August 6, 2009

Evolution's Third Replicator

From New Scientist:
Evolution's Third Replicator: Genes, Memes, and Now What?

by Susan Blackmore

WE HUMANS have let loose something extraordinary on our planet - a third replicator - the consequences of which are unpredictable and possibly dangerous.

What do I mean by "third replicator"? The first replicator was the gene - the basis of biological evolution. The second was memes - the basis of cultural evolution. I believe that what we are now seeing, in a vast technological explosion, is the birth of a third evolutionary process. We are Earth's Pandoran species, yet we are blissfully oblivious to what we have let out of the box.

This might sound apocalyptic, but it is how the world looks when we realise that Darwin's principle of evolution by natural selection need not apply just to biology. Given some kind of copying machinery that makes lots of slightly different copies of the same information, and given that only a few of those copies survive to be copied again, an evolutionary process must occur and design will appear out of destruction. You might call it "design by death" since clever designs thrive because of the many failures that don't.

The information that is copied, varied and selected is called the replicator, and the process is well understood when applied to biology. Genes are copied, mutated and selected over and over again. Assemblages of genes are used to build vehicles that carry them around, protect them and propagate them. These vehicles - the lumbering robots, as Richard Dawkins calls them - are animals and plants, the prolific and exquisitely designed products of the first replicator.

About 4 billion years after the appearance of the first replicator, something extraordinary happened. Members of one species of lumbering robot began to imitate one another. Imitation is a kind of copying, and so a new evolutionary process was born. Instead of cellular chemistry copying the order of bases on DNA, a sociable species of bipedal ape began to use its big brain to copy gestures, sounds and other behaviours. This copying might not have been very accurate, but it was enough to start a new evolutionary process. Dawkins called the new replicators "memes". A living creature, once just a vehicle of the first replicator, was now the copying machinery for the next.
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