The tip of a girl’s 40,000-year-old pinky finger found in a cold Siberian cave, paired with faster and cheaper genetic sequencing technology, is helping scientists draw a surprisingly complex new picture of human origins.

The new view is fast supplanting the traditional idea that modern humans triumphantly marched out of Africa about 50,000 years ago, replacing all other types that had gone before.

Instead, the genetic analysis shows, modern humans encountered and bred with at least two groups of ancient humans in relatively recent times: the Neanderthals, who lived in Europe and Asia, dying out roughly 30,000 years ago, and a mysterious group known as the Denisovans, who lived in Asia and most likely vanished around the same time.

Their DNA lives on in us even though they are extinct. “In a sense, we are a hybrid species,” Chris Stringer, a paleoanthropologist who is the research leader in human origins at the Natural History Museum in London, said in an interview.

The Denisovans were first described a year ago in a groundbreaking paper in the journal Nature made possible by genetic sequencing of the girl’s pinky bone and of an oddly shaped molar from a young adult. Those findings have unleashed a spate of new analyses.

Scientists are trying to envision the ancient couplings and their consequences: when and where they took place, how they happened, how many produced offspring and what effect the archaic genes have on humans today…

Comparing genomes, scientists concluded that today’s humans outside Africa carry an average of 2.5 percent Neanderthal DNA, and that people from parts of Oceania also carry about 5 percent Denisovan DNA. A study published in November found that Southeast Asians carry about 1 percent Denisovan DNA in addition to their Neanderthal genes. It is unclear whether Denisovans and Neanderthals also interbred.

A third group of extinct humans, Homo floresiensis, nicknamed “the hobbits” because they were so small, also walked the earth until about 17,000 years ago. It is not known whether modern humans bred with them because the hot, humid climate of the Indonesian island of Flores, where their remains were found, impairs the preservation of DNA.

This means that our modern era, since H. floresiensis died out, is the only time in the four-million-year human history that just one type of human has been alive, said David Reich, a geneticist…who was the lead author of the Nature paper on the Denisovans…

Although little is known about the Denisovans — the only remains so far are the pinky bone and the tooth, and there are no artifacts like tools. Dr. Reich and others suggest that they were once scattered widely across Asia, from the cold northern cave to the tropical south. The evidence is that modern populations in Oceania, including aboriginal Australians, carry Denisovan genes.

Dr. Reich and others suggest that the interbreeding that led to this phenomenon probably occurred in the south, rather than in Siberia. If so, the Denisovans were more widely dispersed than Neanderthals, and possibly more successful.

But the questions of how many Denisovans there were and how they became extinct have yet to be answered. Right now, as Dr. Reich put it, they are “a genome in search of an archaeology.”

Fascinating studies. Techniques rocket along aiding the speed of research, even the cataloguing of findings.

None of which diminishes the importance of these studies.