The Human Primate

Primatology got started because people wanted to know more about humans. If you want to know what makes us humans different from other animals, it's pretty much a comparative framework you have to use. You must compare humans to other primates and to other animals to see what sets us apart. As we saw last time, language is something unique to humans, but you have to look at which parts are different and which parts are the same for other animals. We're going to look at four ways people have used primates to understand human behavior better.

It is important to keep in mind that sometimes when you begin talking about human behavior using a comparative perspective, people get upset about it and resist it.

This is because of the naturalistic fallacy. This fallacy says that whatever is 'natural' is in some way right or moral. If you think about it, you can see that that is a fallacy- lots of things like disease and famine are natural but we don't think those are right or that they're inevitable. So for instance when you start talking about male sexual coercion or infanticide, and you start to try and understand it from an evolutionary perspective, some people will say that you're trying to justify it and say that it's ok. This is not the case!

There is a difference between what exists and what is right. It is always useful to try and understand what exists in the world even if we don't like it or if we don't approve of it. So remember, what is normal/natural is not necessarily what is moral, right, etc.

Humans are flexible animals and we control our own behavior.

Nonhuman primate species as models

This is one of the earliest forms of the comparative approach- people have chosen a particular species to try and explain how we are now or how our ancestors might have been like. One obvious way that this has been done, and very effectively, is in biomedical research; one primate isn't too much different from another. We have mentioned how the Rh factor came from rhesus monkeys, and how chimps are used in aids research, etc.

People have also used primate species as models of human behavior. This was originally the reason for anthropology departments to study primates. Early scientists, especially Washburn, wanted to know what primates could tell us about early humans. There have been a few ideas about how to choose the species you're going to get your information from- one is that you should look at primates who live in similar conditions to our ancestors- savannah baboons are a good example of this. Other people thought you should look at the most closely related species- chimps or some of the other great apes.

This has pretty much gone out of favor, however. There are several hundred species of primates and at least that many different human cultures-so it's too easy to find correlations and parallels. There's so much variability that you can back up pretty much any argument.

This is not to say that using primate models of behavior hasn't been useful. Particularly when the species and the question have both been chosen carefully, it has been helpful. Experiments with primates have been useful in psychology in studies on topics like motivations, drug addiction etc.

Example: Social development
This was done on rhesus monkeys to study social development in infants. It was found in countless studies that if an infant was deprived of social contact then it would grow up pretty screwed up- it would develop abnormal behaviors, and if you put it in with normal monkeys it would be overwhelmed by all the other monkeys. Then they thought, "Can these guys be resocialized by being put in with young normally raised babies who aren't threatening?" And it turned out that the pathological tendencies went away and they became normal monkeys. Then people did the same thing with kids who had been deprived at crucial parts of their lives and made them better.

Example: Mother-infant separation
This was also studied in rhesus macaques and pigtail macaques. They found that infants, when separated from their mothers, went though all these stages of separations- protest, despair etc. The saw the same thing with rhesus and pigtails, but in bonnet macaques, the infants don't go through all this psychological trauma. It's pretty clear why if you look at their social organization- there are a lot of allomothers in bonnet macaques and babies are often left by their moms in the wild and someone else will take care of it and bring it back to her later. So it's important to pick more than one species and to compare across species when you're doing this comparative approach for behavioral models.

Comparative analysis of human social organization

This method compares humans with what we know about all primates in general.
Up until the 60's, we didn't know anything about nonhuman primate social organization. Levi Strauss said in 1949:

"The social life of monkeys does not lend itself to the formulation of any norm. Whether faced by male or female, the living or the dead, the young or the old, a relative or a stranger, the monkey's behavior is surprisingly changeable. Not only is the behavior of a single subset inconsistent, but there is no regular pattern to be discerned in collective behavior."

Of course we know this isn't true- primates recognize kin, strangers, friends, past sexual partners, and they know who is related to whom.

A more recent analysis
It isn't necessarily true that the main difference between humans and primates is based solely on our widespread use of symbols, but this is what people generally point to for what determines us from other primates. Using standard primatological approaches, however, how do humans look when compared to other primates? Some people here at UM looked at human society as a primate society. Of course there are a lot of different cultures. They focused mainly on traditional cultures which resemble what our ancestors probably lived like.

When you look across human cultures there's plenty of things that are different but there are some features that are pretty common;

None of this is really out of the ordinary.

These people also looked at what kind of relationships were maintained between individuals. They decided that these were crucial relationships in that species.
Males Maintain Relationships with
non-kin onlyno other malemale kin
non-kin onlymantled howlermountain gorillaHamadryas baboon,
red colobus, chimp,
spider monkey
no other femalesaddleback tamaringibbon, titi monkey, orangutan
female kingelada baboon, capuchinblack and white
colobus, bushbaby

They found it interesting that humans are the only species in which both sexes maintain social ties with kin, even after dispersal. This is probably important because it leads to extensive alliances between groups. In most primate species you can find stuff kind of like the human family, but they don't really have too many ties with other groups. But in humans, although we form families, we also make kinships ties through the males and the females. This is in spite of the fact that we don't have day-to-day contact with all these people. Scientists think this is only possible because we have this symbolic communication, and can speak of removed things.

We also are different because we (both sexes) cooperate with non-kin pretty often.
However, males cooperate with each other a lot in conflicts with other males. Females cooperate with each other a lot, but in non-conflict situations. In other primates, females help each other in conflicts, but in humans it's males extensively and females rarely.

This approach is purely descriptive- it's not to explain things or to understand them, but just to know what trends there are. So it's still left for someone else to generate hypotheses and tests and to see which behaviors are causes and which are effects and stuff like that in terms of human evolution.

Human ethology

This is another way of using primatology to study humans. This method uses principles originally adapted for studying animal behavior and applies it to humans. Human ethologists follow pretty traditional ethological principles and use Tinbergen's four questions (development, causation, evolutionary, and survival/reproduction value). Tinbergen said these were the four kinds of questions you could ask about any animal's behavior. Human ethologists have also adopted the same techniques that animal behaviorists use; Usually when people studied a culture, they'd watch it, participate in it, interview people, and ask the why they did certain things. But in studying animals, you can't interview them. So human ethologists use these same methods of direct behavioral observation. This is also useful in studying infants who aren't verbal or in studies of young children whose answers aren't particularly reliable. People used to study the development of friendship in humans, and they would just ask kids who their friends were, but it turns out kids aren't good at distinguishing between who their friends are and who they wish they were. So it's easier to just watch and make notes.

Using principles from primatology

This is the last way in which primatology is used to study humans. This is not so much assuming humans are like any particular primate, and not using the techniques of primatology, but using the theories of primatology and seeing if they can be used to look at humans as well.

Kinship theory
This was traditionally a major focus of traditional socioanthropologists, but has fallen out of favor recently, but has always been popular with primatologists. People began to go back and apply it to humans. Mark Flynn did a study on a village in Trinidad and studied kinships. There were a number of stepfamilies where there were both full and step-children, and he wondered whether it affected the amount of investment from the father and found that it did indeed. Kids received less care when they weren't related to the father.

In this study, he also found that the % of interactions between kid and dad which involved conflict was about 3.5% for the genetic offspring, and 7% for the non genetic offspring. This wasn't child abuse but just conflict of some sort.

Another pair did a study on child abuse in Western society. They hypothesized that child abuse might be related to the amount of investment. They looked at child abuse rates in households with two genetic parents vs households with one genetic parent and one step-parent. Across all age groups, child abuse was much greater in families with one step-parent. Also, it was a lot higher in younger children.

Sexual selection theory
David Busse wrote a book and looked at human mate choice within a sexual selection framework. Remember that males are limited by access to females while females are limited by access to resources so males tend to be indiscriminate and females tend to be choosy. This guy looked at mate choice in humans and found there's a fair amount of choosiness in both species. Based on sexual selection theory, you'd expect males to be more interested in things that reflect a woman's ability to bear children, while women should be interested in the things which show that the male is able and willing to invest in the kids- so men looking for mates should pay a lot of attention to things that could indicate health, youth, fecundity etc, while women would be expected to look at status and wealth which indicate the male's ability to invest in offspring.

Another study has possible parallels which might have already occurred to us, but we might be interested to see results.

The question is, do males and females behave in the way you'd expect from sexual selection theory. Some researchers went to Florida State University and choose nine "reasonably attractive" undergrad helpers.They approached random members of opposite sex and said the following.

"I've been noticing you around campus and I find you very attractive. Will you..."

% Affirmative Answers
"...go out tonight?"5056
"...come over to my apartment?"696
"...go to bed with me?"750

This certainly seems to indicate that humans behave like you'd expect them to as primates.

So these methods don't give us complete parallels, but they can give us information that we wouldn't come by using other methods.