Ages computed from nuclear DNA diversity are larger than ages computed from mtDNA diversity. This is also evidence for an accelerated mutation rate in the
past because nuclear DNA
mutates much slower and would be more affected. But what caused the increase?
There is evidence that
small doses of radiation can lead to unexpectedly high mutation rates in humans (Science 8 February 2002 vol. 295 page 946): ...
researchers led by geneticist Yuri Dubrova of the University of Leicester, United Kingdom, describe a compelling connection
between radioactive
fallout and elevated mutation rates in families living downwind of the Semipalatinsk
nuclear facility ...