Book Club: Darwin’s Unfinished Symphony, 1, are humans unique?

Time to get started with a new book for our occasional, in-depth book club. For our next round I have chosen an intriguing recent volume on cultural evolution, Kevin Laland’s Darwin’s Unfinished Symphony, with the provocative subtitle of “How Culture Made the Human Mind.”

Kevin is a professor of behavioral and evolutionary biology at the University of St. Andrews in Scotland, and one of the architects of the Extended Evolutionary Synthesis. In full disclosure, I collaborate to the EES project, which is partly supported by the Templeton Foundation.

The title of the book reminds us that Darwin was the first modern scientist to begin to investigate the evolution of the human mind, but he was unable — given the state of biological and psychological knowledge at the time — to go beyond some suggestive speculations. As Kevin puts it:

“Comprehending the evolution of the human mind is Darwin’s unfinished symphony. Unlike the unfinished compositions of Beethoven or Schubert, which had to be assembled into popular masterpieces using solely those fragmentary sketches left by the original composers, Darwin’s intellectual descendants have taken up the challenge of completing his work. In the intervening decades great progress has been made, and rudimentary answers to the conundrum of the evolution of our mental abilities have started to emerge.” (p. 14)

The question is far from trivial. As Laland notes, if a complex mind, language and a sophisticated culture are truly advantageous for survival and reproduction, why did they evolve only in the human lineage? And yes, we have discovered that other animals communicate and use tools, but their tool use has not become much more sophisticated over time, so that only we have moved from stone artifacts to computers and rockets, and as Kevin points out, there is a world of difference between a male chaffinch’s song and Puccini’s arias. Nothing at all exists in between those extremes to cover the gap, even though, possibly, some of the hominid species that are now extinct would have provided a bit (but arguably just a bit) of a bridge between Homo sapiens and the rest of the biological world. And don’t except our extraordinary capacities to be in any direct relationship with the only true currencies of evolution, survival and reproduction:

“The men and women who design and build computers and iPhones have no more children than those in other professions.” (p. 2)

A lot of what makes human culture so distinct is that it is the result of long term planning and extensive cooperation among unrelated individuals, again something unique in the animal world:

“With a little training, the same people could build a shopping mall, bridge, canal, or dock, but no bird ever built anything other than a nest or bower, and no termite worker deviated from constructing a mound.” (p. 3)

Kevin, as is clear from his careful discussion of other animals’ behavior in chapter 1 (and then even more so in the remaining four chapters of the first part of the book, which I will cover in future posts), is perfectly aware of the variety and even sophistication of what non humans do. And yet:

“There is no compelling evidence that other apes will go out of their way to teach their friends or relatives anything at all, let alone build elaborate institutions that dispense vast amounts of knowledge, skills, and values to hordes of children with factory-like efficiency. Teaching, by which I mean actively setting out to educate another individual, is rare in nature.” (p. 5)

Moreover, the bewildering diversity of human culture is hardly explained by the main focus of modern Darwinian explanations: genetics. Pace evolutionary psychology, the human genome actually sports comparatively little variability, and it cannot, per se, explain the infinite diversity of our cultural habits and traditions, although of course it has to be part of the story, if for no other reason that it provides the boundary conditions within which human behavioral plasticity can express itself.

One of the most interesting points of this first chapter is that it is culture (and thus cooperation) that makes us so successful, not intelligence per se (though, obviously, the two are related). Laland describes in detail the evolution of the paper clip, and it is a fascinating story that I highly recommend people read. Contra what one might expect, the paper clip did not come out of the mind of a single, brilliant individual, but — in its current form — is actually the product of centuries of evolution and improvements, beginning in the Middle Ages, when enough paper began to be produced and used to necessitate some way of binding it together.

The first solution was to use pins as fasteners, but they rusted and left holes that were not aesthetically pleasing. Eventually, the first patent for a paper clip was filed in 1867, but the things were still inefficient, which led to further trial and error:

“A variety of shapes were experimented with for several decades of the twentieth century before manufacturers finally converged on the now standard paper clip design, known as the ‘Gem.’ What appears at first sight to be the simplest of artifacts was in fact fashioned through centuries of reworking and refinement.” (p. 7)

The point is that many cultural artifacts are originated gradually, through diffuse cooperation among strangers, a process of cumulative culture unknown in the rest of the animal world. Other species learn, of course, and are capable of copying each other (chapters 2 and 3 of the book are devoted to copying as a basic mechanism of behavioral evolution), but reports of cultural traditions are limited in scope, and entirely lack the ratcheting effect that is so normal in the human context:

“The fact remains that humans alone have devised vaccines, written novels, danced in Swan Lake, and composed moonlight sonatas, while the most culturally accomplished nonhuman animals remain in the rain forest cracking nuts and fishing for ants and honey.” (p. 10)

As I reported recently  I was accused of “arrogance” when I stated this simple conclusion during a panel discussion at the New York Academy of Science. But the fact remains true, regardless of pious and well intentioned pleas for getting ourselves off the evolutionary pedestal. As Kevin says later in the chapter, yes, in a trivial sense every species is “unique,” but humans are unique in a highly interesting way, which is not comparable to the uniqueness of dolphins, birds, or what else. Indeed:

“Herein lies a major challenge facing the sciences and humanities; namely, to work out how the extraordinary and unique human capacity for culture evolved from ancient roots in animal behavior and cognition.” (p. 11)

As I have pointed out, even brilliant biologists like E.O. Wilson don’t get that culture isn’t going to be reduced to biology, and therefore that the humanities are not, and never will be, a branch of the biological sciences. That way of achieving “consilience” (really, reduction) between social and biological sciences is a dead end. Kevin’s book is a most refreshing and welcome attempt to seek another, more constructive, way to go about this project, one that fully respects the distinct contributions that different disciplines are capable of.

Laland acknowledges the existence of a long scientific tradition, dating, in fact, back to Darwin, of trying to bridge the gap between humanity and the rest of the biological world. He even suggests that this was necessary, especially at the onset of evolutionary biology, in order to convince people that humans too evolved by natural means and were not specially created. But that necessity is no longer with us (well, unless you live in the south of the United States, or in large swaths of the Muslim world), and it is time to reassess the limitations of that particular Darwinian research program.

Again, Kevin is anything but naive in this regard. He knows that a long list of traits at one point alleged to be distinctively human (e.g., use of tools, imitation, use of signals, etc.) turned out not to be so upon closer examination. Yet, the gap is real:

“In my view, too much has been made of superficial similarities between the behavior of humans and other animals, whether by inflating the intellectual credentials of other animals or by exaggerating humanity’s bestial nature.” (p. 15)

One good example is what Laland calls one of the most misunderstood statistics concerning the relation between humans and our primate cousins, the chimpanzees. We often hear that there is a 98.5% similarity between the genomes of these two species, meaning that we are separated by “only” 1.5% differences in DNA. That, however, translates to a whopping 35 million nucleotide differences, a vast informational gulf even at face value, made orders of magnitude vaster when we realize that many important differences between chimpanzees and us are not to be found in the structure of our respective genes, but in the way gene action is regulated. And gene regulation is highly combinatorial, not simply linearly additive.

“An instructive comparison here is between the English and German languages. In terms of their written symbolic form (i.e., the letters used), these two Indo-European languages are identical, although only German speakers make use of the umlaut, recognizable as two dots over a vowel, which changes its pronunciation. Yet it would clearly be ridiculous to claim that all differences between the two languages are attributable to the umlaut, or that to master German, an English speaker merely has to master the rules of umlaut usage.” (p. 17)

And guess what? A disproportionate number of genetic differences between us and chimps concern the human brain and its function, and are therefore especially pertinent to the issue of behavior and culture.

Much has been made, by primatologists like Frans de Waal of the similarities in behavior between humans and other primates, especially the bonobos, the pigmy chimpanzee. While this research is indeed fascinating, Laland cautions against waxing poetic about having found the building blocks of morality in non human species. Experiments he cites in the book, for instance, clearly show that, when exposed to versions of the so-called ultimatum game, which tests for the tendency to share resources fairly, humans are remarkably fair to strangers, but chimps are not. And the puzzling behavior, evolutionarily speaking, is ours, not theirs. Moreover, while it is true that other species of primates cooperate, they do not do so extensively, certainly not even close to the degree of cooperation found in hunter-gatherer human populations, let alone modern ones.

Kevin attributes this difference, at least in part, to the proportionally limited ability of non human primates to exhibit a “theory of mind,” that is of understanding the perspective of others. Again, while it is the case that some research hints at the existence of a simplified ability to do so in chimps:

“These conclusions remain contested, and crucially, such studies provide no evidence that chimpanzees understand that others may possess false beliefs. In contrast, children typically understand that others can have false beliefs by the age of four years, and possibly much earlier, which implies that this capability evolved in the hominin lineage.” (p. 21)

Humans easily comprehend up to six different levels of beliefs about beliefs, while chimpanzees struggle with first-order intentionality.

Or let us consider language. There certainly is by now abundant evidence of animal communication, for instance vervet monkeys possessing three distinct calls to label avian, mammalian, and snake predators. But primate communication consists of unrelated signals that are rarely combined, i.e., they lack a grammar. Human language, by contrast, is highly open-ended:

“A romance exists around the notion that animals, such as chimpanzees or dolphins, might covertly harbor complex natural communication systems as yet unfathomed by humans. Many of us quite like the idea that ‘arrogant’ scientists have prematurely assumed that other animals don’t talk to each other. … Sadly, all the evidence suggests that this is just fantasy. Animal communication has been subject to intense scientific investigation for over a century, and few hints of any such complexity have arisen.” (p. 22)

I’m not sure why this is sad. It is what it is. As hinted at above, something similar is the case for the so-called moral instinct:

“Equally romantic is the notion that science has not yet gauged the full depth of the moral lives of animals, a premise that sells an awful lot of popular science books and flushes the coffers of Hollywood moviemakers. … Many popular books claim that animals understand the difference between right and wrong, but precious few scientific papers demonstrate this.” (p. 25)

Again, Kevin is not denying the very clear evidence that some animals have rich emotional lives, that they form attachments, and that they have long term memories of their most traumatic experiences. He simply does not think — very reasonably — that any of this amounts to a sense of morality.

But wait! I’m pretty sure that my dog feels guilty when I reprimand him for something wrong he has done! Maybe, responds Laland. But isn’t it more likely, more parsimonious, to assume that your dog has simply learned that a certain kind of behavior on his part gets you to relent from punishing or yelling at him? What about reports of reconciliation after fights in monkeys, which some authors have interpreted as “forgiveness”? Again, maybe, but that interpretation becomes a bit less convincing once we learn that fish — with much more limited behavioral repertoires and brain structures — behave in the same way.

The evidence appears to point to the conclusion that human intelligence and culture evolved in a particular way, with experimental and simulational studies suggesting that selection for more efficient teaching may have been a crucial factor for the evolution of language in our ancestors. Teaching and language, in turn, led to widespread cooperation and a runaway process in which different components of cognition fed into each other. In the end:

“Humans are creatures of their own making. The learned and socially transmitted activities of our ancestors, far more than climate, predators, or disease, created the conditions under which our intelligence evolved. Human minds are not just built for culture; they are built by culture.” (p. 30)