Paleontologists. A lot of parallels. I read a number of books on the asteroid-extinction theory and the controversy around it, including several by paleontologists. I was not impressed by them. Although, to be fair, I don’t remember the paleontologists accusing Luis Alvarez of racism.
Other examples of this pattern?
There is a new article in the New York Times Magazine (Is Ancient DNA Research Revealing New Truths — or Falling Into Old Traps?) , in which some pinhead repeats complaints about David Reich crushing his enemies [archaeologists] , driving them before him, and hearing the lamentations of their women. He doesn’t give them much respect.
They don’t deserve respect. Sure, he has a far more powerful method. Sequencing DNA gives you billions of bits, orders of magnitude more than staring at potsherds. But it is fair to look at how archaeologists did with the tools they had: terrible, horrible, no good, very bad. They really, really wanted to create detailed stories of local social change, stories that didn’t sound like something by Robert E, Howard, full of thud and blunder. Not stories about barbarian conquest, population replacement, and mating with nonhuman races.
But that’s what happened.
The origin of the Polynesian population out in the Pacific is a classic example. Even before ancient DNA was sequenced, we knew that ~94% of Tongan mtDNA was from Taiwan, ~75% of their autosomal DNA was also from Taiwan, while their Y-chromosomes were 65% Melanesian. “Until recently, the dominant model was the slow-boat hypothesis, in which the Taiwanese-derived Lapita culture mixed with Melanesians in New Guinea and the Solomons before sailing out into the deep Pacific. The funny numbers for mtDNA and Y-chromosome were explain by some hand-waving matrifocal cultural bullshit. ”
Ridiculous. Taiwanese were the original settlers, while Melanesians invaded later, conquered, and killed off most of the local men. Confirmed by ancient DNA.
Aryan Invasion theory: An Aryan invasion (!) , offensive to local feelings in India, sounds almost like colonialism, blah blah blah. But correct.
Archaeologists had unreasonable priors, about everything in sight. Given a chance, they assumed that the Maya were a nation of peaceful astronomers [ Just another snake cult !] . Indo-European languages spread because they were so cool, rather than by conquest [even David Anthony fell for this!]. One group couldn’t be biologically superior to another. { Why not? Do the Galactic Overlords forbid that?}
And so on, and so on. They had one job…
Does this mean that David Reich is without sin? No. He occasionally genuflects to the PC powers that be, sometimes smearing the innocent in the process. Is his success going to his head – might he tend to underrate peer review when he has Nick Patterson on his side? Maybe. Should he think very carefully about sample conservation, perhaps saving some for improved future methods? Sure.
But he’s contributing to knowledge, while the archaeologists were sliding backwards, less correct in 2018 than in 1930.
Of indigenous people, when doing archaeology or work on ancient DNA. Because sometimes they’re in a position to stop you. But shouldn’t you really, really care about hurting their feelings, when you find that they didn’t emerge from a giant peach or whatever?
I can’t see why.
Tell the truth.
That guy on the internet was dead wrong in thinking that there was enough gene flow in human prehistory to materially interfere with local adaptation. For a polygenic trait, that would take something like a couple of percent a generation. For an adaptive Mendelian trait, you’d need more influx ( as a fraction) than the selective edge of the causal mutation.
But there’s another interesting question, which he would presumably also be wrong about: how often does even a single copy of an adaptive mutation manage to travel far, and how long does it take? I talked about this here, some time ago. But examples help.
HbS, the sickle-cell mutation, happened once about 7,000 years ago, and has spread to regions with a lot of malaria in Africa, parts of southern Europe, the Middle East, and India.
But it never got to southeast Asia or New Guinea ( until 2002) , even though there’s plenty of malaria there, and a number of local genetic defenses against malaria. Parenthetically, although HbS is found today on different haplotypes, and many people suspected that it had multiple origins, complete absence in Southeast Asia/Melanesia was always a strong hint that it had a single origin.
None of those defenses in PNG or Southeast Asia ever seem to have made it to Africa. And during the last 7,000 years, there were an increasing number of long-distance dispersal mechanisms that didn’t exist before the Holocene: lost-distance trade, ships, the slave trade, etc.
Was a watching a mystery, one in which a major clue was the unknown perp being left-handed. So my wife said a particular actress on the show was obviously the villain. I asked how she knew:
Turned out they’d gone to high school together, been a couple of plays. Ruth knew that actress was left-handed.
Jeff Bezos isn’t my favorite guy, but he has ability and has built something useful. And an ugly, contested divorce would be harsh and unfair to the children, who have done nothing wrong.
But I don’t care. The thought of tens of billions of dollars being spent on lawyers and PIs offer the possibility of a spectacle that will live forever, far wilder than the antics of Nero or Caligula. It could make Suetonius look like Pilgrim’s Progress.
Have you ever wondered whether tens of thousands of divorce lawyers should be organized into legions or phalanxes? This is our chance to finally find out.
There are two reasons that you might see common deleterious recessive alleles in a population.
Founder effects or other bottlenecks: the population is so small that some ungood mutations have become unusually common, just by chance. The total number of bad mutations is generally not higher, but particular ones are. Since they’re usually recessive, a 10% frequency of one bad gene causes more trouble [ 1% homozygotes) than 5% frequency of two different bad genes [ 0.5% homozygotes] .
If you mix a lot with neighboring populations, gene frequencies tend to even out. But endogamy is not the cause: it’s going through a time of very small population size. You’re not going to see a lot of unusually common Mendelian diseases driven by mutation in a population that has been large for a long time, even if they are endogamous.
Second reason is that an allele has heterozygote advantage, increases the fitness of heterozygotes, like sickle-cell or cystic fibrosis. These tend to cluster in metabolic paths related to the selective agent: in areas with lots of malaria, you see a number related to hemoglobin or the red cell. We have fairly recently found a couple that defend against sleeping sickness: likely we will find more.
Common deleterious mutations due to bottlenecks are random: they don’t cluster in metabolic paths.
Most deleterious mutations are rare, haven’t been around for long. If you marry your first cousin, the odds of a kid being a homozygote for some such go way up, since the cousin has a fair chance of sharing that rare mutation. On the other hand, if the mutation is common in your population, due to chance or selection, your children have a noticeable risk for being homozygotes even when you and your mate are not closely related. In other words, Tay-Sachs in Ashkenazi Jews is not a product of inbreeding.
Since the average person has many rare deleterious mutations, with effects ranging from lethal to being a little subpar, children of such consanguineous unions have a spectrum of problems, ranging instant death ( rare) to ” not very healthy”, not so rare. On average, kids of first cousins seem to have have about twice as many serious genetic problems, average about 5 iq points lower & 0.7 cm shorter.
Where is inbreeding a problem? Much of the Moslem world.
Acceptance of consanguineous unions is increasing in liberal circles, since A. It’s an Islamic thing and B. It’s obviously stupid.
