Neanderthal Genes Reveal How Old Our Ancestors Were When They Had Children

Archaic Sequence Length Decay

Archaic sequence length decay (black bands on chromosomes) for different populations sampled at multiple time points. The length of generation intervals (GI) is represented by the color gradient on the tree (yellow : long GI; maroon : short GI). Credit: Moisès Coll Macià, Aarhus University

A new study suggests that generation intervals have fluctuated during the past 40,000 years of human evolution in contrast to what has been commonly assumed. The results indicate that human life history can change appreciably in response to external and cultural factors

The authors from Aarhus University in Denmark and the Max Planck Institute for Evolutionary Anthropology in Germany used Neanderthal fragments scattered in non-African genomes as molecular clocks to estimate generation intervals in Eurasian and American populations.

“This new way of using genomic data enabled us to retrieve information about our human life traits buried in the past, which complements what can be learned from archaeology about our history,” says Professor Mikkel Heide Schierup, leader of the project.

The research team report in Nature Communications on September 7, 2021, that humans in populations in Europe reproduced on average at a younger age than populations from east Eurasia and America over the past 40,000 years.

“We estimate a difference of 3 to 5 years between the mean generation interval among populations. We believe that this difference was probably more dramatic. If the change happened during the last 10,000 years for example, we are probably diluting the signal over the 40,000 years period we study,” says PhD student Moisès Coll Macià, first author of the study.

The results obtained about generation intervals are reflected in the accumulation of genetic changes in different parts of the world.

“Older parents transmit different mutations than younger ones to their children. In this study, we find that populations estimated to have older parents from their Neanderthal legacy also have mutations suggesting older parenthood” says Coll Macià.

These mutational differences also allowed the researchers to tease apart whether changes in generation interval is due to changes in the fathers’ age at reproduction, the mothers’ age at reproduction or both.

“For instance, we see that east Asian populations tended to have older fathers than mothers, while European populations had similar ages for both,” says Coll Marcià”.

So why did the lengths of generations differ historically around the world?

The authors speculate that this was probably a response to changes in the environment. Differences in climate, but also technological and cultural developments in human societies, might have made living conditions more or less favorable to reproduce and thus played an important role in deciding which was the best time to have descendants.

“In the future, we will be able to use the wealth of ancient and modern human genome sequences appearing at a fast rate to make a fine map of changes to age of human reproduction, that we can relate to environmental and cultural conditions,” professor Schierup suggests.

Reference: “Different historical generation intervals in human populations inferred from Neanderthal fragment lengths and mutation signatures” by Moisès Coll Macià, Laurits Skov, Benjamin Marco Peter and Mikkel Heide Schierup, 7 September 2021, Nature Communications.
DOI: 10.1038/s41467-021-25524-4


View Comments

  • East Asians seem to have the most Neanderthal DNA in their genomes, followed by those of European ancestry. Africans, long thought to have no Neanderthal DNA, were recently found to have genes from the hominins comprising around 0.3 percent of their genome.

Aarhus University

Recent Posts

Atlas of Australian Dragon Brain Reveals Secrets of Brain Evolution

Dragons and Brain Evolution These days, dragons are keeping Game of Thrones fans on their…

October 3, 2022

The Fountain of Life: Scientists Uncover the “Chemistry Behind the Origin of Life”

Water Droplets Hold the Secret Ingredient for Building Life Chemists uncover key to early Earth…

October 3, 2022

First Theorized 70 Years Ago – “Rippled Beta Sheet” Created for the First Time

University of California, Santa Cruz, scientists report the creation of three crystal structures of periodic…

October 3, 2022

Scientists Successfully Create Diamonds Out of Bottle Plastic

A research team utilizes laser flashes to replicate the interior of ice planets, which inspires…

October 3, 2022

Don’t Miss: Evenings With Giants, Mars Changes Course, and Meteors From Orion

What are some skywatching highlights in October 2022? Enjoy giant planets Jupiter and Saturn all…

October 3, 2022

Rewriting History – The First Full-Length Genomes for Homosporous Ferns

A new study reveals ferns' history of DNA hoarding and kleptomania. Ferns are infamous for…

October 3, 2022