I thought I should say a few words about this article and the irresponsible things the authors are saying about it in the press, because creationists have latched onto it, or at least onto the sensationalist online coverage of it. phe.rockefeller.edu/news/wp-conten…
The paper is quite a mess, with lots of incoherent arguments jumbled together. The authors' main goal, though, is to put a different spin on data they published elsewhere: onlinelibrary.wiley.com/doi/full/10.10…
The data show that human mtDNA diversity (or at least diversity of one gene, COI, which is often used for "barcoding," i.e. genetic species ID) is low and comparable to a bunch of other species, specifically to a large database from birds.
Just as for nearly every other type of genetic diversity measure, the data do not match the predictions of the neutral theory (i.e. diversity isn't proportional to population size) as the authors show here: journals.plos.org/plosone/articl…
This is Lewontin's paradox, something population geneticists have been studying for decades. The best explanation for this is that linked selection is more effective in large populations, causing larger reductions of neutral genetic diversity in larger populations.
Instead, the authors jump to an odd conclusion: "...the same explanation...for... sequence variation [in] modern humans applies equally to...essentially all other animal species...the extant population...has expanded from mitochondrial uniformity within the past 200,000 years."
Note that this is asserted without any calculation, any statement of empirically estimated mtDNA mutation rate, discussion of the problems of using mtDNA to estimate demographic history, etc. The authors merely state that this is the most plausible hypothesis.
In itself, this hypothesis states simply that the most recent common ancestor of mtDNA in most species is around the same age, 100,000-200,000 years old. This may or may not be true, and it says little about mechanism.
What it definitely doesn't say is that species all originated in that same window, yet this is what the authors are saying to the press.
I first saw the statement in this article: "The study's most startling result, perhaps, is that nine out of 10 species on Earth today, including humans, came into being 100,000 to 200,000 years ago." phys.org/news/2018-05-g…
I initially assumed that was just a misrepresentation of what the authors actually believed, but direct quotes elsewhere showed otherwise.
In their press release, Thaler says "we all likely originated by similar processes and most animal species are likely young." eurekalert.org/pub_releases/2…
Of course this has spiraled out of control. All the creationist blogs have picked it up. "Darwinian evolution is wrong! Species all appeared at once! Scientists now saying species are only 100,000 years old--eventually they'll show it's actually 6,000 years!"
Even Ted Cruz is tweeting about it!
If anyone actually took time to read the study, they'd easily see that the "take home message" is based on flawed logic and assertions without evidence. But no one will. Or they'll read it selectively for what they want to see.
All of that is to say that this is out there in the creationist echo chamber, so be prepared. (END)
PS: Some nice analysis of the paper's flaws by @swamidass here: discourse.peacefulscience.org/t/did-all-spec…
