Higher intelligence is linked with higher rates of mental illness such as schizophrenia and bipolar disorder, causing the “mad scientist” stereotype to have ground in reality.
Scientists studied a parrot for 30 years and found he had the intelligence of a five-year-old human. He had a vocabulary of 150 words and could ask for a banana. If he was offered a nut instead, he would stare in silence, ask for the banana again, or take the nut and throw it at the researcher.
Cows enjoy solving problems and have been known to jump into the air excitedly when they finally crack a tough one.
Dogs will sometimes fake being sick to get attention.
A species of Indonesian parrot called Goffin’s cockatoo can solve complex mechanical puzzles.