A joke has been spreading across the internet recently, and it suggests that humanity’s ultimate destiny isn’t to become cyborgs or upload our consciousness to the cloud. Instead, according to viral memes, we’re all eventually going to turn into crabs. The strange part is that there’s actually some real science behind this humorous idea.

At a small natural history museum on the English coast, staff members report that visitors now arrive daily with the same question. They want to know if humans really will develop claws and start moving sideways. The museum’s director admits he’s found it difficult to give people a satisfying answer. However, evolutionary biologists believe they can explain why the internet chose crabs as evolution’s ultimate form.

The answer lies in something called carcinisation, which is the scientific term for becoming more crab-like. Remarkably, nature has invented the crab body plan at least five separate times over millions of years. Different groups of crustaceans, while facing similar challenges in their environments, independently evolved the same solution: a rounded shell and that distinctive sideways walk.

To understand why this keeps happening, you need to know that crabs belong to a larger family called decapods, which means ten-footed creatures. This group includes lobsters and shrimp, which have long, cylindrical bodies with muscular tails. Those tails allow them to snap backwards at high speed and dig into the seafloor.

True crabs, however, live in a different world. They inhabit shallow coastal waters and rocky shorelines, where a different body plan works better. Crabs have compressed abdomens that are tucked underneath a flattened, rounded shell. This design presents fewer vulnerable spots for predators to grab, and it allows their legs to move sideways so they can escape quickly into narrow crevices.

This is where it gets interesting. At least four other groups of creatures have gradually transformed themselves to look like crabs. Sponge crabs did it. Porcelain crabs did it. King crabs did it. Even something called the Australian hairy stone crab did it. Scientists call these creatures imposter crabs because they evolved their crab-like appearance independently by tucking their tails underneath their bodies over millions of years.

This means that crabs aren’t actually a single biological group. Instead, they’re a collection of different creatures that evolution shaped to look the same. Researchers explain that these imposter crabs sacrifice their muscular abdomen in exchange for better armor and mobility.

This process is an example of convergent evolution, which happens when groups that aren’t closely related come to look similar, although they don’t share a common ancestor that also had those features. Evolution keeps discovering the same answer in different lineages and different places.

Think about birds and bats as an example. Both developed wings because they face similar environmental challenges, despite being completely different species on separate branches of the evolutionary tree. The same principle applies to crabs. They converge on this body plan because it’s an efficient solution to a specific set of physical problems.

A compact, broad, armored body with a tucked abdomen helps with multiple challenges. It provides better defense against predators. It works well for living in crevices. It handles wave-swept environments more effectively. It enables sideways agility. Furthermore, it offers broad protection from above.

Experts say it’s been amusing to watch the internet debate develop. Nevertheless, they want to be clear: the answer is still no. Humans will not evolve into crabs. The convergent evolution of crabs has happened about five times in Earth’s history, but it’s only happened within the group of decapods. We’re vertebrates on an entirely different branch of the evolutionary tree.

Still, there’s something deeply appealing about the idea. Perhaps it’s because the crab represents a kind of evolutionary perfection within its niche. Nature examined the problem of surviving in shallow coastal waters and kept arriving at the same solution. Five separate times, different creatures discovered that becoming more crab-like was the answer.

Therefore, while you won’t be growing claws anytime soon, the next time you see a crab moving sideways on a beach, you’re looking at one of evolution’s most successful designs. It’s a body plan so effective that nature can’t stop reinventing it.