Thursday, June 6, 2019

The Human Animal: Emotions Are Critical in Animal Evolution


For many years, scientists struggled to maintain a barrier between humans and other animals.  There must remain something magical, something inherently superior about humans that was lacking in lesser beasts.  Experiments and studies were conducted in order to conserve that preconception.  But time and a massive tide of new data from a more recent generation of scientists have begun to wash away that barrier, revealing that while humans may be superior in some ways, it is by a matter of degree, not by a fundamental difference.  Frans de Waal is one of the scientists who has been performing the required studies and reporting the results for consumption by a broad, nontechnical audience.  His most recent effort is titled Mama's Last Hug: Animal Emotions and What They Tell Us about Ourselves.  Emotions were once considered an example of a higher order cognitive response that was available to humans, but largely lacking in other species.  De Waal’s purpose is to convince us that emotions are not only common among animals, but that emotional response has been a part of natural selection since quite early in animal evolution.  Human emotional makeup, and that of a chimp for example, both result from the same evolutionary path that extended many millions of years into the past.

It was once thought that animal behavior was mainly instinctual.  Certain stimuli produce certain responses.  It only takes a few minutes of thought to conclude that such a mechanism is insufficient for the complex environments in which animals live.  De Waal uses as an example a male in search of female with whom to have sex.  When a desirable female is spotted instinct would tell him to approach and attempt to copulate with her.  In a real situation, the female may not be interested and could violently object to his approach.  She may already have a mate who is much bigger and stronger and might tear him limb from limb.  Our instinctive klutz is in need of something that arouses the desire to mate with a female in sight but provides a mechanism by which experience and conscious thought can intervene before action is taken.  That is the role emotions have played in evolution.

“Emotions have the great advantage over instincts that they don’t dictate specific behavior.  Instincts are rigid and reflex-like, which is not how most animals operate.  By contrast, emotions focus the mind and prepare the body while leaving room for experience and judgement.  They constitute a flexible response system far and away superior to the instincts.  Based on millions of years of evolution, the emotions ‘know’ things about the environment that we as individuals don’t always consciously know.  This is why the emotions are said to reflect the wisdom of ages”

De Waal is always pleased to point out that some emotional response in a human is often reproduced in other species in order to support the notion that we are all kin.  One example is a fear response in humans that directs the flow of blood from our extremities to our interior.  This means our extremities get colder when we experience the emotion of fear.  We literally get “cold feet.”  The exact same response has been observed in other apes, and even in rats.

Emotions are intimately coupled with bodily responses, and body conditions can also affect emotional response.  Significantly, emotion is usually expressed in some visual manner that conveys to an observer knowledge of the emotion being experienced.  This seems to be purposeful result of natural selection.  Humans are a social animal.  It appears evolution has decided that social animals are more effective as a society if members have some way of interpreting the emotions other members are experiencing. 

Humans have many facial expressions that convey emotion.  Evolution has provided us with the muscles we can use to produce very nuanced expressions.  It was long thought that this presumed unique complexity was consistent with higher order human intelligence and sociability.  However, chimpanzees have the exact same number of muscles and nearly the same muscular topology as humans.

“When a team of behavioral scientists and anthropologists finally tested the idea by carefully dissecting the faces of two dead chimpanzees, they found the exact same number of mimetic muscles as in the human face—and surprising few differences.  We could have predicted this, of course, because Nikolaas Tulp, the Dutch anatomist immortalized in Rembrandt’s The Anatomy Lesson, had long ago reached a similar conclusion.  In 1641 Tulp was the first to dissect an ape cadaver and found it resembled the human body so closely in its structural details, musculature, organs, and so on, that the species looked like two drops of water.”

Darwin was the first to recognize the similarities in expressions between humans and other primates.

“We have thus returned to Charles Darwin’s position in his 1872 book The
Expression of the Emotions in Man and Animals.  Darwin stressed that facial expressions are part of our species repertoire and pointed out similarities with monkeys and apes, suggesting that all primates have similar emotions.  It was a landmark book—acknowledged by everyone in the field today—but it was the only major book by Darwin that, after its initial success, was promptly forgotten, then overlooked for almost a century before we returned to it.  Why?  Because hard-core scientists felt his language was too free and anthropomorphic….Moreover, his suggestion that we convey our own noble sensibilities through facial movements that we share with ‘lower’ animals was roundly insulting.”

There now exists much evidence of the fact that facial expressions are tightly coupled to emotions, that within a species the coupling is nearly unique, and that human emotional expressions are similar to those of our primate kin.  De Waal refers to the work of Paul Ekman in categorizing facial expressions.

“Ekman set up controlled tests with people from more than twenty different nations, showing them pictures of emotional faces.  All these people labeled human expressions more or less the same way, showing little variation in recognizing anger, fear, happiness, and so on.  A laugh means the same all over the world.”

To test whether this similarity could have been spread culturally rather than biologically, Ekman had to test people with little or no communication with the wider world.

“He travelled to one of the farthest corners of the planet to administer his tests to a preliterate tribe in Papua New Guinea.  Not only had these people never heard of John Wayne or Marilyn Monroe, they were unfamiliar with television and magazines, period.  Yet they still correctly identified most of the emotional faces that Ekman held in front of them, and they themselves showed no novel, unusual expressions in one hundred thousand feet of motion pictures of their daily lives.”

There was one more attempt to nail down the biological nature of emotions and their expression.

“If it is true that the environment shapes facial expressions, then children who are born blind and deaf should show no expressions at all, or only strange ones, because they have never seen the faces of people around them.  Yet in studies of these children, they laugh, smile, and cry in the same way and under the same circumstances as any typical child.  Since their situation excludes learning from models, how could anyone doubt that emotional expressions are part of biology.”

Given this notion of emotions being biological constructs, de Wall generalized that finding to conclude that emotions should be thought of as a body organ. All vertebrates have essentially the same set of organs, and all are required to function if the specimen is to live.  Similarly, emotions have specific functions and they are necessary for proper functioning.

“First, as we have seen here for pride, shame, guilt, revenge, gratefulness, forgiveness, hope, and disgust, we can’t exclude their presence in other species.  These emotions may be more developed in us, or they may be used under a wider range of circumstances, but they aren’t fundamentally new.  That some human cultures emphasize some of them more than others hardly argues against a biological origin.”

“Second, it is highly unlikely that any common emotion is functionless.  Given the cost of getting all worked up and passionate about something, and given how much such states affect decision making, superfluous emotions would pose an incredible burden.  They might lead us astray, which is certainly not the sort of baggage natural selection would let us carry.  Hence my proposal that all emotions are both biological and essential.  None is more basic than the others, and none are uniquely human.  To me, this is a logical position given how closely the emotions are tied to the body and how all mammalian bodies are fundamentally the same.  Thus when human subjects were asked to guess the state of emotional arousal of a variety of reptiles, mammals, amphibians, and other land animals, just from listening to their calls, they were remarkably good at doing so.  There seem to exist ‘acoustic universals’ that allow all vertebrates to communicate emotions in similar ways.”

Discussion of emotions in terms of how we understand them as humans and how they are also utilized by other animals can be enlightening as to their functionality.  Consider the role of laughter as an expression of emotional state.  It has a definite physical manifestation, and its basic function is to provide social signals not to enjoy jokes.

“When we laugh, we go crazy.  We become limp, we lean on each other, we turn red, and we shed tears to the point of dissolving the dividing line with crying.  We literally pee in our pants!  After an evening of laughter, we are totally exhausted.  This is partly because intense laughter is marked by more exhalations (producing sound) than inhalations (taking in oxygen) so we end up gasping for air.  Laughter is one of the great joys of being human, with well known health benefits such as stress reduction, stimulation of heart and lungs, and release of endorphins.”

The social origins of laughter become more apparent when we observe the role it plays in bonding between parent and infant.

“The earliest laughter in our lives always occurs in a nurturing context, as it does in the other primates.  A gorilla mother tickles the belly of her tiny baby with her big finger just a few days after birth, producing the very first laugh.  In our own species, mothers and babies have lots of exchanges, in which they pay attention to every shift in each other’s expression and voice, with ample smiling and laughter.”

Mothers seem peculiarly interested in extracting laughter and juicy kisses from their infants.  The tickling response is curiously universal in humans and primates (and even in rats).  There must be some evolutionary function involved that is not obvious in our current human environment. 

“Tickling a juvenile chimpanzee is a lot like tickling a child.  The ape has the same sensitive spots: under the arm pits, on the side, in the belly.  He opens his mouth wide, lips relaxed, panting audibly in the same familiar huh-huh-huh rhythm of inhalation and exhalation as human laughter.  The striking similarity makes it hard not to giggle yourself.”

“The ape also shows the same ambivalence as a child.  He pushes your fingers away, protecting its ticklish spots while trying to escape from you, but as soon as you stop, he comes back for more, putting his belly right in front of you.  At this point, you need only point to it, not even touching it, and he will throw another fit of laughter.”

There is a possible explanation for the importance of teaching infants to laugh beyond that of bonding with a parent that de Waal ignores.  Humans spent most of their existence as subsistence hunter-gatherers.  If an infant is to survive it must be able to attract others who would be willing to care for it while its mother goes about fetching food.  A smiling and laughing baby, even in our day, garners more attention and affection than a crying, unhappy one.  Mothers in modern hunter-gatherer societies have been observed to paint their infants with colorful patterns in hopes of attracting childcare.  Some have even been known to give their child an enema so the friend providing assistance will not have to deal with a bowel movement.  Chimp mothers solve the problem by having hairy bodies to which their infants can cling to while they gather food.  But even chimp mothers will occasionally need assistance from others.  Mothers often band together to protect each other’s children from a male who might want to kill one in order to send the mother back into estrus so the male can bear an infant of its own.  It is always in an infant’s best interest to generate affection as widely as possible.

All the kissing that mothers like to do with their babies probably is associated with a deep memory of the time when solid food had to be prechewed and salivated by the mother and transmitted to the child mouth to mouth.

Laughter has important social functions that have nothing to do with humor.  The purpose of play in juveniles is to practice using their bodies and acquire skills that will be useful in adulthood.  Often such skills involve hunting and taking down prey, so the play can get rough.  Such animals develop “play signals” so actions that appear threatening can be labeled as playful rather than providing real danger.

“Animal play can be rough, as players may wrestle, gnaw, jump on top of each other, and drag each other around.  Without an unambiguous signal to clarify their intentions, play behavior might be mistaken for a fight.  Play signals tell others that they have nothing to worry about, that none of this is serious.  For example, dogs may ‘play bow’ (crouch down on their forelimbs with their butt in the air) to help set play apart from conflict.  But as soon as one dog misbehaves and accidently bites the other, play ceases abruptly.  A new play bow will be required as ‘apology’ so the victim can overlook the offense and resume play.”

“Laughter serves the same purpose: it puts other behavior into context.  One chimp pushes another firmly to the ground and puts his teeth in her neck, leaving her no escape, but since both utter a constant stream of hoarse laughs, they stay totally relaxed.  They know that this is just for fun.”

Laughter serves the same function in playing human children, but it can also be used to change the context of words and actions in many social settings.

“…if I approach a colleague and slap him on the shoulder with a laugh, he will perceive it quite differently than he would if I did so without a sound or without any expression on my face…Laughing reframes what we say or do and takes the sting out of potentially offensive remarks, which is why we use it all the time, even when nothing particularly amusing is going on.”

“When psychologists unobtrusively take notes on human behavior in shopping malls and on the sidewalks of our natural habitat, they find that the majority of laughs occur after mundane statements that are anything but amusing.  Try it yourself.  Notice when people laugh in spontaneous chit-chat, and you’ll see that it’s often about nothing at all—no joke, no pun, no odd remark.  It’s just a laugh inserted in the flow of conversation, usually echoed by the partner.  Humor is not central to laughter: social relationships are.  Our supernoisy, barklike displays announce mutual liking and well-being.  The laughter of a group of people broadcasts solidarity and togetherness, not unlike the howling of a pack of wolves.”

“The loud volume of our species’s laughter gets me every time: apes laugh much more softly, and monkeys can hardly be heard at all.  My guess is that loudness is inversely proportional to predation risk.”

What is most striking about de Waals numerous discussions about emotions and emotional responses is that we, and our kin, the primates, are intensely social animals and our brains and bodies were designed by nature to help us be a successful social animal.  To be what a libertarian claims to be seems a form of psychopathy, and a society of libertarians seems a contradiction in terms.

The title of de Waals book is taken from a video of Mama, an aged ape, who only has a few days left to live.  Mama was once the alpha female in a colony of chimps that lived in captivity.  One of the scientists studying the chimps, Jan van Hooff, had been interacting with Mama for over forty years.  A bond of affection and friendship had formed between them.  The intensity of that relationship became apparent when van Hooff made a last visit just before she died.  On the video it takes Mama a bit of time to realize that she has a visitor, but when she does, her response is one that is easily deciphered by we humans.  The video is worth a look.  It can be found here.


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