The Evolution of Bipedalism: A Key Milestone in Primate History
Ancestral Transition to Walking Upright
Perhaps the most significant advance in primate evolution occurred about 6 million years ago when our ancestors began to walk on two legs. This gradual transition to bipedal locomotion allowed primates to better adapt to different environments and freed their hands to use tools, which in turn accelerated cognitive development. These changes paved the way for modern man.
Uncovering the Genes Behind Upright Posture
The genetic changes that made the transition from articulated running to walking upright possible in humans have been uncovered in a new study by scientists at Columbia and Texas Universities. These genes have shaped the human skeleton over tens of thousands of years, influencing various aspects from the width of our shoulders to the length of our legs.
Implications for Arthritis Research
In a paper published in the journal Science, the research team identified variants associated with arthritis, potentially opening the door to a future where doctors can better predict a patient’s risk of developing arthritis. Hip, knee, and osteoarthritis, the leading causes of adult disability in the United States, were specifically studied and associated with genetic and skeletal variants.
The Significance of Bipedalism
The ability to walk upright, known as bipedalism, is one of humanity’s defining physical features. It provided early humans with an evolutionary advantage, as evidenced by the genetic and anatomical changes seen in the fossil record. Through a combination of deep learning and genome association studies, scientists have created the first map of the genomic regions responsible for the structural changes in primates that lead to upright posture.
Studying the Human Skeleton
For their study, the team analyzed more than 31,000 full-body x-rays from the British Biobank, a comprehensive online database of medical and lifestyle records. Using genome-wide association studies, they identified 145 points in the genome that control the size of the skeleton, providing genetic evidence of the selective pressure on variants that influence skeletal size.
Linking Skeletal Proportions to Joint Disorders
The team also discovered correlations between skeletal proportions and joint disorders. Individuals with a higher hip-to-height ratio were more likely to suffer from osteoarthritis and hip pain. Similarly, those with a higher hip-to-length ratio had a higher likelihood of developing knee arthritis, knee pain, and other knee problems. Additionally, people with a higher torso length-to-height ratio were more prone to back pain.
Overall, the findings highlight the impact of lifelong biomechanical stress on joint health and demonstrate how skeletal proportions can serve as risk factors for various joint disorders.
Source: Independent
