Every man on Earth today can trace his Y chromosome to one male who lived about 190,000 years ago, before anatomically modern humans had evolved, a study suggests.

There were many males around at the time, but only this one left a Y chromosome legacy that persists today, said researcher Michael Hammer.The Y chromosome is one of the 24 kinds of microscopic threads that hold genes. Unlike the other chromosomes, it is passed only from father to son.

The new study also supports the idea that modern humans arose in one place, rather than evolving on more than one continent.

Hammer, an assistant research scientist at the University of Arizona in Tucson, published the work in Thursday's issue of the journal Nature.

He compared the detailed makeup of a tiny piece of the Y chromosome as sampled from eight Africans of various backgrounds, two Australians, three Japanese and two Europeans. The idea was to look for how varied that piece was among the different ethnic groups and then calculate how long it would take for evolution to produce the diversity he found.

The results suggest that all men alive today could trace their Y chromosomes back for about 188,000 years to the same person. "We would all have a Y chromosome that existed in the same guy," Hammer said.

Hammer said the study suggests that the ancestor lived just before anatomically modern humans appeared around 100,000 years ago, a date that is in some dispute among scientists.