“The genomes indicate that Denisovans interbred with yet another extinct population of archaic humans that lived in Asia more than 30,000 years ago — one that is neither human nor Neanderthal.”
David Reich, 2013 Genome Study on Denisovan DNA
Back in 2013 a new study was undertaken which updated the genome sequence of two of our extinct relatives and the findings indicated strongly that these two archaic groups bred with humans and with each other more extensively than previously thought. One of those archaic groups was the Asian Neanderthals and the other was the Asian Denisovans. The findings of this genome study indicate strongly that interbreeding went on between the members of SEVERAL ancient human-like groups in Europe and Asia more than 30K years ago, including interbreeding with an as yet unknown human ancestor from Asia. However, the study also indicated that interbreeding went on between Denisovans and yet another extinct species of unknown archaic human that lived in Asia more than 30Kya that was neither Neanderthal nor human!
When this study says the Denisovans were interbreeding with an unknown species of archaic human that was neither Neanderthal nor human I assume the term “human” means Homo sapiens.
Let me define a couple of terms before I go on……
Hominid — the group consisting of all modern and extinct Great Apes.
Great Apes — include Humans, Chimpanzees, Gorillas, Orangutans plus all of their immediate ancestors.
Hominin — The group consisting of Modern Humans (Homo sapiens), extinct human species and all of our immediate ancestors including members of the genera Homo, Australopithecus, Paranthropus, and Ardipithecus.
So when this study says that the Denisovans interbred with an unknown species of archaic humans that was neither Neanderthal nor Homo sapien but some presently unknown archaic non-human species we are talking about Hominids, the group consisting of all modern and extinct Great Apes and that includes Gigantopithecus!
But is that possible? Is it possible that the Denisovan were not only interbreeding with Asian Neanderthals but with Gigantopithecus? And all this interbreeding taking place a mere 30,000 years ago? Thirty thousand years in paleontological terms is a blink of the eye and if the Denisovans were interbreeding with Gigantopithecus or some other unknown ape in Asia then that means that interbreeding between archaic humans and apes was still going on RECENTLY!
What about the Denisovans? What do we know about them? In March of 2010 the first Denisovan fossil remains were found in Denisova Cave in Siberia. Those remains consisted of a finger bone fragment from a juvenile female who lived about 41,000 years ago in Siberia’s Altai Mountains. The Denisovan Cave is known to have also been inhabited by Neanderthals and modern humans (H. sapiens). Since that time two teeth and a toe bone have also been discovered along with some Denisovan remains found in a cave in Spain that were previously thought to be that of H. Heidelbergensis but are now known to be closer in their genetic makeup to the Denisovans.
When it comes to the precise anatomical features of the Denisovans we actually known very little. The finger bone is unusually broad and robust, meaning BIG, and is well outside variations seen in modern humans. That means that the Denisovans have larger fingers than we do and since this fingerbone came from a juvenile that means it was not yet mature and we can surmise that the fingerbone of an adult Denisovan were most certainly be larger than our own. So what this indicates is that the Denisovans were larger than we are perhaps similar in built to the Neanderthals, however. The tooth shares no morphological features with either Neanderthals or modern humans, incidentally. The toe bone has been postulated to perhaps being from a Neanderthal-Denisovan hybrid. DNA evidence suggests humans, Homo sapiens, produced hybrid offspring with Denisovans.
The DNA evidence shows that the difference between chimpanzees and modern humans is about 1462 mtDNA base pairs. From the analyzed Denisovan fingerbone the difference between it and modern humans is about 385 mtDNA base pairs.
The Denisovan fingerbone was analyzed using DNA sequencing. The DNA preservation in the fingerbone was remarkably well preserved and uncontaminated. The DNA showed an almost complete genomic sequencing. It showed the Denisovans shared a common ancestor with Asian Neanderthals about 640Kya. In 2013 mtDNA analysis showed that a femur bone from H. heidelbergensis found in the Sima de los Huesos Cave in Spain was found to be most similar to a Denisovan femur bone.
Let’s now look at Gigantopithecus. It is believe that this extinct giant ape existed from around 9 mya to as recently as 100Kya. It lived in Nepal, China, India, and Vietnam. Thus it existed in the same time frame as several other hominin species including modern humans, Neanderthals, and Denisovans. Most scientists think it walked on all fours but a few believe it was bipedal.
There are three known species of Gigantopithecus. G. blacki, G. bilaspurensis, and G. giganteus. Gigantopithecus blacki was the largest standing about 3 meters tall (9.8 ft) and remains of this species were found in caves in Vietnam and South China. It is believed to have gone extinct around 100Kya. Fossil remains of this species were also found in Indonesia in 2014. It is estimated G. blacki weighed around 540 ky (1190 lbs). Females were about half the size of males. Some, however, argue that G. black was smaller perhaps only standing as high as 1.8 m (5.9 ft). It was mainly a plant eater. Its actual appearance is unknown but we think it looked gorilla-like.
G. bilaspurensis was smaller than G. blacki. G. giganteus was also smaller and is believed to have lived 5 million years before G. blacki. It was roughly about half the size as G. blacki.
So the question is could the Denisovans interbred with one of these species of Gigantopithecus apes? It is possible but there is no evidence that this is so as yet. It the unknown hominid species the Denisovans interbred with is not Giganto then what was it?
We know the Denisovans interbred with Neanderthals and later modern humans, H. sapiens. But we also know they interbred with some unknown hominid species too. It is possible that they interbred with H. heidelbergensis. Heidelberg Man was robust and in South Africa some of this species got up to 7 ft tall. Denisovan femur bones are similar to Heidelberg femurs and, in fact, have been mistaken for Heidelberg femurs until recently. So it is possible that they interbred with Heidelberg Man. Further, it is believed H. heidelbergensis was the common ancestor of both Neanderthals and Denisovans on one branch and modern humans on another branch. But, wouldn’t we know if Heidelberg Man was the unknown mystery species the Denisovans interbred with? Yes we would and the mystery species DNA does not match Heidelberg Man.
So what is the unknown non-human species the Denisovans were interbreeding with not so long ago? At this point we have no idea but one thing is for certain and that is that there are still plenty more mysteries to be solved when it comes to modern human, Homo sapien, evolution.