Monday, 21 August 2017
Humans Are the Product of Dynamic Processes on Multiple Time Scales
Today I want to talk about dynamic processes that occur on some very different time scales in the human nervous system. To do so, I will describe four examples very briefly, referring to the two graphics in this post.
The first of these processes, represented at the bottom of each graphic, is the evolution of the human nervous system, which occurs on the longest of these time scales, measured in millions of years. Over these very long periods, sexual reproduction has accelerated the diversification of our nervous systems by regularly producing variants or mutations. Some of these variants have proved capable of viable structural couplings with certain environments and have thus enabled their lucky owners to pass these nervous systems down to their descendants. I am purposely avoiding saying that these nervous systems are “better adapted to their environment”, so as not to imply that part of this environment is unchanging or that there is always some optimal level of adaptation that organisms can achieve. To state it succinctly, evolution is more proscriptive than prescriptive: it of course eliminates certain mutations that are too incapable of viable coupling with their environment, but it “allows” all the rest. (more…)
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