Homo Naledi, The New Ancestor

H. naledi cover photo
Source

After the relatively recent discovery of Homo naledi, much has been released about their habits and lifestyle.

For those of you that have not heard about this wonderful fossil excavation, here is some background.

In 2015, a remarkable collection of fossils were found in South Africa(1). These bones were quickly categorized as human-like. While several other human-like species have been discovered (Homo habilis, Homo erectus, just to name a few),non resembled the bone structure of the new specimens. Thus, these bones have been classified as a new addition to our ancestral map.

Cross-section_of_the_Rising_Star_Cave_system_Dinaledi_Chamber.svg
Diagram of Rising Star cave system and Dinaledi Chamber where 15 Homo naledi specimens were discovered. Source

They were given the name Homo naledi. Homo refers to the genus of the species (which we are apart of) and naledi translates to “star” in english (named after the cave where they were found). The unique quality of these fossils was not just the knowledge of a new species, but also what we have learned from them. This particular excavation gave scientists a unique understanding of the behavior of the species. Within the Rising Star cave network, 15 different specimens were located in the same cave, making it the largest assembly of human like fossils discovered in Africa (1).

Note: The original study, located here, discusses the specifics of the fossils found. If you wish to learn more about cranial size, hand shape, and how they compare to other Homo and non-Homo descendents, I recommend reading the article. If you are curious on how H. naledi fits into the current model of human ancestry, stay tuned. This whole topic will be covered in a future blog.

Part of the mystery of H. naledi is the placement of the bodies. Having 15 of the same species within such a small cave structure begs the question of how they got there in the first place.

This has been a hot topic since the discovery, and currently there are two bodies of thought:

The first, suggests that the bodies of the dead were placed as a sort of burial (although the bodies were not actually buried). There are no other fossil types within the cave (except a lone owl), which eliminates the hypothesis of a predator’s cave, and no signs of water or dirt to suggest body movement through river systems or mud slides. Dr. John D. Hawks, a prominent anthropologists, suggests that the bodies were indeed placed deliberately (5).

Another school of thought, related to the first, believes that body placement may have been related to a ritualist demonstration (in this case, not a religious ritual). This hypothesis however, has been placed under scrutiny. At the time of this blog post, no tools or other materials suggest a ritual of any kind, and no evidence on fossils suggest violent deaths that may be associated with rituals (6).

In addition to learning about burial rituals, there is also much left to learn from H naledi as far as their lifestyle, i.e. their diet.

Since the stomach of naledi has been decomposed for an extremely long period of time, we can gather much information from their teeth.

It may seem weird, but teeth have been used extensively to gain insight on the lifestyle of extinct species. A recent study has been released doing just that with H. naledi.

Scientists in the UK first looked at the naledi teeth, and immediately discovered a unique quality; they were chipped. But this didn’t occur from damage over time, rather the chipping occurred before the specimens died (called antemortem)(2).

TEETH
Example of  the “chipped” teeth of H. naledi. Source

What makes this unique is that this has never been seen in other fossils of ancestral species, or even in primate species. 44% of the teeth recovered had damage to the enamel occurring before death. These rates by far surpass other teeth examined from our lineage.(2)

Interestingly, scientists have determined that the chipping has occurred due to their diet. By determining which type of teeth have the most chips (incisors, premolars, etc), the researchers were able to infer that a high “grit” diet from roots or tubers that were commonly eaten.(2,4)

While it may not be “front page news” on what H. naledi ate specifically, it does provide another piece to the puzzle. As we continue to learn and discover more about these extinct ancestors, we will be able answer other questions related to evolution and the development of life on our planet.

As always, thank you for reading. If you have questions or comments, please email us directly at copernicuscalledblog@gmail.com. You can also reach us on Facebook, Twitter, and Tumblr.

 

Remember to always be curious, and stay mindful!

Written By: Cody Wolf

Sources

  1. Berger, Lee R. Homo naledi , a new species of the genus Homo from the Dinaledi Chamber, South Africa. eLife, eLife 2015;4:e09560 DOI: 10.7554/eLife.09560  https://elifesciences.org/articles/09560.
  2. Towle, Ian. Behavioral Inferences from the high levels of dental chipping in Homo naledi. American Journal of Physical Anthropology. 2016. DOI: 10.1002/ajpa.23250. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.23250/abstract;jsessionid=C151DCA7FF6D8C04BBBD29023969E3F8.f02t02
  3. https://en.wikipedia.org/wiki/File:Cross-section_of_the_Rising_Star_Cave_system_Dinaledi_Chamber.svg
  4. Belgastro, Giovanna. Continuity or discontinuity of the life-style in central Italy during the Roman imperial age-early middle ages transition: Diet, health, and behavior. American Journal of Physical Anthropology. 2006. DOI: 10.1002/ajpa.20530.http://onlinelibrary.wiley.com/doi/10.1002/ajpa.20530/abstract
  5. Drake, Nadia (15 September 2015). Mystery Lingers Over Ritual Behavior of New Human Ancestor. National Geographic News.http://news.nationalgeographic.com/2015/09/150915-humans-death-burial-anthropology-Homo-naledi/
  6. Ghosh, Pallab (10 September 2015). New human-like species discovered in S Africa. BBC News. http://www.bbc.com/news/science-environment-34192447
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