Alliances, betrayals, deception, trust, jealousy, adultery, motherly affection- it all sounds rather human. Nevertheless, we humans are animals- males abundant with sperm, female with scarce eggs- and our ancestors were subject to evolution just as much as any pipe fish or jacana. Just as Murray Bookchin wrote, human beings not only belong to nature and have natural activities, humans are the product of a long natural evolution. To understand the murkiness of the matter, we first have to understand where humanity came from.
I.
Many people may theorize that humans have evolved from primates. However our social interactions may be much more closely related that we would ever imagine. In only few species is altruism undermined and animals help strangers without any regard for blood ties. Vampire bats are one. They spend each night searching for animals whose blood they can drink. But if they fail, they can return to their cave and beg for some blood from an unrelated bat that had a more successful hunt. Robert Trivers, a Rutgers University anthropologist, has dubbed cases like these "reciprocal altruism" Evolution can favor reciprocal altruism because in the long run two unrelated animals that help each other may enhance their chances of survival more than if they had behaved selfishly.
Reciprocal altruism may be particularly likely to evolve in species with big brains. If you have the mental capacity to keep in mind who has helped you out and who owes you, you can use reciprocal altruism to your advantage. So it should not be a surprise that some of the best evidence for animals helping strangers comes from our closest relatives - chimpanzees and bonobos( a separate species synonymous with pygmy chimpanzees).
Chimpanzees cooperate with unrelated chimps, do favors for them, and sometimes make sacrifices for them. They may join together on hunting expeditions, looking for duikers or colobus monkeys and sharing their kills. Reciprocal altruism may help chimpanzees gain social power. Two subordinate males can make an alliance to overthrow the top male of their group. They do not hand out favors blindly. They keep track of their kindness, and if they are betrayed they will cut off their generosity or even punish a cheating chimp.
In chimpanzee society, males can take advantage of reciprocal altruism while females cannot. Whereas males spend their whole lives where they were born, females leave their group once they reach adulthood. Once a female chimp joins another group, the demands of raising children keep her from establishing long-term relationships. Lugging a baby makes it impossible for her to keep up with the group while they search for fruit. Because baby chimps depend on their mothers for up to four years, female chimps may end up spending 70 % of her adult life away from her group.
As a result male chimpanzees have all the power. they bond with other males making alliances that help them to climb the social ladder. Reciprocal altruism also allows males to cope with an unstable food supply. Chimpanzees rely mainly on fruit, which requires them to travel continually to find ripe trees. To supplement their diet males can hunt together for meat, and share the spoils, and they can also form raiding parties to attack smaller groups of chimps, taking over their fruit trees.
If a group of chimpanzees comes across food, the females invariably wait while the males have their fill. Male chimpanzees will also inflict violence on the females. They will hit them to coerce them into having sex, and when new females show up to a group with a baby they will kill it. As in other species, female chimpanzees do not suffer passively. They do what they can to protect their offspring and find good mates. Compared to other ape species, female chimpanzees take a long time to reach sexual maturity; some primatologists have suggested that the delay is a strategy for reducing the chances that they will come into a group bearing an infant that may get killed.
Once a female reaches sexual maturity she uses sex to protect her offspring. At the time that she becomes sexually receptive she is only fertile a for a short period of time. On average a female chimp will have sex 138 times with 13 different males for every infant she give birth to. As with lions, female chimpanzees mate with many males in order to defend against the infanticide instinct of males. They are making it harder for males to determine the paternity of their offspring.
II.
Reciprocal altruism may be particularly likely to evolve in species with big brains. If you have the mental capacity to keep in mind who has helped you out and who owes you, you can use reciprocal altruism to your advantage. So it should not be a surprise that some of the best evidence for animals helping strangers comes from our closest relatives - chimpanzees and bonobos( a separate species synonymous with pygmy chimpanzees).
Chimpanzees cooperate with unrelated chimps, do favors for them, and sometimes make sacrifices for them. They may join together on hunting expeditions, looking for duikers or colobus monkeys and sharing their kills. Reciprocal altruism may help chimpanzees gain social power. Two subordinate males can make an alliance to overthrow the top male of their group. They do not hand out favors blindly. They keep track of their kindness, and if they are betrayed they will cut off their generosity or even punish a cheating chimp.
In chimpanzee society, males can take advantage of reciprocal altruism while females cannot. Whereas males spend their whole lives where they were born, females leave their group once they reach adulthood. Once a female chimp joins another group, the demands of raising children keep her from establishing long-term relationships. Lugging a baby makes it impossible for her to keep up with the group while they search for fruit. Because baby chimps depend on their mothers for up to four years, female chimps may end up spending 70 % of her adult life away from her group.
As a result male chimpanzees have all the power. they bond with other males making alliances that help them to climb the social ladder. Reciprocal altruism also allows males to cope with an unstable food supply. Chimpanzees rely mainly on fruit, which requires them to travel continually to find ripe trees. To supplement their diet males can hunt together for meat, and share the spoils, and they can also form raiding parties to attack smaller groups of chimps, taking over their fruit trees.
If a group of chimpanzees comes across food, the females invariably wait while the males have their fill. Male chimpanzees will also inflict violence on the females. They will hit them to coerce them into having sex, and when new females show up to a group with a baby they will kill it. As in other species, female chimpanzees do not suffer passively. They do what they can to protect their offspring and find good mates. Compared to other ape species, female chimpanzees take a long time to reach sexual maturity; some primatologists have suggested that the delay is a strategy for reducing the chances that they will come into a group bearing an infant that may get killed.
Once a female reaches sexual maturity she uses sex to protect her offspring. At the time that she becomes sexually receptive she is only fertile a for a short period of time. On average a female chimp will have sex 138 times with 13 different males for every infant she give birth to. As with lions, female chimpanzees mate with many males in order to defend against the infanticide instinct of males. They are making it harder for males to determine the paternity of their offspring.
II.
The evolutionary conflict between the sexes sometimes lead to male-on female violence, as in the case of chimpanzees but it does not have to. If the conditions are right, apes may evolve a tranquil existence, in which sex becomes more than a matter of survival of genes. It becomes a tool for keeping the peace. The peaceful apes in question are the bonobo species. The differences between chimps and bonobos are more than just anatomical. During WWII the allied forces bombed the German city of Hellabrun. One of the zoos nearby had a colony of chimpanzees , which were not affected by the terrific sound of explosions. Another zoo in the city kept a colony of bonobos and all of them died of fright. Also, bonobo's sex lives are also quite unlike those of chimpanzees. Chimps mate more canum while bonobos do so more hominum. This is a trait bonobos only share with humans. As with many chimpanzees, male bonobos stay in the community where they were born and a female must leave to find a new community when she reaches adulthood. But when she arrives she does not face a gang of bullying males because in the bonobo society females dominate. Male bonobos have a hierarchy of their own, but it is the sons of the dominant females who rank high; among themselves, males form hardly any bonds at all.
While female chimps are receptive 5% of their life bonobo females are sexually receptive 50% of the time. Young bonobos try to mate far before they are able to conceive. Also bonobo sex is not only heterosexual. Among bonobos, sex is not just for reproduction or even protecting babies from angry males. It is a social tool. Sex can also diffuse the tensions that build up in society. "The chimpanzee resolves sexual issues with power; the bonobo resolves power issues with sex," says Frans de Waal, a primatologist at Emory University, in his book Bonobo: the Forgotten Ape.
These unique differences of the evolutionary line of chimps are related to the bonobo habitat. Thanks to the abundance of food, bonobo groups don't have to move as fast as chimp groups. This allows females to keep up and make stronger bonds. And by cooperating the females keep the males in line. As a result, infanticide is unknown in bonobo society. The bonobo males are peaceful and do not wage war when meeting other groups . For female bonobos the benefits of this social structure are clear: they start becoming pregnant earlier producing more offspring than chimpanzees. The difference lies in the fact that the female chimp has to cope with the treat of infanticide. Bonobo females, thanks to their social power, no longer have to worry about that.
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