Mountain-making is much more than a superficial event for the earth. When the Indian subcontinent crashed into Asia, the collision pushed up the earth's crust to form the Himalayas. This formidable mountain range initiated India's powerful monsoon, a concentration of wet weather on the subcontinent which eventually dried out Africa's savanna. Though a subtler change in landscape than a mountain's appearance, the widening grasslands did manage to coax primates down from the trees. The earth hasn't been the same since.