Amazing Spectacle

An amazing spectacle is unfolding across the northeastern United States this month, but it's going largely unnoticed by most people. Millions of green darner dragonflies are heading south in an annual migration the details of which are stunningly similar to those of the monarch butterfly.

Green Darner

From the website of the British Royal Society:

Darners undertake complex long-distance annual migrations governed largely by temperature that involve at least three generations.

In spring, the first generation makes a long-distance northbound movement (further than 650 km) from southern to northern range limits, lays eggs and dies.

A second generation emerges and returns south (further than 680 km), where they lay eggs and die. (This is the movement that's occurring now).

Finally, a third resident generation emerges, reproducing locally and giving rise to the cohort that migrates north the following spring.

In other words, three generations of dragonflies are involved in the cycle and each generation "knows" both to migrate and the direction in which to migrate, either north or south, even though no individual dragonflies ever made the trek before.

One generation knows to migrate north and the next generation knows to migrate south. The third generation knows not to migrate at all. How do they know this?

Researchers have discovered that the migratory behavior is triggered by temperature, but how, exactly, does temperature trigger behavior and where does the information come from that tells each generation of these beautiful insects which direction to fly? No one seems to know.

Moreover, genes code for proteins. Proteins form tissues and catalyze reactions in the cell, so what is the connection between genes and behavior? How does a protein(s) produce a particular behavior in an animal like an insect? Is there something else in the organism in addition to protein that generates, regulates and choreographs behaviors like migration or mating or myriad other activities that animals engage in?

One more question. Why would such a behavior evolve in the first place? Lots of insects, including other dragonfly species, do perfectly well without migrating. What combination of genetic mutations and environmental selection pressures acted in the history of this particular species to produce this particular behavior if it didn't really have pronounced survival value?

Maybe someone knows the answers to these questions, but I don't. They are among nature's most profound mysteries.

Indeed, it seems that the more we learn about living things the deeper the mysteries surrounding them grow and the harder it is, for me, at least, to accept the conventional narrative that what we're observing is merely the result of a long series of fortuitous accidents and coincidences.