actually, this ties in pretty well with the rdos.net neanderthal theory, which also implies visible genetic differences on several levels.
and as a matter of fact; when i had my jaw surgery (my lower jaw was about 2 centimeters too short...), i got told afterwards that i lost a dispropotionately large amount of blood, becouse several arteries were cut that weren't supposed to be there, yet they were almost the same on both sides of my jaw;
also, i was up and running at a rate noone expected; i was kept in hospital for a night for observation and they expected me to leave the afternoon after in a wheelchair, but i was walking to the toilet by myself (ok, leaning on a cane, but still) only hours after the surgery; something that i should not be able to do untill averagely 2 days after surgery; with 'standard' blood loss; so with my extra loss, they expected it'd take a week to be able to take care of myself; yet that week was all i needed to make a full recovery to the point that nothing was visible anymore.