Tomorrow I will be giving a talk about “Integrating palaeoclimate into population genomics” for the Uppsala-Hacettepe Palaeogenetics and Population Genetics (UHPalaeopopgen) webinar series.
If you want to follow the webinar, sign up from this link. The talk will not be recorded.
Thanks to the organisers Gülşah Merve Kılınç (Hacettepe University) and Torsten Günther (Uppsala University) for inviting me!
A new book chapter that I wrote just came out:
Leonardi, M., G. Barbujani, and A. Manica. 2021
Genetic demography: What does it mean and how to interpret it, with a case study on the Neolithic transition
In Ancient Connections in Eurasia, ed. by H. Reyes-Centeno and K. Harvati, pp. 91-100. Tübingen: Kerns Verlag. ISBN: 978-3-935751-37-7. https://doi.org/10.51315/9783935751377.005
The present work describes the basic principles underlying demographic reconstructions from genetic data, and reviews the studies using such methods with respect to the Neolithic Demographic Transition. It is intended as a tool for scholars outside the field of population genetics (e.g., archaeologists, anthropologists, etc.) to better understand the significance and intrinsic limitations of genetic demography, and to help integrate its results within the broader context of the reconstruction of the human past.
Yesterday Andrea Idini interviewed me for the first season of MeetScience.
We have been talking about many topics that I have been studying, from lactase persistence and the digestion of milk, to horse domestication; from ancient human migrations to migraine; from the genetic history of Lucca to the impact of the Neolithic Revolution on human demography; from climate changes in the past to… board games! Here is the video (in Italian).
It just came out in Nature Human Behaviour a new paper to which I collaborated: Climate shaped how Neolithic farmers and European hunter-gatherers interacted after a major slowdown from 6,100 BCE to 4,500 BCE. The article is behind paywall, but there is a read-only version, and the publisher added the full text in Researchgate.
The Neolithic transition in Europe was driven by the rapid spread of Near Eastern farmers who, over a period of 3,500 years, brought food production to the far corners of the continent. However, this wave of expansion was far from homogeneous, with a marked slowdown observed at higher latitudes, which could be related to the different climatic conditions encountered by Neolithic farmers as they moved.
We tested this hypothesis. First, we calculated the expansion routes in the various areas using a large database collating archaeological dates of the first arrival of agriculture throughout Europe. We have identified four of them, shown in the image below.
Along three of these routes, we observed a slowdown (thicker lines in the image) where the value of Growing Degrees Days (reflects the quality of the growing season) exceeds a certain threshold (light green in the map). This suggests that crops that originated in the Near East may have struggled to grow in harsher climatic conditions, not allowing Neolithic populations to produce enough to support population increase and/or expansion.
Furthermore, the study of ancient DNA shows us that in conjunction with the same threshold in growing degree days, the level of admixture between farmers and hunter-gatherers increases, suggesting that unreliable harvests in these regions may have favoured the contact between the two groups.
Lia Betti, Robert M. Beyer, Eppie R. Jones, Anders Eriksson, Francesca Tassi, Veronika Siska, Michela Leonardi, Pierpaolo Maisano Delser, Lily K. Bentley, Philip R. Nigst, Jay T. Stock, Ron Pinhasi & Andrea Manica
The Neolithic transition in Europe was driven by the rapid dispersal of Near Eastern farmers who, over a period of 3,500 years, brought food production to the furthest corners of the continent. However, this wave of expansion was far from homogeneous, and climatic factors may have driven a marked slowdown observed at higher latitudes. Here, we test this hypothesis by assembling a large database of archaeological dates of first arrival of farming to quantify the expansion dynamics. We identify four axes of expansion and observe a slowdown along three axes when crossing the same climatic threshold. This threshold reflects the quality of the growing season, suggesting that Near Eastern crops might have struggled under more challenging climatic conditions. This same threshold also predicts the mixing of farmers and hunter-gatherers as estimated from ancient DNA, suggesting that unreliable yields in these regions might have favoured the contact between the two groups.
Nat Hum Behav (2020). https://doi.org/10.1038/s41562-020-0897-7