She collected data over 2 year period based on focal samples of females who were pregnant or lactating- in other words, not attractive to males. She found that the non-estrous female was attacked once a week. This usually didn't involve biting, but there is always that potential. A female typically got a serious wound once a year- including a slash with canines that will draw blood. A slash is generally not too awful, but it does interfere with foraging and mothering. Only once did she see a fatal attack and she doesn't think the male intended to kill the female.
She thinks that in some cases the male was punishing the female for something she did several hours or several days earlier. Why does she think this? Once she saw a female attack another female who was a friend of a male. Smuts watched the male, and when the attacking female returned, he attacked her. So many of these 'unprovoked' cases might involve earlier incidents which hadn't been seen by the observer. In other cases, she thinks that it's just the male displaying his superiority over the female and reminding her of his power over her so when he tried to mate later, she would be more likely to submit to him.
|Review on male-male competition and female mate choice|
|The main way males can increase their mating success is by fighting with each for mating. Fighting establishes a mating hierarchy where the higher-ranking males have more access to females when the females are likely to be fertile. When you think about it, the outcome of male-male competition doesn't guarantee mating access- one way it does is if females prefer to mate with dominant males. This is apparent in many species including savannah baboons. They might pick dominant males 'cause they have better genes or because they can protect them better, being stronger.|
Another way for the males to increase their mating success is by inflicting costs onto the females if they don't cooperate- this is an alternative to providing benefits. A primary way to inflict costs is by threats or actual aggression.
Definition: Any use of force or threatened use of force by a male against a female that functions to increase that male's mating access to the female, or that functions to decrease the probability that she will mate with another male, or both.
Goodall has a detailed analysis with good data and she noted a few things- a lot of male aggression against female chimps occurred in the first few days of their estrous cycle, before swelling. A female chimp swells for a few weeks and ovulates at the end, but most aggression is at beginning of swelling- it seems that males attack females repeatedly during their first phase to condition them to sexual submission so that as she reaches ovulation, she's more likely to submit to the advances of the male who attacked her. This is mostly based on circumstantial evidence. However, females usually don't reject sexual advances. The best strategy for male to get good mating success is to convince (read: coerce) a female to go away with him and mate in peace. The alpha male doesn't have to do this because he can keep the others away, but lower guys need to, otherwise they'll get interrupted. Some females go with guys they like but others are kept there by coercion. If she tries to leave, he bites her and things like that. So this aggression occurs hours or days before the actual mating- it's not as immediate as in the rhesus.
(Chimps also force copulations infrequently, but it's just been seen in certain individuals in Gombe.)
Female-female coalitions against males are not found only in primates. Lions form female bonded groups and if male lions show aggression, especially toward the infants when they've just joined a group, the females band together against him. They showed that the number of females in a pride affects the number of babies that are killed when a new male moves in.
This strategy of affiliating with the male is most developed in the mountain gorilla. Females are not bonded or closely related. They don't bond with each other, but just with the male. Wrangham proposed that females do this to protect themselves against male harassment- more because of infanticide than sexual coercion but if you think about it, infanticide functions just like coercion because it brings the female into estrous sooner and increases the male's mating opportunity.
In 20 documented cases where the male gorilla died or disappeared and left females and babies, in every case all the babies were killed by another male.
Orangutans are good studies because they're the only nonhuman primate where forced copulations happen and also females travel alone- they have no other females to ally with, and no males to defend them. Smuts thinks this is why they're coerced; they have no protection.
Further evidence comes from a comparison of chimps and pygmy chimps, and
exemplifies why social organization is an important factor.
Chimps are male-bonded. The males form coalitions against males from neighboring communities. Males groom frequently, and they reconcile one another after a fight much more than females do. The closest bond in chimps is males. Females are like 85% the size of males- large females are about the size of small males, and males' teeth aren't that much larger, so sexual dimorphism doesn't do much to explain male dominance over females. However, females invariably pant grunt to males and they don't fight back when males attack them. (Signs of submission)
Contrast with this the pygmy chimps. They also have a social system where males stay and females disperse. They show just as much sexual dimorphism. Within groups, however, social relations are really different. The closest bonds by far are among adult females who are unrelated. Not only do they spend more time together and groom each other, but they have frequent intense sexual interactions. This is called GG rubbing, and it's when females rub their sexual swellings together. Researchers are pretty sure that the females reach orgasm in these homosexual relations as well as their heterosexual ones. This behavior is common in the wild; when they find a tree, before they eat, they all have sex together and then eat. It has been hypothesized that this sex is to keep the bonds close so that females can dominate the males. It has been particularly documented by Amy Parrish, studying bonobos in captivity. In 100s of hours, she never saw male aggression on females, but repeatedly saw females attacking males or inflicting wounds on them. No one has ever seen male coercion in bonobos.
So, the bonding and coalitions between females function to shift the balance of power, protecting them against male coercion.
She has found some social variables that might correlate. The Yanamano people are some of the most aggressive primitive people. They are patrilineal and people have documented very severe incidents of male aggression against females, usually because of suspected adultery.
Contrast a society of pygmies in central Africa. They're traditional hunter/gatherers where men and women gather together and the males do a lot of child-care, more than in many 'advanced' societies. Anthropologists have never seen a man lift a hand against a woman in this culture.
This comparative perspective can help us think about such a difficult issue as sexual coercion in humans and it's not a case of 'oh it's built in and males are just going to do it.' We should pay attention instead to how social bonds affect things.