The transformation of a caterpillar into a butterfly is so intense and radical that it’s really hard to believe we’re talking about the same individual. In fact, were you to be ignorant of the fact that a butterfly needs to live as a caterpillar first, I bet you’d say we’re looking at two different species.
Bearing in mind this unique transformation from a tree clinging, 12-legged pest into a majestic flying butterfly involves the reorganization of the brain and nervous system, can the butterfly remember its life as a caterpillar?
In 2008, Georgetown University researchers tested this hypothesis. They gathered a bunch of tobacco hornworm caterpillars and give them mild electric shocks while exposing the caterpillars to various odors.
Eventually, the hornworms caterpillars or larvae molted into a shiny chrysalis and emerged as moths. When exposed to the traumatic smells that caused pain in their lives as caterpillars, the moths chose to avoid the source. This seems to suggest that they indeed remember their past ugly duckling lives.
A long-standing view of lepidopteran metamorphosis is that once the transformation happens, the caterpillar is no more, and out emerges a completely new and reformed individual.
But the findings challenge this assumption. Instead, the Georgetown University researchers think the caterpillar’s memories are stored in mushroom bodies — the areas of the brain which are directly connected to the antennae.
Biologists know for sure that those mushroom body neurons that are accumulated during early larval development are lost during metamorphosis. Knowing this, it’s only a matter of conditioning the caterpillars at various stages or ages in their larval development.
Indeed, those caterpillars that were conditioned to fear the various odors when they were very young did not remember the smell once they morphed. Oppositely, those caterpillars that were conditioned later in their lives as larvae could remember the smell, as reported in the journal PLOS ONE.
So, there you have it! Butterflies do remember their past lives, because it’s essentially the same life, despite the radical transformation. If anything, these findings make the poetic butterfly metamorphosis even more beautiful.
Dragos has been working in geology for six years, and loving every minute of it. Now, his more recent focus is on paleoclimate and climatic evolution, though in his spare time, he also dedicates a lot of time to chaos theory and complex systems.