The CMAH gene, also found in chimps, is actually broken in humans.
From an evolutionary viewpoint, the ability of humans to maintain long distance running is what helped us catch our prey thousands of years ago. However, it may have also been the main reason we managed to conquer the world. And, according to a new study, this trait is all because of a broken gene.
According to Science Magazine, a new study has delved into just how humans managed to become so great at long distance running. The study has been conducted by Ajit Varki, a physician-scientist at the University of California, San Diego, and his team of researchers. Previously, Varki had been responsible for a study that identified “one of the first genetic differences between humans and chimps.” This study, conducted 20 years ago, identified a gene called CMP-Neu5Ac Hydroxylase (CMAH). Chimps have this gene and so do humans. However, humans have a broken version of the gene.
The new study delved further into the CMAH gene and applied their knowledge of it to tests conducted on mice. Previously, the group knew that CMAH helped to “build a sugar molecule called sialic acid that sits on cell surfaces.” In humans, this sugar is not made.
In the new study, Varki and his team “explored whether CMAH has any impact on muscles and running ability,” according to Science Magazine.
In the lab, UCSD graduate student Jonathan Okerblom placed mice on treadmills. Some of these mice had the normal version of CMAH, others had the human, or “broken” version. The study found that mice with the broken gene “ran 12 percent faster and 20 percent longer than the other mice” in the study. In addition, it was discovered that the “humanized” mice used oxygen more efficiently than the other mice.
The reason behind this vast improvement seems to lie in the fact that the humanized mice had more tiny blood vessels branching out into their leg muscles which led to an improvement in their running ability, in particular, their ability for endurance, or long distance, running.
A human evolutionary biologist at Harvard University, Daniel Lieberman, who was not involved with the study, weighs in on the evidence.
“This is very convincing evidence,” says Daniel Lieberman. “It’s a nice piece of the puzzle about how humans came to be so successful.”
Leiberman also noted that “Nike would pay a lot of money” for this sort of increase in running ability.
Varki’s team suggests that this broken gene helped human’s ability at long distance running some 2 million to 3 million years ago, thanks to the genetic differences among primates and other animals at that point in time.
Andrew Best, a biological anthropology graduate student at the University of Massachusetts in Amherst, and also not involved in Varki’s study, indicates this is somewhat of a surprise.
“[That’s] slightly earlier than I’d have expected for such a large shift in [endurance],” says Best.
This assumption by Best is based on the fact that skeletal modifications don’t show up in fossil records until much later. Although, it is possible endurance was a trait that humans used well before the skeletal modifications presented themselves thanks to humans needing endurance for “walking and for digging up food.”
However, Jason Kamilar, a biological anthropologist, and also not involved with the new study, points out that while this new research is exciting, it needs to be noted that mice are not humans. As a result of this, “the genetic mechanisms in mice may not necessarily translate to humans or other primates.”
Source: Read Full Article