Apparently, the periods hypothesis is not favoured for a variety of reasons... And just because counting to 28 is more useful to women than men (men and women who tracked the moon phases for millennia don't agree) doesn't make it more likely to be periods counting.

Plus the numbers on the bone are not 28 but "are understood to indicate 9, 19, 21, 11; 19, 12, 13, 11; and 7, 5, 5, 10, 8, 4, 6, 3"...

9+19=28, here it is!

LOL that's numerology, not science...