Saturday, February 27, 2016

A Rising Star: What We Currently Know About Homo naledi

Artistic rendition of Homo naledi (Image Source: National Geographic)
 
The subfield of physical anthropology is one of the most diverse of the anthropological subfields, but one division of that subfield is getting quite a bit of notice as of late.  In the past few years several new discoveries of hominids have brought a great deal of attention to physical anthropology and paleoanthropologists, as well as caused a shift and reanalysis in our current understanding of our ancient human origins.  The most recent announced discovery of Homo naledi is the topic of today's blog post, which will discuss what this hominid species means for our current understanding of both human biological and cultural evolution.

The discovery of Homo naledi is actually due to two adventurers, Steven Tucker and Rick Hunter, who in 2013 were exploring the Star cave system in South Africa.  They had heard that there was potential for great discoveries to be found in those caves.  Their explorations led them to a very narrow crevice that seemed to have been unexplored.  The two men, who were lithe in build, were able to squeeze through the crevice, which led to the discovery of bones on the cave floor.  The men thought they had discovered a recent burial, and they brought this find to the attention of local paleoanthropologist, Dr. Lee Berger.  Berger had previously discovered Australopithecus sedibaHe realized that there were more to the bones than what the two novice explorers had believed, but he also recognized that he could not explore the cave himself.  So he put out a call on Facebook seeking small bodied individuals with extensive knowledge of physical anthropology and paleontology, tolerance of being in small and confined places for extended periods of time, etc.  Surprisingly enough, he got over fifty applications but ultimately chose a select few-all women-to join his excavation team.
  
This team worked over two field seasons and collected over 1500 skeletal elements that represent at least 15 individuals, ranging in age from infancy to adulthood.  This discovery was thoroughly analyzed by Berger, the excavation team, and several other scholars, and they all reached the same conclusion: these remains belonged to a whole new and unknown species of hominid.  The species was named Homo naledi, receiving its namesake from the caves that yielded their discovery.  This species exhibits diagnostic traits found in both Australopithecine and Homo species.  A break down can be found in Table 1.  Despite sharing traits with species found in both genera Homo naledi was ultimately classified in the Homo genus due to its systems of locomotion, mastication, and manipulation being so closely related to the Homo species.  Ultimately, this decision is not without heated debate, primarily due to a lack of date associated with this species.  A date cannot be determined at this time because the sediments found in situ (in association) with the skeletal remains are unable to be dated as the best dating techniques require volcanic rock, which was not present.

Table 1: Traits of Homo naledi (Similarities by Genus)

Also under debate is the cultural assertions that Berger has made.  Berger claims that the species were found in such a pristine and complete condition that they must have been intentionally left there.  Further analysis of the remains seems to support this notion as the remains do not exhibit predator marks, which would be suggestive of these individuals having been killed and dragged away.  Berger, who currently believes that the physiological evidence of the species puts them at existing as early as 3 million years ago,believes that Homo naledi would be the earliest species to practice intentional burials.  Again, no definitive date can be assessed at this time, and some scholars believe that this species can be as young as 100,000 years old, which would make it contemporaneous with other hominid species that intentionally buried their dead.  At the present time, it is unclear if the species did indeed intentionally bury their dead and if this is the first incidence or further evidence of a systematic trend among hominid species.

Ultimately, the discovery of Homo naledi enhances our current understanding of hominid evolution and human origins.  As suggested by Berger hominid evolution may not be similar to a tree branch in the sense that a linear progression of species gave rise to the next generation of species that ultimately led to Homo sapiens.  Instead hominid evolution was more similar to a braid, which is where multiple species interbred and different traits were selected for, ultimately producing Homo sapiens.  This idea is supportable regardless if this species is 3 million or 100,000 years old.  As well, the discovery of Homo naledi demonstrates that there is more yet to be discovered in regards to hominid evolution, and that there remains many questions and hopefully someday the answers.  

 

Bibliography




Bascomb, B.  2015.  “Archaeology’s Disputed Genius”.  Nova Next.  Website: http://www.pbs.org/wgbh/nova/next/evolution/lee-berger/


Berger et al.  2015.  Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa.”  eLife 4: 1-35.  Website Accessible: http://elifesciences.org/content/4/e09560
    

Keep, S.  2015.  “Is There Anything Truly Surprising About Homo naledi?”  Understanding Evolution: http://evolution.berkeley.edu/evolibrary/news/151009_homonaledi



Shreeve, J.  2015.  “This Face Changes the Human Story.  But How?”  National Geographic Magazine. Website Accessible: http://news.nationalgeographic.com/2015/09/150910-human-evolution-change/