A gene mutation millions of years ago gave modern humans the ability to run long distances, a new study has found.
This single change in one strand in the DNA completely altered the path of the human species, making forest dwellers into hunter-gatherers who eventually dominated the world.
It's In The Genes
About 2 to 3 million years ago, a single mutation in the DNA of the early human species triggered a series of changes in the body, including the ability to run long distances without feeling exhausted. This is how humans distinguished themselves from other mammals during the hunter-gatherer phase. Instead of releasing a quick spurt of energy like a cheetah to catch a prey, humans pursue their target until it is too tired to keep running.
The tactic proved to be effective especially when the forests in Africa became savannahs and eventually, the human ancestors started to evolve dramatically. Early hominids, who developed longer and springy legs, bigger feet, strong gluteal muscles, lost their fur and expanded sweat glands that helped make the species great long-distance runners.
The gene in question is called the CMP-Neu5Ac Hydroxylase or CMAH. Other primates such as chimps also have the gene that helps them build a sugar molecule. However, humans have a broken version.
A new study led by Ajit Varki, a physician-scientist from the University of California San Diego, wanted to explore the CMAH and its effects on the muscles and the running abilities of the species that has it. For their experiment, Varki and his team put mice with both normal and broken CMAH on a small treadmill. UCSD physiologist Ellen Breen examined the leg muscles of both groups before and after the experiment.
Becoming Excellent Marathoners
"We evaluated the exercise capacity (of mice lacking the CMAH gene), and noted an increased performance during treadmill testing and after 15 days of voluntary wheel running," stated graduate student and study author Jon Okerblom.
According to the study, the mice that have broken CMAH, like humans, were able to run 12 percent faster and 20 percent longer than those who have the normal gene. They also have more blood vessels into their leg muscles that contract longer when in motion.
The researchers also discovered that the mice that have the broken gene controlled their oxygen more efficiently.
"Here is highly convincing evidence," said human evolutionary biologist Daniel Lieberman, who was not involved in the study. "It's an obliging share of the puzzle about how humans came to be so good."
The study was published in Proceedings of the Royal Society.