September 24 (UPI) – Today, a fresh meal is much easier to find than it was 50,000 years ago. All you need is a few dollars and a trip to the restaurant or grocery store – no scavenging or hunting is necessary.
The relative ease of modern life may explain why a variant of the human growth hormone receptor gene known as GHRd3 is now so rare, according to a new study.
The variant, which first appeared 1-2 million years ago, was dominant among Neanderthals and Denisovans, as well as the closet ancestors of modern humans. Today, however, the variant is much less common.
New research, published Friday in the journal Science Advances, suggests that its reduced presence among modern populations is a reflection of technological advances made by humans over the past 50,000 years.
In the past, GHRd3 likely helped early humans and their loved ones survive times of scarcity, but human material conditions have improved dramatically.
The latest genomic analysis reflected this dramatic change.
“You have a massive decrease in the frequency of this variant among the East Asian populations that we studied, where we see the estimated frequency of alleles drop from 85% to 15% over the past 30,000 years.” said study author Omer Gokcumen, an evolutionary biologist at the University of Buffalo, said in a press release.
As the name suggests, human growth hormone receptor genes facilitate the reception of human growth hormone, which dictates a range of cellular processes related to growth. The genes of such an import are generally conserved across species.
But while the variant was common among archaic humans, including several Neanderthal and Denisovan lineages, it has become a common deletion for modern humans.
It’s not that GHRd3A isn’t useful. According to the latest study, the presence of GHRd3 was associated with better survival and health outcomes in children with severe malnutrition. Further experiments showed that the variant helped mice cope with periods of reduced food access.
“Our study highlights the gender and environmental specific effects of a common genetic variant. In mice, we observed that GHRd3A leads to a ‘female-like’ expression pattern of dozens of genes in mice. male livers under calorie restriction, potentially leading to the observed size reduction, âsaid study author Marie Saito, a researcher at the Norwegian University of Life Sciences.
“Women, who are already smaller in stature, can suffer negative evolutionary consequences if they lose weight,” said co-author Dr. Xiuqian Mu, associate professor of ophthalmology at Buffalo.
“So, it is a reasonable and also very interesting hypothesis that a genetic variant that can affect the nutritional stress response has evolved in a gender-specific way.”
Animals did not give up GHRd3A like humans did, making it difficult to discover the reasoning behind its removal in modern humans. Advances in gene-editing technology have allowed researchers to design mouse models without GHRd3A, revealing the effects of deleting the variant.
“This is an exciting time for researching human evolution, where it is now possible to integrate data from ancient genomes, gene editing technologies and advanced mathematical approaches to tell human history into all its glory, âGokcumen said.