Walking on two feet, which is called bipedalism, is one of the main things that remains mysterious in human history. When and how our ancestors learned to walk on two feet is not well known. But, it is surely known that bipedalism pushed human civilization forward. So, are you interested to know who invented walking? Let’s begin the journey to know how our ancestors first learned to walk on their two feet!

 Well, if you are asking, “who invented walking?” – The answer is probably the dinosaurs! Yes, walking existed even before humans came into existence.

Our crossest mammals, the chimpanzees use their four hands and feet in a method called “knucklewalk” to move around.But, humans invented a new type of walking, bipedalism, or walking on two legs. All the other animals have walked on their four legs throughout history except us!

Probably our ancestors from Africa first started to practice bipedalism. Africa is called the birthplace of human civilization. This place has nurtured hominids. Or early humans or human-like species gradually evolved into the modern Homo Sapiens.

But it is not known which of the ancient hominid species started to walk first on the earth. Scientists are still trying to find the answer!

Whatever the case, walking was not invented overnight. Human ancestors first started to walk with bent knees and wobbly feet as the weather became warmer, and grasses grew more frequently during the Pleistocene era. As time passed, the species evolved, and they gained better physiological features to walk with ease. So, it probably took hundreds of years for our ancestors to become perfect with bipedalism.

As per modern research, the hominids or ancient hominid species first started to walk on their two feet, probably 4 million years ago.

But, the ape-like hominids first started to appear on the earth nearly about six million years ago. At that time, these hominids lived in dense forest of Africa. So, it is possible that bipedalism may even older than we think!

A group of researchers, led by Paleontologist Mary Leakey, first discovered a 88ft long trail of something called first-ever human footprint impressions in Laetoli, Tanzania, Africa. It is famously known as “Laetoli foot prints”!

As these foot impressions were made on Lava, they were preserved until modern without any issues. Even though the team discovered it in 1976, it became a centre point of discussion in 1978, when Paul Abell joined the team.

As per the research team, these 70 footprints were of Australopithecus Afarensis,  one of the earliest human species in the world.

These early humans used the heel stroke technique to walk, just like we do. That means the heel of their feet first touched the ground, and then they used their toes to push off at the end of the stride to continue walking.

The discovery of Australopithecus afarensis fossils near the footstep trail proved that these ancient humans were bipedal creatures.

But, their footprints were spaced closely. It proves that these ancient hominids had a shorter stride and shorter legs. Hence, they walked slowly and could only cover a smaller distance per day.

On November 24, 1974, 40% of intact fossilized remains of a female of this species were discovered in Hadar, Ethiopia. Since these remains had a well-formed pelvis, scientists deduced that it was of a grown female. The scientistss nicknamed it Lucy after the Beatles song “Lucy in the Sky with Diamonds”. Till now, Lucy is famous and is often called the first-ever mother of modern humans.

Lucy was a small female with a height of only 3.5 feet. As an Australopithecus, she had powerful arms that allowed her to climb trees and eat food. But due to her curved toes, she was an adept climber and could walk on her feet.

These Australopithecus had longer and larger and curvy big toes. A distinct feature is that their foot structure was distinctly different from the apes. The big toes of the Australopithecus were in line with the rest of their feet, which allowed them more stability in walking on their feet. Hence, walking probably dates back to 6 million from modern day!

Later in 1994, another fossil in Ethiopia offered more insights into how humans invented walking. The anthropologists now decided that hominins were probably bipeds from 4.4 to 4 million years ago.

In 2009, partially intact skeletal remains of the same species were discovered. The researchers deduced that it was an adult female and gave it the name Ardipithecus ramidus.

The Ardipithecus remains, or “Ardi”, were native to Ethiopia, and since now, more than 100 fossils of these hominids have been discovered in the area. These fossils had a special physiological structure that indicated that they were bipeds.

The scientists found that the foramen magnum of Ardipithecus, the hole through which the spinal cord enters, is similar to modern humans. On top of that, it is rear-facing, which indicates that these hominids have a stooped position.

Their leg bones were positioned beneath their pelvic bones and fitted similarly to modern humans. This feature allowed Ardi to walk upright on her two feet. She also had well-formed toes. On top of that, their tarsal region was larger.

Hence, it is clear that Ardi walked upright on her two feet. She may not have been a fast walker like modern humans, but she was a walker indeed!

The Australopithecus amenities, discovered in Kenya, were also bipeds. A leg bone of this species was quite similar to the modern human leg bone and allowed them to walk shorter distances on their feet.

Another site Bouri, Ethiopia, yielded arm and leg bones of Australopithecus garhi. These hominids had elongated femurs. But, their forearm was longer than a modern human. Hence, it is clear that even though these specials were bipeds, they did have a stooped position due to their elongated hands.

Bipedalism started to improve from the birth of Homo habilis. These species have larger brains and smaller teeth. But, they also have shorter femur bones, curved finger bones and a few chimpanzee-like traits. But, they were a little better bipeds due to their physiological features.

The latter species, Homo heidelbergensis, and Neanderthal men were also bipedal. But they were a little faster. They had a broader pelvis with longer femoral necks. These features offered them more stability while walking on their feet.

 Dr. Martin Haeusler, a researcher from the University of Zurich recently said that the early neanderthal men were fully upright hominids with proper bipedalism.

Neanderthal men had fully developed S-shaped spine, which is needed to stand upright for long hours. Dr. Haeusler and his colleagues said these archaic men were closer to modern men and fast walkers.

He explained-
“When reconstructing the pelvis, we discovered that the sacrum was positioned in the same way as in modern humans. By putting together the individual lumbar and cervical vertebrae, we were able to discern that the spinal curvature was even more pronounced.”
He also added, “The very close contact between the spinous processes — the bony projections off the back of each vertebra — became clear, as did the prominent wear marks that were in part caused by the curvature of the spine.”
The team used the Neanderthal remains of the La Chapelle-aux-Saints skeleton from France. This skeleton also had wear marks on the hip joint, which indicates bipedalism as straight upright posture and walking can strain hip bones. The wear marks are natural as the skeleton belonged to an elderly Neanderthal!
In his words, “The stress on the hip joint and the position of the pelvis is no different than ours. This finding is also supported by analyses of other Neanderthal skeletons with sufficient remnants of vertebrae and pelvic bones. On the whole, there is hardly any evidence that would point to Neanderthals having a fundamentally different anatomy.”
Haeusler finished by saying, “Now is the time to recognize the basic similarities between Neanderthals and modern humans and switch the focus to the subtle biological and behavioral changes that occurred in humans in the late Pleistocene.”

But, modern walking came into existence with the birth of Homo erectus. These primitive humans have more developed legs and femur bones with muscles and better pelvic joints. They also had their centre of mass in the pelvic region, which allowed them to remain straight upright while walking. The Homo erectus were thriving between 1.9 million and 135000 years ago.

But, they ceased to exist and were replaced by modern Homo Sapiens, which also shared the same modern features. The Homo Sapiens were fast walker, efficient runner and had greater stamina.

Why humans or early hominids started to walk on their two feet has intrigued anthropologists since the earliest discovery of bipedalism.

In 1871, Charles Darwin first decided to explain this in the book “The Descent of Man”. He said that “…the hands and arms could hardly have become perfect enough to have manufactured weapons, or to have hurled stones and spears with a true aim, as long as they were habitually used for locomotion.”

But, with the discovery of Ardi in 2009, more light was thrown on the cause of bipedalism in humans. Anthropologist C.Owen Lovejoy of Kent State University supported Darwin’s theory.

Scientists claimed that climate change was directly linked to bipedalism. Ardi’s species used to live in forests in small groups. But, as the weather started to become warmer and the ice caps melted, the flora started to change.

The African forest became seasonal, with variable plants due to the weather change. Hence, the grass started to grow more instead of larger trees. The Ardipithecus now had to find new ways to find food and living.

On top of that, the food scarcity became intense, and the hominids needed to travel long distances to get food. Lovejoy theorized that the earlier hominids divided their tasks; men gathered food, and women reared the child.

The male needed to be providers to the women and children to gain a mate. But, to gather food, they needed to have their arms and hands-free. On the other hand, women needed to be swift with children in this new scenario.

Hence, Ardipithecus started to walk bipedally. This allowed them to carry things in their free hands, see from a distance, and evade dangers.

Interestingly, chimpanzees also walk on their feet while carrying valuable foods or their children. Probably the ardipithecus and all other hominids got this idea as a genetic trait from the chimps!

Later during the 1980s, Peter Rodman and Henry McHenry, researchers from the University of California, also offered a similar theory.

They suggested that early hominids needed to adapt to the grasslands of Africa. As the number of trees shrank, these hominids were forced to come to the grounds to live. They could not navigate through the grassland if they stood on all four legs. Instead, bipedalism allowed them to grow taller to see objects from a longer distance amidst the grass. Walking on four legs was not convenient in this case. Hence, they started to stand on their two feet to see objects from afar.

In 2007, another team of researchers found that bipedalism also offered humans more energy reserves. They researched chimpanzees and found that these animals needed 75% more energy than humans if they walked on all four legs. Hence, it is clear that bipedalism allowed humans to walk or run faster without exhausting their physical stamina.

Probably, bipedalism is also linked with intelligence. With evolution, hominids started to get larger brains and grew more intelligent. It may have also influenced bipedalism in earlier humans. Well, more intelligence means more logical thinking. And probably the early humans realized that walking on two legs was better than walking on four legs. 

It seems scientists might have found why some hominids were better bipedal than others. A team of researchers led by David Raichlen from the University of Arizona performed a unique experiment with five chimpanzees.

He trained these chimpanzees to use a treadmill and walk on various speed settings. While these chimps are not good walkers, their performances varied in this experiment. Three of these chimps were extremely bad walkers and had to give real effort to become bipedal. They exhausted more energy than walking on four legs. Their oxygen intake was also increased during bipedal activities.

Interestingly enough, a female chimpanzee nicknamed Lucy performed pretty well. She was a comfortable upright walker and found it easier than “knucklewalking”. Raichlen explained that Lucy walked with her knees and hips more extended than the other four chimps involved in this experiment!

Raichlen theorizes that the hominids or our ape-like ancestors probably had a situation like an experiment. While some species were natural walkers, others were not. Probably, those who were more adept at walking survived. In his conclusion, Raichen said, “That’s what natural selection would be able to work on,”

 As it seems, bipedalism has allowed humans to thrive and become the best species on Earth. But, bipedalism is not an isolated feature. It came naturally as the p[art of human evolution. But, scientists are yet to determine which species first invented walking.

Probably, we need to find more and reach out more to get the answer!