What is uniquely human? A report from The Social Brain Conference

Photo credit: Anders Gade

By James Burkett

James Burkett is a 2014 recipient of the Emory Center for Ethics Neuroethics Travel Award. He is a graduate student in Emory's Neuroscience program, conducting research on social attachment and empathy in Dr. Larry Young's lab.

This October 5^th thru the 8^th I had the pleasure of attending the Federation of European Neuroscience Societies’ (FENS) bi-annual Brain Conference, held in Copenhagen, Denmark. FENS represents the neuroscience societies of 42 different societies in 32 countries, and is the primary organization for neuroscience in Europe. The conference, titled “The Social Brain,” focused on how the brain produces and is affected by social behaviors in humans and in animals. Chaired by eminent scientists Sarah-Jayne Blakemore (Director of the University College London’s Institute of Cognitive Neuroscience), Frans de Waal (world-famous primatologist at Emory University), and Giacomo Rizzolatti (discoverer of mirror neurons at University of Parma, Italy), the conference brought together a wide array of human and animal researchers at the top of their fields. Throughout the conference, this bipolar grouping was frequently brought to the same question: what is it that makes humans different from animals? What is uniquely human? As with a sculpture, this conference seemed to answer this question by chipping away at the monolith of things commonly thought of as unique to the human species.

For a long time, humans were thought to be unique for their tool use [1,2]. However, many surprising examples of tool use have now been seen in animals. Chimpanzees are now known to fashion weapons for use in hunting, as well as using tools for nut cracking and termite retrieval; and will sometimes be seen carrying favorite tools for great distances [1]. Even this behavior is not unique to apes, however: Caledonian crows also craft and use tools for grub retrieval, and even have local tool-making traditions they pass on to the next generation [2]. There are now many internet videos showing crows solving extremely complex tasks with available tools.

Several speakers showed that the human species is not unique in its ability to cooperate and to understand cooperative relationships [1,3,4]. Chimpanzees, for instance, are perfectly capable of learning cooperative tasks without training, and even spontaneously develop individual styles, preferred partners, reputations, and feedback between partners on their choices [1]. They may do this through the use of specialized “mirror neurons,” which are present in motor planning and emotional areas of the brain and fire both when an action or emotion is being experienced, and when it is being observed in others [3,4]. These mirror neurons were first discovered in Rhesus macaques, but have since been found in humans and chimpanzees. Elephants readily learn cooperative tasks as well, even waiting for their partner to arrive when a task is presented that cannot successfully be performed alone [1]. Even more distant from humans was a striking example of inter-species cooperative hunting between groupers and moray eels, where groupers show signs of shared intentionality and referential gesturing in order to get moray eels to help them catch fish [5]. Tiny 5 gram cleaner wrasses, which have more than 2,000 inter-species social interactions a day while cleaning parasites off of other fish, show signs of cooperative strategies, individual recognition, social prestige, audience effects, tactical deception and reconciliation.

If an animal naturally cooperates, it should also be sensitive to the results of cooperation, and there is now ample evidence that this is the case. In a now-famous experiment, capuchins were shown to be sensitive to unfairness: when rewarded for a task with cucumber, they eagerly accept; but when they see another capuchin being rewarded for the same effort with a grape, they bitterly refuse the cucumber [1]. This sensitivity to inequality has since been seen in many other species, including dogs and birds, and may be a general and necessary behavior in cooperative species. Chimpanzees take this one step further by showing a sense of fairness as well, choosing to reward others when there is no benefit to themselves, and sometimes refusing a reward unless a partner is also rewarded.

Photo credit: Anders Gade

Social animals also employ very similar tactics to humans in the maintenance of their relationships [1,6]. In social groups, conflicts are inevitable, and for many years ecologists thought that conflict served to break bonds of attachment and disperse social groups. However, more recent research has demonstrated time and again in many species that social group members actively reconcile after fights, which actually serves to bring group members together and strengthen bonds. Risky pro-social interactions with new group members may also serve to help form new social bonds [6]. In some species, consolation happens after fights as well, typically initiated by individuals with close relationships with the loser. These consoling behaviors have been seen in many great apes, dogs, birds and elephants. In addition, recent experiments in rats show that they are motivated to help their trapped cagemates escape from an enclosure, and once they learn to do so, they will release them very quickly even if they receive less of a food reward after doing so [7]. Finally, the same brain neuropeptides that mediate social behavior and social bond formation in animals seem to influence human relationships as well, suggesting a common evolutionary origin for these mechanisms in the brain [8].

In a talk presenting my own thesis work, I discussed evidence of consolation in the prairie vole, a highly social monogamous rodent [9]. Through a series of laboratory experiments, I demonstrated that male prairie voles will show increased partner-directed grooming toward a male sibling or female partner if that individual has been exposed to stress. I also showed that observing their stressed cagemates induces stress and anxiety in male prairie voles, suggesting that their behavior is based on empathy.

In order to console one another, animals must first be capable to detect each other’s emotional states [1,7,9,10]. This is perhaps one of the most broadly observed capacities of all, being present in virtually all mammals and some other species as well. This is believed, at least in mammals, to have its origins in motherhood. All mammals are raised by a mother, and those mothers who are sensitive to the emotional signals and needs of their offspring are more successful at rearing offspring. As an evolutionary result, nearly all mammals have an implicit awareness of emotional cues, often extending to other adults of their species. Sometimes this sensitivity even extends across species, as has been observed in pet dogs that are responsive to distress in their owners. Empathy shows similar patterns in humans as in other animals: it is most often extended toward those closest to the subject, and the more distressed a subject is by emotional displays in others, the less likely the subject is to extend them help.

Photo credit: Mihaela Vincze

Related to empathy is observational/social learning, or the ability to learn from watching another individual. This, too, is observed widely among animal species, ranging from tool making/using techniques, to child-rearing traditions, to food choices [11]. Some of the most striking examples include the potato-washingJapanese macaques, which learned from one macaque to start washing the dirty potatoes that the caretakers provided. Even when clean store-bought potatoes were substituted, macaques for generations continued to wash their potatoes in the sea. This also seems to suggest a form of culture in animals, which pass along socially learned mannerisms to future generations that sometimes have little or no functional relevance. Indeed, evidence of cultural practices is quite strong in chimps, and some evidence exists even in rats.

Some believe that humans are unique in their capacity to think about the mental states of others, an ability sometimes referred to as “theory of mind.” However, this is also being challenged by clever beasts. Studies have shown that human children develop theory of mind at exactly the same age as they develop mirror self-recognition – a capacity which some of the most advanced animals, including dolphins, elephants and great apes, also show in adulthood [1]. However, even more convincing are recent experiments in Caledonian crows, showing that they recognize the difference between a human-operated and a randomly operated threatening device [2]. Human studies implicate specific areas of the brain – the temporo-parietal junction, superior temporal sulcus, and medial frontal cortex – as regions involved in thinking about the minds of others [12,13]. In studies on Rhesus macaques, analogous brain regions tend to expand with expanding group size, suggesting that they are involved in thinking about group members in other species as well [13].  So, even the imaginative capacity of humans seems not entirely unique.

The answer to the question of human uniqueness could be something seemingly obvious: language [14]. “Language seems to invade almost every aspect of cognition,” added Frans de Waal during a free discussion period. Language itself is a symbolic representation of thought, and the subsequent reliance on symbolic representations is reflected across a wide range of cognitive processes, especially those involved in social communication and learning. However, there is increasing evidence that some bird songs have characteristics similar to language; that chimps and dogs can understand spoken language, and may use gestural communication; and that some parrots may be able to use spoken language in the same way that humans do [14].

Despite all of the shared capacities between animals and humans, there is still significant resistance, even among scientists, to using traditionally “human” terms to describe the emotions, abilities and mental states of animals [15]. Nonetheless, the uniqueness of humanity may be simply a matter of combination and degree. Redouan Bshary, the scientist behind the grouper and cleaner wrasse studies, said in his talk that all animal brains represent a set of solutions to ecological problems [5]. When an ecological problem can best be solved through a single mental capacity, you are likely to find an animal that possesses that capacity. However, you might find it in isolation – for instance, a grouper that can form shared plans and make referential gestures toward a moray eel may not be able to think abstractly, imagine the thoughts of others, or use tools. Each animal independently evolves only those capabilities it needs for its own set of ecological problems. Furthermore, while chimps and crows may build tools, and dogs and birds may understand language, they are nowhere near to matching humans in the degree to which these capabilities are developed. So, humans may represent a unique evolutionary amalgam of capabilities that individually can be seen elsewhere, but rarely all together, and never to the same degree.

Bibliography

[1] de Waal FB (2014 October). Mammalian origins of empathy and pro-sociality. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[2] Gray R (2014 October). Can social and technical intelligence be decoupled? Cooperation, causal cognition and inferences about agency in New Caledonian crows. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[3] Ferrari PF (2014 October). Hard-wired, soft-wired and re-wired. Brain plasticity, sensorimotor experience and early social development in primates. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[4] Rizzolatti G (2014 October). Understanding others from inside: a neural mechanism. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[5] Bshary R (2014 October). The social brain hypothesis applied to fishes. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[6] Calcutt S (2014 October). Chimpanzees in newly formed social groups choose high-risk social investments over low-risk ones. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[7] Mason P (2014 October). Helping another in distress: Lessons from rats. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[8] Young LJ (2014 October). The neurobiology of social relationships: implications for novel therapies for Autism. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[9] Burkett JP (2014 October). Consoling behavior in the prairie vole: neurobiology and basis in empathy. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[10] Keysers C (2014 October). The empathic brain and its plasticity. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[11] Whiten A (2014 October). Imitation, culture, and the social brains of primates. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[12] Mars R (2014 October). From monkey social cognition to human mentalizing. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[13] Rushworth M (2014 October). The medial frontal cortex and social cognition in humans and other primates. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

 [14] Mooney R (2014 October). Neural mechanisms of communication. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

[15] Panksepp J (2014 October). Three primary-process animal social brain networks 9PANIC, SEEKING, PLAY) and development of three new antidepressants for humans. Talk presented at The Social Brain Conference, Copenhagen, Denmark.

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Burkett, J. (2014). What is uniquely human? A report from The Social Brain Conference. The Neuroethics Blog. Retrieved on , from http://www.theneuroethicsblog.com/2014/10/what-is-uniquely-human-report-from.html