The Denisovans were an ancient group of humans that may be less familiar to you than the more commonly referenced Neanderthals. But part of that unfamiliarity may be due to the fact that the entire collection of Denisovan remains includes a pinky bone, three teeth, and a lower jaw. Exactly what our Denisovan relatives looked like has remained a mystery.
But now, a new study published in the journal Cell shows reconstructions of our ancient relatives based on patterns of methylation in their DNA.
“We provide the first reconstruction of the skeletal anatomy of Denisovans,” says author Liran Carmel of the Hebrew University of Jerusalem. “In many ways, Denisovans resembled Neanderthals, but in some traits, they resembled us, and in others they were unique.”
To get these results, the researchers extracted anatomical information from gene activity patterns that they inferred based on genome-wide DNA methylation or epigenetic patterns. These patterns are chemical modifications that influence gene activity, but don’t change the underlying structural sequence of base pairs (the As, Gs, Ts, and Cs that make up a DNA strand).
The researchers searched for differences in methylation patterns between Neanderthals, Denisovans, and humans. They then analyzed what these differences may affect for anatomical features based on known human disorders where these same genes lose their function.
“By doing so, we can get a prediction as to what skeletal parts are affected by differential regulation of each gene and in what direction that skeletal part would change – for example, a longer or shorter femur,” explains David Gokhman, the study’s first author.
Ultimately, they were able to identify 56 anatomical features in which Denisovans differed from Neanderthals and/or modern humans. Of these 54 differences, 34 were in the skull. According to the results, it’s like the Denisovan’s skull was wider than the other two hominid groups, and they probably also had a longer dental arch. However, it’s likely the Denisovan’s shared Neanderthals traits such as an elongated face and wide pelvis.
Carmel notes that while their paper was being reviewed, another study was published that describes the first confirmed Denisovan mandible. In a stroke of unbiased support, it turns out that this jaw bones matches their predictions.
This approach to anatomical reconstruction through DNA methylation could have a wide range of applications in science. “Studying Denisovan anatomy can teach us about human adaptation, evolutionary constraints, development, gene-environment interactions, and disease dynamics,” says Carmel. “At a more general level, this work is a step towards being able to infer an individual’s anatomy based on their DNA.”
By Connor Ertz, Earth.com Staff Writer
Main Image Credit: Maayan Harel