Biology Forum › Evolution › Evolution of human intellect
April 3, 2010 at 3:43 pm #13048ManBearPig89Participant
What drives the evoulution of our brains?
I just saw an interessting documentary on this topic, sugesting that sexual selection is the "driving force" behind the evolution of our brains. The argument made, was that our brains are "overdimentionised", our ancestors did not need a very big brain to "get by" 40 000 years ago. Surely, early humans could survive with… lets say 50% "brain power" ? Thereby, the brain must have been important when choosing a mate…
Also, in what time do we think our brains got so big (or maybe, when did we get so smart) ? Was it in "one big leap" (lets say beginnning of sivillication), or do you think there would be little differece in "brain power" of a stone- age man, and people today?
If we where to travel to 30 000 BC back in time, pick up a new- born, and raise the child in "modern ways", do you think anyone might say (judging only by behaviour, not appearance) : "Ahhh, yes, I can se now that you must have travled back in time and adopted that child! (traveling back in time to adopt babys is pretty common in this exaple 😀 )
April 4, 2010 at 8:51 am #98793skepticParticipant
There is a lot of speculation on this topic and not much hard data. Personally, I doubt the human brain has changed much for quite some time. Fossil evidence indicates that Homo sapiens has existed as Homo sapiens for about 200,000 years. We have a brain of about 1200 cc. Our predecessor, Homo erectus, had a brain size of 900 cc, and probably was not that much dumber than we are, if we compare their brain to Homo habilis (about 650 cc) which came even earlier. Even they were smart compared to chimps with a brain size of 400 cc.
Why did the brain of pre-humans get so big? It may have been social influence. it may have been sexual selection. My own pet theory is that our ancestors learned to depend on simple technology such as stone tools and sharp sticks a long time ago, and the smartest were the best tool users, and thus were better able to survive.
April 5, 2010 at 7:25 pm #98812DarbyParticipant
You’re talking about a lot of processing and storage capacity for second-hand information, thanks to language, on top of a very complex social structure – it might be as simple as that.
April 7, 2010 at 4:39 pm #98852SmigParticipantquote ManBearPig89:If we where to travel to 30 000 BC back in time, pick up a new- born, and raise the child in “modern ways”, do you think anyone might say (judging only by behaviour, not appearance) : “Ahhh, yes, I can se now that you must have travled back in time and adopted that child! (traveling back in time to adopt babys is pretty common in this exaple 😀 )
I don’t think that child should be much different from us, 30 000 years isn’t that much in an evolutionary timescale. The main thing that developed through that time was knowledge, culture and technology, which was all made possible by language. Agriculture was fundamental too later on in allowing humans to settle in villages and so on.
About the reasons for the brain size increase, no one can claim to know exactly, I also have my own pet theories but I’ll keep them for myself in fear of being mocked mercilessly 😉 the general Darwinian view is that the adaptation of bipedalism gave rise to tool use which in turn, gave rise to even bigger brains.
April 7, 2010 at 7:03 pm #98854skepticParticipant
I agree with you, but I suggest one small reversal.
I suggest that bipedalism followed tool use. After all, if a pre-human needed to handle a tool or weapon, it would be much easier to do from an upright stance. Thus, after tool use became the norm, evolution of upright stance to free the hands would be an adaptive advantage. I would suggest that simple tools preceded Ardipithecus. After all, if wild chimps can use tools, so could our predecessors.
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