Mitochondrial Eve, meet Y-chromosome Adam. Call him Y guy—he's a younger man, after all. The scientists who tracked down Y guy see him as a potentially key figure in the debate over the location and timing of humanity's origins. Yet other investigators view Y guy as a statistical apparition generated by dubious evolutionary assumptions.
Y guy is a genetic reconstruction of the common ancestor of males today, according to a report in the November Nature Genetics. He resided in eastern Africa and first trekked into Asia between 35,000 and 89,000 years ago, say the researchers. In contrast, mitochondrial Eve—the hypothetical common female ancestor of all people today—lived in Africa and migrated into Asia around 143,000 years ago, other researchers have concluded from genetic analyses.