Animals in Translation (17 page)

Oxytocin is especially important to all these social activities, because oxytocin is essential to
social memory
: oxytocin is the hormone that lets animals remember each other. An experiment with mutant mice who didn't have the gene for oxytocin found that the mice didn't form social memories. They could remember everything else just fine, but they couldn't remember that they'd already met a mouse who had just been put in their cage, and they'd start sniffing him like he was a total stranger.
²²
(Animals who already know each other never sniff each other as much after a separation as they do when they first meet. You can see this easily with dogs.) Obviously, if you don't have social memory you can't be monogamous, and you're not going to be a very devoted mom, either, if you have trouble recognizing your babies.

This finding has led researchers to speculate that some autistic people might have faulty oxytocin production, since a lot of times autistic people don't seem to remember people they've met before, either. However, a lot of that has to do with
face recognition,
which is extremely poor in autistic people, not face
memory
. This is another
aspect of autism that no one understands, although we do have brain scan data confirming it. There's also a study showing that normal people use different parts of the brain to recognize an object versus a face, whereas autistic people use the
object recognition
area of the brain to recognize objects
and
faces. I have a terrible time recognizing people's faces myself, but I don't have any trouble remembering people in other ways, like through their voices. Oxytocin might be involved in autism; I don't know. But I'm guessing that autistic people's face recognition problems come from something else.

Vasopressin also makes prairie voles sexually possessive. They
mate guard,
which means they stick close to their mate and fight off any other male who approaches. They're more territorial, and they're much more aggressive toward other males even when their mates are not present. One study looked at the relationship between vasopressin and
intermale aggression,
which is a male animal's tendency to attack another strange male that is put into a cage with him.
²³
The researchers found that adult male voles who are still virgins are almost never aggressive. But once they've mated and had their vasopressin levels rise they “exhibit a long-lasting, permanent increase in aggression.” In the study the researchers injected newborn prairie voles with vasopressin over the first seven days of life, then tested them for aggression. The treated voles were much more aggressive, not just toward other males but even toward females.

The montane voles, who have low vasopressin, could care less about their mates or about other males. Once they've mated a female they disappear. They're just not very socially motivated. The montane females are loners, too. Oxytocin is the
maternal hormone,
and montane females have lower levels of it than the prairie females. Montane females abandon their babies soon after they give birth—and the babies aren't too bothered by this, because they aren't very social, either.

Compare that to the way a mama dog acts with her babies. One time Mark's dog Annie accidentally got locked in the kitchen and she couldn't get to her puppies, who were in the attached garage. Annie went crazy. First she violently scratched the door, then she attacked the plasterboard on the wall between the kitchen and the
garage. She was so frantic that she clawed clear through the wall into the garage. Annie was a relatively small dog, only thirty to thirty-five pounds, but she was so desperate to get to her babies she tore through a wall.

Dogs probably have fairly high oxytocin levels. They're highly social animals to begin with, and an animal has to have good oxytocin levels to be highly social. Wolves are often monogamous, and even when they're not strictly monogamous they practice serial monogamy. The dingo and the Carolina dog are usually monogamous, too.

On the other hand, domestic dogs don't look like they're monogamous at all. A male dog on the loose will mate any receptive female he finds and then go tearing off to find any other receptive females in the area. However, that might be due to the fact that dogs never become full adults emotionally, so they don't develop an adult wolf's capacity for monogamy. Also, we don't really know what domestic dogs' social life would be like if they didn't live with people. Very few pet dogs have the option of mating with another dog for life.

A dog's oxytocin levels rise when his owner pets him, and petting his dog raises the owner's oxytocin, too. I'm sure that's one reason why so many people have dogs in the first place. I don't think anyone has researched this yet, but I expect we'll find that dogs make humans into nicer people and better parents. Oxytocin is definitely important in humans. When women have babies their oxytocin levels shoot up right before the birth, and research shows that those high levels spark maternal warmth and care. Oxytocin produces caring “maternal” behavior in men, too. So for parents, owning and petting a dog is probably like getting a “good parent” shot every day. Dogs are probably good for marriages for the same reason.

One of the interesting things about the research on vasopressin is the way behaviors we humans tend to think are “bad,” like aggression and sexual possessiveness, go together with behaviors we think are good, like taking care of the young and being faithful to your mate. Male prairie voles have higher aggression and higher mate guarding, and they're also faithful husbands and nice dads. Male
montane voles don't have much aggression or any mate guarding at all, but they're promiscuous and totally uninterested in their offspring. Take away the aggression and the mate guarding and you lose the devoted mate and the good dad, too. They go together.

The research on testosterone and paternal behavior isn't as clear as the research on vasopressin. A lot of researchers have concluded that testosterone lowers paternal behavior, but the most recent research shows that in a
monogamous
animal, testosterone increases paternal behavior. The body converts testosterone to estrogen, and the estrogen increases nurturing of the young.

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All baby animals make a high-pitched distress call when they're separated from their mothers. (I don't know whether montane vole babies have a distress call, but I assume they probably do if only for a short period of time.) Animal babies are totally attached to their mamas, and when they grow up most animals are strongly attached either to a particular friend or to the members of their social group, or both. Animals love other animals.

Animals make social distinctions between friend and stranger the same way people do, too. I heard a story about a guy who was stealing pigs at an auction a while back. Farmers bring their hogs to auction to sell to buyers from the packing plants. The auctions last for a few days and handle thousands of pigs, so it would be easy to take just one or two pigs a day without anyone noticing, which is what the thief was doing. The only reason they knew someone was stealing was that the trucks were coming up short. A truck holds two hundred animals, and when a farmer delivered a truckload of pigs to the loading dock the stockyard manager would do a head count and find that one pig was missing.

They discovered who the thief was when somebody noticed a pen where none of the pigs were lying together. Each pig was keeping his distance from the others, and the guy who noticed them realized that the pigs in that pen were acting like strangers. The reason they were acting like strangers was that they
were
strangers. They'd come from different farms.

The thief turned out to be an employee who was taking one or two pigs a day out of the thousands at the auction and moving them to a pen in the back where he was keeping them until he could take them home. The pen looked like every other pen, and there would have been no reason for anyone to think the pigs inside had been stolen if the pigs themselves hadn't known they didn't belong there. The pigs' behavior gave him away. They weren't with their friends, and they acted like they weren't with their friends.

People constantly underestimate domestic animals' need for companionship. A good way to understand just how social these animals are is to ask yourself how horses, cows, pigs, sheep, dogs, and, to a lesser degree, cats, came to be domesticated in the first place. Why did wild horses decide it was okay to have people sitting in a saddle on their backs holding a pair of reins? It's pretty incredible.

Most experts believe that the reason these animals became domesticated was that they were highly social. Their innate sociability led them to associate with humans and eventually to accept human ownership and direction. That's a high degree of sociability, and it's still there in all of our domestic animals. Even cats are much more social than people realize; sister cats even help each other give birth.
All domestic animals need companionship.
It is as much a core requirement as food and water.

Some ranchers are beginning to take this into account. In the past I've watched calves being separated from their mamas here at the university when they reached weaning age, which is three to six months. There's a lot of individual variability in how the calves and the mothers react, and some of them would get horribly upset. I remember one mama who was mooing frantically and trying to jump the fence to get back to her baby. The babies acted really stressed and agitated, too.

Now people are starting to do low-stress weaning, where the mothers and the babies are separated by a fence but they can still touch noses. That's all the babies care about by that age. They don't care about the nursing; they care about being together with their mom. If you didn't separate the calves, and just let nature take its course, female calves would probably stay with their mothers for good. You see that a lot in the wild, mothers and daughters staying
together. You also see males stay with their brothers, and in some species males form friendships with other males.

A dog's attachment to his owner is like a baby animal's attachment to his mother, or a human child's attachment to his mom or dad. Pet dogs act the exact same way children do in the
strange situation test.
In the strange situation test the researcher watches how a very young child reacts to a strange new environment when his mother is there with him, and when she's not. Most children will confidently explore a strange environment as long as their mother is with them, but when she leaves the room they'll stop exploring and wait anxiously for her to come back. Dogs do exactly the same thing. This has been tested formally in fifty-one dogs and owners. Most dogs stop exploring and act anxious when their owner leaves the room. Then they relax and start exploring again when their owner returns. When humans say dogs are like children, they're right.

Researchers do ESB—electrical stimulation of the brain—research on social attachment by recording which areas in the brain cause an animal to make separation distress calls when stimulated by electrodes. Using this technique they've been able to map out these circuits and the chemicals that are involved pretty well. Evolutionarily, social distress is linked to three old, primitive systems in the brain:

1. Pain response.
   
2. Place attachment:
   the animal's ability to form an attachment to its nest, breeding territory, or home. (Babies of all species are distressed when left alone, but they're less distressed if they're left alone in their home, not in a strange place.)
   
3. Thermoregulation:
   the regulation of body heat.
   

You can see all three in the language people use to talk about their social attachments, and in the way they act.

The connection between social separation and the pain system is probably the most obvious in our language. We use the same words to describe physical pain and social separation and loss:
pain, anguish, agony,
even
torture.

Place attachment you can see in sayings like, “There's no place like home.”

Thermoregulation comes up all the time when people talk about relationships. We use the expression “maternal warmth,” and we say people are warm or cold. Warm people are loving, kind, and connected, and cold people are the opposite. Also, people and animals who are feeling lonely usually want to be touched, which comes from the fact that in the wild babies keep warm by staying close to their parents' bodies.

I know that sounds strange, but researchers believe that social warmth evolved out of the brain system that handles physical warmth. That should tell you something about how important social attachment is to animals. In all mammals a baby has to have a strong social attachment to its parents in order to survive. A baby wolf needs social contact to stay emotionally warm as much as it needs physical contact to stay physically warm.
Social attachment is a survival mechanism
that evolved partly from the survival mechanism of keeping the body warm.

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The same chemicals in the brain are involved, too. Most people know that the brain has its own painkillers called
endorphins.
Endorphins are
endogenous opioids
: they are nature's version of morphine and heroin. The brain circuit that releases endorphins is called the
opioid system.
The brain releases endorphins when we're injured to reduce pain, and also when we are with people we love, or when someone we love touches us. A lot of neuroscientists think we probably become addicted to or dependent on people in a similar way to heroin or morphine addiction, too. People who are attached to each other develop a social dependence on each other that's based in a physical dependence on brain opiates.