,
11 tweets,
6 min read
Read on Twitter
In 2000 the HGP quoted an audacious statistic about the level of DNA similarity between different humans that was quickly adopted by academics, pro-egalitarian activists, and race-deniers. These groups have loudly championed this statistic with patronizing adulation ever since. 
But is it true? The HGP’s findings were predicated on the assumption that all parts of human genome are identical except for SNPs (changes to single nucleotides that can regulate allelic expression in genes) which they calculated at a maximum variance of 0.1% between all humans.
Studies involving a new trend in molecular genetics called DNA copy number variations (CNVs) that challenges the stat. were first published in 2002 but have been absent from much of the subsequent social commentary and mainstream news articles.
#CNVs are repetitive sequences that can produce disparities in the number of base pairs between each of the two complimentary DNA strands we receive (one from each parent) ..leading to either more or less than the expected number of genes in the tandem sequence.
The human genome contains around 3 billion base pairs and roughly 10 million SNPs. The number of genes is currently estimated at just below 30,000 – quite small in relative terms. To date, about 2000 CNVs have been identified with thousands more predicted.
Until recently it was thought SNPs were the primary loci that control genetic variation. We now know that CNVs contain about 3 times the nucleotide density of SNPs and may be of greater importance in the variation scheme than previously thought affecting things like appearance,
IQ, disease, drug resistance, etc. Other discoveries such as #Indels, segmental duplications (LCRs), and #AluElements along with CNVs have given birth to a whole new understanding of genetic variation that surpasses the previously understood limits restricted to SNPs.
Some studies have shown that CNVs have the capability to control expression not just of genes they overlap or co-locate with, but also of genes as far away from their site location as 2 million base pairs or more denoting an unprecedented level of control at significant distance.
It is becoming recognized and accepted that structural and regulatory functions are more important in the grand variation scheme than the genes themselves. This is the essence of how genetics can be applied to the dichotomy of #RaceRealism vs. #RaceDenial.
For years scientists have been threatened for highlighting biological differences between the races. In 2006 a British study by WTSI showed CNVs place the DNA of different races at a maximum similarity of 88% or minimum disparity of 12% of the genome – invalidating the 99% stat.
