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 beginning of our species, we have 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 Scientific advancesthe study turns to the rapidly evolving regions of human ancestors (HAQER), genetic regulatory regions of the human genome. By linking these HAQERs to communication and tracing their evolution over time, the study shows that these regions, which represent less than 0.1% of the human genome, have a huge impact on language, affecting human linguistic 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,” Jacob Michaelson, study author and professor at University of Iowa Health Care, said in a news release, “not only on who we were as a species, but on who we are as individuals.”
According to Michaelson and his team, these regions are not limited to our own species. Appeared before Homo sapiens-And-Homo-neanderthalensis Divided, HAQERs also appeared in the genomes of Neanderthals, suggesting that our closest cousins were also capable of communicating through complex language.
Learn more: When did humans evolve language?
A language skills “switch”
In the 1990s, Bruce Tomblin, now professor emeritus at the University of Iowa, worked with 350 elementary school students, assessing their language skills and taking samples of their saliva for further study. Now, about 30 years later, Michaelson and his team have completed sequencing the students’ genomes and analyzed them, revealing the genetic regions and variants that affected the students’ skills.
Among these regions were HAQERs, genetic sequences that regulate genes, turning them on and off. “These are not genes we are talking about,” Michaelson said in the release, referring to HAQERs. “These are regulatory regions that act like a volume knob.”
Genetics for complex communication
To trace the evolution of these HAQERs over time, Michaelson and his team generated evolutionary stratified polygenic scores – assessments that helped them assess the ages of genetic variants – which revealed the appearance of HAQER variations over the course of human history.
The findings suggest that these “switches” evolved before modern humans and Neanderthals split into two distinct species, suggesting that the genetics that shape language abilities in one species also shaped them in the other, despite other differences in brain development and intelligence that differentiate the two.
“This aspect of HAQERs, a fragment of the genome, has remained relatively constant,” Michaelson said in the release, “even as other aspects have grown increasingly to make modern humans increasingly intelligent.”
This, Michaelson says, supports the theory that complex communication complemented the culture and social structure of Neanderthals, whose tools, ornaments and artistic artifacts appear in the archaeological record.
Learn more: Hand gestures may have been the start of human language
Support the tongue while remaining small
According to the study authors, HAQERs have remained strikingly similar since their appearance in humans, likely to avoid dangerous outcomes during childbirth. In fact, additional genetic variation in these regulatory regions could fuel developments that enlarge the fetal brain and skull, which would threaten mothers and their children during the birthing process.
“We think that early humans exploited this pathway to the fullest to develop the type of brain that could be a vessel for language, and they hit that ceiling quite early,” Michaelson said in the release, “while other aspects of genetics that enhance brain development for higher intelligence but do not directly affect fetal brain size, continued to evolve.”
Moving forward, Michaelson and his team plan to continue their work with the students, who are now adults, many of whom have children of their own, providing them with the opportunity to continue their education.
“One of the things we’re interested in is disentangling environmental input from genetic input, when you think about how a child masters language,” Michaelson said in the release. “By using this family structure, we hope to separate direct genetic effects on language and what researchers call ‘genetic upbringing,’ in which parents’ genetics influence the environment they create for their children.”
Learn more: Hand gestures aren’t always universal, but we all use them to communicate
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