Mar 28, 2007
Hey good looking, what you got cooking, in those genes?
Here’s a puzzle. If evolution ensures that ‘good’ genes spread through a population, then why are individuals so different? Why don’t people get better and better looking through each generation to the detriment of ugliness and lead to a population of real lookers?
The problem with current evolutionary theory is that it would seem that if females select the most attractive mates, then the genes responsible for their attractive features would spread quickly, leading to all males becoming equally attractive (think peacock tails). Ultimately, further sexual selection would then no longer take place and evolution would stop in its tracks.
This is the so-called lek paradox and it has remained a foil in the weaponry of the intelligent design advocate’s arsenal for many years. Until now.
Thanks to research at Newcastle University, England, this apparent fundamental flaw in Darwin’s theory of evolution, latched on to by creationists can be explained quite effectively by evolution itself. The findings of Newcastle’s Marion Petrie and Gilbert Roberts research suggests that sexual selection leads to increased genetic diversity by a mechanism not previously understood.
Petrie reasoned that as genetic mutations occur naturally anywhere in the genome, some will actually affect those used to produce the DNA repair kit enzymes found in all cells. This would lead to those individuals with a malfunctioning or inefficient repair kit, having more mutations left unrepaired and so greater variation in their genome.
Usually, damaged DNA leads to an unviable organism that either dies quickly of the effects or is otherwise unable to reproduce. However, if those variations are present in sections of the genome responsible for disease defence, then variation can actually be beneficial as greater variation in the genome at these points means more chance of warding of bacteria and viruses.
Petrie modelled the spread of genes in a population and demonstrated that the tendency towards reduction in genetic diversity caused by sexual selection is outweighed by the maintenance in greater genetic diversity generated by mutations affecting genome repair.
The researchers began this research a decade ago and their model genes are now a great fit for the observations of variations. “We find that sexual selection can promote genetic diversity despite expectations to the contrary,” Petrie says. The team publishes details of their findings today in the journal Heredity.
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There is also the effect, even if an attractive muscular man successfully mates with an attractive female to yield a girl. That girl has a relatively high probability of adopting the male’s characteristics, which would make her unattractive (depending on your tastes, of course :p ).
Mitch
As I understand it, this theory suggests that those individuals that have a propensity to produce mutated offspring will be more likely to reproduce under a sexual selection regime because they are the ones most likely to have traits that enhance their fitness at that particular time. As a consequence they are also more likely to produce unfit offspring due to the same genetic mutability.
However simply because damaged DNA usually leads to an unviable organisms I would expect these individuals to produce fewer offspring that go on to reproduce themselves, and even fewer given those that are viable may not be sexually selected due to lacking attractive features.
So while this is an interesting idea, I’ll be interested to see just how powerful this effect turns out to be.
I do think that we women choose the most attractive men and that the more and more cute that we choose them that they continue to be cute but then since we have ancestors the genes we may carry from them are continued to pass on and so then maybe another type of looking men will come along within the centuries!!
If you have 10 men and 10 women, and 3 cute couples pair off, the other 14 men and women will still want a mate too. They will produce children who look like them, and who will go on to continue the cycle. The proportion of attractive to less attractive should stay the same. This of course disregards the effects beauty products, breast implants, cultural biases and advertising have on your perception of beauty.
The problem with looking at the offspring of “cute” couples is, who decides that they’re cute? Different cultures, even different parts of the same society, can have quite different perceptions of beauty, even across the same society fashions for what is considered beautiful vary widely. During the Victorian era, ladies emphasised the size of their behinds, while during the 1920s, a “flat” chest was considered (publicly at least) the prominent beauty feature to strive for. Whereas today, the Western focus seems to be on almost unnaturally enlarged breasts. And, from the other side six-packs are the major concern of health and fitness magazines for men, whereas during the Charles Atlas a big chest was more important.