March 5, 2007

Important human genetics papers

Dienekes points out some interesting abstracts from papers to be presented at the upcoming meeting of the American Association of Physical Anthropologists. Here's a selection from his selection:


Understanding human races: the retreat of neutralism.
Henry Harpending

Discussion and debate about human races has been dominated for decades by neutral theory and statistics. Since this literature never posed a real question, it has never produced an answer. Lewontin's 1972 paper with its claim that a value of 1/8 of a statistic like Fst is “small” and that this means that human race differences are insignificant is a staple of our textbooks.

Recently geneticists have had a closer look and pointed out that Fst of 1/8 describes differences among sets of half sibs and few claim that half sibs are insignificantly related. Anthony Edwards has shown that the significance of differences is in the correlation structure of a large number of traits, again denying the Lewontin assertion that human differences are small. Alan Templeton in 1998 claimed that human races were less differentiated that races of some other large mammals, but he compared human nuclear DNA statistics with statistics from mtDNA in the other species. An appropriate comparison shows that human are more, not less, differentiated than other large mammal species.

Since neutral differences are a passive record of demographic history they are not very significant for issues of functional biology. Newly available data sources allow us to study the natural selection of race differences instead of their drift. It appears that there is a lot of ongoing evolution in our species and the loci under strong selection on different continents only partially overlap. Human race differences may be increasing rapidly.


I wrote about Harpending's change of mind about Lewontin's celebrated statistic in VDARE.com in 2004.


Acceleration of adaptive evolution in modern humans.
J. Hawks and G. Cochran

Humans vastly increased in numbers during the past 40,000 years. Recent surveys of human genomic variation have suggested a large surplus of recent positive selection, indicated by excess linkage disequilibrium and skewed SNP frequency spectra. We applied estimates of prehistoric and historic population sizes to estimate the importance of population growth in explaining the number of recent adaptive mutations. Our estimates are consistent with genomic evidence in suggesting that the rate of generation of positively selected genes has increased as much as a hundredfold during the past 40,000 years.

Do skeletal features reflect this genomic evidence of selection? Under positive selection, rapid appearance of new variants during the terminal Pleistocene and early Holocene would cause maximal phenotypic change during the last 2000-4000 years. We compared original and published series of Holocene cranial data from Europe, Jordan, Nubia, South Africa, and China, in addition to Late Pleistocene samples from Europe and West Asia, to test the hypothesis that the genomic acceleration in positive selection correlates with phenotypic evolution during this time period. A constellation of features in the face and cranial vault, notably including endocranial volume, changed globally during this time period and documents common patterns of selection in different regions. Holocene changes were similar in pattern and chronologically faster than those at the archaic-modern transition, which themselves were rapid compared to earlier hominid evolution. In genomic and craniometric terms, the origin of modern humans was a minor event compared to more recent evolutionary changes.


For example, here's the forensic reconstruction of the 14,000-year-old skull of a woman from Sicily (via Dienekes). What modern race would she be? She's obviously human, but doesn't look particularly like any large group around today. You run into this a lot with older skulls.


Admixture in Mexico City: implications for admixture mapping.
E. Cameron et al.

"The average proportions of Native American, European and West African admixture were estimated as 65%, 30% and 5% respectively."

"In a logistic model with higher educational status as dependent variable, the odds ratio for higher educational status associated with an increase from 0 to 1 in European admixture proportions was 9.4 (95% credible interval 3.8 – 22.6). This association of socioeconomic status with individual admixture proportion shows that genetic stratification in this population is paralleled, and possibly maintained, by socioeconomic stratification."


I'm not sure how to interpret this "odds ratio" but this certainly points in the direction I've been arguing since 2000.


Patterns of admixture in Mexican Americans assessed from 101,150 SNPs.
M.G. Hayes et al.

"No significant differences were observed between the 10 subsets, allowing us to average the admixture estimates across the subsets: 68% European, 27% Asian (as a proxy for Native American), and 6% African."


So, this is the reverse of the Mexico City data above. Are the populations different, or is admixture analysis still unreliable? The people at the illegal immigrant rally in Van Nuys, CA last spring were a lot shorter and more Indian-looking than the Mexican-Americans I grew up with, so perhaps the Mex-Am population is changing, with new immigrants being drawn from a more Indian background. Well, the African percentages in both are in line with earlier estimates of 3% to 8% that I cited in my 2002 article "Where Did Mexico's Blacks Go?"


Intracontinental Distribution of Haplotype Variation: Implications for Human Demographic History.
M.C. Campbell et al.

"These results suggest that diverse African populations were more subdivided with lower levels of gene flow during human history."


I suspect poor transportation and the lack of large states in Africa helped keep gene flow low between regions within sub-Saharan Africa relative to, say, Europe.


My published articles are archived at iSteve.com -- Steve Sailer

11 comments:

Anonymous said...

'Odds ratio' (OR) is the likelihood of something occurring in one group relative to another. If men are three times more likely to get engineering degrees than women (meaning 75% of engineerng degrees go to men), men have an OR of 3 vis-a-vis women for an enginering degree and Larry Summers is out of a job.

So your odds ratio of 9 means white people are 9 times more likely to be highly educated than nonwhites in Mexico. Of course, this doesn't prove genetic racial differences, only that Mexico is racist.

It would explain the short and brown illegal immigrant population; from what I understand the people sneaking over the border are the people at the bottom of the Mexican social pyramid who have been displaced due to social problems on their side.

Anonymous said...

What skull reconstruction, that's a picture of Geddy Lee!

michael farris said...

"from what I understand the people sneaking over the border are the people at the bottom of the Mexican social pyramid who have been displaced due to social problems on their side"

At least until the early 90's (no idea what's going on now). The bottom of the social pyramid had all they could to keeping their heads (barely) above water. There was no way they could afford the reltively expensive process of crossing the border safely and making it to a destination where there was work.
Those who crossed were those from lower (but by no means lowest) class with middle class ambitions and no way to fulfill them in mexico.

Anonymous said...

More good stuff here:

http://groups.yahoo.com/group/palanthsci/message/29309

Anonymous said...

Let's try that again...

Anonymous said...

Mexico's elite is a political elite. Mexico is country where who you know is much more important than what they know. Neopotism is chronic and anti-competitive forces backed up by the Government keep the system in place. This is true for ligitamate businesses as well as the drug and illegal alien trade.

In the US business types look down on Government types. In Mexico it is the other way around.

I had hoped when the PRI monopoly was cracked 6 years ago that things would change faster but change and fast are not words that quickly come to mind when one thinks about Mexico.

Anonymous said...

Go easy on the old Sicilian lady. She was considered attractive back in her day. ; )

She doesn't look too odd. I swear I've met old Sicilian ladies that look like her.

Mexico might become less of an issue; I've heard that birthrates over there are dropping very quickly. If that is the case, we'll eventually see fewer and fewer illegal immigrants. Also, I hear that the more generations a Mexican family has been in the U.S., the closer their birthrate comes to ours. It's possible that Texas may never have a Hispanic majority.

~ Risto

michael farris said...

She doesn't look that odd, if I didn't know where she was supposed to be from I would have guessed southern (or southeastern) europe.

Anonymous said...

The apparent "Indianization" of Mexican immigrants is a phenomenon I noticed in the mid to late 1990s. Before then, a Mexican over here (i.e. not a rich tourist) was nearly synonymous with a very Mestizo looking type, usually medium skin tone, usually loud, cocky and macho. The pure Indians are a different tribe from the Mayan-looking types, short, quiet, oftentimes not literate in Spanish much less English. They do not have the Mayan or Toltec looking features at all.

Earlier, such people stayed in Mexico, I suspect, because they were in effect serfs. Globalization has uprooted them for better or worse, and they can not blend into American culture just as they didn't blend in to Mexican mainstream culture in 400 years.

They seem much less dangerous than the loud, cocky, swaggering mestizo of old, but that could be a dangerous illiusion. It does seem like they are more or less immune to schooling, much like the Roma, who are usually dyslexic and who possess a staggering propensity to (usually nonviolent) crime. I don't know that the Indios are horribly crime-prone, and I suspect their ineducability lies in other characteristics than "dyslexia". Perhaps good old low IQ. I just don't know.

The correlation between educaltional success and Europeannesss in Mexico is probably little due to "Racism" and much more to low educability but there peobably is some level of resistance against highly capable individuals who look more Indian or nonwhite.

In my opinion, it's in everyone's interest to first get Mexico's huevos in our fist by securing the border and making illegal residency here economically untenable, then "negotiating" from a position of strength for reforms that are needed within Mexico to accomplish the goal of having Mexicans work in Mexico on a productive basis. Currently though we are in no position practically or morally to do that.

Anonymous said...

That woman looks like most people from Sicily and southern Italy. I live in NJ, trust me on this one.

Anonymous said...

Steve probably only mixes with WASP-types.