CAN a leech do maths? This is the bizarre question raised by the discovery
that the creature鈥檚 nerve cells use trigonometry to calculate which muscles to
move and by how much
(鈥淪imple minds鈥�, p 28).
Few would object to the idea that leech nerve cells can, along with so many
other mindless physical systems, be modelled using maths. But instinct tells you
that this bloodsucker can no more 鈥渄o maths鈥� than it can play the trombone.
This is a superficial view born of the bogus assumption that maths requires a
mind. All you really need is a system that can encode and manipulate abstract
mathematical 鈥渙bjects鈥� such as sines, cosines and laws of motion. The new
research shows that the nerve cells of dumb leeches will do nicely.
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Perhaps the crux of our confusion is that the leech鈥檚 nerve cells arrived at
trigonometry by an obviously random and undirected
search鈥攅volution鈥攚hereas humans seem to have acquired maths by
intellectual effort. But this may be to give ourselves too much credit. After
all, people have dreamt up an awful lot of wrong and ineffective maths. We try
all kinds of things, but it is only those that work that survive.