Throughout my American Nations series (based on the books American Nations: A History of the Eleven Rival Regional Cultures of North America by Colin Woodard and Albion’s Seed: Four British Folkways in America by David Hackett Fischer) I’ve talked about how North America is divided into distinct ethnocultural regions based on historic settlement patterns.
These various regions are visible in many ways, from dialect, politics, enlistment in the military, support for marijuana, average IQ (Maps of the American Nations), attitudes towards the death penalty, abortion, guns, same-sex marriage, and school corporal punishment, as well as overall health, lifespan, and behaviors such as smoking and drug use (More Maps of the American Nations & HBD Is Life and Death):
Previously I’ve established that these boundaries reflect genetic differences among different Americans in different places. This is because all human behavioral traits are heritable, with “nurture” (as it’s commonly thought of) playing a minimal to nonexistent role in each. This means that genetic differences between different peoples lead to differences in their behavioral traits, which, collectively, manifests as cultural differences. As John Derbyshire put it, “if dimensions of the individual human personality are heritable, then society is just a vector sum of a lot of individual personalities.” See my Behavioral Genetics Page for more.
It’s also important to note that (as I’ve discussed previously in this series) assimilation is largely an illusion. Cultural and behavioral characteristics can persist for many generations as long as the people who exhibit them remain.
And now, a new paper in Nature bears out the genetic roots of the American nations. In “Clustering of 770,000 genomes reveals post-colonial population structure of North America” (Han et al, 2017), we see that Americans can easily be partitioned into distinct regional clusters:
These clusters map very closely to the boundaries of the American nations, as we can see when they’re superimposed:
Using the vast genomic database of Ancestry.com, the authors were able to partition Americans into distinct clusters. As the authors report:
Here we identify very recent fine-scale population structure in North America from a network of over 500 million genetic (identity-by-descent, IBD) connections among 770,000 genotyped individuals of US origin. We detect densely connected clusters within the network and annotate these clusters using a database of over 20 million genealogical records. Recent population patterns captured by IBD clustering include immigrants such as Scandinavians and French Canadians; groups with continental admixture such as Puerto Ricans; settlers such as the Amish and Appalachians who experienced geographic or cultural isolation; and broad historical trends, including reduced north-south gene flow. Our results yield a detailed historical portrait of North America after European settlement and support substantial genetic heterogeneity in the United States beyond that uncovered by previous studies.
They describe their methods:
To investigate recent, fine-scale population structure in the United States, we leveraged one of the largest human genetic data sets assembled to date: genome-wide genotypes of 774, 516 individuals born (96%) or currently residing (4%) in the United States (Supplementary Table 1; Supplementary Fig. 1). All individuals were genotyped at 709, 358 autosomal single-nucleotide polymorphisms (SNPs) using the Illumina Human OmniExpress platform as part of the AncestryDNA direct-to-consumer genetic test, and have consented to participate in research (Methods). In this sample, we analysed patterns of identity-by-descent (IBD)16, which have been shown to reveal signatures of recent demographic history3,17,18,19,20,21. If two individuals share an ancestor from the recent past, they will likely carry one or more long chromosomal segments inherited IBD from that ancestor.
In short, their giant sample and rich genealogical data allowed them to detect large patterns of shared ancestry in living Americans. And, as expected the American nations clearly emerge from the genetic data.