John Hawks Profile picture
Sep 27, 2020 8 tweets 3 min read Read on X
Sometime between 370-150,000 years ago Neandertals got a Y chromosome from a more modern-like source population. This ultimately spread throughout all later Neandertal populations from which anyone has sampled DNA. Map of Europe and western Asia, showing range of Neandertal
The Neandertals and Denisovans originated from a common source population with African ancestors of modern humans sometime between 600 and 700,000 years ago. Population model of Neandertal Y chromosome introgression fr
This means that Neandertals and their Y chromosome donor population had begun to differentiate from each other between 230,000 and 600,000 years before this Y chromosome introgression happened. Neanderthal artist rendering at the Neanderthal Museum, Germ
Modern human groups today descend from populations that began to differentiate genetically from each other within Africa by 350,000-260,000 years ago. We don't know whether the Neandertal Y donor population was within this ancient diversity or somewhat more distant from us. Population model for modern human divergences from Schlebusc
Together these estimates suggest the possibility that some of today's modern human populations may be separated by a longer history than Neandertals were from their Y donor population. Adam and Eve depiction from 1988 Newsweek cover.
There is much more to the story of genetic difference than the time since the common ancestral population. Ancestral humans were much smaller population sizes, with greater drift and less frequent genetic interchange than modern populations of the last 50,000 years. Neandertal artist reconstruction by John Gurche, Smithsonian
Today's humans around the world share a more interwoven network of common ancestry and genetic interchange than Neandertals and their contemporaries did. Isolation and low diversity made a difference to Neandertal evolution, including the fate of introgressed haplotypes. Two Neanderthal reconstructions by artist Elisabeth Daynès.
But.. At the time these ancient peoples were interacting with each other, they were tied by history. The genealogies that we can trace in their DNA reflect a network of contacts across time. And we remain part of that network today. Neandertals reconstructed by artist Elisabeth Daynès for th

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More from @johnhawks

May 17, 2023
Quite like the new paper by my @UWMadison colleague @apragsdale. Fun to see lots of people newly discovering these ideas about metapopulation models! A couple of notes:
nature.com/articles/s4158…
An implication of this population model is that the structure of our species, Homo sapiens, began to emerge several hundred thousand years earlier than the dispersal that led to Neandertal and Denisovan populations.
When added to other evidence of recurring gene flow between Neandertal and African ancestral populations, this very strongly implies that Neandertals are Homo sapiens.
Read 5 tweets
Mar 18, 2022
So this seems very unpopular for some reason, but humans DID evolve from apes. We did not evolve from chimpanzees, gorillas, or any other living apes. They are our cousins. Our close fossil relatives were like living great apes in many ways and more like humans in others. MRD skull of Australopithecus anamensis on the right with a
Today's great apes, including chimpanzees and bonobos, two species of gorillas, and three species of orangutans, are a small surviving remnant of the diversity of apes that once existed. Each evolved in ways that helped them survive, just as our ancestors did. Tree showing the diversity of living great apes and humans.
Paleontologists have discovered many more forms of extinct apes than living ones. They were adapted to their time and place, some Asian, some African, and some European, but did not survive to the present day. Many of them lived in the period before 5 million years ago. Chart showing today's apes on a tree with time of existence
Read 7 tweets
Dec 8, 2021
Some discussion in comments last week in @ScienceMagazine about "paleodemes" with a short defense of the value of the concept. I think the paleodeme concept has most of the problems of paleo species concepts with none of their benefits. science.org/doi/10.1126/sc…
The person probably most responsible for the paleodeme concept in human origins is Clark Howell, whose 1999 paper "Paleo-Demes, Species Clades, and Extinctions in the Pleistocene Hominin Record" defined (although it did not first introduce) the concept. journals.uchicago.edu/doi/abs/10.108…
As presented by Howell, a paleodeme corresponds to a regional sample of fossils across a delimited range of time, with some morphological distinctiveness. These were groups like "Neandertal", "Skhūl/Qafzeh", or "Petralona/Atapuerca-Sima".
Read 5 tweets
Aug 13, 2021
Interesting paper on cutmark evidence from Olduvai, further substantiating early access to animal carcasses by tool-wielding Early Pleistocene hominins. @SciReports nature.com/articles/s4159… Cutmark evidence on animal bones from Olduvai Gorge, from Do
The paper's discussion raises lots of reasons why the anatomy of early Homo supports the idea that they were competent hunters. On this I don't disagree, but I think that focusing on "early Homo" here is misleading for several reasons.
First, "early Homo" fossils overlap substantially in anatomy with Australopithecus and Paranthropus. So much that we cannot always tell them apart (including long-standing arguments about well-known and not-so-fragmentary fossils).
Read 9 tweets
Jun 25, 2021
So, Homo longi. It's such a good name. Dragon people. And an amazing skull discovery. Adds to our knowledge of the Middle Pleistocene in China. But it's sad that the name is not going to stay. cell.com/the-innovation… Harbin skull viewed from the front. Photo by Wei Gao, from T
The boring reason why we can't use the Homo longi name is technical. The research puts the Harbin skull together with the Dali skull, and Xinzhi Wu gave that the name Homo sapiens daliensis more than 40 years ago. So IF there's a species, it has to be H. daliensis. Phylogenetic morphology analysis of Harbin skull, showing it
In case you wonder how close Harbin looks to Dali, here is Harbin on the left and Dali (which has some crushing to the maxilla) on the right. As Weidenreich might have said, they resemble each other as closely as one egg resembles another. Harbin skull (left) compared with Dali skull (right)
Read 13 tweets
Jun 24, 2021
The new report of fossil material from Nesher Ramla, Israel, claims a "previously unknown archaic Homo population" some 140,000 years ago. It's a big claim in an area where most scientists have thought that early modern humans and Neandertals interacted. science.sciencemag.org/content/372/65… Mandible from Nesher Ramla. From Hershkovitz et al. 2021 htt
Looking at the morphology of the mandible NR-2, it falls within the variation of fossils attributed to Neandertals, and is similar to Krapina, which is around the same age, and Sima, which are early Neandertals. This seems like a basic early Neandertal jaw. PC plot showing position of Nesher Ramla 2 next to Neanderta
The other fossil NR-1 is a complete right parietal bone and fragments of the left parietal. The analysis of shape places is near late Neandertals and early Neandertals, but a bit less "barrel-shaped", thereby similar to generalized H. erectus and African Middle Pleistocene Homo. PC plot of Nesher Ramla 1 parietal bone showing its position
Read 11 tweets

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