We staged matings under different sex ratio conditions, and provide evidence that copulation duration is a form of male reproductive investment.
Sexual intercourse (or coitus or copulation) is principally the insertion and thrusting of the penis into the vagina for sexual pleasure, reproduction, or both. This is also known as vaginal intercourse or vaginal sex. Other forms of penetrative sexual intercourse include anal sex (penetration.
Find professional Human Copulation videos and B-roll stock footage available for hd: sexy woman sleeping in bed - human copulation stock videos and b-roll.