The headline is not a metaphor or an Aesop fable, it is that I am going to talk about the cuckoo and the stick insect, literally. Let’s start with the last one. The stick insect, or phasmid, is a full-fledged insect, with its antennae, its legs, its abdomen and everything that needs to be in place, but the shapes it is capable of adopting to blend in with its surroundings are one of the great wonders of zoology. That is why it is not only called a stick insect, but also a leaf insect, sandpipers, devil’s needle and other worse things that reflect its amazing versatility of aspects. Of course, it is not the same individual who knows how to do all these tricks, nor even the same species: phasmids are an entire order that brings together many species. And that’s exactly what makes them so mysterious, because the one who has to be creative here is not the bug, but evolution, and we don’t know how the hell evolution does that.
We just learned something very curious. As untrue as it may seem, there are entomologists armed with patience who have spent since 1990 observing the “walking spikes” (a type of stick insect) in the fields of California and have concluded that its evolution is repeated in cycles. These walking spikes come in various shapes and colors, and the frequency of each of them rises and falls and rises again over time in a predictable manner.
For example, the stick insect Timema cristinae It has three “morphs,” or varieties of camouflage. The smooth green morph blends in with the leaves of lilacs, the white-striped one hides in evergreen bushes and the dark one prefers to make itself invisible in the forests. The 32,000 insects from 10 separate populations that have been censused with admirable tenacity show that the plain green and the white-striped morph alternate in complementary annual fluctuations. One year there are more greens and less stripes, the next year the other way around and start again. The dark forest morph is clumsier and never changes, but the other two show highly predictable cycles, and this in 10 populations that have nothing to do with each other.
Let’s imagine that climate change causes the California lilacs to disappear, leaving only the bushes behind. You don’t need much imagination either. The stick insect Timema cristinae It will not take 10 million years to adapt to that change: it will take exactly one year. As in the classic Darwinian story of the London moths, the birds will gobble up the green morphs that previously hid in the leaves of the lilacs and only the white-striped ones will remain, going unnoticed among the bushes. The following year, the ones that will begin to have a hard time will be the birds, and then directly the forests. But the first to adapt to the world of the dystopian future will be the stick insects, because evolving quickly is in their nature. And because the world will never be dystopian enough for them. They are not lilacs. Are Mad Max.
The cuckoo is another master of creative evolution. As is well known, the parasitic species of this bird lay their eggs in the nest of any unwary and, as soon as they hatch, they kick out the legitimate chicks in one of Mother Nature’s most edifying examples of impersonation. Ornithologists have now found that the most virulent species of cuckoos diversify into new species much more quickly than their milder cousins. The reason is that the victims learn to distinguish the fake chickens, which forces them to change their shape to mislead them again. Evolving quickly is not that unusual. Sometimes it is due to an arms race between predator and prey. Sometimes being forced to disguise yourself is enough to survive.
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