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Or, where moths are concerned, modern life is war…
“Moths fly into the candle flame and it doesn’t look like an accident. They go out of their way to make a burnt offering of themselves. We could label it ‘self-immolation behaviour’ and, under that provocative name, wonder how on earth natural selection could favour it….
Artificial light is a recent arrival on the night scene. Until recently, the only night lights in view were the moon and the stars. They are at optical infinity, so rays coming from them are parallel. This fits them for use as compasses. Insects are known to use celestial objects such as the sun and the moon to steer accurately in a straight line, and they can use the same compass, with reverse sign, for returning home after a foray. The insect nervous system is adept at setting up a temporary rule of thumb of this kind: ‘Steer a course such that the light rays hit your eyes at an angle of 30 degrees’. Since insects have compound eyes (with straight tubes or light guides radiating out from the centre of the eye like the spines of a hedgehog), this might amount in practice to something as simple as keeping the light in one particular tube or ommatidium [any scientists around to explain that one?!]
But the light compass relies critically on the celestial object being at optical infinity. If it isn’t, the rays are not parallel but diverge like the spokes of a wheel. A nervous system applying a 30 – degree (or any acute angle) rule of thumb to a nearby candle, as though it were the moon at optical infinity, will steer the moth, via a spiral trajectory, into the flame. Draw it out for yourself, using some particular acute angle such as 30 degrees, and you’ll produce an elegant logarithmic spiral into the candle.
Though fatal in this particular circumstance, the moth’s rule of thumb is still, on average, a good one because, for a moth, sightings of candles are rare compared with sightings of the moon. We don’t notice the hundreds of [hung on, hung on, hung on!!] moths that are silently and effectively steering by the moon or a bright star, or even the glow from a distant city. We see only moths wheeling into our candle, and we ask the wrong question: why are all these moths commiting suicide? Instead, we should ask why they have nervous systems that steer by maintaining a fixed angle to light rays, a tactic that we notice only when it goes wrong. When the question is rephrased, the mystery evaporates. It never was right to call it suicide. It is a misfiring by-product of a normally useful compass.”
- From The God Delusion, by Richard Dawkins.
‘But we cannot cling to the old days anymore’ .
Granted, the link seems obscure but to me it captures a regular refrain in the sub-text of Morrissey’s songs; an unease about how the world has changed in various ways. New conditions foisted on people in the name of progress are not always welcome or even necessarily beneficial.
Does anybody feel the same way I do?!
And speaking of the challenges of technology etc, I wonder how this effort is going to turn out...
“I feel inexhaustible” - *SNORES*
“Moths fly into the candle flame and it doesn’t look like an accident. They go out of their way to make a burnt offering of themselves. We could label it ‘self-immolation behaviour’ and, under that provocative name, wonder how on earth natural selection could favour it….
Artificial light is a recent arrival on the night scene. Until recently, the only night lights in view were the moon and the stars. They are at optical infinity, so rays coming from them are parallel. This fits them for use as compasses. Insects are known to use celestial objects such as the sun and the moon to steer accurately in a straight line, and they can use the same compass, with reverse sign, for returning home after a foray. The insect nervous system is adept at setting up a temporary rule of thumb of this kind: ‘Steer a course such that the light rays hit your eyes at an angle of 30 degrees’. Since insects have compound eyes (with straight tubes or light guides radiating out from the centre of the eye like the spines of a hedgehog), this might amount in practice to something as simple as keeping the light in one particular tube or ommatidium [any scientists around to explain that one?!]
But the light compass relies critically on the celestial object being at optical infinity. If it isn’t, the rays are not parallel but diverge like the spokes of a wheel. A nervous system applying a 30 – degree (or any acute angle) rule of thumb to a nearby candle, as though it were the moon at optical infinity, will steer the moth, via a spiral trajectory, into the flame. Draw it out for yourself, using some particular acute angle such as 30 degrees, and you’ll produce an elegant logarithmic spiral into the candle.
Though fatal in this particular circumstance, the moth’s rule of thumb is still, on average, a good one because, for a moth, sightings of candles are rare compared with sightings of the moon. We don’t notice the hundreds of [hung on, hung on, hung on!!] moths that are silently and effectively steering by the moon or a bright star, or even the glow from a distant city. We see only moths wheeling into our candle, and we ask the wrong question: why are all these moths commiting suicide? Instead, we should ask why they have nervous systems that steer by maintaining a fixed angle to light rays, a tactic that we notice only when it goes wrong. When the question is rephrased, the mystery evaporates. It never was right to call it suicide. It is a misfiring by-product of a normally useful compass.”
- From The God Delusion, by Richard Dawkins.
‘But we cannot cling to the old days anymore’ .
Granted, the link seems obscure but to me it captures a regular refrain in the sub-text of Morrissey’s songs; an unease about how the world has changed in various ways. New conditions foisted on people in the name of progress are not always welcome or even necessarily beneficial.
Does anybody feel the same way I do?!
And speaking of the challenges of technology etc, I wonder how this effort is going to turn out...
“I feel inexhaustible” - *SNORES*