosophy for an invisible best friend and therefore require my universe to be sufficient to its own existence. This proposition has landed me in plenty of hot water in other forums because it conflicts with the current epistemic paradigms of physics, but we contrarians must simply take such setbacks on the chin.

In the world according to Leo the comprehending observer has evolved for a reason and this reason will be his own to define. Complexity theory mandates the emergence of the uber-predator in a closed information system as long as the environment is favourable, but chaos denies that it needed to be us. Who knows? If the asteroid hadn't blown their chances the dinosaurs may have thrown up an advanced technological civilisation and put you out of a job. The primates would never have happened. If we blow our one and only opportunity then the planet has still got a few billion good years of life left in it. Maybe the chaotic system will chuck out a hundred new candidates for the top job, but only one at a time. The signature feature of the uber-predator is that ultimately there can be only one.

This much at least the evolutionary history of humanity has taught us.

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Re: Human evolution: man is the wolf of man

Postby BioWizard on April 28th, 2014, 12:31 am 

Just a quick point to Leo.

Disclaimer: Some of the examples below are quite trivial, and I'm not implying that you've made any such claims. I'm only including them to make the point about my cautionary remark.

Biological evolution is fraught with examples of systems actually getting simpler, more streamlined, and almost bare boned over time. Whether the complexity of an organism increases or decreases over evolutionary time depends on the survival/reproductive strategy that the organism falls into. The collective complexity of all life, however, tends to increase over time, because of the self amplifying interactions amongst its members. And this is not unique to biology. Think of a snowball getting bigger as it rolls down the side of a mountain.

Now, extending physical laws into biology in a simplistic and straightforward manner is certainly a tantalizing prospect, but it can be incredibly misleading. The drop in the universe's temperature since the big bang does not by itself explain the appearance of biological life and the course of its evolution. If you intend to explain biology directly using nothing but the laws of physics as they apply to, say, elementary particles, then you have to be prepared to break biology down to the level of its elementary particles and then model the interactions between them from the ground up. For instance, you can certainly model the flight of an airplane by applying the laws of physics to the interactions between the body of the airplane and the molecules of air around it. But you cannot model the airplane itself as if it were a molecule of air. A better alternative would be to come up with a modeling shortcut, where you observe things at the macroscale and devise a simpler set of rules that can explain and model the motion of the craft without having to suffer calculating the state of every single atom. That's pretty much what the various scientific "disciplines" attempt to do. And biology is certainly complex enough to warrant its own set of "shortcut" rules, at least until we have the knowledge and computational power to model it starting with the wave-function of its constituent elementary particles.

There will always be analogies between systems at the macro and the microscales. But these analogies only exist because our minds draw them - in their desperate search for patterns. And when you want to explain something such as the behavior of a crowd of people, you'll need more than just Brownian motion.
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 28th, 2014, 2:48 am 

All very true, BioW. I'm aware of of the hazards of oversimplifying complexity modelling and would agree that the sort of reductionism you refer to is not particularly helpful. In general one can only look at the overall big picture and then draw conclusions about the way chaotic systems tend, rather than focusing on the behaviour of the individual components of such systems. For example we can say that our biosphere tends towards informational complexity, in accordance with the negentropy principles of chaos mathematics, and this a perfectly true statement, but such events as the snowball earth and colliding asteroids can then come along and throw a spanner in the works at the drop of a hat. You might call this a setback. But even the entire terrestrial biosphere is not a big enough picture in the wider scheme of things because if Alpha Centauri goes supernova it would likely be curtains down for the whole opera. The planet would probably be a lifeless wasteland until it gets swallowed up by the expanding sun, so in the bigger picture one could describe the exercise as not just a setback but a failed attempt. There are plenty of parallel examples at the lower hierarchical levels of living systems, which are simply called species endangerment and ultimately extinction. The patterns are certainly there throughout the various hierarchies if you employ a suitably wide-angled lens.

In terms of physics we could say that over its 13.8 billion year life-span the universe has become more informationally complex, as the evolution of life within it would testify. Before this could even occur the cosmos itself had to undergo billions of years of evolution just to produce the more complex atoms needed to produce the more complex molecules etc etc. This starts right at the big bang, before there's even such complex things as atoms at all. This is where I say that the epistemic physical models are obscuring the big picture because they regard the universe as a place within which events occur, whereas I regard the universe as the main event itself. It's rather like trying to understand the biological evolution of an individual species in the context of a static biosphere, instead of appreciating that the entire biosphere is evolving as an integrated and dynamic entity and the component units are simply evolving hierarchically within it. I frequently use the imagery of the embedded matryoshka dolls to illustrate this point.

I'm drifting off the "homo hominis lupus est" conclusion, but this notion is in fact perfectly consistent with this sort of modelling. To elaborate on it in satisfactory detail is not a straightforward exercise and I'm pretty sure I wouldn't get a tenth of the way through it before losing all my readers. I don't mind coming across as a crackpot but I'd be horrified to be thought of as a bore.

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Re: Human evolution: man is the wolf of man

Postby BioWizard on April 28th, 2014, 8:08 am 

Leo, the infra structure of the universe and physical reality has not seen any updates since the appearance of life. Everything you've mentioned is merely events playing out in a reality that had already matured in its physical laws. That said, I don't regard the evolution of the universe as a driving force of biological evolution inasmuch as providing the stage for it. Just like a piece of canvas provides the medium for a painting to happen, but the mere existence of canvas neither ensures nor explains a painting.

In the end, we might just be arguing definitions here. I have never considered animate and inanimate systems as discontinuous either, and I do like to think of biology as another chapter in the evolution of the universe. I just don't want people to take that as a license for making categorical errors. I suppose I have a healthy appreciation for the difficulty of naively extending the models of the latter into the former without sufficient rigor. My point is, listen to Paralith when it comes to primate evolution, no matter how much physics you know (and I bet you know quite a bit). :]
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Re: Human evolution: man is the wolf of man

Postby BadgerJelly on April 28th, 2014, 10:14 am 

I've only read the first few posts hear, but I think I could be more or less right in saying that human intelligence has led to our species NOT killing each other rather than the other way around. You can selectively breed mice to run a maze better or worse. It does not mean they are smarter or more stupid, it only tells you that they run the maze better or worse not the reason this is so.

Maybe the tendency to view species as either predator or prey is over simplifying the situation. That said I think everyone can agree that we are our own potential threat and saviour. The latter seems to have been winning out all this time.
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Re: Human evolution: man is the wolf of man

Postby Paralith on April 28th, 2014, 12:22 pm 

Obvious Leo » Sun Apr 27, 2014 6:20 pm wrote:You raise a host of interesting points about the value of co-operative behaviour in predatory success which could easily set me off on a long digression about Dunbar's number and the optimum size of social groupings. I might leave that for another time.

Your arguments about large phenotypic change resulting from minor changes in gene expression are very persuasive, and so you've already got me shifting my position somewhat on my regrettable eyeblink metaphor. Such is the value of discussions such as this. I think we're basically agreeing with each other that such changes are driven by selective pressures which are inevitably multi-factorial and the stronger these selective pressures are the more quickly these changes can come about. I assume this is the point you were making and since it makes perfect sense to me I'm more than willing to go along with it.


I'm glad you're enjoying this conversation, as I certainly am. I would definitely be interesting in talking about Dunbar's number, as I feel sort of skeptical about how specific is. But I haven't reviewed the evidence in a while, and from what I do remember it is fairly compelling. And yes, a stronger selective force will push a given evolutionary change to go faster. We are not in disagreement over how natural selection works, just whether or not it worked in a particularly extreme way in the case of the human brain.

In that sense all I'm really saying is that the selective pressure for greater intelligence was a strong pressure which became self-reinforcing. Smart begat smarter, if you like.


"Self-reinforcing" gives me pause. I can see why, looking at the overall history of evolution of life on this planet, that it may seem like life was always inevitably crawling towards something as smart as us. After all, smarter and smarter animals continued to emerge over time. But for every "smart" species that is on this planet, there are hundreds if not thousands of species of life that most of us can agree are not very smart at all. This planet is literally swarming with single celled life that gets along just fine with nothing but brute biochemical reaction, always has and probably always will. The planet is also swarming with life that took a few more steps "towards" being smart, like insects, and their degree of smartness was sufficient for their strategy of survival and they never "advanced" much further than that, not after millions of years of evolution.

Being smart is just one strategy among many possible strategies that an organism could evolve in order to be successful (stay alive and reproduce). On a world swarming with life, with organisms competing for resources, given enough time some organisms are going to eventually hit upon the strategy of smarts. It so happened that the hominin lineage managed to get there and ramp it up before other lineages did. And once a species or group of species manage to thoroughly conquer a certain niche, it can be difficult for other species to get a toehold in it. That's why bacteria are still bacteria and we aren't.

Given a molecular organization that is capable of evolving (life), given enough time and space for those organizations to proliferate and compete, I do think something smart will eventually emerge. I don't think this is because smartness is self reinforcing, but because it is one of the many different strategies that is available to an organization exploring strategy space through evolution.

All of this does not necessarily conflict with your view that the universe was in fact somehow aimed at the creation of an intelligence. It may even seem to jive with your statement that there can only be one "uber predator" though I think "uber competitor" is a much more apt term. We are smart enough now to make use of many different resources, to gather and harbor those resources and defend them from any other kind of life that may want to take it away, and if we are successful in keeping all these resources to ourselves, our competitors may well die of starvation without our having to make a single offensive attack in their direction. I do feel that something like this must have happened at least once or maybe several times when Homo sapiens came on the scene, and all the other Homo species that once existed fell one by one into extinction.

In the end, I can only really argue with your disparagement of the description of life as a chemical smear. Because though you profess to being an atheist you have about you the attitude of someone who needs there to be more, someone who needs something higher and greater and more meaningful than organic chemicals bumping into each other to justify the existence of our intelligence. And I apologize ahead of time if I'm misjudging you. But I don't see the need, I don't feel this urgency that there must be something more than this. Something more than "mere" chemistry, than "mere" coincidence. There is nothing "mere" about it to me. These are powerful, incredible, fascinating forces and qualities of our universe. I require nothing more, nothing logically and nothing emotionally, to be satisfied with why we are here.
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Re: Human evolution: man is the wolf of man

Postby owleye on April 28th, 2014, 3:38 pm 

Question. The following question may be relevant to the speed of the human evolutionary traits, so I'll ask it. Do we know much about the number of offspring a female has during this early period, their survival possibly depending on factors related to intelligence being passed on. Assuming life expectancy is short, by today's measure, these factors might best serve those of child-bearing ages, or even earlier, if language learning forms part of it. I'm always astounded by the speed at which young children pick up language.
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Re: Human evolution: man is the wolf of man

Postby Paralith on April 28th, 2014, 4:05 pm 

Sorry Owleye, I'm pretty confused by your question. Not really sure what you're asking. Let me try to address some of things you brought up, at least.

It is difficult to reconstruct the life history, the scheduling of major life events like maturation and reproduction, from fossil hominins. Current studies suggest that the Australopithecines (Lucy and her ilk) and early members of the Homo genus like Homo erectus appear to have had similar life schedules to modern chimpanzees, though by the time Homo erectus is nearing the end of its species tenure it has brain sizes of more than twice that of chimpanzees. A life schedule with longer childhoods and longer lives overall doesn't seem to emerge until the late Homo species, us and Neanderthals in particular.

Homo sapiens has an especially short birth spacing compared to other living African apes. Even though a human woman begins her reproductive career later than a chimpanzee, in a natural fertility population she often has more offspring by the end of her life than a chimpanzee does. I don't know if there's much data at all about when this pattern of reproductive scheduling really began. Late Homo species are our best guess, with Homo sapiens really being the only one we can be sure of.

It is also difficult to pinpoint where language really emerged in this timeline. I find it hard to believe that Neanderthals did not have full or close to full language like ours, but when it comes to earlier species like Homo erectus it's really hard to say. They were capable of fairly complex tool making and hunting behaviors, and were probably living and hunting cooperatively, which suggests some form of language to facilitate their working together, but who knows what it was really like.
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 28th, 2014, 5:34 pm 

I love it when conversations tend towards agreement rather than otherwise. We may just have to differ on the self-reinforcing bit for the moment. I regard the evolution of mind as qualitatively different from the other hierarchical steps in the evolutionary web because minds make free choices whereas trees don't, for instance. In that respect human mind is qualitatively no different from mind more generally, only quantitatively so. An information-theoretic model regards a mind as a self-programming computer and it is this self-programming feature of mind which essentially puts mind on an evolutionary pathway of its own, albeit within the context of the broader evolutionary picture.

It is this broader evolutionary picture which makes this point pertinent.

Paralith wrote:I can see why, looking at the overall history of evolution of life on this planet, that it may seem like life was always inevitably crawling towards something as smart as us. After all, smarter and smarter animals continued to emerge over time. But for every "smart" species that is on this planet, there are hundreds if not thousands of species of life that most of us can agree are not very smart at all. This planet is literally swarming with single celled life that gets along just fine with nothing but brute biochemical reaction, always has and probably always will. The planet is also swarming with life that took a few more steps "towards" being smart, like insects, and their degree of smartness was sufficient for their strategy of survival and they never "advanced" much further than that, not after millions of years of evolution.


The big picture often gets obscured when we just consider the individual components of it and thus for want of a less loaded term I could define my perspective as neo-Gaian. If we regard our biosphere as an integrated whole we could effectively say that humans have now evolved into the engineers of it and I intend for this perspective to be taken literally. I've always been intrigued by the fact that we have such an enormous amount of literature which deals with the question of where we evolved from and such a paucity of speculation about what we're evolving into. Clearly this is entirely up to us, but whatever path we choose we take our entire biosphere with us. We're a composite and integrated organism and most of the DNA in our very bodies is not "human" DNA. You might say that the whole of the human is greater than the sum of its living parts. In a very broad sense the same analogy could be applied to the biosphere as a whole, although of course I'm not one of these Gaian crackpots who regards the biosphere as somehow being sentient. The big picture is far more subtle than that.

Although I'm not inflexibly wedded to it I very much like the idea of the transpermia paradigm for the propagation of life throughout the universe. Since the basic building blocks of life are ubiquitous in interstellar clouds of gas and dust it makes perfect sense to me that life emerges from non-life in some unknown way as a part of the process of solar system formation. It only takes a self-replicating molecule to set the ball rolling and if the conditions are amenable then biology can do the rest, rather like Conway's cellular automatons. Complexity emerges spontaneously but it does so non-linearly and this gives us the notion of biodiversity in the form of the matryoshka dolls and also the notion of punctuated evolution.

How common is it for life to emerge in such a way in our galaxy? From a sample size of one your guess is as good as mine. It may be reasonable to suppose that such an event is rare but simply absurd to suggest that it is somehow unique. Likewise the evolution of advanced techno-civilisations with the uber-predator in charge. No doubt this would be orders of magnitude yet more rare, but once again it seems absurd to suggest that we are in some way unique. We can easily get a sense of scale for this when we properly grasp the true vastness of the universe and the fact that its calmed down a bit from its fiery birth. Our cosmos has now evolved into its early middle age and the conditions are now ripe for the evolution of life and mind. Common sense requires us to assume that life and mind have been, are being and will continue to be emerging all over the cosmos and the frequency of this is irrelevant to the overall story. The examined mind does not believe in coincidence and the atheist requires his universe to be sufficient to its own existence, thus he finds both refuge and explanation in complexity theory. I do not hold to the notion of "purpose" in this paradigm, any more than we can regard the evolution of human mind within its biosphere as purposeful. It's simply an inevitable consequence of the fundamental negative entropy laws of chaos, given the right conditions. I've elsewhere described this as the Humpty-Dumpty model, where the second law of thermodynamics is trying to pull the universe to bits while chaos is trying to put it back together again. This notion only works if we regard the entire cosmos as an information system but I'm anxious not to be thought of as some sort of mystic. The majesty of this sort of modelling lies in the sheer simplicity of it and the analogy of Conway's cellular automatons is both simple and descriptive. The cosmos is a blind automaton obeying the simplest of simple laws and these laws inevitably give rise to all the complex structures within it at a host of emergent and integrated levels. But we must never allow ourselves to forget this. Minds make choices, which means the future of the universe is a blank slate onto which the uber-predator can write his own story. The self-programming computer is a loose cannon in the cosmic evolution and thus while we can't ascribe a purpose to the universe as a whole we can certainly ascribe a purpose to our own role within it. Once again this purpose is our own to define and the purpose itself will evolve as time goes on, as will we in a biological sense, in accordance with whatever parameters we elect to define for ourselves.

In a nutshell these are the bullet points of the philosophy of the bloody obvious and I have literally millions more words where these come from. I've always been a voracious reader of philosophy and these principles are soundly rooted in wisdom which stretches back for millennia. They offer a totally new paradigm for physical reality because they imply that time is a physically real phenomenon, which puts me at odds with the physicists, but I'm not too bothered about that because this alternative perspective offers us an interpretation of our physical models which is accessible to reason. From the outset the entire raison d'etre for my philosophical musings was to come up with a model for reality which makes sense. In my opinion it's the most valuable legacy I can bequeath to my grandchildren and thus my journey has been a deeply personal one.

Above all, Leibniz's principle of sufficient reason, which derives from Aristotle's doctrine of causation, requires that a universe without an observer within it to comprehend it would have no reason to exist. If we assume that life and mind are ubiquitous throughout the cosmos we can clearly see that the universe has mandated its own comprehensibility. To suggest that this is some sort of cosmic accident simply beggars belief, so this statement is profoundly true in my own personal case.

Paralith wrote:you have about you the attitude of someone who needs there to be more, someone who needs something higher and greater and more meaningful than organic chemicals bumping into each other to justify the existence of our intelligence.


Once again I need to stress the point that as an uber-determinist I find nothing mystical or supernatural about any of this thinking. The entire scenario derives seamlessly from principles of the most austere simplicity so I regard the philosophy of the bloody obvious as reality for dummies.

Regards Leo

P.S. Sorry James and Paralith for cross-posting you. This was quite a long ramble.
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Re: Human evolution: man is the wolf of man

Postby BadgerJelly on April 29th, 2014, 12:21 am 

Paralith -

I don't think I've ever really sat down and thought before that being less intelligent (whatever that may mean?) may actually benefit future survival! XD

Whole can of worms here ready to be opened ... again!
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 29th, 2014, 1:28 am 

BadgerJelly wrote:Paralith -

I don't think I've ever really sat down and thought before that being less intelligent (whatever that may mean?) may actually benefit future survival! XD

Whole can of worms here ready to be opened ... again!


This sort of brings us back to the quote of Crichton's which actually initiated this thread.
"The survival value of human intelligence has never been satisfactorily demonstrated"

Whilst its easy to see how intelligence in a general sense would have survival value it's also easy to see that the level of human intelligence is likely to have the opposite effect. You could say that we've outsmarted ourselves and have superfluous intelligence which tends to drive the logic the other way. There is a school of thought which suggests that any civilisation which develops the technology to destroy itself will almost inevitably do so. On the balance of the evidence from our sample size of one it's hard not to be persuaded by this argument and our best hope is to cling to the tenuous qualifier of "almost" inevitably.

Regards Leo
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Re: Human evolution: man is the wolf of man

Postby owleye on April 29th, 2014, 8:38 am 

Paralith » Mon Apr 28, 2014 2:05 pm wrote:Sorry Owleye, I'm pretty confused by your question. Not really sure what you're asking. Let me try to address some of things you brought up, at least.


I know it's a complicated question -- lots of factors involved. Human evolution as we understand it derives from the findings of what's left behind. Brain tissue isn't one of the things left behind, so we have to draw inferences. However, what I was looking for, and which you did in fact respond, was the relative birth spacing (a term I hadn't thought of, and I thank you for that) during the early years, coupled with their survival rates (up to their child-bearing ages). It's possible this might be known from the available skeletal remains. Today, by and large, we have a relatively low birth rate, but not long ago, it had been much higher. I'm just not versed in the history of birth rates, and I can't even imagine what it must have been like at the dawn of humanity. What I'd been thinking is that births would have come pretty much as soon as they were biologically possible, and survival would be the result of attrition, in consideration of competition for resources. As such, the offspring of families having the greatest likelihood of survival would be the main driver. You've already pointed out how quickly a positive trait such as intelligence could overwhelm a population. I was trying to add an additional factor to the rate at which humans developed. In any case, I thank you for your response.
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Re: Human evolution: man is the wolf of man

Postby Paralith on April 29th, 2014, 11:36 am 

BadgerJelly wrote:Paralith -

I don't think I've ever really sat down and thought before that being less intelligent (whatever that may mean?) may actually benefit future survival! XD

Whole can of worms here ready to be opened ... again!


Obvious Leo wrote:On the balance of the evidence from our sample size of one...


Sample size of one, Leo? How anthropocentric of you. True, there is only one animal alive today at our level of intelligence, but the planet is full of a variety of animals with a variety of cognitive capacities. This gives us lots of data to think about intelligence and when, where, how, and why it develops. On our planet anyway, at least.

Being smart is expensive. It's expensive in energy costs to build and support a brain, it's expensive in time costs to grow a brain and give it time to learn, it's expensive in risk cost of something going wrong with that complicated structure. All these costs are hurdles that must be "jumped" by any organism that is going to evolve greater intelligence. And if an organism can get away without paying those costs, it certainly will. It's competition with other life on the planet, as niches are taken over and filled up, that eventually drives some organisms to jumping over all the hurdles, that drives them into a niche where jumping over those hurdles is even possible.

In the broadest sense, what is the advantage that intelligence gives an organism? Flexibility. The ability to change what you're doing, in particular in response to changes in the environment around you. This trait becomes especially important when it comes to long term lineage survival, because it's a change in the environment you adapted to that is most likely to kill you. If you are flexible enough to adjust to the change, then you're less likely to go extinct in the long term. But there are other ways to be flexible as a species, and unicellular organisms like bacteria and viruses are the kings of this strategy. Their generation times are so short that they can basically force natural selection to work at overtime speed. As individuals bacteria are not very flexible at all, but as species they are incredibly flexible. And they are the kings of their niche, and the other lineages of life had to find other ways to make do. Intelligence gives you within-lifetime flexibility, allowing individuals to adjust to changes in your environment without having to wait for the generations to roll by in order for natural selection to do its thing.

But you have to be very careful when talking about the long term survivability of a species/lineage in these terms. Because natural selection does not work on those scales. Natural selection works on the scale of generations; natural selection favors traits which function well in the current environment. It is not capable of "seeing" into the future and preparing a species for when that ice age is coming. If flexibility evolves, if intelligence evolves, it has to be for some function in the current environment. Now, some environments are more changeable in the short term, so natural selection may create a species that is able to deal with this short term flexibility, and this can have the accidental side effect of making that species better prepared to deal with big long term environmental changes. But for the most part, natural selection does not make organisms that are equipped to survive whole through massive and sudden environmental changes. This is why the vast majority of species that have ever lived are now dead.

I think human intelligence evolved in the short term for multiple reasons; we were already on a trajectory of increased social intelligence thanks to our primate ancestry, which benefits us directly by improving our ability to work in mutually beneficial cooperative relationships. More particular to the hominin lineage we became more dietarily complex and flexible, able to go after difficult to obtain but energy rich food stuffs (the kind of niche that favors an expensive but smart brain), able to switch over to different kinds of foodstuff should one source go dry, able to support each other so no one in the social group ever goes home hungry. This flexibility that helps maintain a constant flow of food is particularly important for young Homo genus offspring, unable to support themselves but in need of supporting a hungry growing brain.

So like all intelligences, ours was forged in the crucible of natural selection, a short-sighted force that aimed us at surviving well in the niche we currently find ourselves in. It so happened that the creation of this short sighted force is an animal that can use its smarts to expand well past and beyond our old niche, an animal that has the potential to survive all manner of environmental upheaval. Let me emphasize potential, because our intelligence was not honed for long term survival. It was honed for short term survival. It should surprise no one, then, that humans seem prone to doing things with no thought for the long term repercussions. Some of us humans judge our brethren badly for this, saying that something must be wrong with them, their minds must be aberrant for not thinking rationally about the future. In reality, those of us thinking hundreds of years ahead are the aberrant ones. We are the ones bending our minds to tasks they weren't specifically built to handle.
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Re: Human evolution: man is the wolf of man

Postby Paralith on April 29th, 2014, 12:03 pm 

owleye wrote:I know it's a complicated question -- lots of factors involved. Human evolution as we understand it derives from the findings of what's left behind. Brain tissue isn't one of the things left behind, so we have to draw inferences. However, what I was looking for, and which you did in fact respond, was the relative birth spacing (a term I hadn't thought of, and I thank you for that) during the early years, coupled with their survival rates (up to their child-bearing ages). It's possible this might be known from the available skeletal remains. Today, by and large, we have a relatively low birth rate, but not long ago, it had been much higher. I'm just not versed in the history of birth rates, and I can't even imagine what it must have been like at the dawn of humanity. What I'd been thinking is that births would have come pretty much as soon as they were biologically possible, and survival would be the result of attrition, in consideration of competition for resources. As such, the offspring of families having the greatest likelihood of survival would be the main driver. You've already pointed out how quickly a positive trait such as intelligence could overwhelm a population. I was trying to add an additional factor to the rate at which humans developed. In any case, I thank you for your response.


Ah, well I'm glad I got the gist of your question at least.

You're getting into life history evolution here, my friend, one of my most favorite topics. In general principles, you most certainly want to start reproducing as soon as your able. The longer you wait until you reproduce, the greater the chance you'll die somehow before you get the job done. Simple time risks, there. So, animals that wait longer and longer and longer to reproduce (we humans are extremes in this sense, but primates in general compared to other mammals are also like this) have to balance out the cost of this risk. Developing adaptations that help reduce mortality risk to growing young is important; also, whatever it is you're taking the time to grow/develop/learn in that long childhood had better pay off in spades by the time you become a reproducing adult. In primates, it seems that growing and nurturing a sizable brain is at least a part of this extension of childhood. It takes longer, it takes more energy, but by the time you're an adult and that brain is ready to go, it helps you do your job of pumping out the next generation. Primates help ensure the survivorship of their infants by only have one at a time and carrying them around constantly; other mammal mothers stow their numerous cheap babies in a hole somewhere while they go off to find food. Not primate mothers! One precious expensive baby at a time, who for the first few months of their lives never once let go of their mother.

A brain does not evolve by itself. It evolves in the context of an animal's life history, and many aspects of an organism's life schedule have to change in order to support the development of a big brain. If I'm understanding you right, James, then your intuition is right on the money. Understanding these details is important to understanding the evolution of our intelligence.

So, the relative length of childhood, the survivorship curve of juveniles, the birth spacing, the strategies parents use to protect and feed their young, all these things are important data in understanding the evolution of life history and expensive traits like intelligence. As we've already discussed, getting all this data for extinct hominins is really difficult. Especially things like survivorship curves and growth trajectories, which when you're dealing with fossils requires a lot of different individuals at different ages, a luxury we simply don't have. We know some major changes went on, though, just by comparing humans and chimps. Human child survivorship is impressively high compared to poor chimp babies. Only about 35% of all chimpanzee babies born are still alive by age 15. For humans living traditional hunter gatherer lifestyles, that number is 60%. Which still sounds frightfully low by modern industrial standards! This is why hunter gatherer demographic information is so important. In a country like the US I don't know the exact stats, but I'd be willing to bet that child survivorship to age 15 is at least in the 90's, if not hovering right below 100. When an American couple has a child, they can reasonably expect that child will live to a ripe old age. This is probably part of why we don't have very many children anymore. But back in the day, a human woman could reasonably expect to give birth to 8 or 9 children in her lifetime.

If I hadn't fled screaming from academia, understanding life history evolution was the topic I wanted to pursue. Maybe one day I'll be able to go back to it. But until them I'll just ramble incessantly about it on the forum every chance I get. :p
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 29th, 2014, 4:21 pm 

Paralith wrote:Sample size of one, Leo? How anthropocentric of you.


You missed my point, Paralith. I was referring to the pessimistic school of thought which suggests that any civilisation which develops the technology to destroy itself will almost inevitably do so. The sample size of one refers to the fact that we know of only one such civilisation.

On the contrary I regard the intelligence of the so-called "lesser" creatures far more highly than most.

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Re: Human evolution: man is the wolf of man

Postby owleye on April 29th, 2014, 9:44 pm 

Paralith » Tue Apr 29, 2014 10:03 am wrote:You're getting into life history evolution here, my friend, one of my most favorite topics. In general principles, you most certainly want to start reproducing as soon as your able. The longer you wait until you reproduce, the greater the chance you'll die somehow before you get the job done. Simple time risks, there. So, animals that wait longer and longer and longer to reproduce (we humans are extremes in this sense, but primates in general compared to other mammals are also like this) have to balance out the cost of this risk. Developing adaptations that help reduce mortality risk to growing young is important; also, whatever it is you're taking the time to grow/develop/learn in that long childhood had better pay off in spades by the time you become a reproducing adult. In primates, it seems that growing and nurturing a sizable brain is at least a part of this extension of childhood. It takes longer, it takes more energy, but by the time you're an adult and that brain is ready to go, it helps you do your job of pumping out the next generation. Primates help ensure the survivorship of their infants by only have one at a time and carrying them around constantly; other mammal mothers stow their numerous cheap babies in a hole somewhere while they go off to find food. Not primate mothers! One precious expensive baby at a time, who for the first few months of their lives never once let go of their mother.

A brain does not evolve by itself. It evolves in the context of an animal's life history, and many aspects of an organism's life schedule have to change in order to support the development of a big brain. If I'm understanding you right, James, then your intuition is right on the money. Understanding these details is important to understanding the evolution of our intelligence.

So, the relative length of childhood, the survivorship curve of juveniles, the birth spacing, the strategies parents use to protect and feed their young, all these things are important data in understanding the evolution of life history and expensive traits like intelligence. As we've already discussed, getting all this data for extinct hominins is really difficult. Especially things like survivorship curves and growth trajectories, which when you're dealing with fossils requires a lot of different individuals at different ages, a luxury we simply don't have. We know some major changes went on, though, just by comparing humans and chimps. Human child survivorship is impressively high compared to poor chimp babies. Only about 35% of all chimpanzee babies born are still alive by age 15. For humans living traditional hunter gatherer lifestyles, that number is 60%. Which still sounds frightfully low by modern industrial standards! This is why hunter gatherer demographic information is so important. In a country like the US I don't know the exact stats, but I'd be willing to bet that child survivorship to age 15 is at least in the 90's, if not hovering right below 100. When an American couple has a child, they can reasonably expect that child will live to a ripe old age. This is probably part of why we don't have very many children anymore. But back in the day, a human woman could reasonably expect to give birth to 8 or 9 children in her lifetime.

If I hadn't fled screaming from academia, understanding life history evolution was the topic I wanted to pursue. Maybe one day I'll be able to go back to it. But until them I'll just ramble incessantly about it on the forum every chance I get. :p


There's a chicken and egg aspect to this as well. Assuming the intelligence traits first show up in the offspring, moving in the direction of a larger brain, it might happen that it fills a gap in the survivability of larger families, meaning that the mothers wouldn't have to spend all their time nurturing and educating everyone of them, with such a task handled by the older children. And there are as well kinship considerations. Then again, this might not be the direction it takes at all. It might be a son who rises to dominance and spawns children from many wives. In any case, I'll leave you be. It sounds like you could make a name for yourself by tackling this project. Indeed, I suspect you could get research grants if you were able to form some sort of project plan. It has to be a fertile field. Do you know anyone working on it?
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 30th, 2014, 4:11 pm 

Paralith. I share your fascination with life history evolution although clearly not your knowledge base. I've always enjoyed writing on the subject but naturally do so from a highly speculative perspective. The way I see it the physical evolution of homo must have gone hand in glove with the evolution of culture, once human intelligence reached a certain level. When we look at the hunter-gatherer groups in this context it's not hard to see how a more cohesive culture would have conferred survival value on the entire group, thus making them less vulnerable to attack, annihilation or assimilation by more culturally successful groups. It seems likely to me that it was this cultural superiority, possibly as a consequence of language differences, which ultimately did for the Neanderthals. On the basis of the evidence from a single tooth and a fragment of fingerbone we can't say much about the Denisovans, but this doesn't disqualify us from making a similar assumption.

The fact remains that these homo sub-species had an intelligence on a par with sapiens and they nevertheless went extinct. It seems rather absurd to suppose that they were significantly more vulnerable to predation by lions, wolves and the like but makes perfect sense to suppose that they were more vulnerable to the more culturally adaptive sapiens. I find it very difficult to imagine a strictly Darwinian scenario where two such intelligent sub-species could simply vanish off the face of the earth in around about the same time frame other than through predation by sapiens. It is in this sense that I speak of man as his own genetic engineer.

Whilst its not difficult to conclude this outcome at the latter end of our evolutionary journey, I'll agree that I draw a long bow when I conclude that this self-predatory behaviour can be traced all the way back to when we first climbed down from the trees. However our closest relatives, your beloved chimps, have shown us that on occasions they have murder in their hearts. In their current niches this possibly confers very little survival value so they've never developed this lovable trait to the high art form which we subsequently have. However, if we consider a range of plains-dwelling hominin species or sub-species co-existing and competing for essentially the same resources, is it not logical to conclude that murder would acquire some selective advantage, so long as we only look at such advantage in the context of the group situation and not in the individual situation, where it would deliver the opposite outcome? This is where I venture into the evolution of culture and Dunbar's number comes into the equation, but am I making sense so far? If so I'll develop the notion a little further.

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Re: Human evolution: man is the wolf of man

Postby Paralith on April 30th, 2014, 7:11 pm 

Leo, what you're saying definitely makes sense. And it's certainly a view of our prehistory that other people share. However I remain reluctant to declare that we are the last Homo species standing because we directly went out and exterminated all who came before us. Number one, such an extreme scenario would surely leave us with at least some archeaological evidence, a few more Homo erectus skulls with lethal wounds from complex tools, a few more Neanderthals dead from spear attacks, that sort of thing. Number two, if we did indeed go up against groups of hominins with intelligence on par with ours, I'm not sure that more complex culture alone would necessarily give us a definitive strategic advantage in direct combat. But, what does give a definitive advantage in combat? Greater numbers.

What I've sort of touched on a number of times is that, well, humans are the rabbits of the ape world. For something that lives so long and takes so long to grow up we reproduce at an unprecedented rate. This is a key change in our life histories. Unlike all other living apes, we do not wait for one child to become fully feeding independent before we have another child. We stack our babies, giving birth to new infants while still continuing to feed and support our older children. This is how a human woman (and her mate/other dedicated child supporting adult) can out-reproduce the faster maturing chimpanzee. As I've said in my posts in response to owleye, it is difficult to know when this change really occurred. Based on some data from teeth studies, it seems that Australopithecines and Homo erectus had more chimp-like life histories overall, so it seems less likely that they would have accomplished the uptick in birth rate. Neanderthal life histories, again based largely on teeth, fall more in line in with us humans, though on the faster side, so perhaps a little shorter lived than us. But studies on other aspects of their growth like brain growth suggest that they may have taken even longer than Homo sapiens to reach reproductive maturity. A little longer to grow up, a little shorter lifespan, that would probably come together to mean that, even if they stacked babies too, they didn't populate at the sapiens rate.

Now of course we would want more corroborating data before claiming this is definitely how it was, but it certainly offers up a viable alternative hypothesis. There were just more and more and more of us. And of course, that means we needed more and more and more resources. When we found ourselves in conflict over a resource, I'm sure we didn't hesitate to use violence. And even if we were equal to Neanderthals in strategy and even culture, fighting to hold land against our species may have been like trying to hold back a flood. This would not require us going out their homes and camps and killing them all systematically; it would only require that we clash over contested resources, we win those resources, and though most of the Neanderthals might walk away from the fight, they were walking away to smaller and smaller hunting grounds, less and less food available to them and their offspring. And, like Homo sapien hunter gatherers getting pushed to the periphery by agriculturalists, some Neanderthals decided it was better to throw their lot in with the humans, and become our breeding partners instead of our resource competitors.

Once again, I lean towards lauding humans more as the ultimate competitors than as the ultimate predators, especially not as predators that specialized in consuming other members of our genus. Was there violence between species? No doubt. Was there hunting down of one species by another? Was there active pursuit and systematic extermination? This I doubt. Again, the archeaological evidence just cannot bear this up. Or, as is so often the case, was it something in the middle?

Perhaps in the end, as is also often the case, our disagreement is based on terminology. To me, a predator is an animal whose diet primarily consists of its prey, an animal adapted to specifically to hunt and stalk and kill its prey. I'm just not comfortable with saying humans are predators of other humans or other hominins. As violent as chimpanzees certainly can be to each other, chimpanzees are not predators of other chimpanzees. They are competitors with each other. They will use violence if they have to but violence and conflict comes with its own costs, costs chimpanzees clearly try to minimize. When they hear the calls of stranger chimpanzees, their primary reaction is to run in the other direction. If they don't run it's because they are a bunch of males who specifically got together to patrol the boundaries of their territory. And even if patrols encounter strangers, if the two parties are even close to equal in number there will be a lot of hooting and hollering but not that much actual fighting. The real fighting, the real murder happens when ten chimps from one group come across one chimp from another. They only fight to the death when they know they will win.
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Re: Human evolution: man is the wolf of man

Postby Paralith on April 30th, 2014, 7:23 pm 

owleye wrote:There's a chicken and egg aspect to this as well. Assuming the intelligence traits first show up in the offspring, moving in the direction of a larger brain, it might happen that it fills a gap in the survivability of larger families, meaning that the mothers wouldn't have to spend all their time nurturing and educating everyone of them, with such a task handled by the older children. And there are as well kinship considerations. Then again, this might not be the direction it takes at all. It might be a son who rises to dominance and spawns children from many wives. In any case, I'll leave you be. It sounds like you could make a name for yourself by tackling this project. Indeed, I suspect you could get research grants if you were able to form some sort of project plan. It has to be a fertile field. Do you know anyone working on it?


Oh yes, there's a lot of chicken-egg-y stuff coming up when you start getting down to the nitty gritty of how life histories change. There are definitely people who study life history evolution though I'm not aware of anyone currently approaching it the way I had hoped to do it. So I may yet get my chance, but who knows what unpublished studies are currently in the works. And I suppose it is a fertile field in that there is a lot to be learned, but I don't know how fertile it is in terms of being a funding magnet, lol. Hard to show the benefit to humanity in figuring out why chimps start popping out babies before we do. :p
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on April 30th, 2014, 10:07 pm 

Paralith wrote:Perhaps in the end, as is also often the case, our disagreement is based on terminology.


Indeed. I'm a writer and not an evolutionary biologist, and we wordsmiths are a vain breed who like to draw attention to ourselves by the use of hyperbole, whereas you don't have that luxury and are constrained to stick to the facts. Facts are meddlesome things which can routinely stuff up a good story, but what you're saying is not inconsistent with what I'm saying, if I could only curb my natural inclination to exaggerate. For instance I completely agree with this.

Paralith wrote:Once again, I lean towards lauding humans more as the ultimate competitors than as the ultimate predators, especially not as predators that specialized in consuming other members of our genus. Was there violence between species? No doubt. Was there hunting down of one species by another? Was there active pursuit and systematic extermination? This I doubt. Again, the archeaological evidence just cannot bear this up. Or, as is so often the case, was it something in the middle?


Something in the middle is always good for a natural diplomat like me. (lol). I'd imagine that when times were good then neighbouring tribes more than likely got along quite harmoniously simply by keeping out of each others way. However when times were not so good then it's not hard to imagine friction developing between these groups and that such friction would end in bloodshed, with the more powerful group emerging the winner. I'd suggest that this would rarely have resulted in a complete genocide of the weaker group but rather an absorption of the weaker into the stronger. The paranoid and oppressed male in me supposes that the sheilas were spared and the blokes finished up on the menu. Believe me if I was in charge that's the way I'd have been doing it because this was long before the days when we kept our friends close and our enemies even closer. We kept our friends close because they were "us" and we dispatched our enemies because they were "them" and we didn't allow such threats to remain in our midst. To suggest otherwise would require us to come up with a new definition of "intelligence".

This idea can tie in closely with your important points about the human reproductive rate and the notion of baby-stacking. Child-rearing would have been seen as a group responsibility ( there are bird species that do this also ), and this notion of group child rearing could well account for the evolution of menopause in the human female. I don't know how much evidence there is to support this notion but it seems likely to me that the duration of the human female's reproductive span may once have only have been half of what it is today. thus your estimate of 8-9 births per female makes a lot of sense. It's not hard to see how having a good number of such non-reproductive females in a tribal group would make the group more successful as a whole.

However the same cannot be said for the poor old bloke who can't hold his end up in a fight or run down the speedy antelope, but I very much doubt that these guys would have simply been eliminated. This could hardly be conducive to group cohesion, so I'd imagine they just kept going until they dropped.

Paralith wrote:They only fight to the death when they know they will win.


I couldn't agree more but one of them has obviously made a fatal error of judgement. My guess is that human courage is an entirely cultural construct and more than likely one that emerged very late in our evolutionary history. Nine times out of ten our instincts to turn and run will overcome our inclination to stand and fight and my conclusion for the intelligent homo is that he understands the consequences of losing in battle. You either eat or get eaten, so you fight not because you know you're going to win but because you've got no bloody choice.

I take it we can agree that an intelligent predator will not leave a freshly-killed carcass lying on the tropical savannah when his alternative dinner is likely to be last week's rotting antelope or nothing at all.
All this was long before the evolution of squeamishness.

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Re: Human evolution: man is the wolf of man

Postby Paralith on May 1st, 2014, 1:24 am 

Obvious Leo wrote:Indeed. I'm a writer and not an evolutionary biologist, and we wordsmiths are a vain breed who like to draw attention to ourselves by the use of hyperbole, whereas you don't have that luxury and are constrained to stick to the facts.


I appreciate that you phrase that as a compliment, lol. I've gotten into more than a few unnecessary arguments because someone used a word with a different definition in mind than I had.

This idea can tie in closely with your important points about the human reproductive rate and the notion of baby-stacking. Child-rearing would have been seen as a group responsibility ( there are bird species that do this also ), and this notion of group child rearing could well account for the evolution of menopause in the human female. I don't know how much evidence there is to support this notion but it seems likely to me that the duration of the human female's reproductive span may once have only have been half of what it is today. thus your estimate of 8-9 births per female makes a lot of sense. It's not hard to see how having a good number of such non-reproductive females in a tribal group would make the group more successful as a whole.

However the same cannot be said for the poor old bloke who can't hold his end up in a fight or run down the speedy antelope, but I very much doubt that these guys would have simply been eliminated. This could hardly be conducive to group cohesion, so I'd imagine they just kept going until they dropped.


The evolution of human menopause is an ongoing debate. A female Homo sapiens has a reproductive lifespan that is not that different in length from a female chimpanzee. It would seem that while our lifespan extended, someone forgot to amp up the supply of eggs a female is born with. The Grandmother Hypothesis is one famous possible explanation, which is just as you suggest - instead of continuing to have her own children, a woman stops reproducing and funnels her effort into her daughter's children. This helps her daughter achieve that high rate of reproductive output, getting the daughter's reproductive success in during her prime adulthood years and not risking leaving any of it to the older ages she may not survive to. While this hypothesis focuses on women, it could easily apply equally to grandfathers. My old advisor actually found that men in traditional societies tend to stop reproducing when their wives stop reproducing. Sperm production has always been cheap and easy, so I guess there was little need to put a strict biological limit on older men. And what older men may not be able to do in active hunting they can do in childcare and, importantly, teaching their grandsons the skills they've gained over the years.

I couldn't agree more but one of them has obviously made a fatal error of judgement. My guess is that human courage is an entirely cultural construct and more than likely one that emerged very late in our evolutionary history. Nine times out of ten our instincts to turn and run will overcome our inclination to stand and fight and my conclusion for the intelligent homo is that he understands the consequences of losing in battle. You either eat or get eaten, so you fight not because you know you're going to win but because you've got no bloody choice.


I'd have to think about the issue of courage some more. In other mammals and primates, a female has to worry about her current offspring until it's old enough to feed itself, and then her investment is done. She's on to the next one. A male for the most part doesn't worry about his offspring at all, looking out mostly for himself and how he can get access to fertile females. But human mothers and fathers spend at least fifteen to twenty years investing heavily in each of their children, maybe even longer than that when you consider grandmoms and grandpops continuing to help their children's children. Human adult lives are focused on keeping up a constant stream of high quality food flowing into a brood of hungry mouths for years and years. And no one human can do this by themselves - each parent depends on the other for support and help, each family depends on the other families to look out for each other when times are tough. This is a heavy dependence on other members of your species that few animals on this planet can boast. When the people you depend on may be threatened, when the offspring you've devoted so much of your time and effort to might go hungry - I think you might find the biological imperative for courage somewhere in that moment. A good mate, a good cooperative partner, is one who will stand up and do what needs to be done when it matters. If all he cares about is his own skin, he might not be worthy social partner. And if no one will cooperate with him, he's as good as dead anyway.

I take it we can agree that an intelligent predator will not leave a freshly-killed carcass lying on the tropical savannah when his alternative dinner is likely to be last week's rotting antelope or nothing at all.
All this was long before the evolution of squeamishness.


Maybe, maybe. Chimpanzees loooooove monkey. When someone makes a monkey kill, everybody else is all over him just begging for a piece. They wolf the meat down like there's no tomorrow. When they kill an infant chimpanzee, they often eat it. There have been many documented cases of this. And I could be wrong but if I remember correctly, there's never been a recorded case of them eating a dead adult. And wild chimpanzees are pretty much always hungry. I don't know if anyone has any ideas about why this is. If it's not something that resembles their usual food, they might not always think to give it a taste. And if they're not killing other adults that often, they don't have that many opportunities to even consider the option. I suppose there must be a point where you're smart enough to recognize a dead conspecific as a possible food source but not smart enough to be squeamish about eating your dead.
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Re: Human evolution: man is the wolf of man

Postby Obvious Leo on May 1st, 2014, 2:34 am 

I'm glad you've found a use for us poor old has-been grandads. I've no doubt they would have played an important role as educators but suspect that Forest would be able to comment on this far more authoritatively than I could. I find it hard to imagine that the old farts would lose their appetite for sex completely, but in the absence of Viagra "every chance you get" might be supplanted by "every now and then". One also imagines that our cannibals would not have been too ethically fastidious about rape, although I feel certain, for the cohesion imperatives discussed, that "their" women would fall into an entirely different category from "ours", where some very strict social conventions would be more likely to apply.

The grandads could also fulfill an important role on sentry duty, left in charge of the women and children while the young blokes go out to hunt or fight. I realise that none of this speculation will sound very appealing to a 21st century woman such as yourself, but I feel certain that the sisterhood wouldn't have had very much clout back in the day. This is not to suggest that the females would have been powerless, but rather that the various roles would have been more clearly delineated and more strictly adhered to than we've become accustomed to.

Paralith wrote:I suppose there must be a point where you're smart enough to recognize a dead conspecific as a possible food source but not smart enough to be squeamish about eating your dead.


This is my assumption, but it's a tricky one. I don't see a connection between squeamishness and intelligence, since numerous cannibal cultures survived right up until the 19th century, with isolated examples continuing well into the 20th. Certainly the imperatives for such behaviour would have been more socio-cultural than food-supply driven but it's probably impossible to determine when such a transition may have occurred. Another one best left for Forest, I suspect.

By the way, good word "conspecific". It's not one I've encountered before and I'll add it to my lexicon.

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