Unlocking Survival: How Denisovan DNA Shaped the First Americans

The earliest people to set foot in the Americas carried DNA from two extinct human groups: Neanderthals and Denisovans. This ancient DNA may have helped them combat diseases in their new surroundings, according to recent research.

Fernando Villanea, a population geneticist from the University of Colorado Boulder, explained that modern humans today are a mix from several ancient species. As these early people moved into the Americas, they didn’t need to wait for new mutations to adapt to new diseases. Instead, they could utilize genetic traits from Neanderthals and Denisovans to bolster their immune defenses.

The study published in Science examined a gene called MUC19, which is involved in producing mucus. Surprisingly, one in three Mexicans today has a version of this gene similar to that of Denisovans, who lived in Asia between 200,000 and 30,000 years ago.

Past research on MUC19 in Indigenous Americans has shown two trends: people with Indigenous ancestry carry many ancient variants of this gene, and over time, certain MUC19 genes became more common in North American Indigenous groups because they were evolutionarily beneficial.

This new study found that the Denisovan version of MUC19 has grown more common among Indigenous Americans over the years. Villanea noted that this variant came along with Neanderthal DNA, marking the first instance scientists have discovered Denisovan genes that arrived via Neanderthals.

Villanea expressed excitement about these findings, raising questions about whether more such genetic exchanges have occurred in human history.

The team analyzed genetic data from various Latin American populations, including Mexicans, Peruvians, Colombians, and Puerto Ricans. They discovered that Mexicans had the highest prevalence of the Denisovan variant at about 33%, while Peruvians had around 20%. Colleagues believed this is due to Mexicans generally having more Indigenous American DNA than others.

Interestingly, the Denisovan section of the gene was found between Neanderthal-specific DNA, indicating that Neanderthals gained these gene variants via interbreeding with Denisovans, before passing them on to modern humans.

Ripan Malhi, a molecular anthropologist from the University of Illinois, praised the research as impressive and expressed a need to learn more about the role of the Denisovan MUC19 gene.

Moving forward, Villanea and his team plan to analyze biological samples that contain both genomic and trait data to understand better how the Denisovan-specific variants function. These genes could play a role in how the immune system responds to certain pathogens, possibly acting differently from the modern variants.

Overall, this research sheds light on the complex interactions between ancient human species and how they shaped the immune profiles of contemporary populations. Exploring these connections not only contributes to our understanding of human genetics but also offers insights into how genetic variations influence health today.

For more in-depth insights, you can refer to the 1000 Genomes Project and the study published in Science here.

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