Why Did Humans Evolve to Run Long Distances Around 2 Million Years Ago, Unlike Other Primates? — Here’s What Researchers Found Out

Have you ever wondered why humans are so good at running? We are not the fastest or the slowest, but we can run longer than most other animals. Primates like apes and chimpanzees, with whom we have a distant common ancestor, do not run like we do. Instead, they climb trees, walk, and sometimes sprint hop.

This is most likely because of the way our human body adapted to have a tailored anatomical and physiological structure and features to literally be able to run their prey to exhaustion. But why exactly did we develop this body that is so good at running long distances around 2 million years ago? What made us the homo genus species different from other primates? Let’s explore these questions.

What Is the Endurance Running Hypothesis?

The endurance running hypothesis is a theory that states the human species under the genus Homo has developed specific traits that allow them to run long distances. The idea also encompasses the thought that early humans used this skill to run their prey to exhaustion before taking them down. A survival strategy also known as persistence hunting.

The ability to run long distances may also have been used to scavenge at first and not hunt right away. But why did humans need these adaptations in the first place, and not the primates? The reason could be explained by another theory called the open savanna hypothesis.

This idea refers to the changes in the environment that our ancestors lived in. The forestry area, because of climate change, has receded, and the open woodlands, savannas, and deserts have expanded. This created an evolutionary pressure for our ancestors to learn how to walk, stand upright, lose their fur, and eventually be able to run long distances to efficiently scavenge and hunt under the heat of the sun.

There are many other factors that could have influenced those changes in the human body; however, these are some of the most significant, which include the literal change in environment and the adaptations to survive in it.

The endurance running hypothesis is also supported by fossils and is estimated to have occurred around 2 million years ago. The skill to run long distances may have actually evolved earlier, but this is when scientists have recorded having leg bones and traits that are different from those of earlier hominins. It made our ability to run more efficient and longer.

Read more: University of Utah: Endurance running and the evolution of Homo

Which Anatomical Features Changed for Long-Distance Running

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So, which parts of the human body evolved specifically or significantly for long-distance running? First is the structure of the foot and the legs. Earlier Homo species have developed stiffer foot arches, longer lower legs, and changes in heel bones that act like a string. So, at each step, energy is conserved, and they are propelled forward. For long-distance running, this made it less tiring and more efficient.

Longer legs also made each stride reach farther distances. This increased the speed of running without proportionately increasing the energy expenditure. Another is the Gluteus Maximus Muscle, which stabilizes the trunk while running. It is noticeably larger and more prominent in humans than in primates.

There was also a change in the upper body and especially in the head and neck areas. Humans developed a ligament at the back of their neck that allowed the head to stay in position and not shake around while running. The upright position of our bodies and the spine’s shape also support energy-efficient long runs.

Why Did This Start Around 2 Million Years Ago?

So, what exactly happened around 2 million years ago for fossil evidence to begin showing changes in the hominin species to adapt a body that is suited for long-distance running? Earlier, we mentioned the open savanna hypothesis, but let’s explore more of this idea.

When the climate changed, and the forests receded and the grasslands expanded, it did not only mean that humans would have to occupy smaller habitable areas. That is most probably what the apes did, as they stayed mostly in the forestry areas where, up to this day, they are still perfectly adapted to.

However, human ancestors ventured long distances to find more food, water, shelter, and other resources. In this new environment, being able to run a long distance became more advantageous. Around 2 million years ago, hominins were not yet the undeniable apex predators on whom no other species could prey.

They were smaller, weaker, and lighter, so hunting prey would prove to be difficult, even after developing some basic stone tools. Other animals were a lot faster, so humans may have hunted using persistence instead of burst speed. They stalked, tracked, chased, and waited patiently during the heat of the sun until their prey was exhausted and too weak to run away. Examples would be antelopes and deer.

Over time, these behaviors and survival strategies proved advantageous. Traits that helped with running long distances were favored naturally. In other words, those who can walk and run long distances better were able to survive longer, reproduce, and then pass on their genes. Humans of the genus Homo show these changes in fossils.

Read more: Smithsonian

How Do We Know It’s Different from Other Primates?

How Humans Evolved To Become The Best Runners On The Planet

Whereas humans evolved to run longer distances, most other primates or hominids did not, and these are some of the differences. First, chimpanzees, gorillas, and others have noticeably shorter legs relative to their body, flatter feet, and longer toes for climbing. In other words, their bodies are adapted not to long ground travel but to climbing in trees and surviving in the forestry areas.

Another difference is sweating. Humans sweat a lot more than other species because it allows us to thermoregulate our bodies to be able to run longer under the heat of the sun. However, the lower density of sweat glands and thicker fur in primates limit their abilities to walk or run long distances during the heat, as they are at risk of overheating without the right body structure to cool down.

Author's Final Thoughts

Based on the way our bodies developed in modern times, and as suggested by the fossils found from millions of years ago, humans evolved to run long distances. It resulted in traits and changes in our limbs, feet, posture, muscles, and cooling systems. These changes also did not happen randomly; most were advantageous in helping our ancestors survive the changing landscape and be able to pass on their genes.

Our ability to run long distances or endurance running is a part of what makes humans and species under the genus Homo special. It is one of the key survival strategies and adaptations that led us to who we are and how we move today.

Read next: Why Did Humans Evolve to Have Such Long Childhoods Compared to Other Animals? — Here’s What Experts Say

References & Further Reading

Bramble, D. M., & Lieberman, D. E. (2004). Endurance running and the evolution of Homo. Nature. https://doi.org/10.1038/nature03052

Carrier, D. R. (1984). The energetic paradox of human running and the evolution of hominid hunting. Current Anthropology. https://doi.org/10.1086/203165

Lieberman, D. E., & Bramble, D. M. (2007). The evolution of marathon running: Capabilities in humans. Sports Medicine. https://doi.org/10.2165/00007256-200737040-00004