Caveman study reveals genes NOT passed to modern man
![Caveman study reveals genes NOT passed to modern man](http://www.thelocal.es/userdata/images/article/w468/15cc483105af1d5ba325c76d4b220504f7d65b0dd8a89659c2abbab17944c413.jpg)
The first examination of a long-extinct Neanderthal's Y chromosome suggests that fertility problems may have prevented Neanderthal men from successfully mating with modern human females, researchers said on Thursday.