Why Did So Many Other Human Species Vanish Around 50,000 Years Ago? — Here’s What Scientists Think Happened

Homo sapiens is the last remaining human species today, but it was not always like that. Just 50,000 years ago, at least 5 other hominins existed with modern humans, including Neanderthals, Denisovans, and smaller-stature island dwellers like the Hobbits or Homo floresiensis.

But over time, something happened around that time that caused these other human species to one by one go extinct. Scientists have lots of ideas about what could’ve caused this phenomenon. It was all derived from the fossils they left, DNA, and climate records during the time they roamed the Earth. Let’s explore each idea.

Competition, Interbreeding, and Blending Lives Together

While there is no single theory that explains why the other human species went extinct, the best answer could still be derived from a combination of factors and hypotheses. One of the most prominent ideas is the presence of competition, specifically the modern human species.

Around 50,000 years ago, coincidentally or maybe not, was also the estimated time when Homo sapiens migrated out of Africa to the rest of the world, starting in Europe and Asia. Modern humans may have outcompeted other human species in their own environment because of superior technological innovation, such as projectile weapons and spears.

Homo sapiens also had bigger groups and could hunt better compared to species like Neanderthals, who were few in numbers and lived in small groups. This allowed our species to have a positive repeating loop of being able to have more offspring and spread faster to gather more resources, which in turn reinforced the benefits of having a larger population.

This led to another theory that is supported in our DNA today. The other species may not have gone extinct, but instead just mixed in with us. Because, for example, people who are not from Africa today have about 1 to 4% of their DNA coming from Neanderthals. That means humans and Neanderthals interbred, and even if they are gone now, some part of their genes lives on, through us.

Read more: LiveScience

Climate Change Hurt Many Human Groups

What happened to the other Human Species?

One of the most possible explanations too is climate change, especially around 50,000 years ago, when Earth’s climate was transitioning fast. In Europe, the land was decimated by the Ice Age, making food sources scarce. This condition most likely contributed to the loss of population of Neanderthals, then they faced the modern humans who were far greater in number coming out of Africa.

This created a scenario often called the perfect storm, where a set of survival challenges was presented to the human species around the world. The rapid changes in the environment make it harder to reproduce and adapt fast enough. In history, this often leads to a genetic bottleneck, which would limit a species’ chances to survive.

Genetic Isolation Can Be a Silent Killer

Scientists in France found a Neanderthal named “Thorin.” They studied his DNA and discovered that their lineage separated from the major population of Neanderthals for nearly half a century. They did not mix in with other groups and just stayed to themselves.

This is the same scenario that could lead to a genetic bottleneck we mentioned above. It pertains to a population that is not big enough to be able to create beneficial mutations that will help them combat genetic challenges like diseases, as well as environmental problems.

This could help explain why a lot of modern human species’ evolutionary cousins went extinct, while Homo sapiens, who continually reproduced in a bigger population setting, and with other species, too, were the ones who outlasted the rest.

Read more: Business Insider

Even the Sun Could Have Played a Role

Why Is There Only One Species of Human? - Robin May

There is also a newer idea that since our ancestors originated from Africa, they may have learned how to combat the harmful effects of the sun, which the other human species do not possess.

At around the same time, the Earth’s magnetic poles are shifting, which temporarily weakened the planet’s protection from UV rays and radiation from the Sun, especially in Northern Europe and Asia.

This last theory may not have contributed as much as the first few ones in the disappearance of all the other human species, but it adds up to that perfect storm. A mix of climate change, environmental problems, genetic bottlenecks, and the arrival of Homo sapiens in every corner of the globe is what most likely caused the extinction of our evolutionary cousins.

Author's Final Thoughts

There is no single theory that could explain why only the modern human species was able to survive. But it is still an interesting timeline, because our migration out of Africa coincided with the disappearances of other human species, around 50,000 years ago. Could we actually have caused it all, or did we absorb them into our own lineage? Only one thing is for sure: some parts of them still live within us.

Read next: Archaeologists Just Discovered a Tiny Human Species Called “The Hobbit” — Here’s What Makes Them So Strange

References & Further Reading

Hawks, J., Hunley, K., Lee, S.-H., & Wolpoff, M. H. (2000). Population bottlenecks and Pleistocene human evolution. Molecular Biology and Evolution. https://doi.org/10.1093/oxfordjournals.molbev.a026233

Gilpin, W., Feldman, M. W., & Aoki, K. (2016). An ecocultural model predicts Neanderthal extinction. PNAS. https://doi.org/10.1073/pnas.1524861113

Van Holstein, L. A., et al. (2024). Diversity-dependent speciation and extinction in hominins. Nature Ecology & Evolution. https://doi.org/10.1038/s41559-024-02390-z

Vaesen, K., Scherjon, F., Hemerik, L., & Verpoorte, A. (2019). Inbreeding, Allee effects and stochasticity might be sufficient to account for Neanderthal extinction. PLOS ONE. https://doi.org/10.1371/journal.pone.0225117