A new study has found that neanderthal DNA sequences still influence how genes are turned on or off in modern humans, adding to traits like height and susceptibility to schizophrenia.
"Even 50,000 years after the last human-Neanderthal mating, we can still see measurable impacts on gene expression," said Joshua Akey, of University of Washington in the US.
"Those variations in gene expression contribute to human phenotypic variation and disease susceptibility," Akey said. Previous studies have found correlations between Neanderthal genes and traits such as fat metabolism,depression and lupus risk.
Researchers analysed ribonucleic acid (RNA) sequences in a data set called the Genotype-Tissue Expression (GTEx) Project, looking for people who carried both Neanderthal and modern human versions of any given gene, one version from each parent.
For each such gene, the study then compared expression of the two alleles head-to-head in 52 different tissues.
"We find that for about 25 per cent of all those sites that we tested, we can detect a difference in expression between the Neanderthal allele and the modern human allele," said Rajiv McCoy, post doctoral researcher at University of Washington.
Expression of Neanderthal alleles tended to be especially low in the brain and the testes, suggesting that those tissues may have experienced more rapid evolution since we diverged from Neanderthals about 700,000 years ago.
"We can infer that maybe the greatest differences in gene regulation exist in the brain and testes between modern humans and Neanderthals," Akey said.
One example uncovered by the study was a Neanderthal allele of a gene called ADAMTSL3 that decreases risk ofschizophrenia, while also influencing height.
"Previous work by others had already suggested that this allele affects alternative splicing. Our results support this molecular model, while also revealing that the causal mutation was inherited from Neanderthals," McCoy said.