Those who are born to parents from diverse genetic backgrounds tend to be taller and have sharper thinking skills than others, the major international study has found.
But can we unharness the cart from the horse here? Wouldn’t smarter people be more likely to look to genuine advantage as opposed to narrow bigotry, when picking mates?
Researchers analysed health and genetic information from more than 100 studies carried out around the world. These included details on more than 350,000 people from urban and rural communities.
The team found that greater genetic diversity is linked to increased height. It is also associated with better cognitive skills, as well as higher levels of education.
It’s at least worth noting that small stature can be (but of course is not always) related to malnutrition, which is less likely among smarter people, given a chance.
Here’s the abstract:
Homozygosity has long been associated with rare, often devastating, Mendelian disorders1, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness2. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power3, 4. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10-300, 2.1 × 10-6, 2.5 × 10-10 and 1.8 × 10-10, respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months’ less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples5, 6, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection7, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been. (paywall) – Peter K. Joshi, Tonu Esko, Hannele Mattsson, Niina Eklund, Ilaria Gandin, Teresa Nutile, Anne U. Jackson, Claudia Schurmann, Albert V. Smith, Weihua Zhang, Yukinori Okada, Alena Stancáková, Jessica D. Faul, Wei Zhao, Traci M. Bartz, Maria Pina Concas, Nora Franceschini, Stefan Enroth, Veronique Vitart, Stella Trompet, Xiuqing Guo, Daniel I. Chasman, Jeffrey R. O’Connel, Tanguy Corre, Suraj S. Nongmaithem et al. Directional dominance on stature and cognition in diverse human populations. Nature, 2015 DOI: 10.1038/nature14618
All we really know about human evolution.
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