Three articles published in the journal “Nature” describe as many genetic studies that aim to reconstruct the genetic history of modern humans’ migrations. The results agree that non-African populations show traces of a single expansion started from Africa about 75,000 years ago. However, one study suggests that at least 2% of the DNA of the inhabitants of today’s Papua New Guinea comes from a previous migration. One of the studies shows that Aboriginal Australians split from the Papuans about 37,000 years ago.

It’s now taken for granted that Homo sapiens was born in Africa and from that continent at some point started migrating slowly colonizing other continents, where sometimes found other species of hominids such as Neanderthals and Denisovans. Various genetic research were conducted in recent years to try to trace the variations in the DNA that follow the migrations of different populations. However, with the improvement of genetic techniques it was possible to conduct more thorough research such as those now published.

The search for traces of ancient migrations required thorough analyzes and the team led by Drs Luca Pagani and Toomas Kivisild of the Department of the University of Cambridge’s Department of Archaeology and Anthropology eventually found them. The “genetic signatures” found in today’s inhabitants of Papua New Guinea (photo ©♪ ~) suggests that at least 2% of their DNA is derived from a previous migration from Africa.

The analysis of haplotypes, meaning the combination of variants along a chromosome or chromosomal segment, of Africans suggests that the split between Africans and the first Papuans occurred about 120,000 years ago. This population may have settled some lands out of Africa at that time and that DNA present in Papuans seems to be the only trace left after the subsequent migration occurred 45,000 years later led to the colonization of other continents.

The complexity of this type of research can be seen by the fact that the other research, conducted by geneticists at Harvard Medical School, found no traces of the earlier migration. This research was conducted analyzing the DNA of 300 people from 142 different populations while the one conducted by Luca Pagani and Toomas Kivisild’s team was conducted analyzing the genomes of 379 people from 125 populations. It’s possible that it took a little luck to find the genetic traces of the earlier migration.

The third study, conducted by an international team in collaboration with the Australian Aboriginal communities, focused on the analysis of the history of the ancient colonization of Australia. The result is that the DNA of Aboriginal Australians shows the traces of the migration from Africa that in this research is estimated at 72,000 years ago, meaning a result consistent with that of the research.

The DNA of the Aboriginal Australians shows a divergence from the people of Papua New Guinea dating back to about 37,000 years ago. The research also shows the genetic diversity that developed over thousands of years among Aboriginal Australians. Anna-Sapfo Malaspinas, first author of the article on the subject, explained that the genetic diversity among groups of the southwestern desert Australia is greater than that between Native Americans and Siberians.

These are very interesting results that provide some new answers on the migration from Africa but also pose some questions. The interpretation of the data is made more difficult by the need to eliminate from the analyzes the genes derived from the interbreeding with other hominid species. The history of homo sapiens is really complex but at the same time fascinating so the research continues.