Story of Evolution, Evolution of Stories
Bryn Mawr College, Spring 2004
First Web Paper
On Serendip

"So I raise this question, although there is nobody around to answer it: Can it be doubted that three kilogram brains were once nearly fatal defects in the evolution of the human race?"
Kurt Vonnegut, Galapagos

On reading the text What Evolution Is by Ernst Mayr, one single fact among all that upheaval of information and opinion has stuck with me and continued to occupy my own big brain: that "the human brain seems not to have changed one single bit since the first appearance of Homo sapiens, some 150,000 years ago". In contrast, the two million years before that was a period of rapid brain growth for our forbearers: the approximate volume occupied by the brains of our forbearers effectively tripled in this period of time which is, in terms of evolution, relatively short. (214) Although body mass at this time was also increasing, the rate at which our brains were increasing in size far outstripped that of the body.

Why then, some 150,00 years ago, did that process suddenly halt? As is evidenced by the fossil record, there was apparently some selective pressure towards bigger brains size that eventually leveled off and stopped. Why do we no longer have natural selection in favor of that bigger brain size? Two logical explanations present themselves: either the circumstances that caused our brains to begin increasing were satisfied, or some other circumstances occurred that effected brain size in the opposite direction. One hypothesis that has presented itself to me is that the latter has occurred, but as a side effect of our own evolving intelligence; that we, in effect, became "too smart for our own good". What byproduct of our intelligence could be so powerful as to provide a selective pressure against intelligence itself? Altruism. Guilt. Compassion. All those human emotions that have such a complex understanding of self and other that they endeavor to put another organisms needs above our own.

One theory as to why the increase in brain size evolved in the first place is now dubbed the 'machiavellian intelligence hypothesis'- brain size was driven up by the demands of the social world in terms of lying and deceiving others in order to best serve one's own needs. (Cartwright 134) This is related to another theory called order of intentionality, a way of demarcating the ability to cognitively recognize interpersonal relationships. Awareness of self indicates first order intentionality. Realizing that others are also aware indicates second order intentionality. Third order intentionality indicated that the self is aware that others are aware that the self is aware. Order of intentionality continues on this way; it is easy to see why selective pressure for a bigger brain would have occurred while trying to keep track of these complex interpersonal relations. Machiavellian intelligence involving deceit requires at least a third order intentionality, and it is thought that adults today handle about five orders of intentionality in everyday relationships. (Cartwright 135). Like deceit, the capacity for altruism, guilt and compassion also requires at least second order of intentionality, and discussion of the self-reflexive benefits of altruism require at least a third order. However, altruism is thought to be a result of increased intelligence and the evolution of culture, whereas deceit is a selector for increased intelligence. Could it be true, then, that an increased need for complex social interactions and deceit begat intelligence, and intelligence in turn begat culture and morality ( and hence, altruism) which is in turn leading toward a trend away from increased intelligence and towards mediocrity?

To asses the plausibility of this argument, it is necessary to examine the first recorded incidence of altruism. As early as 80,000 years ago, ceremonial burial customs were first practiced by Neandertals, a practice which shows at least second order intentionality, if not direct altruism. (Eccles 115)The evidence of burial appears relatively soon after brain size had leveled off for homonids. Less than 20,000 years after that, the first concrete incidence of altruism occurs: the skeleton of a Neanderthal man who was severely incapacitated from birth is found. The man apparently was kept alive through the support of others for almost forty years. (Eccles 115) Such an incapacitated man could not have survived on his own, and his age at death indicates that there was someone who was willing to care for this decidedly unfit member of society for his entire lifespan. This shows a marked breakdown in the principals of the popular tenet of Darwinian evolution: survival of the fittest. The rise of altruism has allowed more and more "unfit" specimens to survive and reproduce. This has led to a breakdown in the "forward change" that is often associated with evolution in terms of adaptedness. Having a culture that is largely based on morality and altruism has taken selective pressure off of increased brain size. What, then, has it been transferred to? What is now the trait in humans which displays the most adaptedness: altruism? Ability to elicit pity in others? Although all our cultural complexity still requires considerable brain power, is it entirely unreasonable to hypothesize that our collective intellect could actually decrease in the coming evolutionary period? It is interesting to entertain the possibility that we have in fact become too smart for our own good, and that our intellect is now producing some emotions which will in turn counteract the drive towards more intellect. All the advances that humankind has made since the age of the Neanderthals 150,000 years ago have been a product of our creation of cultural knowledge rather than a result of any increase in our brain size. It is perhaps because of this evolution of culture, and the ideals inherent in it, that our brain size has not selectively increased in the past 150,000 years.

Works Cited

Cartwright, John H. Evolutionary Explanations of Human Behaviour. Routledge: New York, NY, 2001.

Eccles, John C. Evolution of the brain. Routledge: London, England, 1989.

Mayr, Ernst. What Evolution Is. Basic Books: New York, NY, 2001.

Vonnegut, Kurt. Galapagos. Dell Publishing Co.: New York, NY 1985.


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