It’s a natural part of the female life cycle – so why don’t we talk more about the menopause, its debilitating effects and possible mitigation? Read the whole article here
The Guardian 26.8.2019  by Hannah Devlin

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In terms of evolution, what’s the point of the menopause?

One of the most compelling evolutionary explanations for menopause is the “reproductive conflict hypothesis”. The idea is that when multiple generations live together in a patrilocal set up (that’s to say, a woman moving in with her husband’s parents), a woman would compete with her mother-in-law for the resources needed for babies and children if their reproductive schedules overlapped.

Research by Prof Virpi Lummaa, of the University of Turku in Finland, using a 200-year dataset on pre-industrial Finns, showed that simultaneous reproduction by daughters-in-law and mothers-in-law was linked to a far worse chance of children surviving.

The daughter-in-law is unrelated to the children of her mother-in-law, so – evolutionarily – has no motivation to contribute to their survival. For the mother-in-law there’s a trade-off as she has 25% of genes in common with her grandchildren. And so if at some point in ancient history a “menopause gene” emerged, it would carry the evolutionary advantage of boosting the chances of survival of grandchildren.

“Our modelling work showed that such costs of two women reproducing simultaneously in the same household were sufficient to generate selection against continued reproduction beyond 51 years,” Lummaa says.

It’s interesting to note that this evolutionary trade-off only happens when males continue to live with their families as adults. Lummaa’s team studied Asian elephants employed in timber camps in Myanmar and found that calves survived better if their grandmother was nearby. However, Asian elephants do not show a clear-cut menopause and have been observed to reproduce into their late 60s.

A crucial difference could be that elephants live in matriarchal herds, led by a dominant older female. So, thanks, prehistoric patriarchy.

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Other News

Simon's latest work on the demography of grandmothers is now out in PLoS ONE. 

We were delighted to host Professors Martin Daly and Gretchen Perry for a day of excellent talks, with a particular focus on grandmothering and alloparental behaviour.

Robert Lynch is at the Human Behavior and Evolution Society (HBES) conference 2018 in Amsterdam

The manuscript "The transition to modernity and chronic disease: mismatch and natural selection" by Stephen Corbett, Alexandre Courtiol, Virpi Lummaa, Jacob Moorad and Stephen Stea

Two papers out now from Simon's PhD project!

1) Changes in the Length of Grandparenthood in Finland 1790-1959, published in the Finnish Yearbook of Population Reasarch. In this paper, the team investigated how the shared time between grandparents and grandchildren changed across the demographic transition and with industrialisation. This shared time was low and stable before these major events, and began to increase rapidly after they began.

2) Limited support for the X-linked grandmother hypothesis in pre-industrial Finland, published in Biology Letters. Here, we tested whether slight differences in relatedness via the X-chromosome might lead to differences the survival of male and female grandchildren with maternal or paternal grandmothers. Though two of three predictions were supported, we concluded that the X-linked grandmother hypothesis cannot account for lineage differences by itself. 

Our latest paper shows that early-life environment is associated with sex differences in adult mortality and expected lifespan. Out now in Ecology Letters:
http://doi.wiley.com/10.1111/ele.12888

Figure 3a+b, from Griffin et al. 2017

Our review of the contribution of human studies to evolutionary biology is out now in Proceedings of the Royal Society B:
http://rspb.royalsocietypublishing.org/content/284/1866/20171164

Virpi was given the inaugural Phoenix Award from the Turku Finnish University Society on Friday in recognition of and encouragement for her consistently creative and internationally high-quality re

We had the pleasure of hosting Silke van Daalen from the University of Amsterdam for three weeks this September. Silke is a PhD student working with Hal Caswell on identifying individual stochasticity in life-history traits of long-lived populations with a mathematical modelling approach, and came to learn about our dataset and how she might be able to use it in her work. We wish her the best of luck with the rest of her PhD studies, and hope to see her again soon!

Another year, another project meeting! This time we stayed on the beautiful island of Seili, again with the lovely people from the Myanmar Timber Elephant Project, for a few days of talks, drinks, and sauna. Needless to say, there is plenty of interesting and exciting work underway - keep your eyes peeled for the results, coming soon (hopefully) to peer-reviewed journals near you!