According to a new study published in Nature Communication, tiny genetic changes that emerged in early humans may have played a role in our unique ability to communicate sounds.
Rockefeller University researchers have identified a single amino acid substitution in a protein called Nova1 that is unique to modern humans and appears to affect the vocalization pattern of mice designed to carry this human-specific genetic variant.
The study provides insight into small changes in how human evolution promotes genetic changes in our spoken language abilities.
“NOVA1 is a neuron RNA-binding protein expressed in the central nervous system and is critical for the normal development of mice and humans,” explains the research team led by Yoko Tajima, César DM Vargas and Robert B. Darnell.
Nova1 is highly conserved among transmammals, meaning it has remained almost the same over millions of years of evolution. But after splitting with Neanderthals and Denisovos, somewhere in our lineage, there was a letter in our genetic code that changed, resulting in isoleucine substitution at the Nova1 protein position as valine.
Now, this I197V variant is almost universal in modern humans. When the researchers analyzed genomic data from 650,000 people, they found that only six people carried the ancestral version of the gene – five of which are of Asian descent.
To understand what functions the functional impact of this tiny genetic change might have, the team used CRISPR gene editing to create “humanized” mice carrying the modern human version of NOVA1, rather than the ancestral versions that exist in most mammals.
It is worth noting that these mice develop normally, but when the researchers analyzed the brain, they found how Nova1 affects how NOVA1 affects RNA processing (an intermediate molecule between DNA and protein).
The most interesting discovery was when they recorded the vocalization from these mice. Both pups isolated from mother and male adults during courtship showed altered ultrasound statement patterns compared to normal mice.
“These findings suggest that this human-specific NOVA1 substitution may be part of a selective sweep of ancient evolution, and in a common ancestral population, it may promote the development of spoken language through differential RNA regulation during brain development,” the researchers noted.
Co-author on paper, Erich D. Jarvis, an expert on neurogenicity in vocal learning, found that highly expressed in brain regions associated with mouse vocalization supports the idea that modifying these ancient circuits could lead to advanced vocal capabilities in humans.
The study is based on previous studies of genes potentially involved in human language evolution. FOXP2 is sometimes called the “linguistic gene” and has been extensively studied since it was discovered in a family with severe speech and language problems. Interestingly, the researchers noted that the vocalization of its humanized Nova1 mice had similarities with those in mice carrying the human version of FOXP2.
However, unlike the FOXP2 variant that also exists in Neanderthals, the Nova1 I197V change seems to be unique to modern humans, suggesting that it has recently emerged in our evolutionary history.
The researchers conducted extensive molecular analysis to understand how this single amino acid change affects Nova1’s function. They found that while this change does not affect the ability of proteins to bind to RNA, it does change the processing power of specific RNAs, especially those involved in vocalization.
Professor Simon Fisher, director of the Max Planck Institute for Psycholinguistics, who was not involved in the study, commented that the study “adds an important work to how specific genetic changes in modern humans affect our complex communication abilities.”
Although this study does not claim that this single genetic change gives humans the gift of language, it suggests that the accumulation of genes that affect brain development and vocal cords may jointly promote the unique communication capabilities of our species.
These findings also highlight how to study the effects of human-specific genetic changes in animal models that can provide insights into human evolution that cannot be obtained only from fossil records.
As we continue to compare the modern human genome to the genome of our extinct relatives and test the function of human-specific genetic mutations, we may gain a deeper understanding of the biological basis that makes us unique to human traits.
The study was published in Nature Communications on February 8, 2025.
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