If you know anything about anthropology especially Paleoanthropology then you know that the first rule is “everything is provisional.” Meaning, as new evidence is uncovered the facts change. For many people this is somewhat confusing because they get the wrong idea that human evolution is “set in concrete.” But, human evolution is NOT “set in concrete” at all and never has been. As new analysis on known proto-human and human bones are conducted new results are gained which help us to better understand where the find fits into human evolution so the evolutionary paradigm changes a bit. The same can be said for the discovering of entirely new species of hominins. What’s a “hominin”? A hominin is a clade that includes all humans, human ancestors, and human relatives that are more closely related to us than chimpanzees are. Considering we share anywhere from 96% to 98% of our DNA with chimpanzees, hominins are even more related to us! But, sometimes it turns out that what we thought was a hominin is not or what we thought was not a hominin actually is as new evidence is uncovered.
I tend to be one who pays more attention to DNA sequencing when it comes to human evolution. As it stands today the oldest hominin DNA ever sequenced comes from a Denisovan species found in caves in Spain. These finds were dated at 400,000 years old and they are unusual because the only other place we’ve found Denisovan remains is in Siberia. It gave scientists a shock to also find them in Spain recently and they are still trying to clarify what Denisovans were doing in Spain.
The oldest Homo sapien (modern human) DNA ever sequenced comes from a thigh bone found in Siberia and it is dated at 45,000 years old. It’s known as the Ust’-Ishim Femur Bone.
In general, the way it stands today, we think that the Denisovans, Neanderthals, and Homo Sapiens came from a common hominin ancestor know as Heidelberg Man,” Homo heidelbergensis. However, some anthropologists believe Heidelberg Man was nothing more than a species variation of Homo erectus which, frankly, may or may not be the case.
Current theory is that Heidelberg Man split off into 3 species of hominins. The Neanderthals and Denisovans split off into one branch while Homo sapiens (that would be us) split off into another branch. I think this is correct. So, Heidelberg Man is a common ancestor for us, the Neanderthals, and the Denisovans. But, there’s something more to Heidelberg Man.
Personally, I don’t think Heidelberg Man was a species variation of Homo erectus. Rather, I think Homo heidelbergensis was an evolved hominin, the next step in human evolution after H. erectus. In fact, I’d call Heidelberg Man a “transitional species” or MISSING LINK! A missing link between H. erectus and modern humans, Denisovans, and the Neanderthals. But, is Heidelberg Man the only missing link?
The answer to that question is a resounding NO in my opinion. I think Homo habilis, commonly called “Handyman,” is another missing link. Although there is continued debate over whether Handyman should be classed in the genus of the Australopithecines or the Homo genus I think it is a member of the Homo genus and I also think H. habilis is yet another MISSING LINK! A missing link between the Australopithecines (the real Ape Men) and Homo erectus/ergaster.
So when people claim there are no missing links discovered in human evolution, sorry, but they are WRONG. Heidelberg Man and H. habilis are only two and there are more.
Because everything in paleoanthropology is “provisional” sometimes one thinks it’s all a bit confusing but it really isn’t as long as you understand that everything is provisional and subject to change with the discovery of new evidence which is happening all of the time. Further, I don’t doubt that human evolution is a FACT! I can see ancient human ancestor traits in humans today and so can you if you know what to look for. Also, I think as we are able to sequence more and more DNA from ancient human ancestors the progression of human evolution will become more and more clear and some of the confusion will, thusly, be alleviated.