"Homo neaderthalensis" (usually called Neanderthal man) lived from about 250,000 to about 30,000 years ago. Also, less usual, as "Homo sapiens neanderthalensis": there is still some discussion if it was a separate species "Homo neanderthalensis", or a subspecies of "H. sapiens". While the debate remains unsettled, evidence from mitochondrial DNA and Y-chromosomal DNA sequencing indicates that little or no gene flow occurred between "H. neanderthalensis" and "H. sapiens", and, therefore, the two were separate species. In 1997, Dr. Mark Stoneking, then an associate professor of anthropology at Pennsylvania State University, stated: 