CHAPTER 14. SOCIAL EVOLUTION WITHIN AN ECOLOGICAL CONTEXT
In the second volume dealing with anti-racism in this anti- racist trilogy, we emphasized that the evolution of animals occurred within a social context. This chapter recovers some of this ground, but more importantly, stresses the ecological context in which this social evolution took place.
Evolution is not just physical evolution. It is also social evolution. And social behavior patterns are just as subject to evolution by natural selection as any of the purely biological patterns. Nevertheless, social evolution is still physical evolution. Pannksepp (cited in Benton and Brain, 1988:229-230) has an hypothesis that there are circuits in the brain that modulate social interactions of various kinds. This idea has been supported by a number of pharmacological studies that have shown that any and all social behaviors are modulated by a range of neurochemicals. Virtually all types of social behavior that have been examined (including maternal behavior, play, social affiliation, and aggression) have been found to be influenced by neurotransmitters. These studies are still very limited in scope, but are certainly on the right track.
The theory of social evolution explains the development of altruism among species. Altruism has actually been found in a number of species. The sociobioloigst William D. Hamilton provided the answer to the puzzle of altruism (Barash, 1982:68-69). In two important papers published in 1964, he argued that animals, like the warning call of the prairie dog seeing an oncoming wolf, act in an altruistic manner because natural selection works to insure a maximum number of an individual's genes in future generations. Therefore, natural selection does not simply maximize the personal reproductive success of the individual prairie dog, but its chances of improving group survival so that its genes can continue to exist.
Because of the importance of altruism, nature is just as much cooperation as conflict. American culture emphasizes conflict because it pushes the idea of a competitive racist equality of opportunity struggle. But in nature, both animals and plants limit competition through many mechanisms, one of them being segregation into various well-developed niches in the environment.
The social nature of animals has been confirmed by studies that follow animals closely. One such is the discovery that animals have a certain amount of culture that is taught through social learning. For instance, studies of lowland gorillas in Africa have shown that the infant gorillas actually have to be taught how to act like gorillas.
Social evolution works quite like regular evolution not involving social factors, but instead of natural selection, there is a social natural selection of characteristics. Indeed, biologists are demonstrating how most social behaviors are based on evolution. Animals that cooperate in groups have definite advantages over those that do not cooperate. Natural selection insures the survival of those traits of sociality because the more communal animals have advantages in the struggle for existence. In a similar way, cultural factors become important, for those animals that can adjust to social demands have a better chance of survival.
In this chapter we want to focus on the ecological context of the behavior of animals. The social nature of animals evolved in various ecological contexts just as their other behavior patterns did. The ecological determination of family patterns illustrates just how silly it is for humans to argue whether nature is moral or immoral. The behaviors of animals vary by the ecological setting. Barash (1982:chapter 12) has a chapter on the ecology of social systems. In the chapter, he tries to determine what types of relationships (monogamy, polygamy, polyandry, or promiscuity) will exist between males and females in various species. He found that the patterns primarily depend on the degree of parental investment of the mates in the rearing of the young. For instance, monogamy usually occurs where there is near equality in parental investment by both mates. Promiscuity prevails when there is no pair-bonding between the mates. But the most important factors determining the type of parental investment required of the mates were the ecological ones. Of these, the primary factor appears to be resource distribution. For instance, among weaverbirds of Africa, the typically polygynous ones are found in savannas and nest in large, conspicuous colonies. The monogamous weaverbirds tend to be found in the forests and make isolated, inconspicuous nests.
Whether an animal is aggressive or passive depends primarily on its ecological situation. An example can be taken from the animals of the Galapagos Islands that Darwin made so famous. The lack of fear of the Galapagos animals has been long commented on by nature observers. This lack of fear constitutes a major problem for conservation measures on the islands. For instance, the Galapagos hawk is so tame that humans can touch this magnificent bird. The hawks occasionally hunt the small chickens of the human settlers. To defend their property against the hawk, all the settlers had to do was take a stick, walk up to the hawk, and kill it with several blows (Eibl-eibesfeldt 1961:168). The lack of fear among the Galapagos animals has also made them easy prey for the animals brought to the islands by humans. Native species are threatened by the now wild cats and dogs on the islands. The plant life is also, threatened, especially by the goats introduced by settlers.
Another example of the ecological context determining the degree of aggression and passion is provided by a study of non-human primates. One especially informative comparison is of the differences between old world and new world monkeys. For instance, many monkeys that have little competition are very passive in nature. Such is the case for new world monkeys. The baboons of the old world monkeys, and chimpanzees of the ape group, are both relatively aggressive because their environment differs so much from that of the new world monkeys (Moynihan 1976).
The New World monkeys occupy different habitats in different ways and this limits competition. New World monkeys do not commonly exhibit serious aggression and fighting. They are certainly less aggressive than baboons or macaques. The latter are terrestrial or semi-terrestrial and often stray into open, disputed territory. New World monkeys have social groupings of two types. The first is the nuclear family where there are both parents caring for the infant. The second type is the troop. There is an intermediate sized and a large troop. Forming troops are the spider monkey (Cacajao genus) and capuchins. In the troops there are more females than males.
In the family Callitrichidae are found the Tamarins and Marmosets. The tamarins are small monkeys; they prefer to eat insects. There is some causal link between small size and insectivorous habits. The Tamarins look like squirrels with monkey faces. They have long, thin tails. Many have elongated tufts and ruffs of hair which is important in visual signaling. They have sharp claws on their fingers and on all their toes except the hallux (the big toe). The cerebrum is comparatively smooth (not the brightest). Marmosets greatly resemble the Tamarins. In common with the Tamarins they are of small size, have claws, and some similar locomotory and feeding habits. They may rest at noon. They tend to remain very quiet in order to avoid predators. Like squirrels they like to dodge behind trunks and branches and often advance in spirts like lizards. Following the thesis of evolution as conflict, one might expect the Tamarins and Marmosets to fight each other, but they usually to do not overlap with Tamarins. An interesting example of a very peaceable Marmoset is the Pygmy Marmoset (Cebuella pygmaea) from tropical Columbia, Peru, and Ecuador. It is the world's smallest primate, weighing just 3.5 - 4.2 ounces. Its most distinctive feature is its almond-shaped eyes. The ears are completely hidden by the mane. It spends most of its time chewing through tree bark to reach the gum and sap that are the major components of its diet. While sap sucking appears to be the most important part of their diet, these small primates also eat fruits and insects. They live in extended family groups and defend small territories of 2/10 to 7/10 of an acre.
There are many South American monkeys, but the point is that there is very little conflict among these species. Indeed, these primates have become so intelligent that they have a certain amount of "social independence" from their ecological environments (Moynihan 1976:188). They can combine different social relations even when they have similar feeding habits. And likewise, they can have similar social relations with different feeding habits.
Still another example of a peaceful animal is that of the Lowland Gorilla (Gorilla gorilla gorilla -- superfamily Hominoidea, family Pongidae) from western equatorial Africa. The gorilla lives mainly on the ground, and adults only venture into trees to build nests, though young gorillas often play in trees. On the ground, it is quadrupedal and the weight of the body rests at the front on the central phalanges of the fingers in a kind of locomotion called knuckle-walking. This animal is very scary looking to human beings, but the gorilla is a peaceful creature, and will only attack if attacked. A diurnal vegetarian, it lives in groups of two to thirty individuals, always dominated by a large male.
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