Gears evolved in nature long before humans 'invented' them
A gear system similar to those used on
bicycles has been found in insects,
proving that nature developed cogs
long before humans.
The juvenile Issus - a plant-hopping
insect found in gardens across Europe
- has hind leg joints with curved, cog-
like strips of opposing "teeth" that
inter-mesh, rotating like mechanical
gears to synchronise the animal's legs
when it launches into a jump,
University of Cambridge researchers
said.
The find demonstrates that gear
mechanisms, previously thought to
have been pioneered by humans, have
an evolutionary precedent.
The cogs allow precise synchronisation
of the insect's hind legs when it jumps.
Photograph: Burrows/Sutton/PA
The gears in the Issus leg work in a
similar way to those found on
bicycles and inside car gear-boxes.
The gear teeth on the opposing hind
legs lock together like those in a car
gear-box, ensuring almost complete
synchronicity in leg movement. This
helps with the powerful jumps the
insects use to get around.
Professor Malcolm Burrows said:
"This precise synchronisation would
be impossible to achieve through a
nervous system, as neural impulses
would take far too long for the
extraordinarily tight co-ordination
required.
"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.
The gear teeth on the hind legs lock
together like those in a car gear-box.
Photograph: Burrows/Sutton/PA
Co-author Gregory Sutton, now at the
University of Bristol, said: "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.
"These gears are not designed, they
are evolved - representing high-speed
and precision machinery evolved for
synchronisation in the animal
world."
The gears are only found in juvenile
insects and are lost as they pass into
adulthood.
