The genetic changes that made possible the transition from knuckle-based scampering in great apes to upright walking in humans have now been uncovered in a new study by researchers at Columbia University and the University of Texas.
Using a combination of deep learning (a form of artificial intelligence) and genome-wide association studies, the researchers have created the first map of the genomic regions responsible for skeletal changes in primates that led to upright walking. The map reveals that genes that underlie the anatomical transitions observed in the fossil record were strongly acted on by natural selection and gave early humans an evolutionary advantage.
Many skeletal changes occurred on the path to modern humans, resulting in bipedalism but also susceptibility to musculoskeletal diseases. Kun
et al. used imaging data from more than 30,000 UK Biobank participants to characterize skeletal proportions, assessing the genetic basis of these features, as well as their relationships to each other. They found that limb proportions are uncorrelated with body width proportions, that there are associations between hip- and leg-related skeletal proportions and osteoarthritis, and that there is enrichment for loci associated with skeletal proportion in genomic regions associated with human-specific evolution. The mentioned study demonstrated the utility of using imaging data from biobanks to understand both disease-related and normal physical variation among humans.
Humans are the only bipedal great apes, owing to our distinctive skeletal form. Morphological changes that contribute to our skeletal form have been studied extensively in paleoanthropology. With the exception of standing height, examining the genetic basis for differential and specific growth of individual bones and their evolution has been challenging because of limited sample sizes.
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