Secrets of our ancient relatives: Neanderthal genes deform mice

Morphological differences between hominid and human species.

However, the researchers noticed distinct morphological differences between these ancient hominid species and modern humans, including elongated and low crania, larger brow ridges, and broader rib cages.

Seeking to understand how the ancient form of the GLI3 gene influenced the development of our extinct cousins, the scientists engineered mice to carry a faulty version of the gene. The results were startling, as the rodents developed severe skull and brain deformities, along with polydactyly. This experiment confirmed the vital role of a functioning GLI3 gene in healthy embryonic growth.

In contrast, mice engineered to carry the Neanderthal and Denisovan version of the gene displayed altered skeletal structures, such as enlarged craniums, distorted vertebrae shapes, and rib malformations. These findings suggest that while the ancient gene didn't entirely disrupt embryonic development, it did significantly impact the morphology of our ancient human relatives.

Compared to regular mice, those with the archaic gene exhibited fewer vertebrae and stronger rib torsion, reminiscent of the differences observed between modern humans and Neanderthals. Intriguingly, some of these mice displayed asymmetric rib cage shapes associated with scoliosis, a condition that recent studies have indicated Neanderthals may have been susceptible to, along with macrocephaly or enlarged head size.

These findings indicate that the archaic version of the GLI3 gene carried by Neanderthals and Denisovans may have played a significant role in shaping their distinctive head and body structures. The scientists involved in the study suggest that these traits are linked to the predicted lifestyles of Neanderthals, hinting that the ancient gene provided beneficial characteristics for our extinct hominin relatives.

It is important to note that the study is currently awaiting peer review. Once published, these findings are expected to ignite further research into the fascinating world of human evolution, offering valuable insights into the genetic and physical attributes that make us who we are today.