I know, I know, you’re boring me to tears with your pedantic explanations that it’s pedantic to insist on “who” for people and “that” for animals, and yes, you have a cat WHO can read the Bible in the original, and Shakespeare exclusively used “that” to refer to his characters, blablablayaddayaddayadda, but it seems to me that somewhere on the biological scale, even the softest-hearted anthropomorphicist will agree that you don’t speak of a “tulip who is growing in my garden” or “an amoeba who was viewed under a microscope.”
Me, of course, I continue to apply “who” to people and “that” to even the most humanlike creature, but that’s just me. I consider “who” for animals to be a marker either of a lazy mind incapable of the broadest grammatical distinctions or of an overly sentimental approach to animals, but, hey, that’s just me. Those who are less strict than I (or should that be “Those that are less strict than me”?) draw the line in different places. Where’s your line?
Humans and pets get the “who” treatment. Babies, on the other hand, are always its. Not only because they are sources of endless noise and odors, but sometimes you cannot identify the gender of the object in the stroller and this usage avoids awkward moments.
I have five dogs. From time to time, one of them commits a sin, and I hear about it. I ask someone else (a person) in the household ‘who’ chewed such and such up, or ‘who’ is barking and won’t shutup. Conversely, I may refer to a person as ‘it’ or ‘that’ out of contempt. Children frequently earn a ‘that’ or ‘it,’ because I don’t like children. Sheep, who have an identifiable and known personality, earn the ‘who.’ Chickens, that I can’t tell one from another, are ‘that.’ If the animal has personality, it’'s who. If they’re something along the lines of chickens or lesser, with no predictable personality and are pretty solely instinct-driven in behavior, it’s ‘that.’
I say “who” for humans, and also for animals in “talking animal” stories and sentient mythical creatures. (I’m a children’s author, so this comes up a lot for me.)
I will consider saying “whooo” for owls, and maybe ghosts.
I voted people only, but came into the thread to be pedantic. I don’t believe there’s such a thing as a "highly-evolved’ mammal, as that implies that other mammals are less highly evolved. Humans are smarter than pigs, which are smarter than dogs, which are smarter than cats, which are smarter than rats, which are smarter than lemmings, but none of them is more or less highly evolved than the other–just evolved in different ways from our common ancestor.
Most normal human beings make a differentiation between animals and inanimate objects from the time they are toddlers. There are plenty of psychological studies showing this.
Meanwhile, most people haven’t been taught anything about formal grammar. It never occurred to me that using who for animals might even be wrong.
I had no idea until just now that there was a distinction.
Yes, even for plants, if I’m feeling affectionate, I’ll use personal pronouns like “she” and “his” (“Did you see the maple tree this morning? She’s really gorgeous this year.” “Careful near the raspberry bush; he bites!”)
I don’t think I’d use “who” in those sentences just because it feels awkward and isn’t necessary. But I wouldn’t use “that,” either. “A tulip growing in my garden” or “an amoeba viewed under a microscope” work just fine.
I use “who” for a dog I know personally. “Rex is a dog who really loves his kibble!” “That” is for a dog I don’t know. “The black dog that bit the neighbor girl seems to be a Terrier mix.”
If it has a name, it is a “who.” Except for nameless abominations. They can be a “who” if they show purposeful behaviour, but are a “that” if they’re just shambling horrors.