Offspring fertility and grandchild survival enhanced by maternal grandmothers in a pre-industrial human society

Simon N. Chapman, Mirkka Lahdenperä, Jenni E. Pettay, Robert F. Lynch & Virpi Lummaa 

Abstract

Help is directed towards kin in many cooperative species, but its nature and intensity can vary by context. Humans are one of few species in which grandmothers invest in grandchildren, and this may have served as an important driver of our unusual life history. But helping behaviour is hardly uniform, and insight into the importance of grandmothering in human evolution depends on understanding the contextual expression of helping benefits. Here, we use an eighteenth-nineteenth century pre-industrial genealogical dataset from Finland to investigate whether maternal or paternal grandmother presence (lineage relative to focal individuals) differentially affects two key fitness outcomes of descendants: fertility and survival. We found grandmother presence shortened spacing between births, particularly at younger mother ages and earlier birth orders. Maternal grandmother presence increased the likelihood of focal grandchild survival, regardless of whether grandmothers had grandchildren only through daughters, sons, or both. In contrast, paternal grandmother presence was not associated with descendants’ fertility or survival. We discuss these results in terms of current hypotheses for lineage differences in helping outcomes.

Read more: Chapman, S.N. et al. Offspring fertility and grandchild survival enhanced by maternal grandmothers in a pre-industrial human society. Sci Rep 11, 3652 (2021). https://doi.org/10.1038/s41598-021-83353-3

Other News

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!
 

John Loehr with his workgroup received EUR 225.000 grant from Kone Foundation in 2016 for their project Learning from the past: the effect of forced migration from Karelia on family life.
Karelia-project had their kick-off meeting at the University of Turku 19.4.2017. Intense discussions, good spirit and a lot of inspiration among the team!

Menikö luonnonvalinnalla jotain pieleen: Miksi nainen elää menopaussin jälkeen lähes saman mokoman vaikkei voi saada jälkeläisiä?

Virpi Lummaa

Our multidisciplinary research team is looking for a post-doctoral researcher for a three-year project investigating life history, social integration and the influence of kin in forced migrants in a 20th century Finnish population.

The project is an exciting opportunity to investigate the consequences of forced migration of over 400000 people during World War II from an evolutionary ecology and sociology viewpoint. These migrants encountered much the same traumas and faced similar prejudices and resentment that current migrants face today, making the study of this population particularly appropriate to gain insight into the present and future of current migrants.
 

John Loehr with his workgroup received EUR 225.000 grant from Kone Foundation in 2016 for their project Learning from the past: the effect of forced migration from Karelia on family life.

The plight of migrants has come to the forefront recently as masses of people have migrated to Europe seeking asylum from predicaments faced at home. Many people in Finland seem to have forgotten that over 400,000 Finnish people had to abandon their homes in Karelia as a result of World War II. In this cross-disciplinary project, directed by John Loehr, an ecological scientist, biologists, sociologists, historians and demographic researchers study how enforced migration has affected family relations, having children, and integration into the community.

Kimmo Pokkinen is a man behind the Finnish church book data which he has been collecting for years. He had a big day recently and there was a fair reason to serve some birthday cake for him at the university. Congratulations!

Carly, Verane, Simon, Kimmo, Virpi, Jenni, Samuli, Martin, Mirkka

The research group spent three intense days having a brilliant Project Meeting in Tampere, Finland in August 2016. The venue was the most beautiful place by the lake, surrounded by the pristine Finnish nature. A perfect venue for the best conference ever! Special thanks to our hosts Jenni and Esko.
Photos from the Project Meeting in Kesämaa, Finland, August 2016. Photos by Esko Pettay / Wild TechPhotos Oy.

Virpi Lummaa's Group: Project meeting in Finland, August 2016. Photo by Esko Pettay

Virpi Lummaa is an outstanding evolutionary biologist and her work has led to significant advances in our understanding of the ecological causes and evolutionary consequences of variation in reproductive success and longevity. Her research on humans, based on detailed pedigrees, and birth and death records, revealed the selection pressures shaping life history in pre-industrial populations, and in so doing allowed for the first rigorous, scientific examination of human behavioural ecology. These findings have revealed the complex trade-offs shaping recent human evolution.
The Scientific Medal, Britain's zoological Oscar, is awarded to scientists with up to 15 years postdoctoral experience for distinguished work in zoology.

Virpi Lummaa Scientific Medal 2016 Zoological Society of London