This quote from Anders Bergström @pontus_skoglund @ChrisStringer65 @DrEleanorScerri @MatejaHajdi carries an essential message: Genomic data today are not good enough to tell us how and when today's populations of humans started to emerge. doi.org/10.1038/s41586… Quote from Bergström et al ...
One way of casting this lack of knowledge is to say maybe there was no "origin", that we are looking backward through a cloudy lens at a gradual mixing process that never had a beginning. This idea comports with what we know about continued Neandertal-African mixing.
Yet with Neandertals we intently focus on mechanism: "How much mixing happened, on how many occasions, and how much did it matter?" Surely this must factor into the way we look at evolution within Middle Pleistocene Africa also. With more data, we will focus on those questions.
I think we have to continue to ask, if a pattern of isolation of subpopulations with occasional mixing was the one by which today's people evolved, and that occasional mixing is what tied them together, then on what principle do we exclude Neandertals from this pattern?

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with John Hawks

John Hawks Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @johnhawks

20 Mar
The MH2 #hominin mandible is still being built, fragment by fragment, as pieces are recovered from Malapa and prepared in the lab. The skull of this adult Australopithecus sediba individual may be found within the breccia as well. #paleoanthropology Illustration of MH2 hominin...
If you're following this series of illustrations, you may recognize that MH2 is my first repeat, as I earlier featured the MH2 pelvis. The Malapa skeletons are amazing examples of discovery, as each piece emerges from the site, it allows us to test new hypotheses.
Some scientists claimed that the difference between MH1 and MH2 mandibular ramus shape must mean that one is Australopithecus and one Homo. Ritzman and coworkers (2016) examined this, finding them compatible with normal within-species variation. dx.doi.org/10.1016/j.jhev… Image showing MH1 and MH2 m...
Read 6 tweets
20 Mar
Some say MSA/Middle Paleolithic hominins used ochre for sun protection, blocking any conclusions about marking or other symbolic uses. I say traditions of processing and using mineral pigments for sun protection are more complex and less universal than cosmetic uses.
Some archaeologists have focused on cosmetic uses of pigments, but it remains much more common to see ochre and other pigments framed in terms of "symbolic marking" or "marking".
Of course, cosmetics are used for symbolic marking, and also other kinds of marking, and much use of cosmetics across cultures is directed toward mimicry, enhancing the visual impact of features, or reducing the visual impact of features, not "symbolic" in a strict sense.
Read 4 tweets
19 Feb
So, I've started tracking down the citations in this Magnetodeth paper. It will be a surprise to no one that the papers on genetic bottlenecks do not support the 42,000-year-ago event that the new paper says they do.
For example, the paper claims that thylacines underwent a bottleneck 42,000 years ago, citing Lauren White et al. 2018 doi.org/10.1111/jbi.13… That paper actually says 20,400 years. Page on demographic history...
In the Australian case, the cited papers note that extinctions had a regional pattern that began by 48,000 years ago, the number 42,000 refers to a particular Bayesian analysis and not actual last appearance dates (which are more dispersed) doi.org/10.1038/s41467…
Read 8 tweets
28 Jan
Lactase persistence and dairying on the surface seem to be a simple and compelling example of gene-culture coevolution in humans. And yet there are patterns that confound the simplistic story. I appreciate that @Maddy_Bleasdale et al discuss some of those. nature.com/articles/s4146… Illustration showing allele frequencies associated with lact
Several aspects of lactase persistence genetics are not being covered well by press accounts of this paper. Journalists have gone with a pretty simple "counterintuitive lede", i.e., people were drinking milk before lactase persistence mutations were common.
A look at the great frequency maps in the paper is enough to remind folks of the reality that most lactase persistence-associated alleles *still* aren't very common. They have frequency maxima of 2-5% today and are highly localized. Frequency clines of lactase persistence-associated alleles i
Read 7 tweets
27 Jan
A lot of problems in science come down to whether larger amounts of noisy data are better or worse than smaller amounts of high-precision data. Of course, in paleoanthropology we usually are faced with small amounts of noisy data.
Our problems are that paleoanthropologists make up for shortfalls in data by carting in models and assumptions. These take on a life of their own, so much that even new discoveries that provide high-precision data cannot make a dent in most people's research direction.
I'm reading very carefully today an article by @Keilmesser and Marlize Lombard, which presents a very conventional view that large-brained hominins must have made MSA toolkits and smaller-brained hominins could not have done so. It's a thoughtful paper, but I'm unpersuaded.
Read 8 tweets
6 Oct 20
Most people have around a chromosome's worth of DNA from Neandertals, spread in small pieces across all 46 chromosomes.
Or, if you're of male sex, 45 out of 46 of them.
For western Eurasian peoples, the average amount of Neandertal DNA across the genome is around 120 megabases. Eastern Eurasian peoples have a bit more. Chromosome 13 is 114 Mb and 12 is 133 Mb.
Read 5 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!

Follow Us on Twitter!