The other Hominid species were not as lucky as Homo sapiens. About 200,000 years ago, at the time of the evolution of hominids, Africa was chock full with many different kinds of walking apes/primates. They were all much like us. We were kin—close kin. There were, for example, Neanderthals, Denisovans, and Homo erectus of whom we know very little.
There is some confusion about terminology here that I would like to dispel, but I am not sure I can. The two words “hominid” and “hominin” are similar and definitions have varied over time. Hominids were originally only humans (homo) and their closest extinct relatives. Those are now usually called hominins. Other than humans, all hominins are extinct. The 21st century meaning of the word “hominid” includes all the great apes (including those that are still around) and humans.
Denisovans or Denisova hominins are a recently discovered species of human in the genusHomo. In March 2010 scientists announced that they had discovered a finger bone fragment of a juvenile female who lived 41,000 years ago in a remote Denisova Cave in the Altai Mountains of Siberia. She has been called “X woman.” I wish they had given her a better name. That was a cave that had been inhabited by Neanderthals and modern humans. Since then 2 teeth from different members of the same population have been found.
Analysis of the mitochondrial DNA (mtDNA) of the finger showed to the scientists that it was genetically distinct from the mtDNAs of Neanderthals and modern humans. Subsequent evidence has showed that the genome from this specimen suggests that this group shares a common origin with Neanderthals and modern humans. Apparently they ranged from Siberia to South East Asia. They lived with and even interbred with some ancestors of modern humans. DNA evidence discovered in Spain suggests that Denisovans at one time resided in Western Europe. Previously it was believed that only Neanderthals lived there. A comparison with the genome of Neanderthals from the same cave in Spain revealed significant interbreeding. The evidence also strongly suggests that the Denisovans also interbred with an as yet unidentified ancient human lineage. Other pieces of bones are now being analyzed.
Later mtDNA analysis revealed that this new hominin species was a product of an earlier migration out of Africa and was distinct from later out-of-Africa migrations associated with modern humans. It was also distinct from Homo erectus. The addition of this new hominin species makes the history of humans much more complex than it was earlier. It also creates a more complex picture of the Late Pleistocene. This research suggests that the Denisovans were a sister group to the Neanderthals, branching off from the human lineage about 600,000 years ago and diverging from Neanderthals, probably in the Middle East about 400,000 years ago.
Anthropologist Niobe Thompson visited a number of recognized experts on human origins and the African world of our ancestors. These experts, shown on the television show I watched, included Rick Potts the Director of the Smithsonian’s human origins program. As well he visited archeologist Curtis Marean, whose South African excavations are telling us how humans escaped the threat of extinction, and Chris Henshilwood, whose discovery of the earliest symbolic thought and art-making is revolutionizing our understanding of the beginnings of the “modern human.” Along with other scientists they are changing how we think about our origins. These new views are fascinating.
A lot of recent archaeological evidence has been gathered in southern Africa in recent years. I saw some of those sites in 2013 during my visit to Africa with Christiane. Now scientists say that they have found evidence that southern Africa was “the cradle of the human mind.” This is where there is evidence that the Homo sapiens were reduced to pitifully small numbers. Yet miraculous they survived while the other hominins perished.
According to Thompson “some of our cousins were so like us that we ‘married’ into their lines, or they ‘married’ into ours. Our DNA carries the signals of those meetings”
All other species of hominins disappeared. That was because life during and after the last Ice Age was tough—very tough. All died out, except Homo sapiens. Some of these species were bigger than us. Some had larger brains! Yet Homo sapiens survived. Their story is remarkable. It is worth thinking about that story. Our ancestors, like all indigenous people, were remarkable.
It does seem strange that Homo sapiens now occupy a “lonely branch of the evolutionary tree.” Why did Homo sapiens manage to do what all other species of hominins were unable to do? That is a very important question well worth contemplating. If the unexamined life is not worth living, as Socrates said, and as I believe, this is a question worth pursuing. Why were Homo sapiens special enough to survive while all of their cousins went extinct?
I like to think that Homo sapiens survived because they learned to cooperate with each other, better than other species. Of course, liking to believe something does not necessarily make it so.