How a Few Small Mutations Allowed for Bipedalism in Humans

How a Few Small Mutations Allowed for Bipedalism in Humans

Benjamin Pruss
BIOL-2110-001 GENETICS
Professor Guy F. Barbato
November 11th, 2025

    

    Recently, two small genetic mutations were found that helped early man achieve bipedalism. All of our cousins, the great apes, are quadrupeds that can only walk on two legs for short periods of time. However, because of a set of small mutations, we can live our lives on two legs.

    These mutations, which affect the pelvis, or more specifically, the ilium, did two things: firstly, they rotated the pelvis 90 degrees. This changed the way the muscles were attached to the pelvis, becoming better suited to standing on two legs than walking around on four. Secondly, the amount of time it takes for the ilium to harden increased, allowing the pelvis to grow wider, which helped stabilize the body for an upright lifestyle.

    The discovery was made by Gayani Senevirathne and peers in 2025, when they were comparing human, chimp, and mouse pelvic tissue while studying hip disorders. Bipedalism was an important evolutionary change that helped shape humanity as a species. "One of the most significant things about this change is it shows how critical it was to establish the ability to stand on one foot at a time, which lets us walk on two feet," says anthropologist Carol Ward from the University of Missouri. One of the authors of the research article, Terence Capellini, also believes that the widening of the hips also led to a larger birth canal, which would have allowed for larger-brained babies.

Sources

https://www.sciencenews.org/article/genetic-shifts-helped-humans-walk-two-legs

https://www.nature.com/articles/s41586-025-09399-9

Pre-Historic Humans Survived Despite Risky Genes

In a recent study, researchers found that before the ice age a gene that reduces height and increases the risk of osteoarthritis was favorable for survival. As humans migrated north towards colder climates the mutation may have helped the early humans retain warmth and avoid frostbite due to their shorter size. This gene may also have helped humans to avoid bone fractures when they fell on ice. This may come as a surprise due to the fact that today this gene would be seen as detrimental and puts an individual at a higher risk for developing arthritis. Scientist looked into the GDF5 gene, which is known to be involved in skeletal growth. They found a mutation in a single nucleotide, in an area named GROW1 and noticed its prevalence in Europeans and Asians, but not Africans. The researchers then tested the gene in mice and found that it shortened their bone length, similar to what was found in humans. The paradoxical effect of this gene is similar to that of sickle cell anemia and it's protection from malaria. I believe this shows just how complex the human genome is and how different genes play a role in human survival. It is possible that having a detrimental gene could be the key to our survival.

Article

Say Hello To Your Cousin

A new branch in our family tree was just recently added. After a long and close quarters expedition into a cave named Rising Star, (South Africa) the skeleton of a never before seen primitive human was completely excavated. Everyone say hello to Homo Naledi, the newest edition to a growing list of early human hominids.

This specimen exhibited many humanesque features such as the hands, feet, and skull along with displaying some australopithecine features. Figuring out naledi’s place in our evolutionary tree will take some time. Some predictions so far could completely change our tree putting naledi as a very close cousin to homo sapiens or they could be placed right in the beginning next to australopithecus. Studying these bones also helps us understand early human genetics and how we were shaped into the living organisms that we are today. Considering the fact that naledi’s skull cavity was about 50% the size of today’s human skull size, I would like to think some major genetic changes have occurred since then. By understanding these past humans, we may even be able to see where we are headed in the future. Although it is hard to see, we are all still evolving!

The more in depth article can be found here!