NEW YORK – Genetics has largely contributed to changes in height that occurred among Europeans during the last 38,000 years, a new analysis has found.
Height has been variable over the course of human history, with the mean height of early anatomically modern male humans reaching about 175 centimeters (5 feet 8 inches) during the Paleolithic, though then declining to about 164 cm during the Mesolithic before rebounding slightly to about 167 cm during the Bronze Age. Today, the mean adult height of European men ranges between 170 and 180 cm. Bothe genetic and environmental factors — such as genetic drift, climate, and diet — are thought to have influenced these variations.
To tease apart the effects of genetics and environment, a University of Pennsylvania-led team applied a polygenic risk score for height to data from more than 1,000 ancient individuals from Western Europe. As they reported in the Proceedings of the National Academy of Sciences today, they compared that genetically predicted height to heights deduced from bone samples.
"We show that changes over the past 35,000 [years] are largely predicted by genetics," UPenn's Iain Mathieson and colleagues wrote in their paper.
He and his colleagues developed a PRS for height based on GWAS summary statistics from the UK Biobank. They applied this score to published DNA data on 1,071 ancient individuals who lived in Western Eurasia between 38,000 and 1,100 years ago. At the same time, they generated stature estimates for 1,159 individuals who lived between 33,700 and 1,100 years ago based on skeletal data. The researchers noted, though, that while these samples came from similar temporal and geographic locations, there was limited overlap between those datasets, only 12 individuals.
Still, they found that PRS-based estimates of height and skeletal measurements both decreased, as expected, from the Early Upper Paleolithic, more than 25,000 years ago, to the Mesolithic periods and then increased between the Neolithic and post-Neolithic periods.
This initial decrease in height, the researchers noted, correlates with a time of population replacement and these new groups may have been shorter because of cold adaption or changes in resource availability. Meanwhile, the second change in height, an increase, correlates with the influx of Steppe ancestry into Central and Western Europe.
When they broke their PRS down into a score for sitting height and a score for standing height, the researchers noted that, as predicted by the genetic scores, sitting height changed less than standing height. But they also noted that the genetic score predicted a slight sitting height increase in the post-Neolithic era, which was not represented among their skeletal samples. This, they noted, could be due to the influence of environmental factors, opposing genetic effects, or their limited skeletal data.
They also uncovered shifts in height that correlated with geography, noting that even today Northern Europeans tend to be taller than Southern Europeans. In particular, they found that genetically predicted height did not increase with latitude in the Early Upper Paleolithic through Neolithic periods, but does in the post-Neolithic.
The researchers cautioned, though, that their analysis has a number of limitations. In particular, they relied on a PRS developed from a modern population whose underlying genetic population structure differs from these ancient populations, though they noted they tried to account for these differences.
"We must therefore be cautious in the interpretation of predicted genetic patterns where phenotypes cannot be directly measured, even if it is possible to control stratification," they added. "Predicted genetic changes should be used as a baseline, against which non-genetic effects can be measured and tested."