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 I had the pleasure of taking part to the Webinar “Women in climate change – Donne e cambiamento climatico”, part of the campaign organised by Wikimedia Foundation Sustainability Consortia to increase the visibility of women that are playing a crucial role in climate change.
You can find below the video of the whole event (in Italian), my talk starts at the 28th minute.
Yesterday I had the honour and the pleasure to give a talk at the Department of Anthropology at UCL, within the Evolutionary Anthropology Seminar Series.
The title of my presentation was “How to integrate Anthropology in (academic) careers within other disciplines”, and it sparked a lively discussion where we covered a lot of topics from career choices to grant opportunities, and much more.
I am very honoured to announce that, starting from tomorrow, I will be working on a new Leverhulme-funded Research Project as the nominated researcher.
The project is called “Neanderthal Palaeoecology: the whens, hows, and whys of a species’ journey“, I co-wrote it together with my PI, prof. Andrea Manica, and it involves the collaboration with internationally renowned scholars (see the list at the end of the post).
Description
The following text is an extract of the article we wrote for the 2021 February’s Newsletter of the Leverhulme Trust (cover and page 16).
Neanderthals (Homo neanderthalensis) are a human species that lived in western Eurasia between approximately 350,000 and 30,000 years ago. Since the discovery of the first fossil in 1856, a huge body of research from multiple disciplines has helped us uncover more and more about this species.
Genetic analysis of DNA from fossil remains from multiple locations and periods has revealed a major population replacement between 90 and 120 thousand years ago in central Asia. Unfortunately, genetic data, which are very powerful at detecting change, cannot inform us of the processes behind such population dynamics. Climate is an obvious candidate in explaining this population turnover, but formally demonstrating its role is not easy.
We gathered an interdisciplinary team composed of archaeologists, ecologists, paleoclimate modellers and cultural evolution specialists. Together, we will investigate the role of climate in shaping the population dynamics of Neanderthals over their whole temporal and geographic range. We will also incorporate cultural information to see if and how different Neanderthal populations changed and adapted their behaviour in response to climatic fluctuations.
By doing so, we will be able to put the population turnover that occurred 120 thousand years ago into context, providing a clear test of whether climatic changes are a likely explanation. But most importantly, for the first time, we will be able to test for the role of climate in the whole species’ journey of Neanderthals, integrating cultural evolution into the big picture, to better understand the whens, hows, and whys of the journey of this fascinating human species.
Stay tuned for exciting news and research outputs!
Collaborators
The project will be in collaboration with the following scholars (the order is the same in which they joined the project).
So excited to have contributed to this amazing new preprint!
In this study, we quantified the role of climate and mountains in shaping modern and ancient human genetic diversity.
Genomics shows that contemporary human populations result from the mixing of ancestral groups that are genetically distinct (ancestral genetic lineages) with unknown origins. In theory, ancient DNA could help disentangling their origin, but not in this case because we don’t have enough samples of the right age.
For this reason, we used a different strategy. We explicitly simulated the genetic history of humans in their spread out of Africa testing different values for demographic parameters and physiological responses to the changing climate. By doing so we could see if we can reconstruct the observed genetic diversity (spoiler alert: yes) and which parameters and climate variables shaped it.
For example, we find that aridity is the key factor controlling the timing for the out of Africa and mountains can be huge genetic barriers but only in some areas (e.g. Caucasus and Himalayas, not the Urals).
Thanks to this study, not only we could reconstruct such an important part of our genetic history, but we could also quantify the differential role of climate and topography through space and time in our spread out of Africa.
Preprint
Pierpaolo Maisano Delser, Mario Krapp, Robert Beyer, Eppie R Jones, Eleanor F Miller, Anahit Hovhannisyan, Michelle Parker, Veronika Siska, Maria Teresa Vizzari, Elizabeth J. Pearmain, Ivan Imaz-Rosshandler, Michela Leonardi, Gian Luigi Somma, Jason Hodgson, Eirlys Tysall, Zhe Xue, Lara Cassidy, Daniel G Bradley, Anders Eriksson, Andrea Manica Climate and mountains shaped human ancestral genetic lineages bioRxiv 2021.07.13.452067; doi: https://doi.org/10.1101/2021.07.13.452067
Abstract
Extensive sequencing of modern and ancient human genomes has revealed that contemporary populations can be explained as the result of recent mixing of a few distinct ancestral genetic lineages. But the small number of aDNA samples that predate the Last Glacial Maximum means that the origins of these lineages are not well understood. Here, we circumvent the limited sampling by modelling explicitly the effect of climatic changes and terrain on population demography and migrations through time and space, and show that these factors are sufficient to explain the divergence among ancestral lineages. Our reconstructions show that the sharp separation between African and Eurasian lineages is a consequence of only a few limited periods of connectivity through the arid Arabian peninsula, which acted as the gate out of the African continent. The subsequent spread across Eurasia was then mostly shaped by mountain ranges, and to a lesser extent deserts, leading to the split of Europeans and Asians, and the further diversification of these two groups. A high tolerance to cold climates allowed the persistence at high latitudes even during the Last Glacial Maximum, maintaining a pocket in Beringia that led to the later, rapid colonisation of the Americas. The advent of food production was associated with an increase in movement, but mountains and climate have been shown to still play a major role even in this latter period, affecting the mixing of the ancestral lineages that we have shown to be shaped by those two factors in the first place.
