How the Skeletons of Our Prehistoric Ancestors Evolved to Modern Human Frames

It’s no surprise that modern-day human bone structure varies greatly from that of our ancient ancestors. As society has advanced and new technologies developed, so too has our bone structure.

Thanks to modern technology, researchers are now better able to pinpoint just when those bony changes began. Food played a major factor in shaping our skeletal frame, but not in the way you may think. 

Although the study of anthropology dates back centuries, biological anthropology is a relatively new discipline made possible in the 1990s with the rise of computer tomography and other technology, says Timothy M. Ryan, professor and head of anthropology at Pennsylvania State University.

“That spurred a lot of what we do,” Ryan says. “That was the beginning of the modern approach to skeletal variation.”

Within the last 10 years, Ryan says many researchers have been able to access micro scanners and computer software that allow them to analyze and compare bones.

This means they can compare bones among prehistoric peoples as well as modern humans. They can even add in athletes from various sports and then see how people living in the Late Stone Age compared with modern swimmers, cross-country runners, or couch potatoes. 

Read More: How Many Bones Are in the Human Body, And Other Fascinating Facts About Skeletons

In general, anthropologists have found that modern humans have lighter skeletons when compared to hominids and earlier humans like Homo erectus.

“We relatively lightly built,”  Ryan says. “This contrasts sharply with what we see in the fossil record.”

Ancient humans had to be more active in order to survive, and their bones reflect their constant on-the-go lifestyle.

“Early modern human bones were more robust,” Ryan says. “There seems to be a transition with the shift to agriculture. When we reduced our mobility and our physical activity, we began to not build as much bone because we weren’t as active.” 

Ancient bone structures differ from modern skeletons in many ways. When it comes to heft, heavier bones began to become lighter around 12,000 years ago as most civilizations transitioned from nomadic to agrarian.

Read More: Fun Facts About Bones: More Than Just Scaffolding

Lighter skeletons can mean that modern humans are more prone to fractures as well as bone diseases such as osteoporosis. Earlier humans’ heavy skeletons typically had more rigidity, which meant they could better withstand stress from bending, compression, tension, or torsion.

However, not all early humans lived similar lifestyles, and anthropologists have found variations among ancient and modern humans, particularly among athletes. 

According to research, athletes have stronger bones. In a 2013 study in Journal of Evolution, researchers looked for variations among a wide range of bone samples. They looked at fossils from the Pleistocene period (the Ice Age) that lasted from 258 million years to 11,700 years ago.

They also looked at fossils from the Upper Paleolithic age (about 35,000 years to 10,000 years ago) and the Holocene period (last 11,700 years or so). This included both Homo sapiens and Homo neanderthalensis. The study also had access to bone scans of modern humans, including a control group, cross-country runners, and swimmers.

There was variation among the Holocene H. sapiens. Southern Africans living in the Later Stone Age had the highest relative rigidity in their tibial bones. In contrast, Maritime Andaman Islanders had the lowest.

Although modern humans had less bone rigidity, some had more rigidity than others. Cross-country runners had more than swimmers. Controls were typically in the middle.

Read More: How Strong Were Ancient Humans? Modern-Day Athletes Are a Window to the Past

Anthropological biology has typically favored males during analysis, and often this has to do with the availability of fossils. However, researchers are increasingly trying to understand how ancient female bones were different from their male counterparts as well as women today. Understanding these distinctions can tell scholars more about how ancient women lived and what duties they assumed.

In a 2017 study in Science Advances, researchers looked at fossils from prehistoric Central Europeans who lived an agrarian life sometime between 5300 B.C.E and 850 A.D. They compared their bones with modern women, including a control group and then athletes involved with rowing, running, or soccer.

The ancient tibial bones varied in terms of rigidity and actually tended to be more similar to modern sedentary women. Modern soccer players and runners’ tibial bones actually had higher rigidity than the ancient fossils.

The humeral (arm bone) rigidity, however, told a different story. The ancient women had greater humeral rigidity than modern women.

Modern rowers did share one key factor with ancient women — a similar load intensity biased toward the upper limb. In essence, the rowers trained for about 21 hours per week and had stronger upper bodies. The ancient women also had a stronger upper body, which indicated their lives were spent in agrarian work. 

Read More: Prehistoric Females Were Strong As Hell

The ancient bones of female farmers gave researchers much insight into their lives. Because their leg bones were less rigid, they indicated they were part of stationary civilizations that raised crops and some domesticated animals.

The bones also gave insight into how the women worked. Stronger upper bodies meant these women were working with primitive tools to till the land, plant crops, and harvest. Devices like plows or animal-driven equipment didn’t yet exist.

The women were also likely tasked with food processing and production with jobs such as grinding grain. Their lives were arduous, and although they didn’t have to walk hundreds or thousands of miles to hunt down food, their daily existence required a massive effort that is no longer the experience for most modern humans.

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Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review them for accuracy and trustworthiness. Review the sources used below for this article:

• PNAS. Gracility of the modern Homo sapiens skeleton is the result of decreased biomechanical loading

• Wiley. Biomechanics/mechanobiology

• Journal of Human Evolution. Extreme mobility in the Late Pleistocene? Comparing limb biomechanics among fossil Homo, varsity athletes and Holocene foragers

• Science Advances, Prehistoric women’s manual labor exceeded that of athletes through the first 5500 years of farming in Central Europe