Why is “cheating” so prevalent? Is it because we animals are simply rotten to the core? Is it a by-product of some other adaptive trait or behavior? Or can infidelity itself be adaptive?
New research asserts that sexual infidelity of the straying-female variety may in fact be adaptive. At least for birds.
The study has shown that these extra-pair fertilisations can result in a higher diversity of specific genes which detect disease and trigger an immune response in offspring. As a consequence, the offspring survive longer probably as a result of having greater resistance to a wider range of diseases.
Hmm. Genetic diversity is a good thing. And for quite some time now it has been affirmed that sexual reproduction itself has the essential advantage of helping the individuals in a population stay one step ahead of parasites and viruses, etc. So the above makes sense. But does it hold true for humans?
There is a problem with making a direct comparison of birds to humans by way of this one study, however. Among the birds studied, warblers on a small island, “This extra pair fertility was found to be common – accounting for 40 per cent of offspring.” So questions arise. Certainly, 40 percent of human offspring are not the result of female infidelity. Even the 10 percent level bandied about for many years has been thrown into question. It is more likely in the 2 to 3% range. And then there is the “small island” element. Do warblers on large continents show different infidelity rates? What about humans and small islands?
The question remains an important one. Why do human beings stray? Of course, there may be many reasons why. But I strongly suspect that there is an underlying genetic predisposition to do so. A predisposition that becomes manifest in certain people in under certain conditions.
As a scientific thinker, I have a hard time considering infidelity to be a sin, an ultimately bad thing. Of course, as a social creature I can easily condole those affected by it, and frown upon perpetrators of it. But I mostly just want to understand.
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Source: Eurekalert, Birds may increase their offspring’s survival through infidelity
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