Genetic studies have revealed that modern humans have some of the DNA from their now-extinct hominid species. There is also molecular evidence for the ancient interbreeding between Neanderthals and humans.
INTERBREEDING WITH NEANDERTHALS
Even though it is hard to believe that long ago, humans mated with different species, the molecular evidence proves it true. In 2010, Neanderthal genome was sequenced and the results showed that 1 to 4 percent of DNA of non-Africans is inherited from Neanderthals.
Neanderthals are known to be closest related species to humans. They got extinct over 40,000 years prior. Expansion of modern humans out of Africa can be proved by the interbreeding between modern human and Neanderthal. Even though humans interbred with Neanderthals, a major portion of the genome is from Africa.
In 2016, a new Neanderthal DNA sequence was formed from Altai Cave in Siberia, Spain and Croatia which dated interbreeding between human and Neanderthals back to 1,00,000 years prior. The molecular evidence was found in the toe bone of a Neanderthal woman who resided in Denisova Cave in the Altai Mountains in Siberia, Russia almost 50,000 years ago. On analysing the genome, it was found that she had inherited DNA from Africa’s modern humans including the gene for speech.
This pushes back the date of interbreeding between modern humans and Neanderthals. Some of the modern DNA seems to have come from Denisovans (closely related to Neanderthals who interbred with ancestors of present Melanesians). The Denisova girl carried ancient DNA from Homo erectus (direct human ancestor who lived 1.8 million years ago). This proves that modern humans interbred with various other now-extinct species.
The low levels of DNA exchange from these encounters suggest that it was limited to few trysts only. However, the carried on genes from Neanderthals are responsible for shaping the health of Europeans. Interbreeding between Altai Neanderthal resulted in getting DNA of modern human-related with the immune system, speech and sperm production.
Present species mate with other closely related species in nature like in the case of olive baboons and hamadryas baboons. The human inter-species breeding has not been fully explored. There are various studies taking place for exploring the DNA of fossils.
Interbreeding between modern humans and other now-extinct species has resulted in genetic diversity. This has been helpful for adapting to new lands during the expansion of humans into foreign places.