Thursday, September 12, 2013

Biological Gears has a report about a British leaf-hopper, a small insect of the genus Issus which moves by taking large leaps, much like a grasshopper. This particular insect, however, is especially noteworthy because the legs which propel its leaps are synchronized not by nerves but by mechanical gears.

Here's an excerpt from the article:
A plant-hopping insect found in gardens across Europe - has hind-leg joints with curved cog-like strips of opposing 'teeth' that intermesh, rotating like mechanical gears to synchronise the animal's legs when it launches into a jump.

The finding demonstrates that gear mechanisms previously thought to be solely man-made have an evolutionary precedent. Scientists say this is the "first observation of mechanical gearing in a biological structure".

The gears in the Issus hind-leg bear remarkable engineering resemblance to those found on every bicycle and inside every car gear-box.

Each gear tooth has a rounded corner at the point it connects to the gear strip; a feature identical to man-made gears such as bike gears – essentially a shock-absorbing mechanism to stop teeth from shearing off.

The gear teeth on the opposing hind-legs lock together like those in a car gear-box, ensuring almost complete synchronicity in leg movement - the legs always move within 30 'microseconds' of each other, with one microsecond equal to a millionth of a second.

This is critical for the powerful jumps that are this insect's primary mode of transport, as even miniscule discrepancies in synchronisation between the velocities of its legs at the point of propulsion would result in "yaw rotation" - causing the Issus to spin hopelessly out of control.

"This precise synchronisation would be impossible to achieve through a nervous system, as neural impulses would take far too long for the extraordinarily tight coordination required," said lead author Professor Malcolm Burrows, from Cambridge's Department of Zoology.

"By developing mechanical gears, the Issus can just send nerve signals to its muscles to produce roughly the same amount of force - then if one leg starts to propel the jump the gears will interlock, creating absolute synchronicity.
This is all incredibly fascinating, but almost as fascinating is what the discoverers of these gears say about them next in the article:
"We usually think of gears as something that we see in human designed machinery, but we've found that that is only because we didn't look hard enough," added co-author Gregory Sutton, now at the University of Bristol.

"These gears are not designed; they are evolved - representing high speed and precision machinery evolved for synchronisation in the animal world."
I'd like to ask two questions: First, how does Mr. Sutton know these gears weren't designed? When a structure bears such a close resemblance to a structure we know to be designed by an intelligent agent we conclude by analogy that the original structure has a reasonable possibility of being similarly designed. This is the principle, widely accepted in science, that like effects are reasonably attributed to like causes. Why should we simply acquiesce to the view that such wonders are the product of unintelligent forces plus chance plus time?

Second, isn't a bit embarrassing for scientists to always have to impute such a marvelous capacity for innovation and engineering to blind impersonal processes? When amazing structures such as this gear system or the outboard motor that propels bacteria are discovered Darwinians express no reservations about dutifully waving their magic wand of mutation and natural selection, squirting a little pixie dust into our eyes, and declaring that even though it nay seem like magic to the benighted, functional gears and outboard motors are the sorts of miracles that purposeless forces and chance can build a dozen times before breakfast every morning.

It seems to me that one has to be either a) very gullible or b) resolutely committed a priori and with religious tenacity to metaphysical naturalism in order to believe such prodigies uncritically. Someone with a healthy scientific/philosophical skepticism would judge claims like Mr. Sutton's to be at best rash and at worst superstitious nonsense.

Scientists don't, or at least shouldn't, invoke magic or miracle as an explanation.