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    Competition Gets The Blame For Our Oversized Brain (Not Global Warming)
    By News Staff | June 22nd 2009 12:00 AM | 4 comments | Print | E-mail | Track Comments
    Human brains have tripled in size over the past 2 million years,  growing much faster than those of other mammals.

    What might the reasons be for such dramatic brain expansion?

    University of Missouri researchers studied three hypotheses for brain growth: ecological demand,  social competition and climate change.

    Yes, climate change.   They're not stupid.   An entire presidential cabinet is stuffed with carbon dioxide true believers so it's good diplomacy to at least consider global warming may make us devolve - that would be terrific marketing for a carbon trading scheme.   Luckily, the much more likely social competition was determined in their analysis as the major cause of increased cranial capacity.

    To test their hypotheses, they collected data from 153 hominid (humans and ancestors) skulls from the past 2 million years.  They examined the locations and made a best guess at the global climate changes at the time the fossil was dated, the number of parasites in the region and estimated population density in the areas where the skulls were found.

    They determined that population density had the biggest effect on skull size and thus cranial capacity.  Sounds vague?  Well, there are few rules in psychosocial sciences and a lot of assumptions.

    "Our findings suggest brain size increases the most in areas with larger populations and this almost certainly increased the intensity of social competition," said David Geary, Curator's Professor and Thomas Jefferson Professor of Psychosocial Sciences in the MU College of Arts and Science. "When humans had to compete for necessities and social status, which allowed better access to these necessities, bigger brains provided an advantage."

    Climate change isn't completely out of the question tangentially, since global climate change and migrations away from the equator resulted in humans becoming better at coping with diverse environments. But the importance of coping with a changing climate was much smaller than the importance of coping with other people.

    "Brains are metabolically expensive, meaning they take lots of time and energy to develop and maintain, making it so important to understand why our brains continued to evolve faster than other animals," said Drew Bailey, MU graduate student and co-author of the study. "Our research tells us that competition, whether healthy or not, sets the stage for brain evolution." 

    Article:  "Hominid Brain Evolution," Human Nature, co-authored by Geary and Bailey.

    Comments

    Steve Davis
    the much more likely social competition was determined in their analysis as the major cause of increased cranial capacity.
    Unfortunately for this conclusion, society is by definition based on cooperation, not competition.
    "Our findings suggest brain size increases the most in areas with larger populations and this almost certainly increased the intensity of social competition,"
    No, this increased the likelihood of division of labour, a form of cooperation.
    logicman
    Steve: you beat me to the punch.
    "Our findings suggest brain size increases the most in areas with larger populations and this almost certainly increased the intensity of social competition,"
    I suggest that increased intelligence preceded larger populations, and most probably made those larger populations possible through cooperation.  As a group increases in size it must either disperse and forage for food, or cooperate in the provisioning of a population too large to be supported in its home area by simple foraging.  A gathering of clans requires a gathering of food.
    Climate change isn't completely out of the question tangentially, since global climate change and migrations away from the equator resulted in humans becoming better at coping with diverse environments. But the importance of coping with a changing climate was much smaller than the importance of coping with other people.
    I disagree strongly.  Climate change, by changing our ancestral environment into one in which gestural language was not efficient due to line-of-sight limitations, could well have accelerated or even precipitated the evolution of spoken language.  Given that human language is a tool that must be shared in order to be of any evolutionary/survival value, logic demands that language evolved in and with a social, i.e. cooperating community.
    Gerhard Adam
    Yes, you beat me to the punch also.

    This connection is complete rubbish.  The societies they're examining aren't miniature replicas of how we live today, and there's absolutely NOTHING to suggest that a tribal group could have or would have survived with internal competition of the sort they are describing.

    As Patrick indicated, larger brain sizes would've probably paralleled advances in language acquisition which would have enabled larger groups to form, but even then, a critical question is in establishing how large a group are they actually referring to. 

    Coping with climate change is completely and utterly irrelevant, since it would have presumably had to increase the brain sizes of every other creature that had to cope.  To assume that only humans had such a need is completely ridiculous.

    I'm also not convinced that human migration was the result of climate (as I stated, this would affect every other creature in the environment as well).  I suspect that the evolution of human intelligence was an extension of existing capabilities whereby many animals have the ability to abstract solutions to problems that they face.  I would suggest that humans evolved the ability to abstract problems, which enabled them to anticipate such issues and prepare solutions.  It was this ability that allowed them a far greater range to migrate.  In other words, they developed the ability to plan and anticipate unforseen possibilities.

    If one moves from the equator to the northern temperate zone and suddenly encounters freezing weather previously unknown ... you can't sit around and wait for your brain to evolve to come up with solutions.  The intrinsic ability must already exist, so larger brains had to PRECEDE migrations and not follow them.
    Mundus vult decipi
    Steve Davis
    All good points Patrick and Gerhard. Now you can see why I tend towards the obsessive when it comes to combating selfish gene theory. Assumptions are made with no thought at all.