Do butterflies regain any of the memories or anything else from when they were a caterpillar?

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Could be extended to any other form of life that goes through similar changes.

In: Biology

We think so, at least in one species tested they delivered electric shocks to caterpillars near a specific smell. Once butterflies they avoided the same smells.

Surprisingly, yes!

This is surprising because when caterpillars change in the cocoon they release an enzyme that more or less turns their entire bodies into protein goop. It’s less [Animorphs](https://www.theparisreview.org/blog/wp-content/uploads/2019/01/animorphs.jpg) and more [The Thing](https://static.wixstatic.com/media/eeff86_8c8b556b999643b492726075954dc79e~mv2.gif). Only a few cells survive this self-digestion intact, and they’re *not* brain cells.

As /u/Monkey_with_a_knife mentioned, scientists have done tests where they give caterpillars a very mild electric shock that is associated with a particular stimulus, like a smell. It’s just enough to cause pain without seriously inuring them. Later, if you present that same stimulus – that same smell – the caterpillars recoil, expecting to get shocked, and they avoid that stimulus.

The butterflies (and moths) that grow from those caterpillars recoil from the same stimuli, while the control group that was never shocked do not. This suggests that the butterflies somehow remember that the stimulus is associated with pain!

How they manage to do this is a mystery because, again, almost their entire bodies are digested in the cocoon down to loose proteins and carbs. Their brains don’t survive the process – the butterflies leave the cocoon with brain new brains rebuilt from the DNA in the few non-brain cells left intact as the rest of the body dissolves. That itself is a bit of a mystery, too – the ability to not just regenerate, but completely rebuild their entire bodies! That’s not *too* perplexing, though, because if you can build a body with a single cell and some energy in the egg the first time then there’s no good reason you can’t do it again. That’s basically what cloning is, and we can do that with a lot of animals (albeit with special equipment and a whole lot of science).

But a clone doesn’t retain the memories of the donor animal because memories, as far as we know, are encoded in the connections between nerve cells of the brain. If you destroy those connections (by destroying the cells) then you lose those memories and there’s no way to get them back. Even if you build a new brain using the same DNA, the connections are made through experiences that cannot be replicated. In any case, that’s how humans work. So how do caterpillar-turned-butterflies manage to do it? Nobody knows!

>Could be extended to any other form of life that goes through similar changes.

Generalizing this concept is probably not possible, although a lot of insects do go through radical transformations between larval stages and adult stages. I’m not a biologist and I’m not aware of any research into similar changes, and I don’t know enough about how other species transform to comment on them. I know many insects, like cicadas, don’t go through the same extreme transformations that caterpillars do: they don’t completely dissolve their bodies, they just make some major changes to the bodies they start with. Their brains are left alone, more or less, so keeping their memories isn’t that big of a deal.