Every friend of dogs, cats, or birds knows what some researchers struggle to prove. Let’s take a look at what they found:
Recently, a research team announced that marmosets — small highly social New World monkeys — display personality traits, whether they are wild or captive… While a marmoset’s personality typically did not change, those who became dominant in family hierarchies grew bolder over time.
But, we might ask, why should anyone have been surprised? Why shouldn’t animals have personalities? They have individual bodies and individual experiences. They certainly don’t need human-like intelligence to have a personality. A working memory is probably good enough.
Another recent study allowed us to know that dogs are aware of their own bodies…Denyse O’Leary, “Why do researchers wonder whether animals have personalities?” at Mind Matters News
We end up looking at personality among reptiles, with some surprising results.
Mammals, birds, and reptiles differ by ability but those that have been studied seem to have individual personalities within the frame of their intelligence. What they don’t have or make little use of is abstract reasoning.
See also: The real reason why only human beings speak. Language is a tool for abstract thinking—a necessary tool for abstraction—and humans are the only animals who think abstractly. (Michael Egnor)