Is IVF changing the course of human evolution?

Sep 3, 2016 by

by Michael Cook, Bio Edge:

Evolution is caused by the differential reproduction of individuals with certain features. So surely IVF, which enables people to reproduce who are unable to do so naturally, must be having an effect upon human evolution.

This tricky but important question was tackled by Norwegian scientists in a recent article in the journal Human Reproduction. “Assisted reproduction is redefining human society and biology and, in the face of profound ethical issues, it is important to understand the technical and conceptual principles that underlie this new paradigm,” they write.

They point out that IVF systematically changes selection pressures, involving “a combination of artificial environments and selection criteria that are distinctively different from those of natural reproduction”.

The human eggs which survive the selection process are different from normal eggs. IVF favours sperm that swim fast for a short distance while nature “favours long-distance swimmers that are able to navigate the female reproductive tract”. IVF embryos have to survive freezing and the culture media in a Petri dish. There may be differences in how IVF embryos survive implantation and miscarriage. And even the couples come from a distinct subgroup: “Overall, the limited availability of IVF favours healthy sub-fertile couples in stable relationships who live in high-income societies over other sub-fertile couples”.

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