Summary: [EDIT: No longer confident in this post, see edit note at bottom. May formally partially-retract it later.] Yesterday’s post reviewed research showing that animals’ intelligence seemed correlated with their number of cortical neurons. If this is true, we could use it to create an absolute scale that puts animals and humans on the same ladder. Here are the numbers from this list. I can’t find chickens, so I’ve used red junglefowl, the wild ancestor of chickens. I can’t find cows, so I’ve
