Modern Humans and Neanderthals May Share Genetic Regions Linked to Complex Language
Language is one of the things that makes modern humans modern. Since the start of our species, we’ve communicated complex ideas in complex ways, with structured systems of rules related to sounds, words, and sentences. Now, a new study helps explain how this works from a genetic perspective.
Published in Science Advances, the study turns to Human Ancestor Quickly Evolved Regions (HAQERs), genetic regulatory regions in the human genome. By linking these HAQERs to communication and tracing their evolution over time, the study shows that these regions, which comprise less than 0.1 percent of the human genome, have a huge impact on language, affecting human language abilities almost 200 times more than other genetic regions.
“What we’re seeing is how a very small part of the genome can have an outsized influence,” said Jacob Michaelson, a study author and professor at University of Iowa Health Care, in a press release, “not just on who we were as a species, but on who we are as individuals.”
According to Michaelson and his team, however, these regions aren’t restricted to our own species. Emerging prior to the Homo-sapiens-and-Homo-neanderthalensis split, HAQERs also appeared in the genomes of the Neanderthals, suggesting that our closest cousins were also able to communicate through complex language.
Read More: When Did Humans Evolve Language?
A Language-Skill “Switch”
Back in the 1990s, Bruce Tomblin, now a professor emeritus at the University of Iowa, worked with 350 elementary school students, assessing their language ability and taking samples of their saliva for further study. Now, around 30 years later, Michaelson and his team have finished sequencing the students’ genomes and have analyzed them, revealing the genetic regions and variants that affected the students’ skills.
Among those regions were HAQERs, genetic sequences that regulate genes, turning them on and off. “These aren’t genes we’re talking about,” Michaelson said in the release, referring to HAQERs. “They’re regulatory regions that act like the volume knob.”
Genetics for Complex Communication
To trace the evolution of these HAQERs over time, Michaelson and his team generated evolutionary-stratified polygenic scores — ratings that helped them assess the age of genetic variants — that revealed when HAQER variations emerged throughout human history.
The scores suggest that these “switches” evolved before modern humans and Neanderthals split into two separate species, hinting that the genetics shaping language abilities in one species also shaped them in the other, despite the other differences in brain development and intelligence that differentiate the two.
“This HAQERs aspect, a sliver of the genome, has remained relatively constant,” Michaelson said in the release, “even as other aspects have been going up and up and up to make modern humans smarter and smarter.”
This, Michaelson said, supports the theory that complex communication supplemented the culture and social structure of the Neanderthals, whose tools, adornments, and artistic artifacts appear in the archaeological record.
Read More: Hand Gestures May Have Been the Start of Human Language
Supporting Language While Staying Small
According to the study authors, HAQERs have stayed surprisingly similar since their emergence in humans, possibly to prevent dangerous outcomes during childbirth. In fact, additional genetic variation in these regulatory regions could fuel developments enlarging the fetal brain and skull, which would threaten mothers and their children during the delivery process.
“We think that early humans maxed out this pathway to developing the kind of brain that could be a vessel for language, and they hit that ceiling pretty early on,” Michaelson said in the release, “while other aspects of genetics that improve brain development for higher intelligence but don’t directly affect fetal brain size, continued to evolve.”
In the future, Michaelson and his team plan to continue their work with the students, who are now adults, many with children of their own, offering opportunities for further study.
“One of the things we’re interested in is disentangling the environmental input from the genetic input, when thinking about how a child masters language,” Michaelson said in the release. “Using that family structure, we hope to separate the direct genetic effects on language and what researchers call ‘genetic nurture’ where the parents’ genetics influence the environment they create for their kids.”
Read More: Hand Gestures Aren’t Always Universal — But We All Use Them to Communicate
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