IVF and human evolution

ABSTRACTHumans are shaped by evolution through natural selection, as are all species. While evolution is central to all biological processes, the key stage for competition and selection is reproduction, which encompasses various events from courtship and mating to fertilization and pregnancy. In humans, IVF is used to aid the intrinsically inefficient reproduction by coitus, and in several countries, the proportion of children born after IVF is increasing. While IVF is an enabling technology for infertile patients, it also circumvents reproductive barriers and changes selection pressures. This grand theme review describes the systematic differences between IVF and coitus in selection pressures on reproducing cells, individuals and populations. At the cellular unit of selection, for example, IVF favours different traits in spermatozoa (fast swimmers over short distances) than coitus does (forward mobility over longer distances). Similarly, a male with low sperm quality and a female who decides to delay her first birth to an advanced age, can both increase their reproductive fitness by IVF compared to if reproduction by coitus is their only option. In as much as delayed reproduction is a cultural trait, IVF thus enables cultural practices that may in their turn affect human evolution. A main point in this review is to discuss the interactive effects of biological and cultural traits in the context of IVF, and how they act in concert as drivers towards increased demand for IVF. ...
Source: Human Reproduction Update - Category: OBGYN Source Type: research