The Tinbergen’s framework of evaluation of mother-offspring interaction behavior proposes that the behavior must be analyzed in terms of avoidance of danger (adaptation), phylogeny (evolutionary stages), causation (the workings of the eye), and ontogeny (process of individual development). Adaptation is based on Darwin’s theory of evolution which explains why a primate is best suited to reproduce in its habitat. Mothers nurture their young ones so that more offsprings can survive. Phylogeny helps understand the unique behavior of the organism, causation explains transmission of signals that regulate behavior while ontogeny explores whether behavior is genetic or is acquired through social and environmental interactions.
Differences in maternal behaviors among primates are caused by life styles, reproductive and mating habits, life history, and social systems. There are six basic compositions of social groups among primates: single female and her offspring; polyandrous family group; monogamous family group; multi-male-multi-female group; one male several female group; and fission-fusion society. Non-human primates are only aware of their matrilineal descent since they know who their mother is but do not know their fathers. Chimpanzees maintain matrimonial bonds with their mothers even when they become adults. Primate mothers rarely mate with their sons due to this bond, but fathers often mate with their daughters since they do not know each other.
Species of the prosmian group of primates have small bodies, are nocturnal and solitary. The offspring usually lives in a nest; maternal interaction involves visits to the nest by the mother to nurse and groom the infants. Apes, old world monkeys, and new world monkeys are diurnal and have bigger bodies and higher life expectancy. Their offspring are usually carried for days, months or years depending on the environmental factors. In the Callitrichidae family of the new world monkeys, females usually give birth to twins. Adult males and older males assist the mother in carrying and taking care of the infants. When two females breed in the same social group, they kill each other’s infants during the final stages of the pregnancy)
In the columbine monkeys, females usually carry their infants without help during the entire postnatal period. They also carry older offsprings when they are going for long distances. They restrain their offsprings from breaking contact in order to protect them from predators. The infants are encouraged to walk independently by their mothers, but they carry them instantly if they spot potential danger. In apes, mothers assist their infants to transit from milk to other foods by sharing food with them. The mothers also help their offsprings to establish social bonds by choosing dominant social partners for them. Human mothers wean their offsprings until they are full grown adults, and they never severe contact with their offsprings permanently.
The debate over whether infants of non-human primates wean themselves or are actively weaned by their mothers is still ranging. Wild baboons usually reject their infants early. Those infants that are lucky enough not to be rejected early stay close to their mothers, suckle, and ride even when they become old). Interaction of primate mothers with their offspring is influenced by pregnancy and lactation. Neuropeptides (prolactin, progestogens, oxycotin, and estrogens) and other reproductive hormones affect the mothers’ attitudes towards interacting with their offspring. The concentration of the sex hormones fluctuates unpredictably and dramatically. The hormones affect the maternal behavior and responsiveness of primates. Wild chimpanzees usually reject their infants during the mating seasons when they resume mating and consortium with males. When the mother is on heat (estrus), chimpanzee infants are rejected even when they are one month old.
The interaction of the mother with the offspring often influences the mother’s reproduction cycle. The offsprings make several attempts to contact the mother, but their advances are usually rejected. When a chimpanzee infant attains the age of three months, roles change. The duty of the mother to maintain contact with the offspring changes; from then on, the offspring is mandated with the obligation to maintain contact with the mother (Lancaster, 2007). In Macaques, the weather affects the interaction of primate offsprings with their mothers. A study found that a decrease in temperatures resulted in higher rates of rejection of the offspring by their mothers.
Both primate mothers and offsprings determine the extent to which post natal care is carried out and the amount of time spent on weaning. When mating season gets closer, most primate females try to limit interaction with the offspring so that they can have time and space to nurture another offspring (Nitecki & Kitchell, 2009). Sometimes, it is the independent infants who reduce interactions with their mother by cutting contact, for instance, through refusing to breastfeed at an early age. Mothers also reject interactions with infants due to environmental factors and climatic changes. Even after weaning, some primate infants such as those of humans and chimpanzees still retain contact with their mothers creating a strong maternal bond. Research needs to be done to establish the effects of variations in maternal interactions and the behavior of the primate infant.