Evolution works because of differential reproduction. If an organism has a harmful gene, it will perish before reproducing or fail to have offspring. Infertility may be nature’s way of decreeing that this man or this woman, or this couple, are not “fit” in the evolutionary sense.
So surely IVF, which enables people to bypass their infertility, must be having an effect upon human evolution.
This question was tackled by Norwegian scientists recently in the leading journal Human Reproduction. They wrote: “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 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”.
They give examples. IVF eggs can survive harsh laboratory conditions, including puncturing it to insert a sperm. IVF also 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 survive contact with plastic surfaces, exposure to light, mechanical manipulation, living in a Petri dish and abrupt temperature changes....
