Science editor Alan Boyle's blog: Scientists say an African-American's odd genetic signature suggests that the human Y chromosome's lineage goes back further in time than they thought — perhaps due to interbreeding with other populations such as Neanderthals.Science editor Alan Boyle’s weblog: Scientists say an African-American’s strange genetic signature suggests that the human Y chromosome’s lineage goes again additional in time than they notion — in all probability as a result of interbreeding with different populations equivalent to Neanderthals.