9781422276334

group, the raccoons and coatis, and a third comprising the canine species—wolves, foxes, coyotes, dogs. All three modern groups—bears, raccoons, and canines—are exceptionally intelligent by comparison with most other mammals, yet the ancestral miacids had small brains relative to their body size and could not have been blessed with comparable intelligence. A possible explanation of this paradox is the theory that primeval prey was easy to capture, but during the ensuing millions of years some of the prey species became more wary and elusive. As the prey became smarter, natural selection favored more effi- cient predators, and the bears, raccoons, and canines survived by evolving larger, better-developed brains. Some paleontologists hold that the oldest known creature that legitimately could be called a bear was Ursavus elemensis, a dog- sized predator inhabiting subtropical

The polar bear’s diet of ringed seals (the Arctic’s most abundant large mammal), bearded seals, and an occasional disabled walrus ends wherever a summer thaw drives bears ashore. Here, a mother bear, two cubs, and a subadult search for eggs, nestlings, rodents, and berries. Good fortune may also bring them a caribou calf. These cubs are just over a year old. When playing in trees, one will often clamber onto a higher branch and swat at the sibling below, but rarely if ever is a cub dislodged.

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