There’s not one way to define intelligence. I like to define intelligence as the mental ability to adapt; to take whatever situation you’re in, and turn it around to your advantage. Others like to define intelligence as the mental ability to problem solve. Still others like to define intelligence as the ability to reason abstractly. Ultimately all these definitions are the same. If you can reason at the most abstract (least specific) level, you can adapt to the widest range of problems, and thus solve them.
Another definition of intelligence is the ability to use tools. One could be really precise and say intelligence is the mental ability to use whatever physical abilities you have, as a tool to use whatever environment you’re in to your advantage. The two main physical tools humans are born with are our hands and our vocal cords. And we use these tools to manipulate the physical environment to our advantage.
So we use our hands to use objects as tools (grabbing a sharp rock for hunting) and we use our vocal cords to use other people as tools (communication).
This is why it makes sense that IQ tests like the Wechsler have traditionally been divided into two main sections: Verbal IQ (using your vocal cords as a tool to your advantage), and Performance IQ (using your hands as a tool to your advantage). So Verbal IQ measures abilities such as vocabulary, and Performance IQ measures largely spatial abilities such as making designs using multi-coloured blocks.
However if the human mind were placed in the body of a snake, our Verbal IQ would be virtually useless because we’d have no vocal cords with which to speak, and our Performance IQ would be virtually useless too because we’d have no hands to manipulate the physical environment. So no wonder snakes have such tiny brains. Evolution is not going to select for metabolically expensive and physically burdensome brain mass when the animal can’t use it.
But when we sum up a person’s Verbal and Performance IQ, have we really captured all of intelligence? Perhaps there is life on other planets, far more intelligent than us, but that doesn’t use either of these systems to adapt to its environment. Perhaps they can’t hear or see, so both verbal IQ and Performance IQ are useless to them, but they have other senses that we can’t even imagine. And if our minds were put in their bodies, we would experience these senses, and we would have a different body to make use of them, but our mindss (which evolved to speak and use our hands) would not be able to use them to our advantage. We wouldn’t be able to adapt.
The most intelligent organism in the universe is the one whose mind, when placed in the body of as many different organisms as possible, organisms with many different goals as possible, in as many different environments as possible, can adapt these situations to its advantage as effectively as possible.