49 about six months ...to well over a year. If there is only one part of the year that is favourable, such as spring and early summer in the temperate climates, then each species must make an evolutionary choice, so to speak, as to which parts of the reproductive cycle - conception, gestation, lactation or weanin- must be protected and which can come in less favourable times of the year. The rhesus and langur monkeys of northern India give birth during the time of year when temperatures are hottest and wells and tanks are often dry. However, gestation and the later months oflactation come...