In 2013 there was a trove of hominin fossils in quantity unlike anything discovered before. The fossils would be discovered in South Africa in Rising Star Cave deep underground ,40 m to be exact, having to crawl and climb in uncomfortable compact space until they reached there treasure chamber Dinaledi. There, lead by Lee Berger, they collected over 1500 pieces of bones and at least 15 individuals ranging in age from infancy to old adulthood and there are still bones there to be further excavated!
With examination of the bones it was certain they were in our own genus Homo and became the species Homo naledi. The Homo naledi was a interesting mosaic of human and primitive feature. They had a very small sized brain about the size of a large orange, and a more ape-like thorax/ shoulders. Their feet and ankles were defiantly made for bipedal locomotion and almost indistinguishable between ours. And they had longer leg bones then Australopiths, with a more human gait. Their hands and hips are an odd blend of both homo and austhralopiths. Their hands had shorter fingers and a long opposable thumb for power grip, but also curved fingers remnant of the austhralopiths. You could draw a line across their hips, the upper portion looking like Australopithecus afarensis, but the lower half looking a lot more human.
But how old are they? They have had trouble putting a date to these bones. Mostly because they where found in mixed soil and not rock, like hominins in East Africa that allowed them to be dated. There was also no animal fossils to be found to put a relative date on them. But until very recently, on April 25 to be exact, Lee Berger announced that the bones only date back around 300,000 to 200,000 years ago. And that the methods and data to reach that conclusion will be disclosed in the next following weeks. So what does this new data mean? Well it most likely means that there is no direct ancestral connection between Homo naledi and us because the split between Australopiths and early Homo would be around 3 million years ago. But it still could be a early Homo originating around 2 million years ago but remaining unchanged and persisted becoming a relic of a specious still with quite a few primitive feature that are 2 million years old.
There is still more that can be done to further understand this specious. They are exploring a second chamber that has uncovered three more individuals. They are also trying to extract DNA from the bones but have so far become unsuccessful. But If they did it would reveal a lot more about the species and possibly, if it is a relic specious, information about australopiths, but that could be wishful thinking.
Then there’s the mystery of them being in Dinaledi chamber in the first place. They didn’t live there or there would be animal bones or possibly flint tools. They weren’t prey because there are no signs of any of the 15 individuals being mauled by a big African cat. They weren’t rushed in there by a flood or there would be other animals or rocks/rubble or plants that would have been deposited as well. But there is only them and fine grain soil that covers the bottom of the tomb. With all the other known alternatives not possible Bergers team has come to a rather extreme conclusion that these are signs of ritualistic burial. Saying the distribution of the bones suggest they have been placed there over a long period of time. And that it was unlikely that that many individuals like mothers with infants and very old individuals would just go in and get lost or stuck and die. There are obviously critics of this idea, most professionals don’t support it, and it is true the team has shown no evidence of this kind of complex behavior, only eliminated the other alternatives. For now this remains a big puzzle.
More Information: Just keep in mind that the new data on the age doesn’t support the idea that they are right at the base as a 3 million year old Homo species.
http://www.pbs.org/wgbh/nova/evolution/dawn-of-humanity.html : a good documentary by nova broadcast by PBS about the discovery and findings at Rising Star and also a bit on human evolution,