This is a short, supplementary write-up for my article on ‘relaxed selection’ here.
In that article, I have elucidated the idea that certain human capabilities, such as seeing, hearing, ambulation and cognition, may become compromised in future generations, since any deleterious genetic mutations affecting these traits are (in general) not being selected against by natural selection.
This is because our society contains the infrastructure, and technological capacity to allow those with disabilities equal opportunity to survive and reproduce as their ‘able’ counterparts.
Yet this is not entirely true, since sexual selection, or at least, the ability to acquire a mate is, in fact, not homogeneous across the spectrum of people with and without disabilities.
This figure compares the marriage rate of people with various types of disabilities with the marriage rate across the entire population.
The percentage of disabled people who are married is ~41%, compared with ~72% for the entire population.
Given that marriage rates are strongly correlated with one’s likelihood of reproduction – these statistics indicate that indeed there will still be selection pressures against certain disabilities – namely, those which reduce one’s likelihood of being married.
However, this does not contradict the argument that relaxed selection will eventually manifest worrisome consequences upon human populations:
There are plenty of human disabilities that certainly would not affect one’s chances of reproduction – such as mild losses of any of the abilities reflected in the above figure, or even total loss of some less consequential faculty – such as a sense of smell.
Further, with ever-improving medical treatments, we may reach a point where even the most injurious genetic disability can be treated so effectively that is barely even a hindrance.
In this case, relaxed selection would wreak utter havoc upon our genetic code, so that we would become totally reliant upon palliative medical solutions. In such an eventuality, the required health-care expenditure could be crippling.
The reality holds – we will eventually require a means of altering our genetic code – this is perhaps the only tenable solution to the looming problem of relaxed selection on humans.
I also wanted to address a somewhat myopic generalization that was made in the main article – namely, the assumption that humanity everywhere is living in conditions of ease and abundance.
Obviously I was referring only to first-world countries, where the necessities of survival – health-care, food and shelter – are readily available.
There are many human populations over the globe for whom life is a constant strenuous battle for survival – and so among these peoples, relaxed selection will not be nearly as prevalent.