How Did Denisovans Survive for Over 200,000 Years in Harsh Ice Age Environments? — Here’s What Experts Suggest

Denisovans are an archaic human species that once existed with earlier Homo sapiens, Neanderthals, and Homo erectus. They are thought to have lived in several parts of Asia, about 200,000 years ago until roughly 40,000 years ago, when they are believed to have gone extinct.

Although other species have existed far longer, like Homo erectus surviving for nearly 2 million years or Homo habilis for around 1 million years, Denisovans still managed to live in cold and harsh environments for hundreds of thousands of years, which is still impressive for a species. However, how exactly were they able to survive, and what was it like to live in their habitats? Let’s explore these questions in this article.

Living in High, Cold Places — Adapting to Altitude and Cold

One of the biggest clues about Denisovans was a fossil found in the Tibetan Plateau that was dated back to around 160,000 years ago. It tells us that they may have lived in higher altitude places. Their habitats could be remote, with thin air and colder temperatures.

Living in such extreme conditions where oxygen is most probably scarce is an incredible feat even for a homo genus species. Most modern humans today who did not inherit the right genes would probably be gasping for air every moment in these environments, and would find it hard to survive, let alone during the ice ages.

This is because scientists have identified a key genetic variant, the EPAS1 gene, which is linked to survival in low oxygen environments. This was thought to be inherited by current-day Tibetans from Denisovans. It is a gene that helps the human body efficiently regulate oxygen circulation to prevent sickness related to the altitude.

In other words, Homo sapiens, or the modern-day humans, interbred with Denisovans in the past. They were already adapted to these high-altitude and harsh environments, so their genes have likely been crucial and helpful for Homo sapiens to survive when they arrived in these places around 50,000 years ago, particularly in the Tibetan Plateau.

Read more: Nature.com

How Denisovans Got Food and Resources

How Denisovans Survived in Tibet 200,000 Years Ago

So, how exactly did the Denisovans able to live in such an extreme environment, especially during glacial periods or ice ages? One theory is that they stayed in protected areas like valleys that may have retained some vegetation and animal presence even if the surrounding areas are cold.

At Baishiya Cave, researchers found cut marks, tools, and animal bones that suggest Denisovans were resourceful hunter-gatherers. They may have hunted animals like large mammals, even in cold environments, and adapted their diets to the available resources in their habitat.

In warmer periods, the plants and vegetation in the Tibetan Plateau may have been abundant, but during the ice ages, they likely relied on edible vegetation that survived in the protected areas, like caves, valleys, or other sheltered areas. However, the key here is their adaptability and flexibility in their diet and resources, especially for surviving in fluctuating climates.

Coping with Climate Swings and Isolation

Denisovans were believed to have lived in their habitats for hundreds of thousands of years, which meant that they likely lived through several ice ages, warming periods, and environmental shifts. During the extreme cold, they probably moved to safer places like mountain caves or valleys, in a smaller but mobile population group.

They were also believed to have control of fire, the ability to make clothes, reuse toolkits, and share food or resources with their close group. These combinations of characteristics are probably what helped them survive in a remote and isolated place like the Tibetan Plateau.

However, this habitat, aside from its harsh conditions, also may have had some downsides that contributed to the eventual extinction of the Denisovans. Due to the geographical location, lack of abundance of natural resources, and the changing climate, the Denisovans may have faced a lack of diversity in their genetics due to the isolation of each group.

These are not definitive and lack sufficient evidence to support them, but it is a plausible theory. It is because the environmental conditions of the time, finite resources, and climate changes could have presented a challenge to the Denisovans, which caused the limitation of their population. A smaller and isolated group with limited gene flow is more vulnerable to diseases and being outcompeted by other hominins.

Read more: ScienceDirect

Genetic and Cultural Advantages and Disadvantages

Denisovans: Decoding the Secrets of Our Mysterious Ancient Cousins | Prehistoric Humans Documentary

Denisovans’ isolation was thought to have been a double-edged sword. On one side, it could have resulted in less competition as they are well-adapted in their own environment, allowing individual Denisovan groups to thrive in their specific ecological habitats. On the other hand, it could have also contributed to their eventual extinction, combined with other factors.

When Homo sapiens arrived in Asia, they were believed to have interbred with Denisovans, which is why the EPAS1 gene is still present in modern-day Tibetans. This also could mean that Denisovans may have gotten helpful traits from our ancestors.

However, if an isolated group of Denisovans with a limited gene pool were the ones to encounter Homo sapiens and have been infected with a disease that they carry, it could have wiped them out due to the genetic vulnerability. Isolation as a species just naturally made them more vulnerable to widespread environmental or biological risks.

Homo sapiens were also much more interconnected and lived in larger and more genetically rich groups. So, over time, our ancestors, with their growing numbers and expanding territories, may have outcompeted them completely. It is also more likely that the cause of Denisovans’ extinction is a mix of all these challenges, rather than just one particular factor.

Author's Final Thoughts

Denisovans are gone now, but the fact that they may have survived for over 200,000 years in harsh conditions that even a modern-day Homo sapiens that does not have their genes would struggle with is an amazing feat. Up to this day, the Denisovans’ DNA continues to influence human evolution and biology.

Despite living in some of the toughest conditions, hominins, or the homo genus species, have faced, their legacy still lives on with some of us today. They gave us genes that help us live at high altitudes and adapt to those unique cold environments. Overall, their story should remind us just how much adaptability, environment, and biology shape who we are as humans today.

Read next: How Did Neanderthals Survive for Over 350,000 Years Until Their Extinction Around 40,000 Years Ago? — Here’s What Researchers Found Out

References & Further Reading

Chen, F., et al. (2019). A late Middle Pleistocene Denisovan mandible from the Tibetan Plateau. Nature. https://doi.org/10.1038/s41586-019-1139-x

Huerta-Sánchez, E., et al. (2014). Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA. Nature. https://doi.org/10.1038/nature13408

Slon, V., et al. (2018). The genome of the offspring of a Neanderthal mother and a Denisovan father. Nature. https://doi.org/10.1038/s41586-018-0455-x

Bae, C. J., Douka, K., & Petraglia, M. D. (2017). On the origin of modern humans: Asian perspectives. Science. https://doi.org/10.1126/science.aai9067