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.

Nonhuman primate species as models

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

"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."

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;

• Usually, females disperse and males stay in their natal groups.
  
• Social organization is usually fission-fusion; We live in larger communities but don't all stay together at once. We break into smaller parties for daily life.
  
• We do, however, collect into stable groups to sleep together at night in a central place, while most fission-fusion primates sleep with whoever's there when night falls.
  
• Humans are mostly monogamous, but mildly polygynous.

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
Females Maintain Relationships with	non-kin only no other male male kin non-kin only mantled howler mountain gorilla Hamadryas baboon, red colobus, chimp, spider monkey no other female saddleback tamarin gibbon, titi monkey, orangutan female kin gelada baboon, capuchin black and white colobus, bushbaby human

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

Using principles from primatology

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

	Question	Males	Females
	"...go out tonight?"	50	56
	"...come over to my apartment?"	69	6
	"...go to bed with me?"	75	0

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.