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What Drove the Evolution of the Human Brain?
- Thread starter Sunstone
- Start date
ThereIsNoSpoon
Active Member
We didn't evolve "large" brains, we only evolved larger brains.
Why ?
I think the most obvious answer would be (as usual) the benefit for selection.
Larger brains means more storage capacity in order to remember and learn.
Since (in my view) we are rather imperfect animals (compared to other ones) with great difficulties for surviving solely based on our physical features we needed to evolve a brain in order to make up for our lack of speed, strength and sharp teeth.
Wit and cleverness were needed.
As far as i know thats the difference between neandertalers and homo sapiens sapiens.
While the first didn't evolve "technologically" the second did. The first got extinct the second didnt.
Why ?
I think the most obvious answer would be (as usual) the benefit for selection.
Larger brains means more storage capacity in order to remember and learn.
Since (in my view) we are rather imperfect animals (compared to other ones) with great difficulties for surviving solely based on our physical features we needed to evolve a brain in order to make up for our lack of speed, strength and sharp teeth.
Wit and cleverness were needed.
As far as i know thats the difference between neandertalers and homo sapiens sapiens.
While the first didn't evolve "technologically" the second did. The first got extinct the second didnt.
monta
.
Oh lord , I think we are going to have a Chicken v. Egg fight 
:sorry1:
I suspect that rather than being the weaker species having to adapt our brain to compete, we may have been a strong species whose sucess meant more nourishment and thus more raw material to grow, our sucess as a result of being community based and not individual hunters, Obviously we had predators, and a hostile environment to deal with we became more and more adaptive.
The phenomena of cooking our food is a significant I can't recal a wild animal that processes food in anything resembling this way, although some let it rot or pulverise it.
Cooking means we don't need to have a large jaw which gives more room for the brain, it also means more calories are easily ingested and processed,thereby more fuel, to allow further development, and of course it is effective way of killing disease.
Ultimately I think it is impossible to site one source, it must be a variety of factors, a lottery of genes, the right environment and then we begat our little hearts out and voila.
:sorry1:I suspect that rather than being the weaker species having to adapt our brain to compete, we may have been a strong species whose sucess meant more nourishment and thus more raw material to grow, our sucess as a result of being community based and not individual hunters, Obviously we had predators, and a hostile environment to deal with we became more and more adaptive.
The phenomena of cooking our food is a significant I can't recal a wild animal that processes food in anything resembling this way, although some let it rot or pulverise it.
Cooking means we don't need to have a large jaw which gives more room for the brain, it also means more calories are easily ingested and processed,thereby more fuel, to allow further development, and of course it is effective way of killing disease.
Ultimately I think it is impossible to site one source, it must be a variety of factors, a lottery of genes, the right environment and then we begat our little hearts out and voila.
Last edited:
ThereIsNoSpoon
Active Member
I think there is evidence to support my case (on which i do not however insist in case of better information).
As you said we had predators. Basically what i meant with "weaker" species was exactly that. We did have predators and our physical abilities are not suited to avoid them. Homosapiens sapiens evolved in africa and i doubt that a human of that time could withstand a lion any more than he can now without some "tool" to help him.
Logically the only tool available was wit and cleverness. Exactly what you need to build "tools" like the ones needed for cooking, hunting, and of course especially killing.
The idea with the cooking, more fuel and further development was good but of course it is based on an already improoved brain. As you say ... chicken vs egg. And i think the tools are a result that increased the pase of brain development but it was itself the result of a first change in size.
As you said we had predators. Basically what i meant with "weaker" species was exactly that. We did have predators and our physical abilities are not suited to avoid them. Homosapiens sapiens evolved in africa and i doubt that a human of that time could withstand a lion any more than he can now without some "tool" to help him.
Logically the only tool available was wit and cleverness. Exactly what you need to build "tools" like the ones needed for cooking, hunting, and of course especially killing.
The idea with the cooking, more fuel and further development was good but of course it is based on an already improoved brain. As you say ... chicken vs egg. And i think the tools are a result that increased the pase of brain development but it was itself the result of a first change in size.
Caladan
Agnostic Pantheist
Darwin proposed to see the moment of separation between us and the other primates in the moment that man started to walk on two legs and his hands were free to use tools as a substitute for the large teeth of the other primates. but later on we came to realize that walking on two legs and the well fitted teeth for eating hard plants came before the growth of brain size, or.. there wasnt a need for a more developed intelligence than that of the primates in creating tools to have the large fangs be reduced in size and for the teeth to look more human.
Later on Dart, who discovered the first Australopithecines- bipedal primates, built a scenario in which a few of the branches of the australopithecines evolved into being meat eaters, hunters, and they were our ancestors. or in other words, the idea was that the human direction in evolution was determined by the hunter nature of the Australopithecus africanus. other researchers spread this theory in the 40s and 50s, the idea that the hunting instinct wich pushed the Australopithecus to find effective weapons stimulated the development of human intelligence and encouraged it. this concept also gave background to see human beings as the 'Killer ape'.
Now, during the 60s, more and more voices shook the basic theory of the killer ape, pretty fitting for the spirit of the 60s when American campuses were overridden by pacifism. other than the hippies, a great deal of information from observations in the wild on our primate relatives accumulated. this information made it clear that a great deal of the intelligent abilities and complex behaviors have developed as a result of a social selection process, the interaction of individuals, and interaction of groups within an intense experience of social frame. this means, that intelligent abilities could develop from social pressures without a direct link to the natural habitat- the non human one, and without being manifest in material products.
The idea that there have to be material products in a social system, many say is part of the western world view of the previous centuries.
there was also a change in the archaeological perception. it became clear that there isnt actually any evidence that a certain type of Australopithecus or even Homo habilis were hunters. in regards to the Australopithecus it was actually found that the animal bones which were found together with their own bones were not left over of their meals, but because the Australopithecus WAS the meal.
So, the assumption that we are the offspring of hunters which forever changed the life forms map over planet earth, could be correct for the situation some 10s of thousands of years ago, but there are no evidence that make it so for earlier periods.
Furthermore, we came to realize that all primates, and especially the chimps, love meat, and prefer it to all other kinds of food. chimps were seen going hunting and do it quite successfully. some groups of chimpanzees have meat as about 10% of their diet. the hunters are usually a few young males who cooperate. so, it can be said that there is a potential for hunting in other primates and it is put to action in some way or the other, meaning that humans are not entirely unique for their craving for meat or in hunting skills.
the dependency in food distribution must have caused organized food distribution methods and the need for cooperation between males was born. as a result it was said that emotional triggers that come with a long standing cooperation came to be, so different kind of sensations and emotions take place, emotions like conscience, shame, regret, forgiveness, arguing and many others were experienced in the process of the integration of human society, and in some part they are unique to human beings. the new environment stimulated development of potential and also encouraged it directly. there was a need for intensive study of the environment, and the more there was to learn during childhood, probably also came a need to accelerate the learning pace. changes in the brain matched this process as well, the importance of the complexities of behavior grew, both in the social system and everything to do with dealing with a new environment.
So to summarize, when the first man first created tools, he was already with a complex brain, and human in its shape. these changes took place before the first evidence for the skills of man appeared.
Later on Dart, who discovered the first Australopithecines- bipedal primates, built a scenario in which a few of the branches of the australopithecines evolved into being meat eaters, hunters, and they were our ancestors. or in other words, the idea was that the human direction in evolution was determined by the hunter nature of the Australopithecus africanus. other researchers spread this theory in the 40s and 50s, the idea that the hunting instinct wich pushed the Australopithecus to find effective weapons stimulated the development of human intelligence and encouraged it. this concept also gave background to see human beings as the 'Killer ape'.
Now, during the 60s, more and more voices shook the basic theory of the killer ape, pretty fitting for the spirit of the 60s
when American campuses were overridden by pacifism. other than the hippies, a great deal of information from observations in the wild on our primate relatives accumulated. this information made it clear that a great deal of the intelligent abilities and complex behaviors have developed as a result of a social selection process, the interaction of individuals, and interaction of groups within an intense experience of social frame. this means, that intelligent abilities could develop from social pressures without a direct link to the natural habitat- the non human one, and without being manifest in material products.The idea that there have to be material products in a social system, many say is part of the western world view of the previous centuries.
there was also a change in the archaeological perception. it became clear that there isnt actually any evidence that a certain type of Australopithecus or even Homo habilis were hunters. in regards to the Australopithecus it was actually found that the animal bones which were found together with their own bones were not left over of their meals, but because the Australopithecus WAS the meal.
So, the assumption that we are the offspring of hunters which forever changed the life forms map over planet earth, could be correct for the situation some 10s of thousands of years ago, but there are no evidence that make it so for earlier periods.
Furthermore, we came to realize that all primates, and especially the chimps, love meat, and prefer it to all other kinds of food. chimps were seen going hunting and do it quite successfully. some groups of chimpanzees have meat as about 10% of their diet. the hunters are usually a few young males who cooperate. so, it can be said that there is a potential for hunting in other primates and it is put to action in some way or the other, meaning that humans are not entirely unique for their craving for meat or in hunting skills.
the dependency in food distribution must have caused organized food distribution methods and the need for cooperation between males was born. as a result it was said that emotional triggers that come with a long standing cooperation came to be, so different kind of sensations and emotions take place, emotions like conscience, shame, regret, forgiveness, arguing and many others were experienced in the process of the integration of human society, and in some part they are unique to human beings. the new environment stimulated development of potential and also encouraged it directly. there was a need for intensive study of the environment, and the more there was to learn during childhood, probably also came a need to accelerate the learning pace. changes in the brain matched this process as well, the importance of the complexities of behavior grew, both in the social system and everything to do with dealing with a new environment.
So to summarize, when the first man first created tools, he was already with a complex brain, and human in its shape. these changes took place before the first evidence for the skills of man appeared.
sandandfoam
Veteran Member
Great post Caladan!
That's the important point: Homo sapiens already had human brains before tool use was prominent; the tool use does not appear to have a profound link with brain growth.
As for the most widely supported idea there's the Expensive-Tissue hypothesis which bascally says brains are caloric machines and require a large intake of calories and proteins to function. Early humans compensated for the large amounts of brain energy by decreasing the metabolic rate in the digestive system, forcing the primate to obtain energy-dense foods. For humans the consequence was a strong desire to eat caloric rich foods with a high fat content while non-human primates like gorillas are fine eating things we couldn't digest like leaves. So brain size was intimately tied to the gut.
And then I'm reminded of the Tuber Protein hypothesis that had just reared its head when I was an anthro' grad' student back in the late 90s. This idea ties with what Monta mentioned: cooked food and the brain. So larger brains, smaller teeth, a modified digestive system, limb proportions and, though controversial, male/female bonding were the result of cooking and eating tubers rather than meat.
monta
.
I can't for the life of me remember where I read it, but I read somewhere that the greatest advantage palaeolithic man had over the neanderthals was our ability to throw stones, there was a study to measure the bone structure of the arms of both and it was found that there was no bone rotation or substantial size difference between the two arms in neandethal man where there was in palaeolithic which indicates, palaeolithic man threw stones and neanderthal man didn't. The first arms race maybe?
I vaguely remember reading something along those lines in The Social Life of Early Man by Washburn.
Dunbar is interesing in that his idea also incorporates human monogamy, which is a sticking point in that humans are weird in that aspect: we're on all sides of the spectrum when it comes to pair bonding.
Though Dunbar's number, or group size and neocortex size is correlated, seems reasonable. The thing is many different factors likely contributed to the increase in brain complexity, not unlike the various conditions responsible for abiogenesis. We often want one explanation when a whole host of contributing factors may have been selective pressures.
Doh! Caladan beat me to it.
Tool use may have been more of a spandrel, an offbranch of brains that were already large. Australopithecines had a brain about 30% bigger than gorillas, but there's no indication of tool use. But it's hard to say, the tool use/brain size direct connection is no longer fully accepted and, as Caladan said, the social and language development is now considered a great influence. Early basic tool use and brain size may have been connected in pre-humans, but early Homo sapiens sapiens had the same brains we do and whatever tool/brain connection existed was already done.
Tool use may have been more of a spandrel, an offbranch of brains that were already large. Australopithecines had a brain about 30% bigger than gorillas, but there's no indication of tool use. But it's hard to say, the tool use/brain size direct connection is no longer fully accepted and, as Caladan said, the social and language development is now considered a great influence. Early basic tool use and brain size may have been connected in pre-humans, but early Homo sapiens sapiens had the same brains we do and whatever tool/brain connection existed was already done.
monta
.
Jumping forward and into untestable waters, I remember reading a book written by ...some dude 
it's late soz.
He hypothesised that humans has a bicameral mind whereby the brain itself was divided into two distinct chambers one side instructed the other as though it were external to it, he felt disorders such as shizophrenia were throwbacks to this. Very weird stuff seemed plausable when reading it but for the life of me I can't remember why.
it's late soz. He hypothesised that humans has a bicameral mind whereby the brain itself was divided into two distinct chambers one side instructed the other as though it were external to it, he felt disorders such as shizophrenia were throwbacks to this. Very weird stuff seemed plausable when reading it but for the life of me I can't remember why.
Julian Jaymes Bicameral mind theory? Fascinating book, but I'm not sure how much it falls into the "cool but pseudoscience" or "cool but not yet confirmed" categories.Jumping forward and into untestable waters, I remember reading a book written by ...some dude
He hypothesised that humans has a bicameral mind whereby the brain itself was divided into two distinct chambers one side instructed the other as though it were external to it, he felt disorders such as shizophrenia were throwbacks to this. Very weird stuff seemed plausable when reading it but for the life of me I can't remember why.
I'm in no position to critique Jaymes since I'm hazy on much of what he says. I am but a humble layperson...
Jumping forward and into untestable waters, I remember reading a book written by ...some dude
Julian Jaynes, I suspect. "The Origin of Consciousness in the Breakdown of the Bicameral Mind"
Ooops! You beat me to it! I agree his theory was more interesting than conclusive.
guilo
Undercover Nudist
The cradle of humankind is based in South Africa, interestingly my country of origin. A large reason why humans could evolve their brain size as they did is because of the rich protein content of their food on the coasts of South Africa. Most animals would not be able to sustain such a large brain due to the amount of nutrients it consumes. At the time, the availability of food and energy in South Africa made it possible for the individuals with bigger brains to use it to their advantage, instead of being disadvantaged by it's high consumption. (This is a supported view, not just something I thought of)
Precisely 3.20769 horse power.