Posts Tagged ‘Max Planck Institute for Evolutionary Anthropology’

More women than men – throughout history

September 26, 2014

The Max Planck Institute for Evolutionary Anthropology is pioneering many new techniques of investigative genetics and is causing minor revolutions in many areas of anthropology. Perhaps the best known of these is Svante Pääbo and his group’s work on extracting and analysing ancient DNA.  Their work on the Neanderthal genome is changing the previously accepted history of Modern Humans and their relationships with Neanderthals, Denisovans and other ancient branches of homo erectus.

A new paper reports on a DNA study of 623 males from 51 different populations and comes to the conclusion that throughout history women have outnumbered men. The study compared the paternally-inherited Y chromosome (NRY) with maternally inherited mitochondrial DNA (mtDNA). The researchers developed a high-resolution Y chromosome sequencing assay that allowed them to get paternal and maternal histories of similar quality and resolution. Female populations were larger before the out-of-Africa migration(s) and remained so throughout almost all subsequent migrations. Women migrated more (presumably as they were married out) and men stayed put more. For most of our history a greater proportion of women in the population reproduced than men leading to females making a larger genetic contribution to the current global population than males did. Men tended to fertilise multiple females (perhaps an indicator of polygyny).

CBS News: …. people in East Asia and Europe have larger genetic differences for paternal than for maternal DNA, suggesting high levels of female migration. In contrast, populations in Africa, Oceania and the Americas have bigger differences for maternal DNA than for paternal DNA.

Human paternal and maternal demographic histories: insights from high-resolution Y chromosome and mtDNA sequences, Sebastian Lippold, Hongyang Xu, Albert Ko, Mingkun Li, Gabriel Renaud, Anne Butthof, Roland Schroeder and Mark Stoneking, Investigative Genetics 2014, 5: 13

Eurekalert:

Female populations have been larger than male populations throughout human history, according to research published today in the open access journal Investigative Genetics. The research used a new technique to obtain higher quality paternal genetic information to analyse the demographic history of males and females in worldwide populations.

The study compared the paternally-inherited Y chromosome (NRY) with maternally inherited mitochondrial DNA (mtDNA) of 623 males from 51 populations. The analysis showed that female populations were larger before the out-of-Africa migration and remained so throughout almost all subsequent migrations. The main drivers of this trend are likely to be processes such as polygyny, where one male mates with many females, and the fact that in most societies, women tend to move to live with their husbands. This has resulted in females making a greater genetic contribution to the global population than males.

Previous research on genetic history has used different techniques to analyse NRY and mtDNA, which has led to an ascertainment bias in the results. In this study, researchers from the Max Planck Institute for Evolutionary Anthropology developed a high-resolution Y chromosome sequencing assay that allowed them to get paternal and maternal histories of similar quality and resolution, so they could make a direct comparison. The results confirmed previous findings that when comparing human populations on a global scale, there are greater genetic differences in paternal NRY than in mtDNA. However, these differences are not as large as previously thought and the authors were surprised to see substantial variation in relative amounts of NRY vs. mtDNA differentiation at the regional level.

The authors argue that using this new technique, greater analysis can be undertaken at a regional level to create a clearer picture of the paternal and maternal influences on specific populations. In the African populations they studied, they saw lower paternal genetic diversity, which may be a direct result of the Bantu expansion into eastern and southern Africa beginning about three thousand years ago. In samples taken from the Americas, initial results suggest higher maternal genetic diversity, indicating that there were fewer males than females among the original colonisers.

Dr. Mark Stoneking, Department of Evolutionary Genetics, Max Planck Institute, an author on the paper, said: “Our new sequencing technique removes previous biases, giving us a richer source of information about our genetic history. It allows us to take a closer look at the regional differences in populations, providing insights into the impact of sex-biased processes on human genetic variation.”

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DNA sequenced from a 400,000 year old hominin from Spain

December 4, 2013

After developing techniques for extracting and analysing DNA from ancient (c. 40,000 years ago) Neanderthal and Denisovan specimens the Max Planck team have now taken a giant leap backwards in time in extracting and analysing an almost complete mitochondrial genome sequence of a 400,000-year-hominin. The specimen is from  Sima de los Huesos, a unique cave site in Northern Spain. The results show that it is related to the mitochondrial genome of Denisovans, extinct relatives of Neandertals in Asia. DNA this old has until recently been retrieved only from the permafrost.

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The Sima de los Huesos hominins lived approximately 400,000 years ago during the Middle Pleistocene. © Kennis & Kennis, Madrid Scientific Films

The result itself is of great interest but it is the development of the techniques for extracting and analysing – without any contamination – and with sufficient confidence, the entire MtDNA sequence in such old specimens that is quite revolutionary. Archaeological evidence – and particularly of of such age – is subject to a great deal of subjective interpretation. But dating techniques and now DNA extraction techniques are removing much of this subjectivity and they are now providing the anchor points around which the evolutionary narrative must be built. And this narrative is now of a much more complex story of hominin expansions and admixture than has generally been thought. Ancient and presumed extinct hominin species are now showing themselves within us.

“Our results show that we can now study DNA from human ancestors that are hundreds of thousands of years old. This opens prospects to study the genes of the ancestors of Neandertals and Denisovans. It is tremendously exciting” says Svante Pääbo, director at the Max Planck Institute for Evolutionary Anthropology.

Matthias Meyer, Qiaomei Fu, Ayinuer Aximu-Petri, Isabelle Glocke, Birgit Nickel, Juan-Luis Arsuaga, Ignacio Martínez, Ana Gracia, José María Bermúdez de Castro, Eudald Carbonell, Svante PääboA mitochondrial genome sequence of a hominin from Sima de los HuesosNature, 2013; DOI: 10.1038/nature12788

Read the whole post in 6,000 Generations

 


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