The finding is based on a language development test, revealing average dogs can learn 165 words (similar to a 2-year-old child), including signals and gestures, and dogs in the top 20 percent in intelligence, can learn 250 words.
So which dogs are the smartest? According to data collected from more than 200 dogs, Border collies, poodles, and German shepherds, Golden retrievers, and Dobermans, in that order. Compared with other dogs, these breeds may be smarter, in part, because we've bred them to be so.
In saliva, scientists have found hints that a “ghost” species of archaic human may have contributed genetic material to ancestors of people living in Sub-Saharan Africa today. The research adds to a growing body of evidence suggesting that interracial cross-species interbreeding between different archaic human species may not have been unusual.