Sunday, February 19, 2012

Inbreeding Effects on Fertility in Humans

This is a bit late, my apologies, but the most interesting topic I've had so far is on inbeeding and fertility in humans. The main research paper source I used is here. There have been studies on problems with inbred children, but this is one of the few on inbred adults that I've seen.

The researchers focused on Hutterites, specifically the S-leut (Schmiedeleut) Hutterites of South Dakota.  These Hutterites are a reproductively isolated population and have high birth rates, making them ideal for this kind of study, but more importantly, socioeconomic standing is fairly equal throughout the population because they practice a communal lifestyle.

All present married adults (396) who participated were required to fill out a detailed reproductive history questionnaire, detailing family births, deaths, and marriages. Married women participants who were of reproductive age were provided with journals so they can note their menstrual cycles and with pregnancy tests that they were instructed to use if their menses was late.

In order to determine fertility, three tests were used. First, interbirth intervals in the married women were examined under the assumption that longer intervals meant a harder time conceiving or a problem with fetal loss. Second, they examined the time between a woman's first menses after a pregnancy and the menses before the next pregnancy. Women using birth control were excluded from this part of the study. Last, they examined family size and in all the S-leut women born after 1900, including families throughout the United States and Canada.

The main conclusion drawn was that the more inbred a woman is, the more reduced her fecundity. The scientists hypothesize that this reduction could result from "recessive alleles that could influence pathways involved in gametogenesis, hormonal cycling, sperm transport, ovulation,
fertilization, or implantation". Duh.

1 comment:

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