Debate Magazine

Evolutionary Exchanges

By Cris

Among the many misunderstandings that surround evolution, perhaps the most pervasive is that “it” is always progressive. Aside from the fact that “evolution” is not an agent or force — it is simply a word that describes a process and which connotes alteration over time, evolutionary change is not always progressive. Evolutionary transformations are not, in other words, slowly unfolding sequences toward ever increasing complexity and cleverness.

In 2007, Sana Inoue and Tetsuro Matsuzawa published a study (“Working Memory of Numerals in Chimpanzees”) showing that chimps have better short-term memory than humans. The experiments conducted to reach this sobering conclusion reminded me of the light-sequence memory game Simon, which was frustratingly popular in the 1980s. In a recent Guardian article, Justin McCurry recaps the study:

In a landmark test of short-term memory conducted in public in 2007, the chimp Ayumu demonstrated astonishing powers of recall, easily beating his human competitors, who had been in training for months.

The strength of Ayumu’s cognitive functions surprised even Matsuzawa, who has studied the mental dexterity of chimps for 36 years. “We’ve concluded through the cognitive tests that chimps have extraordinary memories,” Matsuzawa says. “They can grasp things at a glance. As a human, you can do things to improve your memory, but you will never be a match for Ayumu.”

The results stunned observers. In the tests, Ai and Ayumu, and two other pairs of a mother and offspring, were shown the numerals 1 to 9 spread randomly across a computer screen. Their task was to touch the numbers in ascending order. To complicate matters, the game was altered so that as soon as the chimps touched the digit 1, the remaining eight were immediately masked by white squares. To complete the exercise, they had to remember the location of each concealed number and, again, touch them in the correct order.

In an even harder version, five numbers appeared on the screen before turning into white squares. The animals and their human counterparts displayed the same degree of accuracy – about 80% – when the numbers remained visible for seven tenths of a second. But when the time was reduced to four tenths of a second, and then just two tenths, Ayumu maintained the same level of accuracy, while his mother and the human volunteers floundered.

Why might chimps have what is commonly called photographic or eidetic memory? And why do most humans lack this obviously useful ability? Matsuzawa offers an evolutionary explanation:

As humans evolved and acquired new skills – notably the ability to use language to communicate and collaborate – they lost others they once shared with their common simian ancestors. “Our ancestors may have also had photographic memories, but we lost that during evolution so that we could acquire new skills,” he says. “To get something, we had to lose something.”

Humans and chimps diverged from a common ancestor some 6-8 million years ago. It seems likely that this common ancestor had superior, or chimp-like, working memory and recall. At some later point, our hominin ancestors lost or exchanged this ability for others. While total recall would have been nice to retain, where there are benefits to be had, costs must be paid. This is, in the end, a nice example of evolution that is not simple accretion or straightforward advance.

This brings to mind a classic article, by Jack Goody, that I was reading yesterday. As some may know, Goody contends (in The Domestication of the Savage Mind) that the epoch changing event in human history was the invention of writing and spread of literacy. If anything can be said to mark the transition from so-called “primitive” to “modern” ways of thinking, it is this. Goody is, however, skeptical of the idea that evolution is inevitably or inherently progressive, especially when it comes to cultural matters:

When we think of long-term evolutionary change, it is inevitable that we think primarily in terms of technological developments. For the archaeological record, which provides the only evidence of early societies, is based upon the resurrection of man’s material products and these display certain well-established sequences which show general changes in the human economy from hunting to food production to more complex agriculture, and finally, in the age of writing, through to industrial manufacture. Archaeology, as has often been pointed out, makes Marxists of us all, since it has to treat material objects (the tools of production) as the basis for further deductions not only about the mode of production but about the social system as a whole.

While no one can fail to recognize long-term (‘evolutionary’) changes
in the economy, such sequences are less easy to establish in the other social domains, in kinship, in religion, in law, in politics, and in the general field of ‘thought’, of ‘culture’.

On this important latter point, I’m not sure why Goody hedged: material and cosmological complexity are not linked. Having said this, there is little doubt that writing changes the way people think. But in gaining predominantly literate culture, we lost true oral culture. This loss was not without consequences. Both of these modes, literate and oral, are what Goody calls “technology of the intellect.” They are radically different technologies that require and engender different ways of thinking. Each calls on different cognitive abilities and stresses different modes of mind.

In observing these facts, Goody is not suggesting there is any difference in the underlying brains or minds. “Primitives” are not, in other words, much different from “moderns.” With this in mind, Goody concludes:

In this essay I have tried to take certain of the characteristics that
Levi-Strauss and others have regarded as marking the distinction between primitive and advanced, between wild and domesticated thinking, and to show that many of the valid aspects of these somewhat vague dichotomies can be related to changes in the mode of communication, especially the introduction of writing. The advantage of this approach lies in the fact that it does not simply describe the differences but relates them to a third set of facts, and thus provides some kind of explanation, some kind of mechanism, for the changes that are assumed to occur.

A recognition of this factor also modifies our view of the nature of those differences. The traditional characterization is essentially a static one in that it gives no reason for change, no idea of how or why domestication occurred, it assumes the primitive mind has this particular character, the advanced has that, and it is due to the genius of the Greeks or the Western Europeans that modern man emerged. But modern man is emerging every day in contemporary Africa, without, I suggest, the total transformation of processes of ‘thought’ or attributes of ‘mind’ that existing theories imply. The content of communication is clearly of prime significance. But it is also essential, for social theory and historical analysis, to recall the limitations and opportunities offered by different technologies of the intellect.

Oral technology has one set of limitations and opportunities; literate technology has another and different set. This strikes me as a non-progressive evolutionary exchange or trade-off.


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