Tag Archives: Edge

I’m feeling Edge-y about Human Evolutionary Exceptionalism

Unless your Internet has been broken for the past few days, by now you’re probably aware that John Brockman, via his Edge.org web site, has published the responses to his Annual Edge Question of the Year. For more than 15 years, John has been inviting people who think and write about science and the science-culture interface to respond to a provocative question. The question for 2014 was “What scientific idea is ready for retirement?” Brockman explains:

Science advances by discovering new things and developing new ideas. Few truly new ideas are developed without abandoning old ones first. As theoretical physicist Max Planck (1858-1947) noted, “A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.” In other words, science advances by a series of funerals. Why wait that long? What scientific idea is ready for retirement? Ideas change, and the times we live in change. Perhaps the biggest change today is the rate of change. What established scientific idea is ready to be moved aside so that science can advance?

I received an invitation to participate this year, and it didn’t take me long to settle on a topic. Something has been bugging me about the application of evolutionary thinking to human behavior for a while, and the Question of the Year was the perfect place to condense my thoughts into a 1000-word essay. What scientific idea, in my opinion, is ready for retirement? I nominated Human Evolutionary Exceptionalism. Here’s how I framed the problem:

Humans are biologically exceptional. We’re exceptionally long-lived and exceptionally cooperative with non-kin. We have exceptionally small guts and exceptionally large brains. We have an exceptional communication system and an exceptional ability to learn from other members of our species. Scientists love to study biologically exceptional human traits such as these, and that’s a perfectly reasonable research strategy. Human evolutionary exceptionalism, however—the tendency to assume that biologically exceptional human traits come into the world through exceptional processes of biological evolution—is a bad habit we need to break. Human evolutionary exceptionalism has sown misunderstanding in every area it has touched.

In my essay, I went on to describe examples of how human evolutionary exceptionalism has muddled the scientific literatures on niche construction, major evolutionary transitions, and cooperation. You can read my entire essay over here, but for this blog I’m reproducing what I had to say about the major evolutionary transitions—for reasons that I will make clear presently. The most critical part below is bolded and italicized. Here’s what I wrote:

Major Evolutionary Transitions. Over the past three billion years, natural selection has yielded several pivotal innovations in how genetic information gets assembled, packaged, and transmitted across generations. These so-called major evolutionary transitions have included the transition from RNA to DNA; the union of genes into chromosomes; the evolution of eukaryotic cells; the advent of sexual reproduction; the evolution of multicellular organisms; and the appearance of eusociality (notably, among ants, bees, and wasps) in which only a few individuals reproduce and the others work as servants, soldiers, or babysitters. The major evolutionary transitions concept, when properly applied, is useful and clarifying.

It is therefore regrettable that the concept’s originators made category mistakes by characterizing two distinctly human traits as outcomes of major evolutionary transitions. Their first category mistake was to liken human societies (which are exceptional among the primates for their nested levels of organization, their mating systems, and a hundred other features) to those of the eusocial insects because the individuals in both kinds of societies “can survive and transmit genes . . . only as part of a social group.”…

Their second category mistake was to hold up human language as the outcome of major evolutionary transition. To be sure, human language, as the only communication system with unlimited expressive potential that natural selection ever devised, is biologically exceptional. However, the information that language conveys is contained in our minds, not in our chromosomes. We don’t yet know precisely where or when human language evolved, but we can be reasonably confident about how it evolved: via the gene-by-gene design process called natural selection. No major evolutionary transition was involved.

This past Monday morning, right as I was about to go to the Edge web site to check out some of the other essays, someone e-mailed me to let me know about an uncanny coincidence. Just hours before my Edge essay came out—in which I was calling for the retirement of the misconception (among others) that human language was the outcome of a major evolutionary transition, Martin Nowak had published an essay on the Templeton Big Questions web site in which he was pushing in exactly the opposite direction. Here’s what Nowak had to say (my emphasis in boldface and italics):

I would consider these to be the five major steps in evolution: (i) the origin of life; (ii) the origin of bacteria; (iii) the origin of higher cells; (iv) the origin of complex multi-cellularity and (v) the origin of human language. Bacteria discovered most of biochemistry, higher cells discovered unlimited genetics; complex multicellularity discovered intricate developmental processes and animals with a nervous system. Humans discovered language.

Human language gave rise to a new mode of evolution, which we call cultural or linguistic evolution. The enormous speed of human discovery and invention is driven by this new mode of evolution. An idea or concept that originates in one brain can quickly spread to others. Structural changes (memories) are imprinted from one brain to another. Prior to human language the most crucial information transfer of evolution was mostly in terms of genetic information. Now we have genetic and linguistic evolution. The latter is much faster.  Presumably the collective information in human brains evolves at a much faster rate than any previous evolutionary system on earth. The growing world wide connectivity speeds up this linguistic evolutionary process.

Now, Nowak and I both agree that human language is a Very Special Way of transmitting information, but I say human language was not the outcome of a major evolutionary transition. Nowak says it was. We can’t both be right, so what’s going on? With respect, I think it’s Nowak who’s muddling things.

It was John Maynard Smith and Eörs Szathmáry who were actually responsible for popularizing the idea that human language was a major transition in evolution (see my essay and read between the lines; you’ll know whom I’m talking about even though I followed Brockman’s instructions to talk about ideas rather than the people who promote them). But as I wrote in my essay, Maynard Smith and Szathmáry made a category mistake when they did so: Here’s the first sentence from the description of their book, The Major Transitions in Evolution: “During evolution, there have been several major changes in the way that genetic information is organized and transmitted from one generation to the next.”

The critical word in the last sentence is “genetic.” Evolutionary transitions are about information stored in DNA, not about information in people’s minds. So, by Maynard Smith and Szathmáry’s own definition of major evolutionary transitions, human language categorically, absolutely cannot be one of them.

This has got to be incredibly obvious to anyone who takes a moment to think about it, so I’m not quite sure why influential people keep the misconception going. Equally puzzling to me, though, is why Maynard Smith and Szathmáry committed this error in the first place. Those gents are/were smart (Maynard Smith died in 2004; Szathmáry is still with us), and few people have ever had cause to doubt Maynard Smith’s judgment (though read Ullica Segerstrale’s biography of Bill Hamilton to learn about a striking exception to that rule). In any case, I can’t understand why Nowak continues to promulgate the notion that the evolution of human adaptations for nice things like human societies (as he did here) and human language (as in the Big Questions Online piece)—often using Maynard Smith and Szathmáry’s book for citation firepower—are comparable to actual Major Evolutionary Transitions that involved actual “major changes in the way that genetic information is organized and transmitted from one generation to the next.”

Human language is fascinating, puzzling, and a prime target for theory-building and research. Ditto for human cooperation and human societies. But these interesting features of human life are made neither grander, nor more comprehensible, by trying to get them into The Major Evolutionary Transitions club. They just don’t have the proper credentials.