THE BRAIN FROM TOP TO BOTTOM (original) (raw)
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         Why You Can Have No More Than About 150 Real Friends All of us know our recent personal histories and can say what we did this morning or last year. But typically, we know very little about our ancient history, when the human brain was developing. Yet this ancient history of our brains has at least as important an effect on our behaviour. It is this history, of the brains that preceded our own — those of animals and of the first human beings — that evolutionary science in general and evolutionary psychology in particular explore, in an attempt to help us understand ourselves better.  |
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Evolutionary psychology is an approach that attempts to answer complex questions such as why we fall in love, why we place so much stress on beauty, why we want to have children, why so many people are unfaithful to their spouses, and why there is so much conflict and injustice in the world. Evolutionary psychology is not a sub-discipline of psychology. It is a way of approaching the questions of psychology from the special perspective of evolution. This approach is justified because the nervous system that generates our individual behaviours is the product not only of our personal history but also, and most of all, of the evolutionary history of our species. The human species did not evolve in modern cities or even in villages. An estimated 99% of the evolutionary history of Homo sapiens took place in an environment resembling today's African savannah. Throughout this period of over 2 million years, our ancestors lived in small nomadic groups of hunter-gatherers. It was only 10 000 years ago that some of them started to become sedentary and to practice agriculture.  The Dorobos of Tanzania still live as hunter-gatherers, but their way of life is being threatened by the gradual loss of their ancestral lands. The key idea in evolutionary psychology is that the human brain should be seen as a vast set of specialized units or “modules” adapted to the problems that our hunter-gatherer ancestors encountered in their environment (see sidebars). In other words, instead of regarding the human brain as a machine that can learn anything, evolutionary psychologists see it more like a Swiss Army knife: a collection of various tools, each of which performs a specific function. Naturally, evolutionary psychologists do recognize that all individuals develop their own personal preferences and abilities in the course of their lives. But according to evolutionary psychology, behind these personal attributes lie certain universal attitudes that are found in all cultures. This “human nature” is the result of the long process of hominization that has led to human beings as we now know them. Throughout their evolution, the ancestors of today's human beings must have very often encountered venomous animals, such as snakes and spiders, in their natural environment. Those humans who were more afraid of such animals or had a spontaneous aversion for them probably received fewer fatal bites and therefore probably reproduced more than those who were braver . As a result, they passed their healthy fear of snakes and spiders down to their descendants. In contrast, many people have been killed by automobiles, but since automobiles have been around for only about a hundred years, not enough time has passed for any special evolutionary selection to take place. Thus, we continue to have a fearof snakes and spiders that no longer represent any real threat to us, while we feel no such fear of automobiles, even though they cause thousands of deaths each year. Thus we see a good example of how evolutionary psychology can shed light on a universal behaviour: by looking not at our current environment , but rather at the environment in which almost all of our ancestors lived. Thus, in a sense, inside our modern skulls we still have Stone Age brains. |
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| | In a sense, the distance that still separates evolutionary psychology from the empirical neurosciences reflects the parallel paths that psychology and biology followed throughout the 20th century. The lively discussions that for many years have characterized what are now known as the cognitive sciences represent necessary efforts to draw closer connections between the various levels at which researchers study the human mind. | | THE CRITIQUE OF EVOLUTIONARY PSYCHOLOGY There is no doubt that human beings are the product of evolution, and that the evolutionary history of our species has left its traces on our psychology just as it has on our anatomy. But what conclusions can we really draw from the fact that the human mind is the product of evolution? Evolutionary psychology holds that we can immediately deduce a certain number of effects of evolution on the way our minds operate. Evolutionary psychologists see natural selection as having exerted a preponderant influence over our cognitive faculties in the process of hominization. But this view has been criticized by some neurobiologists. Their critique begins with the difficulty of determining exactly how our ancestors lived.
Was our ancestors’environment really the way we think it was? Next, these neurobiologists ask whether focusing on the environment of the first human beings, as evolutionary psychology does, is sufficient to explain our current behaviours. These scientists suggest that it may be necessary to go further back in time and give equal attention to the evolutionary pressures that shaped the brain structures of all mammals, for example.These critics also question the concept of specialized modules on which the logic of evolutionary psychology is based. Lastly, because it is hard to know anything for certain about our Paleolithic ancestors’ way of life, these critics suggest that the explanations that evolutionary psychology has developed about the selective pressures our ancestors faced may be only one of many possible sets of hypotheses. Some serious criticisms have thus been levelled at the most active proponents of this evolutionary approach to psychology, primarily by people who study the actual circuitsand chemistry of the brain. Without questioning the influence of evolution on the human mind, these critics warn against the classic excesses that can result from the hasty adoption of a new scientific paradigm. | |