Are you envious of Dutch men and Latvian women? They are, after all, the tallest people on the planet, and there are a variety of theories as to why this may be. As a new study by researchers at the University of Washington’s School of Medicine (UWSM) reveals, Neanderthals may have had something to do with it.
Homo neanderthalensis, our ancestral cousins that suddenly died out around 42,000 years, had a thing for getting frisky with H. sapiens. This naughty interaction meant a lot of gene-swapping, and plenty of the human population today derives part of their genome – and its physical effects – from Neanderthals.
Writing in the journal Cell, a team of geneticists wanted to know whether some of these genes were inactive, or whether they played an active role in our own evolution and contemporary biology. As it turns out, these genes affect the way other genes behave or “express” themselves so often that traits like disease resistance and, yes, height, are influenced by them.
“Even 50,000 years after the last human-Neanderthal mating, we can still see measurable impacts on gene expression,” study co-author Joshua Akey, a geneticist at UWSM, said in a statement.
Although working out how much of someone’s genome originates from Neanderthal interbreeding isn’t actually that difficult, isolating individual genes linking them to individual physical traits or behaviors is incredibly difficult, regardless of where they come from.
In order to get around this problem, very specific people were used for this study – those that carry both the Neanderthal and human versions or “alleles” of any given gene, with one coming from each parent. That way, they could directly compare the way these alleles expressed themselves on a head-to-head basis.
They found that in 25 percent of all comparisons, the alleles from the Neanderthal expressed themselves in a different way to their human equivalents. This suggests that, in a quarter of incidences, Neanderthal genes directly impact the biological features of their host human.
It's all about the alleles. Tatiana Shepeleva/Shutterstock
The Neanderthal allele of the gene ADAMTSL3, for example, decreases the risk of schizophrenia in any living human that possess it. This allele also appears to influence height to some degree.
Another allele, CEP72, influences your susceptibility to getting cystic fibrosis. INTS12 is linked to how well blood flows through your lungs if you’re a smoker.
“Hybridization wasn't just something that happened 50,000 years ago that we don't have to worry about anymore,” Akey adds. “Those little bits and pieces, our Neanderthal relics, are influencing gene expression in pervasive and important ways.”
Work will soon be underway to clarify whether or not the Denisovans – another ancestral cousin of humanity – and their interbreeding with humans played a similar role with regards to our genetic expression.