We homo sapiens are the only surviving humans around. In fact, it has been that way for the last 10,000 years. We tend to forget that at some point, there were many types of humans (of genus Homo) on earth like the Homo neanderthalensis (Neanderthals), Homo soloensis, Homo floresiensis, Homo erectus, and Homo denisova (Denisovans). While the Neanderthals are the most famous among all of these, sapiens co-existed with the others and intermingled with them. We may even have caused their extinction
While all of us have some Neanderthal ancestry (1 – 4%), some of us (Australians, Indians) have more Denisovan ancestry (5%). This intermingling happened much after the Neanderthal mixture. This happened because all these three — sapiens, Neanderthals and Denisovans — were not different species, but of the same species. They produced offsprings together.
A new paper analyzed the amount of Denisovan ancestry and found that Indians have the largest admixture after the people in Australia. Among the Indians, the largest were among people in the Himalayan region and South and Central India. What is not known is this: Was there a single introgression of Denisovans into sapiens and it got diluted in various rates among the populations of the world or there were three different introgressions.
Looking at this paper, Sunil Deepak asks an interesting question.