Why do so many of us plonk ourselves down in front of the television receiver with a microwave meal after a tiring day ? Because it ’ sulfur convenient ? Or because television receiver meals are “ the natural consequence of hundreds of thousands of years of homo development “ ?
Stop laughing. You ’ ve credibly made alike assumptions. For merely about every expression of our bodies and demeanor, it ’ s easy to invent evolutionary “ Just So ” stories to explain how they came to be that direction. We tend to assume that everything has a function, but frequently we are ill-timed .
Take male nipples. male mammals clearly don ’ t need them & colon they have them because females do and because it doesn ’ thymine price much to grow a nipple. indeed there has been no pressure for the sexes to evolve distinguish developmental pathways and “ switch off ” nipple growth in males. Some people claim the female orgasm exists for the same reason as male nipples, though this is a far more controversial idea.
then there ’ s our sense of olfactory property. Do you find the aroma of roses overwhelming or do you struggle to detect it ? Can you detect the distinctive smell that most people ’ s urine acquires after eating asparagus ? People vary greatly when it comes to smell, largely due to casual mutations in the genes that code for the smell receptors rather than for adaptive reasons .
yet other features are the solution of selection, but not for the trait in question. For case, the light stature of pygmies could be a english effect of choice for early childbirth in populations where deathrate is high gear, preferably than an adaptation in itself .
Another reason why apparent adaptations can be side effects of excerpt for early traits is that genes can have different roles at different times of development or in different parts of the consistency. So choice for one version can have all sorts of apparently unrelated effects. Male homosexuality might be linked to gene variants that increase birthrate in females, for example.
A non-adaptive or damaging gene discrepancy can besides spread quickly through a population if it is on the like DNA maroon as a highly beneficial random variable. This is one cause why sex matters & colon when bits of deoxyribonucleic acid are swapped between chromosomes during sexual reproduction, good and bad variants can be split up .
other features of plants and animals, such as the wings of ostriches, may once have been adaptations but are no longer needed for their original purpose. such “ vestigial traits ” can persist because they are neutral, because they have taken on another affair or because there hasn ’ t been enough evolution to eliminate them even though they have become disadvantageous. Take the appendix. There are enough of claims that it has this or that function but the attest is clear & colon you are more probably to survive without an appendix than with one .
so why hasn ’ t it disappeared ? Because evolution is a numbers bet on. The global human population was bantam until a few thousand years ago, and people have few children with farseeing periods between each generation. That means fewer chances for evolution to throw up mutations that would reduce the size of the appendix or eliminate it altogether – and fewer chances for those mutations to spread through populations by natural survival. Another possibility is that we are stuck in an evolutionary Catch-22 where, as the appendix shrinks, appendicitis becomes more likely, favouring its retentiveness .
Wisdom teeth are another vestigial leftover. A smaller, weaker call on the carpet allowed our ancestors to grow larger brains, but left less board for molars. yet many of us hush grow teeth for which there is no room, with potentially fateful consequences. One possible argue why wisdom teeth persevere is that they normally appear after people reach generative historic period, meaning excerpt against them is unaccented .
For all these reasons and more, we need to be disbelieving of headline-grabbing claims about evolutionary explanations for different behaviours. evolutionary psychology in detail is ill-famed for attempting to explain every aspect of demeanor, from gardening to rape, as an adaptation that arose when our ancestors lived on the African savanna.
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gratuitous to say, without solid tell, claims about how, for example, television dinners “ evolved ” should be taken with a large pilfer of salt .
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