Category: bioculture

Race, Ethnicity, Culture, and Epigenetics

Interesting findings.

If we ignore the PC-oriented nonsense about “social constructs” as well as the confusion about ethnic identification and ancestry, there are some interesting points in this article.

Excerpts, emphasis added:

These researchers report that they have identified signatures of ethnicity in the genome that appear to reflect an ethnic group’s shared culture and environment, rather than their common genetic ancestry.

“We found that both self-identified ethnicity and genetically determined ancestry were each significantly associated with methylation levels at 916 and 194 CpGs, respectively, and that shared genomic ancestry accounted for a median of 75.7% of the variance in methylation associated with ethnicity,” wrote the article’s authors. “There was a significant enrichment…of ethnicity-associated sites amongst loci previously associated environmental exposures, particularly maternal smoking during pregnancy.”

Roughly one-quarter of the epigenetic difference between the two ethnic subgroups could not be accounted for by differences in the children’s genetic ancestry. This difference, the authors suggested, could reflect a biological stamp made by the different experiences, practices, and environmental exposures distinct to the two ethnic subgroups.

It demonstrates in a whole new way that race combines both genetics and environment.

Studies by the Burchard group and others have found that using genetic ancestry rather than ethnic self-identification significantly improves diagnostic accuracy for certain diseases.

But the new data showing that a large fraction of epigenetic signatures of ethnicity reflect something other than ancestry suggests that abandoning the idea of race and ethnicity altogether could sacrifice a lot of valuable information about the drivers of differences in health and disease between different communities.

The nonsense about distinguishing more accurate “genetic ancestry” from less accurate “ethnic self-identification” fails the smell test since the Risch lab a while back showed near-perfect correspondence between identify and ancestry.  True enough, there is a social component to these things, since humans give simple labels to complex categories.  Thus, both Colin Powell and a pure-bred Nigerian would both identify as “Black” although there is quite a difference in their ancestry.  But that does not mean that ethnicity/race and genetic ancestry are different things; it instead means that human beliefs about ethnicity/race may not always be the same as genetic ancestry.

In any case, the main point here is that about 75% of the epigenetic differences between “ethnic sub-groups” are associated with genetic ancestry and cultural/experience differences associated with ethnicity accounted for the other 25%.  

Therefore, there is a two-way interaction between the biological and the social/cultural. Biological differences inform the foundation of ethnic/racial identity (influenced socially by human beliefs about these groups), and cultural differences stemming from these identities can feed back and affect the biology.

“Back in the day” Ursus Major, affiliated with the EASU, talked about a “Race-Culture.”  He was more right then he knew.

Human Biology News: Social Mobility Genes Identified

It’s all in the genes…or at least some of it is.

Dr. Belsky and colleagues matched the genotypes of Dunedin Study participants with the genome-wide associations with educational attainment that had been reported previously. The results revealed that genetic links with educational attainment predict outcomes that go well beyond the completion of schooling, as Dr. Belsky and colleagues hypothesized. 

Details of the Duke study appeared June 1 in the journal Psychological Science, in an article entitled, “The Genetics of Success: How Single-Nucleotide Polymorphisms Associated With Educational Attainment Relate to Life-Course Development.” The study reported five main findings. 

1. Polygenic scores predicted adult economic outcomes, even after accounting for educational attainments.
2. Genes and environments were correlated: Children with higher polygenic scores were born into better-off homes.
3. Children’s polygenic scores predicted their adult outcomes even when analyses accounted for their social-class origins; social-mobility analysis showed that children with higher polygenic scores were more upwardly mobile than children with lower scores.
4. Polygenic scores predicted behavior across the life course, from early acquisition of speech and reading skills through geographic mobility and mate choice and on to financial planning for retirement.
5. Polygenic-score associations were mediated by psychological characteristics, including intelligence, self-control, and interpersonal skill.

Of course the major question: does this differ between population groups? 
What about all the hand-waving about “the associations are small?” 
Three points: 
1. Additional studies may uncover new genotype-phenotype associations that increase the fraction of the “social mobility phenotype” influenced by genes.

2. Even if the associations remain small, these small effects need to be multiplied over large numbers of people, particularly if differences exist between population groups, and over evolutionary time, and one will therefore likely see important large scale gene-based behavioral patterns emerging at the mass level, based on these “small” associations. 

3. Point #2 of the paper is key: the correlation between genes and the environment. 
Even if the genetic influence is “small,” that influence can alter the environment and that environmental change can not only directly affect phenotype, but can further select gene frequencies. Therefore, a positive feedback loop between genes and the environment, connected through resultant phenotypes, can be established even with “small” associations. Those associations “get the ball rolling” and the effects are amplified; the “better off homes” noted by the authors are the result of the parents’ genes and those of the surrounding population.