As mentioned a few times already, I have just been to the 74 Symposium at Cold Spring Harbor Laboratory. The many experiences I had there will continue to fill the pages here for quite some time. Now, I'd like to summarize an interesting talk given by Matt Ridley: "When Ideas Have Sex: The Role of Exchange in Cultural Evolution"
Ridley started by comparing two objects that both are made to fit neatly in the palm of a human hand, a stone chipped for throwing, and a computer mouse. The difference is that the stone is made by one brain, while the mouse is made by many brains. Most likely there isn't a single person who could make a mouse. He then gave the example of the steam machine. Six of them, with Watts' the fourth in a line of machines each built on principles of the former. James Watts is often given the credit, but he didn't invent the steam engine any more than Fender invented string instruments. Ridley quoted a Francois (last name?): "To create is to recombine," driving home the point familiar to evolutionary biologists that recombination (a genetics term) generates variation on which novelty is built, and that this is true in cultural evolution as well. He argued that the invention (of appearance) of bipedalism, use of tools, use of fire, and language is not enough to increase cranial capacity to the point where it is today. Instead, he contends, what really required such an astounding, and otherwise disadvantageous increase in cranial volume, was the emergence of exchanges, or trade (yes, several disadvantages to having such a large brain must be overcome: high energetic cost, large skulls leading to high rates of death during birth, high costs of caring for what is basically premature infants). As evidence for this he notes that no animals exchange food. Tests have been made with monkeys, but no matter how hard they try to induce them to trade with each other, they never do. This lead him to the formula that the difference between us and them is one of kind, rather than degree. In humans this in turn led to the sexual division of labor, which is also not observed among other animals. There is not even evidence to suggest that Neandertals divided tasks differently between male and female, while there is evidence that they had language, tools, fire, and walked on two feet. Of course, one could object that Ridley's hypothesis doesn't square so well with the fact that Neandertals had larger brains that humans, though it could be hypothesized (but not tested) that the human brain is different in kind, while not larger than that of Neandertals.
What can be invented and produced further depends on the size of society. The more people can exchange ideas and items, the more technology (i.e. novel products) is created. People who have been isolated from contacts with foreigners, for example on the island of Tasmania with only 4,000 individuals, never developed new tools, but in fact their technology simplified over time. It is the differentiation of professions within society that enables large-scale constructs, like airplanes and electric guitars, none of which could ever be produced if everyone carried out all the same tasks.
Technologies evolve building on top of previous ones, but on top of that similarity to evolutionary biology, technologies may also speciate, as when a subpopulation of E. coli evolves the ability to metabolize citrate, or when dog breeds become so different that they cannot interbreed anymore, as with chihuahuas and great danes (this is at least true if all other dog breeds of intermediate size went extinct). As an example of that Ridley mentioned the internet, which he proposed is about to split into two different things: "What my daughter do [on the internet] is vastly different from what I do." If that's the only example, then I would say that this speciation hypothesis was contentious at best, but if I think about it, computers are so diverse in forms now as to compare with dog breeds, so perhaps I cannot reject the comparison.
Matt Ridley is the author of four books on human nature, and one biography of Francis Crick. His newest book will be on evolutionary economics.
Previous posts on the 74th Symposium at CSHL:
Second day at CSHL
First day at CSHL
74th Symposium at CSHL
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