How Did Early Humans Survive the Ice Age That Began Around 2.6 Million Years Ago? — Here’s What Experts Discovered

When people talk about the ice age, they usually refer to the glacial period that ended around 11,700 years ago and peaked around 20,000 years ago. By this time, the modern human species, Homo sapiens, has been developing for over 200,000 years, and the genus Homo has been around for nearly 2.5 million years.

So, when this last glacial period occurred, humans were already equipped with some of the necessary abilities, tool set, and cognition they would need to survive an ice age. They knew how to create fitted clothing, they have good mastery of fire, and they live in large groups, cooperating with each other to survive.

But what about during an ice age, before all these traits and characteristics in human lineage developed? A time when we don’t have control of fire, do not know how to create clothing that fits our unique bodies, and are only beginning to develop a larger brain. How did our ancestors survive in this changing world 2.6 million years ago? Let’s explore the past to answer this question.

Quaternary Ice Age, Movement, Habitat Selection & Using Natural Shelters

The Quaternary Ice Age began around 2.6 million years ago. Around this period, the genus Homo, such as species like Homo habilis, was only starting to develop and exist. The hominin lineage that was also present and more established was Australopithecus. They are bipedal species that could walk on land, but have retained the abilities necessary to climb trees. Their primary diet involves a diverse variety of plant-based food, such as underground roots, leaves, and other tough edible plant materials.

They are a genus that predates Homo, and are believed to be the ancestors of early Homo species. When the Quaternary glacial period began, the natural habitats of Australopithecus had shifted. Some of the woodlands and forested areas receded, and the grasslands and open savannas expanded. This phenomenon resulted in the Australopithecus having to adapt to new conditions that may have led to the Homo genus.

Earlier Homo genus species, like Homo habilis, developed a larger brain and higher cognition compared to their predecessors. It is attributed to many different factors, such as a change to a new diet that involves meat and bone marrow, giving their bodies the necessary nutrients and calories to develop a bigger brain.

Another would be their tool usage, such as the Oldowan stone tools, which they may have used to obtain these new food sources, allowing them to cut off meat and reach the marrow in the animal carcasses they scavenged.

This increase in cognition, larger brain, and a slightly more refined bipedalism than Australopithecus could be what helped them survive the start of the Quaternary ice age. They develop higher mobility because of the combination of these factors, leading to them having better ability to adapt to new environments, which allows them to move from one place to another, even in open areas like savannas.

They were able to find temporary natural shelters like caves and rock overhangs. These protected them from the wind, cold temperature, and nighttime chills, even if they don’t have complete mastery of fire. But they are still mostly nomadic and use open-air camps.

Read more: Sapiens

Tool Use, Scavenging & Natural Fire Opportunism

How Did Early Humans Survive the Ice Age? – Food, Fire, and Shelter

The control of fire was recorded to be about 1 million years ago, with later hominins mastering it closer to 400,000 years ago. This meant that during the start of the Quaternary ice age, there was probably only opportunistic use of fire from natural sources like wildfires, instead of early humans deliberately utilizing it.

The Homo species that just developed the Oldowan tool industry highly likely used their basic stone tools more than fire. They sharpened a stone by hitting it with another stone. This allowed them to cut off the meat from the carcasses and break the bones to obtain the marrow, which is rich in fat, calories, and other nutrients.

They likely were able to get this meat not from directly hunting animals, but from scavenging resources from other top predators of their environment. Moreover, even if they did not command the use of fire extensively, they probably were able to utilize the wildfire to heat or cook food. The combination of these factors could be what helped them find food sources and adapt to the changing environment, especially during an ice age.

Behavioral Flexibility and Clothing

Survival during the cold does not only depend on a species’ ability to collect food sources, it also on their ability to be flexible. Humans of the genus Homo have developed a larger brain compared to the species that preceded them, and this may have played a crucial role in their increasing behavioral complexity. They were able to learn and adapt from the challenges they faced.

It is likely that they already lose some of their fur during this period; even if not all of it, it would still be necessary to develop some form of clothing to stay warm. Their developing bigger brain may have allowed them to use their Oldowan stone tools to cut off the animal hides and skin to act as covering or clothing. It is not as fitted yet, and is probably more like a cape that covers their bodies to keep warm.

These animal hides and skins could also be used as draping over their rock beds to maintain as much heat as possible during the night. They may have even huddled and slept closer together in their own groups for their own warmth and safety. In other words, they were also developing increased social complexity and cooperation. All these complex behaviors for a hominin may have enabled them to survive the periodic cold even without habitual use of fire.

Read more: History Facts

Diet, Resource Flexibility & High‐Energy Food Sources

How Early Humans Survived in a Frozen World...

The cold environments, even if they are present periodically, pose a challenge to the human body. Our ancestors needed more calories in order to adapt to the changing conditions, but the very shifts in the environment are making it harder for vegetation to be rich. The extra calories would have helped their metabolism to keep their bodies warm, and they would have supported the development and maintenance of other parts, such as the brain.

So, to survive, early humans had to adapt to a higher-energy and more nutrient-rich diet, such as meat and bone marrow. Before, early human groups like Australopithecus relied primarily on a plant-based diet, but the newer species, like Homo habilis, were able to switch between plants, animals, fish, and whatever was readily available in their environment.

This change in diet, or rather the flexibility, is what gave them a huge advantage. It could be one of the biggest factors, along with the other reasons, for why Australopithecus disappeared, while the genus Homo persisted.

Author's Final Thoughts

Around 2.6 million years ago, the genus Homo, which the modern human species belongs to, was only starting to develop and exist. Unlike the Last Glacial Maximum, over 11,500 years ago, the earlier hominins did not yet have complete mastery of fire to keep them warm, the ability to make fitted clothing, and the large brains capable of higher cognitions.

Instead, they relied on their recent developments and traits, such as developing a bigger brain, the flexibility of dietary choices, and increasing social cooperation. These factors allowed them to find higher-energy food sources, choose smart habitats, and be able to move and adapt to new environments. Over time, they eventually added the mastery and control of fire to their toolkit, but before that, the foundations that were laid were their flexibility, cooperation, and creativity.

Read next: Why Did Early Humans Begin to Develop Larger Brains Nearly 2.5 Million Years Ago? — Here’s What Scientists Suggest

References & Further Reading

Semaw, S., Renne, P., Harris, J. W. K., Feibel, C. S., Bernor, R. L., Fesseha, N., & Mowbray, K. (1997). 2.5-million-year-old stone tools from Gona, Ethiopia. Nature. https://doi.org/10.1038/385333a0

Plummer, T. W., et al. (2023). Expanded geographic distribution and dietary strategies of the earliest Oldowan hominins. Science. https://doi.org/10.1126/science.abo7452

Berna, F., Goldberg, P., Horwitz, L. K., Brink, J., Holt, S., Bamford, M., & Chazan, M. (2012). Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa. Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.1117620109

Maslin, M. A., Brierley, C. M., Milner, A. M., Shultz, S., Trauth, M. H., & Wilson, K. E. (2014). East African climate pulses and early human evolution. Quaternary Science Reviews. https://doi.org/10.1016/j.quascirev.2014.06.012

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