How Did Homo naledi Survive in Africa Around 250,000 Years Ago Despite Their Small Brains, and Why Did They Eventually Go Extinct? — Here’s What Researchers Found Out

The modern human species, Homo sapiens, originated in Africa and existed with many other hominins. One of these is Homo naledi, which was believed to have a small brain that is roughly the size of a chimpanzee, or older hominins like Australopithecus. However, what makes them even more fascinating is that they possess a mix of advanced and modern human-like features, as well as primeval parts, despite their brains being relatively small.

So, that leads us to the questions: how exactly did they survive in Africa 250,000 years ago, and why did they eventually go extinct? Since they coexisted with us a long time ago, could they have been simply outcompeted, or were there other factors that contributed greatly to their disappearance? Let’s dive deep into their story in this article.

Who Homo naledi Was — Anatomy, Time, and Habitat

Homo naledi was estimated to have existed in Africa about 335,000 and 236,000 years ago, which meant that they coexisted with other hominins, including the modern human species, Homo sapiens. One of their most identifying trait is their primitive brain size, which is about 465 to 610 cubic centimeters, similar to older hominins or present-day chimpanzees.

Their body is also made up of primeval and modern human-like traits. They have hands, feet, and lower limbs that are similar to modern hominins. They could walk and stand upright, and hold or manipulate objects, which suggests that they could maybe use basic stone tools. In other words, other hominins with their hand features were capable of it, but there’s no direct evidence for Homo naledi’s tool usage.

However, their shoulders, upper body, and hips are more similar to hominins that existed millions of years ago, instead of modern humans. This makes them a fascinating and unique human species that is still full of mysteries.

Their fossil remains were found nearby or inside caves, leading scientists to believe that they lived in habitats that closely resemble these environments or around them. This could include mountainous or rocky chambers that could be inhabited by smaller hominins.

Read more: PubMed Central

How They Might Have Survived — Adaptations, Niche, and Behavior

New Human Ancestor Discovered: Homo naledi (EXCLUSIVE VIDEO) | National Geographic

So, for a smaller-brained hominin to survive the harsh and competitive environment of Africa, around 250,000 years ago, what exactly could their survival strategy be? One of the theories could be that they filled a niche and a distinct ecological place, and even diets that are less utilized by other bigger-brained hominins like Homo sapiens or Homo heidelbergensis.

This is a hypothesis inferred from their fossils, such as their teeth, which were different from many other hominins during their existence. In other words, their diets could be comprised of food sources that are different or inaccessible to others. Additionally, their fossils suggest they have a smaller body compared to Homo sapiens, so they could be using less energy to maintain their bodies; therefore, fewer resources are needed to survive.

This is an especially helpful adaptation for an environment that is lacking in resources, or for a species that is not as good a hunter-gatherer or scavenger as the others. Moreover, the locations of their remains suggest they may have been able to exploit caves or harsher terrains that hominins avoided.

The Challenges They Faced — Competition, Environment, and Vulnerability

One of the biggest challenges that Homo naledi faced is most likely the active competition with other hominins in the area. Examples include Homo sapiens, which possesses a bigger brain and advanced tool-making and using abilities. These species did not just use basic stone tools, like the Oldowan version from millions of years ago; instead, they also utilized weapons like spears, bifacial sharpened stones, and other specialized tools.

The larger brain’s advantage isn’t only about the cognitive abilities to make advanced weapons to hunt and obtain more resources; it was also helpful in social structures and the formation of larger populated groups. This meant that, compared to Homo naledi, other hominins could have existed in higher numbers, working together to hunt, protect themselves against predators and other groups, and just be a more adaptable group overall.

Another challenge was the environmental shifts in Africa, where some forests and vegetated areas receded while deserts and open grasslands expanded. The climate changes brought green corridors where hominins could exist, but they also created droughts and fluctuations in the availability of food and water sources.

For Homo naledi, which was already probably ecological niche, a massive, sudden, and prolonged change in the environment could push the population to the brink of extinction.

Read more: Smithsonian Human Origins

Why They Likely Went Extinct — Hypotheses and Evidence

Homo Naledi: The 'Star Man' | Prehistoric Humans Documentary

There are likely several reasons that contributed to the extinction of Homo naledi instead of just one single factor. First could be the competition with other hominins, especially Homo sapiens. The modern human species, even back then, may have had better technological advancements, cognitive abilities due to larger brains, and a social structure.

Over time, gradually, the Homo naledi populations may have been forced out of their habitats or fragmented as a group. This could have led to their already small numbers, possibly due to a lack of social cognition compared to Homo sapiens, to an even smaller number. When a group is low in population and isolated, it increases their chances of inbreeding, developing genetic problems, and being more vulnerable to biological diseases.

Secondly, there are environmental shifts and the risk of their ecological niche. If they really only relied on caves and specialized habitats, changes to these locations brought by climate change or natural disasters could be fatal to the species.

Lastly, their small brains could be a sign that they do not have enough cognition to be able to adapt and innovate under pressure like Homo sapiens. This makes them more prone to both hominin competition and environmental shifts, as they would not be able to adapt fast enough to the mounting changes. The combination of all these factors could be why they are not here with us anymore, and not just one reason.

Author's Final Thoughts

The discovery of Homo naledi’ species back in 2013 in the Rising Star cave system of South Africa was surprising and very mysterious. Their brains were of the same size of hominins that existed over 2 million years ago. Their bodies were a mix of modern human-like features and also primitive parts.

However, the world they lived in is just too competitive, with pressures coming from a multitude of factors such as a changing climate and environment, and the presence of smarter and bigger human species like Homo sapiens. The combination of these is what likely led their population into extinction. Their story reminds us that survival is not guaranteed, no matter how unique one may be, and that this world favors those who are able to adapt, change, and respond to the challenges they may face.

Read next: How Did Homo antecessor Survive in Europe Between 1.2 and 0.8 Million Years Ago, and Why Did They Eventually Go Extinct? — Here’s What Scientists Believe

References & Further Reading

Berger, L. R., et al. (2015). Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa. eLife. https://doi.org/10.7554/eLife.09560

Dirks, P. H. G. M., et al. (2017). The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa. eLife. https://doi.org/10.7554/eLife.24231

Berger, L. R., et al. (2017). Homo naledi and Pleistocene hominin evolution in subequatorial Africa. eLife. https://doi.org/10.7554/eLife.24234

Harcourt-Smith, W. E. H., et al. (2015). The foot of Homo naledi. Nature Communications. https://doi.org/10.1038/ncomms9432

Garvin, H. M., et al. (2017). Body size, brain size, and sexual dimorphism in Homo naledi from the Dinaledi Chamber. Journal of Human Evolution. https://doi.org/10.1016/j.jhevol.2017.06.010

Laird, M. F., et al. (2017). The skull of Homo naledi. Journal of Human Evolution. https://doi.org/10.1016/j.jhevol.2016.09.009

Martinón-Torres, M., et al. (2024). No scientific evidence that Homo naledi buried their dead and produced rock art in the Rising Star Cave system. Journal of Human Evolution. https://www.sciencedirect.com/science/article/abs/pii/S0047248423001434