In the first instance from the roots of teeth from some of the original Neander Valley specimens and more recently from the marrow of rib bones from specimens in the middle East. Both studies showed the same thing. One researcher described neanderthal DNA as "about halfway between ours and that of a chimpanzee". That eliminated the neanderthal as a plausible ancestor for modern man, at least via anything remotely resembling gradual change or evolution.