Thereâ€™s a great recent article in Scientific American entitled â€œWhat Finnish Grandmothers Reveal about Human Evolutionâ€ highlighting the research of biologist Virpi Lummaa. Iâ€™ve mentioned before that while genetics is a useful tool for genealogical research, genealogy can also be a useful tool for genetic research! Dr. Lummaaâ€™s research does exactly that.
Dr. Lummaa used 200 years of genealogical records to study the influence of evolution on reproductionâ€
â€œThe 33-year-old Finnish biologist, aided by genealogists, has pored through centuries-old tomes (and microfiche) for birth, marriage and death records, which ended up providing glimpses of evolution at work in humanity’s recent ancestors.â€
Dr. Lummaa proposes the following findings from her research of pre-modern Finns
- Male twins affect the mating potential of their female twins – the females are 25% less likely to have children and were 15% less likely to marry than female twins born with a sister. (Donâ€™t worry, the article discusses many of the other variables that the study addressed). This finding is odd, because it suggests that there should be selection AGAINST opposite-sex twinning.
- Mothers who gave birth to sons had shorter life spans than those who gave birth to daughters. Dr. Lummaa proposes that this is due to larger birth weight, the testosterone that crosses the placenta, and the fact that boys tend to leave the nest while girls tend to stay close.
- Grandmothers are important to the survival of grandchildren. The presence of a grandmother might improve the reproductive potential of her grandchildren. This could, in part, explain why humans live so long after the end of their reproductive stage.
- Hereâ€™s another controversial finding – child mortality was higher in mainland towns than on the islands of Finlandâ€™s Archipelago Sea, presumably because mainland women replaced motherâ€™s milk with cowâ€™s milk much earlier.
Itâ€™s important to keep in mind, of course, that this research was carried out by studying the records of pre-modern people. Additionally, there are numerous cultural and social aspects that might influence the results, although Dr. Lummaa addresses some of them in the article.
(I just received a Google alert about this article – Iâ€™m not sure why it took so long for the article to be indexed. By the way, if youâ€™re interested in the latest news about a certain topic, I highly recommend setting up a Google Alert. I donâ€™t think a blogger could survive without it!).