Posted by:
SL Cabbie
(
)
Date: May 15, 2015 04:31PM
A few weeks ago some here were engaging in what I saw as some "unnecessary--and over-hyped--dramatics" on one off-topic subject or another, and I countered with some simple facts and "common sense" analysis...
That one prompted a "Buzzkill" retort from one of the the D.Q.'s (that's not "Dairy" folks), and it's a label I'll wear proudly. Afterall, we cabbies are routinely charged with the sacred duty of transported inebriated sorts to their domiciles, and that occasionaly entails "slapping them sober"--at least verbally--in order to get some coherent answers/directions.
Anyway, I was deeply bothered from the get-go by the claims of "Neanderthal DNA in the modern human genome." I discussed this subject in e-mails with Simon Southerton, who answered the "contamination issues" nicely, and added that Svante Pääbo had "developed new methods" that other geneticists were still "working hard to understand."
Okay, I didn't have a problem with that; my problems had to do with the "geography of the deed," i.e. where did these cross-cultural couplings take place? Asia is a really big place. I also stuck in a one liner about how ancient Cro-Magnons--or whichever H. sapiens did the deed--might've had trouble finding compliant Neanderthal women, given that one of those gals could snap a human forearm as easily as we break a dry turkey wishbone during the holiday season...
Here are some "consensus" claims that have emerged:
a) The Neanderthal DNA sequences are found in every human population outside of Africa, from Europe to aboriginal populations in New Guinea and Australia (as well as Native Americans in this hemisphere).
b) They have not been found in African populations, which is what gave rise to the "Interbreeding Theory" in the first place. However, African DNA has not been extensively sampled, and given that humanity's origins are found there, the genetic variability is greater there than anywhere else. This was what first confirmed the "Out of Africa" theory about human migrations, of course.
c) Neanderthal Y-chromosome and mitchondrial DNA has not been found in modern humans, which was what led the first researchers to conclude we were not closely related.
I also get really troubled when the percentage of Neanderthal DNA suddenly jumps from the original 1-4 percent to the 20% figure given in the Nat Geo article "lastofthewine" just linked.
I love Nat Geo; I've recommended subscribing here repeatedly, noting it's wonderful "anti-BOM" reading in addition to helping innoculate people in other areas such as the claims of the Creationists, etc., but as Simon has pointed out, it's often "soft science." In his blog article on those West Eurasian origins of Native Americans he identifies one statement as obvious hyperbole, and having tried to argue with TBM parrots on that one, I couldn't agree more.
National Geographic has "other priors" in my book as well I'll doubtless mention at some point, but right now I'll content myself with pointing out some parts of that organization have apparently been infected with the "Fox virus," and I find that particularly disturbing.
For those not wholly smitten by the "Geico Cavemen sure are sexy!" hype, here's an alternative voice I find particularly compelling:
http://www.geneticliteracyproject.org/2015/05/12/more-mystery-about-neanderthal-and-humans-how-reliable-is-ancient-dna-analysis/>These questions were long a matter a mere speculation. However, advances in DNA technology during the past decade have opened the questions up to scientific investigation. In May 2010, it was reported that a research team led by Paabo had sequenced “the whole Neandertal genome from powdered bone fragments taken from three females who lived in Europe 40,000 years ago.” The sequencing revealed that “[b]etween 1% and 4% of the DNA in modern Europeans, Asians and those as far afield as Papua New Guinea, was inherited from Neanderthals.”
As I noted, there's a huge gap between one and four percent and 20 percent...
>To be perfectly clear, Paabo and his colleagues did not really sequence “the whole Neandertal genome” in precisely the same sense that the whole genome of a person living today can be sequenced and analyzed. As soon as any organism dies, its DNA begins to break down and decay as the nucleotide bonds fall apart. Chemical reactions with water in the ground accelerate the decay. After examining such factors, Danish and Australian researchers reported in 2012 that DNA has a half-life of only 521 years.
>These challenges and complexities raise the possibility of the inadvertent introduction of errors in the sequencing process—even when all precautions are taken by highly professional researchers. These issues also open up any obtained data to different interpretations and to possible limitations in the application of the data.
>Nevertheless, these analytical limitations have not prevented some media outlets from reporting each latest find as if it is clearly definitive and absolutely conclusive. This can give the public faulty impressions of the findings. There is also a disturbing current trend among academic and scientific institutions and agencies (all types of science, not only anthropology) to inflate the significance of certain finds—perhaps to raise the public prominence of their institutions or to increase their chances of obtaining more government funds. The press and public relations departments of science-related institutions and university departments are light-years ahead of where they were a couple decades ago, in terms of their media savvy.
No fooling...
I trust interested--and skeptical--sorts will read the rest of the article (there are also some worthwhile links to discussions of GMO "issues" as well).
>In addition, a little old-fashioned journalistic cynicism could go a long way toward furthering public understanding of complex scientific topics. Journalists should ask tough questions of scientists, just like they do of politicians. (But then, they don’t often do that anymore either, do they?) It would also help if scientists themselves (or their public relations representatives) used less hyperbole in their press releases and other communications with the public.
Edited 1 time(s). Last edit at 05/16/2015 02:52AM by SL Cabbie.