Fly Nervous System Exceeds Expectations

One look at this nerve diagram
should eliminate thoughts of evolution

Sometimes a few diagrams say more than words. The diagrams of the nervous system of a tiny fruit fly speak volumes.

From takeoff to flight, a map of a fly’s nervous system (University of Washington, 26 June 2024). “Scientists explore the circuitry controlling leg and wing movements that propel fruit flies into the air.” What does it take to get a leg or wing to perform these feats? Scientists at UW were surprised at their results when they began mapping the nerves and muscles:

Although fruit flies seem like simple creatures, the researchers said that their motor system contains “an unexpected level of complexity.”

“A typical fly motor neuron receives thousands of synapses from hundreds of presynaptic premotor neurons,” the scientists observed. “This number is on par with the scale of synaptic integration in pyramidal cells of the rodent cortex.”

The press release contains animation of the diagrams in 3-D. Here is one frame from the animation:

An anatomical reconstruction of motor neurons that control muscles of the fly leg and wing. (Tyler Sloan Quorometrics Studio, from UW press release).

A fruit fly doesn’t have as many muscles or neurons as a mammal or hummingbird. “Although the fly’s motor neurons are few, it performs remarkable aerial and terrestrial feats,” the press release states. The fly gets more out of less by combining inputs and outputs: “Various motor units, activated in different combinations and sequences, collaborate to achieve a myriad of movement behaviors.”

Each of the parts above is functionally essential and placed in a specific way with other parts. One viewing of the animation in the article should dispel any thoughts that all these parts came together by accident or trial and error.

See also my article about the fly’s wing hinge at Evolution News 23 May 2024.