Our ape-like ancestors were not unlike the existing gorilla, chimpanzee, and orang-utang. They lived in large herds and were prolific; polygamy was in vogue, and at the courting season love-duels were fought among the males. They chiefly inhabited the ground, but ascended the trees in search of fruit, and also built platforms of sticks and leaves, on which the females were confined, and which were occasionally used as sleeping-places, just as birds sometimes roost in old nests. These animals went on all fours, rising to the upright posture now and then, in order to see some object at a distance, but supporting that posture with difficulty, holding on to a branch with one hand. They were slow in their movements; their body was almost naked, so scantily was it clothed with hair; the males had but poorly developed tusks, or canine-teeth; the ears were flattened from disuse, and had no longer the power of being raised; the tail as in all great apes had disappeared beneath the skin.