Early humans preferred the mountains, and it changed our evolution

We all know that food is central to survival, but have you considered how the diversity and abundance of food in our surroundings might have played a significant role in our evolution?

A recent study suggests that food diversity in steep mountainous terrains had a significant impact on early human species. The research was led by a team at the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea

The allure of mountain diversity

The research team analyzed an extensive dataset of hominin fossils, artifacts, high-resolution landscape data, and a simulation of Earth’s climate dating back 3-million-years.

The goal was to answer an intriguing question: Why were our evolutionary ancestors more inclined towards mountainous regions than flat landscapes?

Archeological sites show that early human settlements, primarily hominins, were often nestled in or near mountain regions.

Early humans in the mountains

Mountains are rich in biodiversity due to the climatic shifts caused by variations in elevation. Flora and fauna thrive under diverse environmental conditions, and mountainous regions host a myriad of ecosystems and vegetation types, also known as biomes.

Such ecological prosperity drew our early ancestors to these landscapes, providing them with an abundant supply of food resources and a means to withstand climate changes. This concept is the basis of the Diversity Selection Hypothesis.

Elke Zeller is a PhD student from the IBS Center for Climate Physics and lead author of the study.

“When we analyzed the environmental factors that controlled where human species lived, we were surprised to see that terrain steepness was standing out as the dominant one, even more than local climate factors, such as temperature and precipitation,” noted Zeller.

Balanced equation of mountain diversity

However, living in these steep regions wasn’t exactly easy. The rugged terrain posed considerable challenges, from difficulty navigating the land to high energy consumption.

The researchers assessed how human adaptations over time gradually swayed the cost-benefit equilibrium of residing in such challenging environments.

Adapting to steeper environments

Human resilience is evident in the adaptive journey of early Homo habilis, Homo ergaster, and Homo erectus, who gradually acclimated to steeper environments until about 1 million years ago.

After a brief disappearances, the topographic signal resumes around 700,000 years ago, with the emergence of more culturally advanced species such as Homo heidelbergensis and Homo neanderthalensis. These groups demonstrated higher tolerance for colder and wetter climates and also learned to control fire.

“Whether it’s all a coincidence, or the intensifying glacial climate shifts contributed to the genetic transitions in early humans, remains an open question,” said Axel Timmermann, co-author of the study.

Puzzle of human evolution

The debate on human evolution and how we adapted to environmental challenges continues to spark scientific discussions worldwide. However, this South Korean team’s findings shed light on one piece of the human evolution puzzle.

The analysis suggests that it was indeed beneficial for early human groups to populate mountainous regions, despite the increased energy consumption needed to navigate these environments.

“Our results clearly show that over time hominins adapted to steep terrain and that this trend was likely driven by the regionally increased biodiversity,” said Zeller.

The data – averaged over hundreds of thousands of years, spanning different species and continents – confirm that our ancestors were, indeed, “steeplanders.”

Mountain life and social bonds

Mountainous regions not only presented a diverse array of food resources but also likely influenced early hominin social structures and innovations.

The rugged terrain and varied ecosystems would have required early humans to develop cooperative strategies for survival, as foraging and hunting in these challenging environments often demanded group effort.

This need for collaboration may have encouraged the development of early social bonds and the sharing of resources, leading to more complex social behaviors over time.

Human tool innovation in the mountains

In addition to social adaptation, the challenging environment of mountainous areas likely spurred the invention and refinement of tools.

Early hominins in these regions may have relied on rudimentary tools to navigate the terrain, hunt diverse prey, and process different plant materials.

These innovations allowed them to exploit a broader range of food sources and adapt to the ever-changing conditions found at higher altitudes.

By pushing hominins to adapt both socially and technologically, these steep and varied landscapes may have been a driving force behind some of the earliest forms of human innovation.

The study is published in the journal Science Advances.

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