Yawning as Empathy?

Empathic behavior has always been somewhat of a paradox to scientists: why would an organism which is bent on individual survival want to understand the emotions that another is feeling? The answer, of course, is complex, revolving around the idea that empathic behaviors contribute both to society and personal health—the former of which may also, in some way, contribute to individual fitness. To gain more insight on this answer, scientists are interested in what other kinds of behavior and parts of the brain empathic behavior is associated with, and whether humans are the only ones that exhibit it.

Platek et al. (2003) hypothesized that contagious yawning is an empathic behavior. To test this idea, they had subjects watch tapes of people laughing, yawning, or with neutral expressions. Laughing was the control, as it is also understood as a contagious behavior. Subjects were observed during the process, to see how much they yawned. All the subjects had to fill out a Schizotypal Personality Questionnaire, for those with schizophrenic personality treats are less empathic, and for that reason the researchers hypothesized that those with more schizophrenic personality traits would exhibit less contagious yawning. In addition, one group of the subjects had to do some theory of mind tasks, reading stories in which a successful task would mean they recognized first and second-order false beliefs in others. Another group did some self-recognition tasks, in which the speed in which they recognized their own faces among ‘ faces was recorded. Recognition involved pressing a key, and researchers tested the speed of both the left and right hand.

The results fit the hypothesis well. People who had less schizotypal personality traits exhibited significantly more contagious yawning, and these people also scored significantly better on the theory of mind tasks and self-recognition tasks using the left hand (which implicates the right brain, which functions in empathy). Theory of mind, of course, is understood as a kind of empathic behavior, and many researchers hypothesize that self-recognition precedes and is necessary for empathic behavior. A later study by Platek et al. (2005) located brain activation for contagious yawning which supported their empathic modeling hypothesis. There was significant activation in the bilateral precuneus and posterior cingulate, which have also been shown to be involved with recognizing self-referent information, and the second of which may show structural asymmetries and disorders in schizophrenic patients. They conclude contagious yawning is a primitive and unconscious form of empathic modeling that “…is subserved by substrates that are precursors to a more sophisticated and distributed system involved in conscious self-processing.”

If contagious yawning is primitive, then perhaps it is found in other animals. Anderson et al. (2004) found that 33% of their subject group of female chimpanzees exhibited contagious yawning (for humans it is between 40 and 60%). Like human infants, chimpanzee infants did not show contagious yawning. The fact that chimpanzees have contagious yawning, can perform some theory of mind tasks, and can recognize themselves in the mirror may mean that chimpanzees have some empathic abilities.

This is all very interesting evidence, linking yawning with a primitive empathy, but it may be that researchers are jumping the gun. Yawning has always been an enigma, so perhaps researchers are too eager about this new hypothesis. They may be making the mistake of simplifying the brain, by localizing similar functions into one area. The failure of “limbic system” terminology testifies to this type of error. Certain parts of the brain may house a variety of seemingly unrelated functions.

In addition, chimpanzees, surely, exhibit some empathy, but it is not because they have contagious yawning; their empathy is manifested in theory of mind and self-awareness. Yawning seems to be tacked on to the mix. There are definitely other possible reasons for contagious yawning. For example, yawning might contribute to fitness in a more proximate way (e.g. cooling the brain), and the tendency to mimic another that yawns could be an important adaptation for survival in evolutionary history. Certainly the necessity of classifying yawning as a primitive empathic behavior is questionable.

Works Cited

Anderson, J.R., Myowa-Yamakoshi, M., and Matsuzawa, T. 2004. Contagious yawning in chimpanzees. Proceedings of the Royal Society of London, Series B: Biological Sciences 27:468-70.

Platek, S.M., Critton, S.R., Myers, T.E., and Gallup, G.G., Jr. 2003. Contagious yawning: the role of self-awareness and mental state attribution. Cognitive Brain Research 17:223-27.

Platek, S., Mohamed, F., and Gallup, G.G., Jr. 2005. Contagious yawning and the brain. Cognitive Brain Research 23: 448-53.

Do Apes have Theory of Mind?

Much effort has been made in cognitive science to understand the extent to which apes have theory of mind. Theory of mind, Gazzaniga describes, was first put forward by Premack and Woodruff, and is “the ability to observe behavior and then infer the unobservable mental state that is causing it” (2008). Humans develop it in full by the age of four.

The false-belief task, some researchers believe, is important in demonstrating theory of mind, so Call & Tomasello (1999) put 4-5 year old children, chimpanzees, and orangutans to the test. In this task, the subject is not allowed to watch as adult A hides a reward (a sticker for children, and food for apes) underneath one of two containers, while adult B watches. The subject is allowed to watch as adult B marks the container he or she believes to contain the reward. In this case, the subject would always choose the marked container to uncover the reward. However, in the false belief trial, Adult B watches the hiding, but then leaves for a period of time, during which the subject watches Adult A switch the containers. After Adult B comes back in the room, marking the container which he or she believes to hold the reward (the wrong one, of course), the subject must choose which container has the reward. The results of this study are that the 4 and 5 year old children recognized that Adult B has a false belief, and picked the correct container that Adult B had not marked. The apes, however, picked the container Adult B had marked. They did not recognize that Adult B had a false belief.

This experiment is an especially good measure of false belief, because 1) it is nonverbal, so apes can participate in it, and 2) it involves tasks that the apes have already mastered. Some past studies on false belief had produced ambiguous results because it was not certain whether the apes were so focused on trying to perform the task that they could not even begin to attempt to understand the mind of another.

The researchers ultimately concluded from this study that apes do not have much of a theory of mind, at least in the sense of understanding that others may hold false beliefs. Though, Gazzaniga brings up the point that theory of mind is certainly more than just being aware of false belief.

A crucial problem with the experiment is that it leaves out the possibility that apes do have theory of mind, but with conspecifics, not with humans. Humans, certainly, cannot accurately infer the mental state of another animal; our epistemology is staunchly anthropocentric. Just the same, it may be very difficult for an ape to infer something about the state of a human mind. Thus, this study does not really prove that apes have no theory of mind in regards to their peers. Call & Tomasello try to buttress the validity of human theory of mind, and thus its reliability as a standard for all, by pointing out how humans so readily attribute mental states not only to animals but to inanimate objects. However, their argument collapses: there is a good chance that humans are attributing wrong mental states to animals and inanimate objects. Therefore, the apes may also be attributing a wrong mental state to Adult B, not due to deficit theory of mind, but due to inaccurate theory of mind.

Whether apes do have some degree of theory of mind or not, and whether or not humans even have the ability to detect it and describe it, are not the only important issues broached by this experiment. The other is what it really means for our understanding of the human mind to be able to compare human and ape cognition. It is especially notable that, as Gazzaniga points out, younger children (at least below the age of 2), autistic children, and apes all perform similarly (that is, badly) on the false-belief task. It is definitely an interesting notion that ontogeny recapitulates phylogeny, that at one point in the womb humans have gills like a fish, and by the age of 2 they have similar cognition to that of an ape. The continuum between humans and animals is evident: humans are surely animals that are higher-functioning. In addition, however, the idea that autistic children and apes are on a similar social level is consequential. How a human person can be defined is called into question, as the autistic child, by the theory of mind classification, loses something distinctive to humanity.

References:

Gazzaniga, M.S. 2008. Human: The Science Behind What Makes Us Unique. Harper Collins: New York.

Call, J., and M. Tomasello. 1999. A nonverbal false belief task: The performance of children and great apes. Child Development 70:381-95.

A Unique Frontal Lobe Size?

For a long time it was assumed that humans engaged in particularly human cognitive activities such as creative thinking, future planning, language, and high-functioning memory because humans, compared to other apes, have a higher frontal lobe to brain ratio. In an important experiment, Semendeferi et al. (1997) found evidence that severely countered this assumption.

The experimenters measured the volumes of frontal lobes and whole brains of living human brains and of post-mortem brains of the chimpanzee, gorilla, orangutan, gibbon, and the macaque. To measure the volumes they took magnetic resonance (MR) scans of the brains and then three-dimensionally reconstructed the scans. Major landmarks common to all species were used to distinguish the boundaries of the frontal lobe. In addition, they measured the volumes of the 3 frontal lobe sectors (dorsal, mesial, orbital) across the species. In order to account for any possible differences between living and dead brains, like shrinkage, they compared the living human frontal lobe to a post-mortem human frontal lobe.

The results of the experiment indicated that humans do have the largest absolute volume of both the brain and the frontal lobe; however, all of the hominoids have a similar frontal lobe to brain ratio. In other words, humans do not have a larger frontal lobe than a human-sized primate brain would be expected to have. In addition, the relative size of the three sectors were similar across the primate species.

Semendeferi et al. would, however, call attention to some qualifications. First of all, the relative human and chimpanzee frontal lobes values are most similar, while there is a slight, but steady decrease in relative frontal lobe size as the species are located further up the human phylogenetic tree. For example, the relative values for the orangutan brain are at the low end of the human range, as are the gorilla values. The researchers suggest that the data may indicate that frontal lobes becoming relatively larger is a trend of hominoid evolution, but not specifically of hominid evolution. After the split of chimpanzees from the common African hominoids, there was apparently no further increase in relative frontal lobe size all the way to modern humans.

There is, of course, plenty of scientific critique to this study, and the researchers know it. Their sample size is small, and they admit their samples may include outliers (especially the gorilla!). In this 1997 study, however, they intended merely to begin a database of brain volume measurements, using repeatable techniques, to which future studies may contribute. A humble and meager start, which can only produce tentative conclusions.

The study, nevertheless, debunks a classically held assumption, and leaves scientists really wondering what it is about the human brain that is unique. If the human and the chimpanzee have equal relative frontal lobe sizes, and yet only one can speak and write and create grand oeuvres d’art, what accounts for this great difference? Certainly, the study did not address other aspects of the frontal lobe besides overall relative size: perhaps organization of the frontal lobe changed during hominid evolution. Gazzaniga (2008) lists four hypotheses regarding how the human frontal lobes can account for high functioning: reorganization and enlargement of some cortical areas, richer connections between frontal sectors, modification of circuitry in frontal subsectors, and other micro- or macroscopic subsectors added or removed. In addition, the relative prefrontal cortex was not measured in this study, and perhaps the prefrontal cortex to frontal lobe ratio may be important in distinguishing between human functioning and ape functioning. The role of the prefrontal cortex in high functioning is especially implicated in a study by Baare et al (1999), which found that in schizophrenic patients, problems with verbal and visual memory and semantic fluency may be related to a decrease in volume of frontal lobe (especially prefrontal) structure.

This study, especially, delivers a slight blow to a philosophical understanding of human personality as being very distinct from that of an animal’s. Here, we do not see relative frontal lobe enlargement as being a unique derived character during hominid evolution, but it is a shared character among all hominoids. The clearest line this study draws is not between humans and the rest of apes, but divides humans and chimps from the rest of the apes. This is further evidence that humans are not qualitatively distinct from other apes, but that brain changes amongst species can be pinpointed on a rather blurred continuum. A win for reductionism of the human mind? Not necessarily. Much more work needs to be done to show how high-functioning human brains materially evolved over time from lower-functioning ape brains.

References:

Semendeferi, K., H. Damasio, R. Frank, G.W. Van Hoesen. 1997. The evolution of the frontal lobes: A volumetric analysis based on three-dmensional reconstructions of magnetic resonance scans of human and ape brains. Journal of Human Evolution 32:375-88.

Gazzaniga, M.S. 2008. Human: The Science Behind What Makes Us Unique. Harper Collins: New York.

Baare, W.F.C, H.E. Hulshoff, R. Hijman, W.P.T. Mali, M.A. Viergever, R.S. Kahn. 1999. Volumetric analysis of frontal lobe regions in schizophrenia: relation to cognitive function and symptomatology. Biological Psychiatry. 45:1597-1605

Kirk Vanacore1: Evolution and Infanticide

Kirk Vanacore

Evolution and Infanticide

 

Evolution is link directly to reproductive success. If a trait enhances one’s chances of reproducing, the trait is more likely to become prominent. One question rises: are we mentally prone to act in this way? Michael S. Gazzaniga is certain this is so: “To be sure, the human brain is a bizarre device, set in place through natural selection for one main purpose – to make decisions that enhance reproductive success.”[1] A prominent biologist, Edward O. Wilson, agrees: “The human mind is a device for survival and reproduction.”[2] But it seems rather narrow minded to reduce all of humanities actions to these two ends. After all it seems that humans don’t spend most of their time gathering essential resources and having sex. There is also one major contradiction Gazzaniga brings up himself: infanticide. Many animals, including our closest relatives the primates, will kill babies – sometimes with the purpose of simply mating again with the mother. So, if the human brain’s goal were reproduction, why would one kill the products of reproduction – infants?

 

Gazzaniga states “infanticide is a typical behavior in many species within every group of animals – birds, fish, insects, rodents, and primates.”[3] The reason, he explains is economic:

What makes it possible for these species to kill, just as it is possible for some to indulge in infanticide, is once again economic. It is cheap to kill. The cost-to-benefit ration is good. When you kill and infant, you don’t really risk being injured yourself, so the cost is low. You gain either a food source or increased change of mating with the female because when her infant is dead, she will stop lactating and ovulate again.[4]

Infanticide is done because it will benefit the killer; the animal will gain something whether it is simply more food or a chance to reproduce. Studies have even shown that infanticide is an evolutionary adaptation meant to increase the killer’s chance in mating. One German study of langur monkeys showed that the monkeys who committed infanticide, often mated with the mothers of the dead infants.[5]

While this may explain part of the brain’s instinct toward infanticide, there is another side to the tendency. A study by Doctor Susan Levitzky found that some human mothers had thoughts of infanticide. The children of the mothers had infant colic syndrome, a condition where the infant may scream perpetually for long periods of time due to stomach pain. The study revealed that 70% of the mothers considered aggressive actions against their children and 26% considered infanticide.[6] This raises a major question about the human brain: if the brain’s two main goals are survival and reproduction, why would mothers consider killing their offspring when they do not threaten their mother’s survival? This case suggests that are other considerations, like comfort or peace, that may even trump reproduction when the human brain makes decisions.

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[1] Gazzaniga; “Human: The Science Behind What Makes Us Unique;”  Harper Collins, New York (2008), p29.

[2] Wilson; “On Human Nature;” Harvard University Press (1978).

[3] “Human” p68.

[4] “Human” p 72.

[5] Borries, Launhardt, Epplen, Epplen, Winkler; “DNA analyses support the hypothesis that infanticide is adaptive in langur monkeys,“ The Royal Society; Proc. R. Soc. London; B (1999) 266.

 

[6] Levitzky, MD; “Infant Colic Syndrome—Maternal Fantasies of Aggression and Infanticide” Clinical Pediatrics, Vol. 39, No. 7, 395-400 (2000).