As a result of interbreeding
between our human ancestors and archaic humans, many Europeans and Asians today have about 2 percent of Neanderthal DNA in their genome.
Ancient DNA shows signs of interbreeding
between now-extinct Neandertal relatives known as Denisovans and ancient humans.
"There was lot of interbreeding
that we know about and probably other interbreeding
we haven't yet discovered." The genome analysis will be published in the Dec.
He said that the only place where such a genetic signal exists appears to be in areas east of Wallace's Line and that is where we think interbreeding
took place - even though it means that the Denisovans must have somehow made that marine crossing.
Ms Shapiro, said climate change in Arctic regions could see brown and polar bears interbreeding
The researchers say that such high levels of interbreeding
points to very small territories and smaller colonies.
Modern-day Melanesians carry a two-pronged genetic legacy of ancient interbreeding
that still affects their health and well-being, researchers say.
The scientists also found that this Neanderthal genetic signal was higher in North African populations whose ancestors had relatively little recent interbreeding
with modern Near Eastern or European peoples.
In such instances, there is a wide "gray zone" of speciation - an intermediate state in which it is hard to distinguish one species from the other, and within which interbreeding
is still possible to some extent.
Evidence of that Stone Age interbreeding
was uncovered when researchers found traces of Neandertal DNA slipped into the pages of the human genetic instruction book.
"It appears some level of interbreeding
may have occurred in many parts of the world at different times in human evolution," said University of Arizona geneticist Michael Hammer, who conducted the study with a team of evolutionary biologists, geneticists and mathematicians.
In addition, researchers have been able to speculate that the evolution of mankind occurred through migration and continuous interbreeding
Research by immunologist Peter Parham suggests that interbreeding
with Neanderthals gave our ancestors a ready-made cocktail of DNA invaluable in fighting diseases common in northern climates.
An analysis of DNA from a roughly 36,000-year-old modern human fossil found in Russia dates human-Neandertal interbreeding
to about 54,000 years ago, researchers report November 6 in Science.
The team, with researchers from the Pontifical Catholic University in Brazil and Universidade Federal do Rio Grande do Sul, said there is no evidence of interbreeding
between the two types of tigrina.