Back in 2011 researchers Michael Hammer with the University of Arizona published a paper providing evidence that Homo sapiens not only interbred with Neanderthals in Eurasia but they also interbred with several other species of ancient human ancestors in Africa. OFTEN not every now and then according to Hammer! “We think there were probably thousands of interbreeding events. It happened relatively extensively and regularly,” Hammer wrote.
Another paper published in 2010 by Swedish evolutionary biologist Svante Paabo in the journal “Science” was considered “ground breaking” because it brought genetics into the evolutionary equation. Paabo provided GENETIC PROOF that Homo sapiens migrated out of Africa and into Neanderthal Eurasia. There they met and mated with more primitive human ancestors! This discovery was made by Paablo and his team when they compared samples of Neanderthal DNA with modern human DNA. His discoveries have been called the “Leaky Replacement Hypothesis.”
Prior to modern humans “replacing” the Neanderthals they interbred with them and produced viable hybrid offspring. Further, these hybrid offspring were apparently functional enough to integrate into human society at the time and had children of their own according to Paabo and the Leaky Replacement Hypothesis.
All humans today that are non-Africans carry between 1-4% Neanderthal DNA and the more we research the more we discover that this Neanderthal DNA is NOT dormant in us but is still active and sometimes plays an important role in our health.
Hammer in his paper says that this interbreeding of human species did NOT stop with Neanderthals. He suggested that due to environmental conditions we are not able to conduct genetic research with our African ancestors because Neanderthals lived in colder non-tropical climates that better preserved viable DNA while our African ancestors lived in tropical environments which are usually NOT conducive to fossil formation or preservation. I might also add that in addition DNA from other human species such as Homo erectus, Homo habilis, etc has not been obtained because of the age of the fossils and the DNA is to degraded to sequence.
Hammer and his team at the U of A came up with a brilliant alternative approach in my opinion. They wrote a computer program and using human DNA they were able to SIMULATE HISTORY! You might call this “reverse engineering” of human DNA 🙂
What Hammer and his team learned from using these computer simulations was nothing short of amazing because they found EVIDENCE that Homo sapiens not only interbred with Neanderthals but they ALSO INTERBRED WITH HOMO ERECTUS, HOMO HABILIS, AND OTHER ancient human ancestors!!
Hammer and his team upset the apple-cart because there was (and still is today) a lot of skepticism when it comes to the idea that human species interbred. Further, our ethnocentrism and false idea that we Homo sapiens are “special” is DISPROVED by Hammer and his research results as even though we like to think of our own species as being an exception to some of the laws of evolution our DNA proves otherwise! What Hammer and Paabo both showed is that we are NOT immune to the laws of evolution!
After these two ground breaking papers the question remained as to why archaic species “died off” leaving only Homo sapiens remaining. Paabo at the time said we don’t know the answer. Hammer’s evidence gives us some clues about ancient human ancestor migrations around the world. Personally, I do NOT think these ancient species “died off.” In fact I think all ancient human ancestors interbred a lot and produced viable offspring right up to our own times. And I think we modern Homo sapiens today are the end result of all that past interbreeding of different human species!
Paabo and Hammer add evidence to what I’ve always thought and hypothesized. I do NOT think Homo sapiens “replaced” any ancient human species OTHER THAN via interbreeding and hybridization. The “Out of Africa” theory is also known as the “Replacement Theory” and, frankly, I think some revisions of that theory need to be made. Clearly, DNA evidence is telling us….PROVING to us….that our ancient human ancestors interbred FREQUENTLY not rarely and that viable hybrid offspring were being produced. And, the end result (thus far) is modern humans whom I believe are a culmination of ALL past species of ancient human ancestors known and unknown! We are HYBRIDS!