14 DAY TRIAL // Shallow-explaining creationists cling on an apparent paradox of the evolutionary theory: why do un-attractive persons exist?
This mystery puzzled evolutionary scientists for years ... if "good" genes are favored by evolution, why are individuals so different?
The "lek paradox", that sexually-selecting species like humans should have much less individuality than is the case, has been employed by creationists as an argument that Darwin's theories are fundamentally flawed.
But this ignored the monogamy system in people, than allows reproduction of theoretically all individuals. And this makes males selective, too, fact that impedes the unlimited spreading of the "beauty" genes...
Leaving behind the concrete factors in human society, the problem with the current evolutionary theory was that if females choose the most attractive mates, the genes responsible for attractive traits should spread quickly through a population, resulting in males becoming similarly attractive, to the point where sexual selection wouldn't exist. (this theories do not apply much to humans, where the sex ratio is 50:50, and this combined with monogamy, means that practically all individuals, indifferent of their attractiveness, get a chance to reproduce...).
But a new research by Professor Marion Petrie and Dr Gilbert Roberts of the Evolution and Behavior Research Group in the School of Biology at Newcastle University, England, points out the fact that sexual selection can in fact induce greater genetic diversity by a mechanism not previously understood.
Petrie supposed that since mutations can occur anywhere in the DNA, some will damage the "DNA repair kit". This can be harmful in most cases, but it can be translated to tissue degeneration or cancers and in some parts of the genome, it can be even positive, as this variation can help in the resistance to disease.
It is known that higher DNA variation in the disease defense encoding regions will turn an individual more resistant to bacteria and viruses attacks.
The computer simulation made by Petrie and predicting how the genes spread in a population showed that the tendency towards decrease in genetic diversity caused by sexual selection is outweighed by the maintenance in greater genetic diversity caused by mutations on DNA repair. "We started this research ten years ago and our model has now produced a good fit with what we observe in terms of genetic variation, which leads us to believe that our theory is correct. We find that sexual selection can promote genetic diversity despite expectations to the contrary", said Petrie.
In 2005, Petrie's team showed that men with higher genetic diversity in disease defense DNA patches, thus transmitting better disease resistance to their offspring, presented a number of physical traits which women found attractive.
They made genetic tests on those men and presented photographs of them to women, who gave marks for attractiveness. The marks matched strongly the genetic diversity.