March 2, 2010
So What Really Makes Us Human?
Elephants have trunks; giraffes have necks; anteaters have tongues. What do we humans have that makes us unique? At first blush, it seems that answering that should be pretty easy, since we do so much that no other animal does: we build cities, write books, send rockets into space, create art and play music. But these are all the results of our uniqueness, not the cause. OK, how about language? That seems to be something universal to all human beings, which no other animal possesses. Language definitely is a major element in human uniqueness. But what if we try to go back even further, before language as we know it fully developed? What was it about our early ancestors that caused them to even begin the process that ended in language?
The influential cognitive neuroscientist Merlin Donald has suggested that, beginning as far back as two million years ago, there was a long and crucial period of human development that he calls the “mimetic phase.” Here’s how he describes it:
a layer of cultural interaction that is based entirely on a collective web of conventional, expressive nonverbal actions. Mimetic culture is the murky realm of eye contact, facial expressions, poses, attitude, body language, self-decoration, gesticulation, and tones of voice.
What’s fascinating about the mimetic phase is that we modern humans never left it behind. We’ve added language on top of it, but our mimetic communication is still, in Donald’s words, “the primary dimension that defines our personal identity.” You can get a feeling for the power of mimetic expression when you think of communications we make that are non-verbal: prayer rituals, chanting and cheering in a sports stadium, expressions of contempt or praise, intimacy or hostility. It’s amazing how much we can communicate without using a single word.
So before we talked, we chanted, grunted, cheered and even sang. But that still doesn’t explain how we started doing these things that no other creature had done over billions of years of evolution. Over the past twenty years, a powerful theory, called the Social Brain Hypothesis, has gained increasing acceptance as an explanation for the development of our unique human cognition. This hypothesis states that “intelligence evolved not to solve physical problems, but to process and use social information, such as who is allied with whom and who is related to whom.”
The underlying logic of this approach is that, when hominids first began adapting themselves to a less wooded environment, they didn’t have a lot of physical advantages: they couldn’t compete well with other predators for food, and were pretty vulnerable themselves to hungry carnivores. So, more than ever before, they banded together. As they did so, they faced ever-increasing cognitive demands from being in bigger social groups. And it wasn’t just the size of the group, but the complexity of the lifestyle that increased. If you were going out with your buddies on a long hunting trip, how could you know for sure that nobody else was going to jump into bed with your partner while you were gone?
With dilemmas like this to face, early hominids got involved in “an ‘arms race’ of increasing social skill”, learning to use “manipulative tactics” to their best advantage. But a newly emerging implication of this line of research is that cooperation may have played just as large a part as competition in contributing to our human uniqueness. Neuroscientist Michael Gazzaniga summarizes this viewpoint as follows:
although cognition in general was driven mainly by social competition, the unique aspects of human cognition – the cognitive skills of shared goals, joint attention, joint intentions, and cooperative communication needed to create such things as complex technologies, cultural institutions, and systems of symbols – were driven, even constituted, not by social competition, but social cooperation.
In fact, some prominent anthropologists go farther and suggest that it was “the particular demands” of our unusually “intense forms of pairbonding that was the critical factor that triggered” the evolution of our large brains.
Whether it was competition, cooperation or love, all these new forms of social complexity required a radical breakthrough in the human brain: the ability to look at others and realize that they had a mind that functioned somewhat like your own; to realize that when they did something, they were most likely being motivated by the same sort of things that motivated you. This realization has been called “theory of mind,” and in the past thirty years, has come to be recognized as fundamental to human development. 
Once you become aware that other people seem to have minds like yours, you will naturally start speculating on what goals, beliefs and intentions they might be holding in those minds. And at that point, it takes only a small step to turn the gaze inward and start asking the same questions about your own mind. A small step, but a gigantic leap for mankind. Because that inward gaze, that application of “theory of mind” to one’s own mind, was what led to the dramatic emergence of self-awareness, the consciousness of oneself as an autonomously existing entity.
It was in this momentous evolutionary transformation that the human prefrontal cortex (pfc) first initiated what Terrence Deacon calls “the translation of social behavior into symbolic form,” which I refer to as its “stirrings of power.” Neuroscientists have identified that the unique pfc-mediated attributes known as “executive function” – self-awareness, inhibition, symbolization, etc. – are the same skills required for theory of mind and other aspects of social interaction. In particular, a part of the pfc called the medial frontal cortex has been identified as having “a special role in social cognition,” including knowledge about the self and perceptions of the motivations of others.
In terms of daily survival, this meant that our early ancestors could take the same cognitive tools they were using to figure out the motivations of others, and apply them to the external world. This would have opened up an enormous set of possibilities for better foraging. Archaeologist Steve Mithen gives a great example of identifying hoofprints. “Footprints,” he points out, “just like symbols, must be placed into an appropriate category if correct meaning is to be attributed.” A deer’s hoofprint looks nothing like the deer itself, so only a human mind, equipped with its symbolizing pfc, is capable of imputing the meaning of the one from the other.
Another powerful capability arising from this new cognitive toolkit was a sense of past and future. Research in neuroscience has shown that “thinking about the future, remembering the past, and taking another person’s perspective activate a common brain network involving the prefrontal cortex.” As has been noted by psychiatrist Russell Barkley, without a sense of the future, it would be “nearly impossible” to exercise self-control. After all, you’re not going to stop yourself from instant gratification unless you can convince yourself that the same “you” will still be existing in some future period. This is the reason why little children, with undeveloped pfcs, have such difficulty deferring immediate rewards.
The cognitive toolbox of the pfc, in Deacon’s words, “provides a means of representing features of a world that no other creature experiences, the world of the abstract.” But these great leaps in human capability didn’t come without some dire costs. Perhaps the greatest of them all is awareness of our own eventual deaths. As psychologist Gordon Gallup points out, “to be aware of your own existence raises the possibility of confronting the inevitability of your eventual demise… Death awareness is a unique price that we pay for self-awareness.”
We humans, alone among the animals of this world, know that we’re going to die. We’re also alone, as far as we know, in asking the question “Why?” The “social intelligence”-driven question of “Why did my partner do what she did?” eventually leads to: “Why does the sun rise in the morning?” “Why did my loved one have to die?” and ultimately: “Why are we here?”
Other animals, to varying degrees and in different forms, ask the other major questions in life: “What?” “Who?” “Where?” and even to a limited extent “When?” But only we humans seem to have the capability to ask “Why?”
So the next time someone asks you what’s really unique about humans, I suggest that the best way to respond to them is with this very simple, profound and memorable verse:
Fish gotta swim Bird gotta fly Man gotta sit and say Why why why.
 Other animals such as chimpanzees, parrots and dolphins, have been shown to have the rudimentary capabilities of language; but no other animals appear able to communicate with each other using the complex, recursive web of symbols characteristic of human language.
 Donald, M. (2001). A Mind So Rare: The Evolution of Human Consciousness, New York: Norton, 265.
 A number of recent theories of language suggest that we sang long before we spoke, and raise the possibility that language evolved from a form of song. See, for example, Mithen, S. (2006). The Singing Neanderthals: The Origins of Music, Language, Mind, and Body, Cambridge, Mass.: Harvard University Press.
 Emery, N. J., and Clayton, N. S. (2004). “The Mentality of Crows: Convergent Evolution of Intelligence in Corvids and Apes.” Science, 306(December 10, 2004), 1903-1907, summarizing the original hypothesis published by Byrne & Whiten in Machiavellian Intelligence: Social Evolution in Monkeys, Apes and Humans.
 Byrne & Whiten quoted by Gazzaniga, M. S. (2009). “Humans: the party animal.” Dædalus(Summer 2009), 21-34.
 Gazzaniga, op. cit. describing the so-called “Vygotskian Intelligence Hypothesis” of Henrike Moll and Michael Tomasello.
 Dunbar, R. I. M., and Shultz, S. (2007). “Evolution in the Social Brain.” Science, 317(7 September 2007).
 See Povinelli, D. J., and Preuss, T. M. (1995). “Theory of mind: evolutionary history of a cognitive specialization.” Trends in Neurosciences, 18(9:November 9, 1995), 418-424; also Singer, T. (2006). “The neuronal basis and ontogeny of empathy and mind reading: Review of literature and implications for future research.” Neuroscience and Biobehavioral Reviews(30 (2006)), 855-863.
 See Povinelli & Preuss; Singer op. cit. Note that some theorists (e.g. Gallup, G. G. Jr. (1998). “Self-awareness and the evolution of social intelligence.” Behavioural Processes, 42, 239-247) propose a different direction of development than my description, from self-awareness to theory of mind.
 See Barkley, R. A. (2001). “The Executive Functions and Self-Regulation: An Evolutionary Neuropsychological Perspective.” Neuropsychology Review, 11(1), 1-29; also Roth, G., and Dicke, U. (2005). “Evolution of the brain and intelligence.” Trends in Cognitive Sciences, 9(5: May 2005), 250-253.
 Amodio, D. M., and Frith, C. D. (2006). “Meeting of minds: the medial frontal cortex and social cognition.” Nature Reviews: Neuroscience, 7(April 2006), 268-277.
 Mithen, S. (1996). The Prehistory of the Mind, London: Thames & Hudson, 161-2.
 Liberman, N., and Trope, Y. (2008). “The Psychology of Transcending the Here and Now.” Science, 322(21 November 2008), 1201-1205.
 Barkley, op. cit.
 Deacon, T. W. (1997). The Symbolic Species: The Co-evolution of Language and the Brain, New York: Norton, 423.
 Gallup, op. cit.
 Quoted by McEvilley, T. (2002). The Shape of Ancient Thought: Comparative Studies in Greek and Indian Philosophies, New York: Allworth Press.