So one of our readers asked us this question the other day: Given enough time could a crab, snail or anything really eventually evolve to become as intelligent as us?
As long as increased intelligence was competitively advantageous from a fitness perspective, the rest of evolution is up to random mutation.
In a hypothetically infinite time scale, mutations that increase crustacean intelligence certainly could accumulate.
However, it’s also important to keep in mind that “intelligence” is not some sort of evolutionarily apex quality. Most living things are quite well adapted to their environments already and face a cross-section of different selective pressures than early hominids. Optimizing energy balance, disease resistance, evasion of or defense against predators, ability to attract mates and beget fit progeny, exploiting new ecological niches, etc are all extremely powerful forces that may improve with increased intelligence, but are largely unrelated.
In addition, any intelligence needs to be utilizable in order to be a benefit. If we consider “tool use” as a marker of intelligence, that would be incredibly challenging for a creature with the body pattern of a snail. Higher order brains are energetically very expensive, and they need to be worth it.
One example I like to use is dinosaurs. They lived for over 100 million years on Earth with no intelligence. Humans have lived roughly 2 million. Dinosaurs may have had multiple ‘intelligent’ species, but over 100 million years none evolved to a massive technological society. The reason humans did is a happy accident; not the endpoint. There is a huge misconception that evolution is a linear thing with intelligence as an endpoint.
So the answer is yes. Anything could evolve into anything given enough time and the right environmental factors. A turtle could transform, over millions of years, into a bass guitar that plays itself, if for some reason that was a survival advantage. It also has to be within the realm of random mutations, and the random mutations can’t require a step where an offspring wouldn’t be viable.