For many animals, laying the eggs is the last act of parenting. In others, elephants are a good example; the care of the young lasts years and is a task that is not restricted to the mother alone. Female elephants live in close-knit groups of around 20 individuals, all of whom are related. A baby elephant is surrounded by its mother’s sisters all of whom will guard it or rescue it if it gets into danger. The baby may well be suckled for the first 4 to 5 years of life, even though it will be able to walk a couple of hours after birth and feed itself after about 4 months. Elephants display real ‘family life’, as do many monkeys and apes, and some of the big cats. Although antelope may form huge herds this is a defence against predation and not an element of family life.
The age at which young animals become independent of their parents is very variable between species and sometimes even within species. There are a great number of varieties of the mouse Mus musculus – called strains. Each strain has a slightly different genetic make-up and the young from some strains have very different development rates. New born mice are naked and blind. They are also unable to maintain their own body temperature and they rely on the mother and their siblings to keep the nest warm. Any newborn that rolls out of the nest will cool and it then starts to emit ultrasonic cries that stimulate the mother to retrieve it and return it to the nest. This calling is a very powerful stimulus for the mother and she will retrieve anything that produces ultrasonic calls, even a tiny loudspeaker! Comparing a couple of strains of mice has shown that the young of one strain develop hair and the ability to maintain their own body temperature within 5 days of birth. In the other strain, the young reach that same stage only after 10 to 14 days. The first strain is described as precocial and the second as altricial. Chicks of domestic fowl are fluffy and active within a couple of minutes of hatching from the egg. Contrast these with young of many species of song bird that nest in our parks and gardens, where the young are helpless when they hatch, being naked and sightless. There is an obvious correlation between the amount of parental input and the degree of precociousness.
Parenting is not restricted to females. Most birds form a pair to rear young, either for a season only (most song birds) or for life (parrots and albatrosses are examples) with both partners contributing to bringing up the young. There are species, however, where the male takes no part in rearing the young. Males of some grouse species, for example, congregate in leks and attract females to mate, but after mating each female goes off and rears the young alone. By contrast, female phalarope desert the male as soon as the eggs are laid and the male completes the rearing alone.
The apes have a variety of social systems. Gibbons live in monogamous groups, a pair of adults and their young. Perhaps surprisingly, this grouping, which is common amongst birds, is unusual in mammals. Gorillas live in polygamous groups with a dominant male, several females and their offspring, though both male and female offspring leave the group as soon as they are mature. So, the females in the group are unlikely to be related to each other.
Chimpanzees and bonobos have contrasting social groups. The chimps are a male-dominated grouping in which the females and young live in a group that is protected by the male members, who are closely bonded together as they grew up together within the group. This is a very flexible social organisation, capable of responding to changing habitat conditions and is probably the social structure that is ancestral to the human one. Bonobo society is organised very differently in that females bond together, forming larger groups than those seen in chimps – groups that include both sexes and all ages. Males don’t have to leave the group when they mature. So in these ape societies, who you are reared with is very important in later life. Orangs are rather different. They do have a loose social structure, but without the bonding seen in chimps and bonobos. There is little contact between males and females and so the female brings up her young in a largely solitary environment. The mother-child relationship is the only strong bond formed in orang society. The home range of a male is large and may include within it the home range of more than one female, but they would rarely meet. The male uses sound to advertise his position, which both warns other males off and attracts females if they are sexually receptive.
It is because apes are so close to our own ancestors, that study of the relation between parents and their offspring is such a fascinating area and, of course, you can make observations yourself by watching monkeys and apes at wild-life parks or zoos. So when you do, think about the social structure, see if you can pick out who is dominant to whom and, look particularly at the young and how they fit into the social group. Although zoos are artificial environments, you can still learn a lot about parenting and sociality in our closest living relatives.