Flies

I've just made it to the start of the second round of a certain Vaccination debate and I'm taking a break.

Some birds deliberately swoop low to the ground to stir up bugs and insects that may be sitting there. Other birds swoop in front of cars to snag the bugs that have been stirred up by their passing. We see a similar action in fish as well.

I've noticed that often times Flies seem to exhibit this same behaviour, seemingly flying in complicated swooping patterns for no apparent reason. Given their small size, I can't imagine they do this for fun, surely they'd have to be reasonably efficient with their energy expenditure... so why do they do it?

I can think of several possible reasons but I was wondering if anyone actually knew.

nzlockie: Weirdly enough I was randomly browsing reddit today and came across this: http://www.reddit.com/r/askscience/comments/1dbnt9/

A fly brain is very simple. They most likely have nothing resembling what you would call cognitive thought. They have sensory neurons that give their nervous system an input. When the stimuli causes a particular nerve to fire at a certain threshold value (fast or slow) it causes a change in the behavior of another neuron that it is connected to. In some animals it takes as little as 4 neurons to control a behavior as complex as say a moth flying toward the light. So let's imagine that a fly is trying to fly. It must continue moving forward to stay aloft. So it starts flying, but soon it starts heading toward a wall. As soon as the distance between the wall and the fly reaches a threshold value, a nerve response kicks in to turn the fly say 90 degrees. Rinse and repeat. Here I have implied, assumed, simplified, omitted and falsely described, but the idea remains the same. The fly is satisfying an extremely simple set of "instructions" set up by it's very simple nervous system. In all of reality the fly is probably trying to reach a certain level of light, heat, wind, noise, movement, and food/mate availability.

The interesting thing to think about though, is that we all exist using the same principles as the fly. We may have many many more neurons, and different sensory inputs, but it all comes down to threshold values of the neurons (particularly the sensory neurons). That threshold determines whether or not a signal is passed to an already existing nervous system with ready response to that input. Cascading events make simple stimuli seem incredibly complex, and falsely make behavior appear to be coming from something intangible other than the brain.

admin: That makes me feel better about swatting them with my electrified racket.