a change occurred to your car so that it got much higher than the EPA estimated miles-per-gallon rather than much lower? Thus, the vast majority of DNA mutations result in changes to the body (also called the phenotype) that hinder reproduction. Occasionally, however, a mutation occurs that results in a change to the phenotype that facilitates reproduction. Because this mutation can be passed on to offspring, and because this mutation tends to result in more offspring, the mutation becomes more frequent in the population. Over time, this process will result in organisms that have a sophisticated repertoire of mechanisms that facilitate reproduction We now have the answer to the question posed above: what functions is the brain likely to perform? If brain tissue is organized like all other tissue, it will perform precisely those functions that facilitate reproduction. More accurately, because evolution by natural selection is an historical process, and because the future cannot be predicted, the brain and body will perform functions that facilitated reproduction (note the past tense). Whether they currently do so will depend on how closely the present resembles the past. If we can develop an accurate picture of a species' reproductive ecology--the set of physical transformations that had to occur over evolutionary time for individuals to reproduce--we can infer those properties the organism is likely to have in order to ensure that those transformations reliably took place. Evolutionary time, the time it takes for reproductively efficacious mutations to arise and spread in the population, is often taken to be roughly 1000-10,000 generations; for humans, that equals about 20,000-200,000 years. Over the last 200,000 years, humans regularly encountered spiders and snakes, creatures whose toxins would have significantly impeded the reproduction of individuals unlucky enough to get injected with them. Over the last 100 years, humans have regularly encountered automobiles, encounters that also can seriously impede reproduction (e.g., by getting run over). Because 200,000 years is long enough for humans to evolve protective mechanisms, but 100 years isn't, we can predict that humans may well possess an innate aversion to spiders and snakes, but not to automobiles--even though far more people are currently killed by cars than by spiders or snakes. Once we have firmly established that avoiding spiders and snakes would have reliably facilitated the reproduction of ancestral humans, we can then design experiments to determine whether humans in fact possess an innate, cognitive ability to detect and avoid these animals (more on how to do this below). A major lesson of evolutionary psychology is that if you want to understand the brain, look deeply at the environment of our ancestors as focused through the lens of reproduction. If the presumptions of evolutionary psychology are correct, the structure of our brains should closely reflect our ancestral reproductive ecology. Thus, evolutionary psychology provides a method for perceiving the functional organization of the brain by studying the world--currently a far more tractable problem than disentangling neural assemblages.Edward H. Hagen, Institute for Theoretical Biology, Berlin(fonte: http://www.anth.ucsb.edu/projects/human/evpsychfaq.html)