for National Geographic News
Crows make tools, play tricks on each other, and caw among kin in a dialect all their own.
These are just some of the signs presented in a recent book that point to an unexpected similarity between the wise birds and humans.
"It's the same kind of consonance we find between bats that can fly and birds that can fly and insects that can fly," said Candace Savage, a nature writer based in Saskatoon, Canada.
"Species don't have to be related for there to have been some purpose, some reason, some evolutionary advantage for acquiring shared characteristics," she added.
Savage's book, Crows: Encounters with the Wise Guys of the Avian World (October 2005), explores the burgeoning field of crow research, which suggests that the birds share with humans several hallmarks of higher intelligence, including tool use and sophisticated social behavior.
The shared traits exist despite the fact that crows and humans sit on distinct branches of the genetic tree.
Humans are mammals. Crows are birds, which Savage calls feathered lizards, referring to the theory that birds evolved from dinosaurs.
"I'm not positing there's anything mythological about this or imagining crows are in any way human," she said.
"But whatever it is that has encouraged humans to develop higher intelligence also seems to have been at work on crows."
Alex Kacelnik is a zoologist at Oxford University in England who studies tool use in crows. He said study of the birds advances understanding of how higher intelligence evolves.
As a sign of crows' advanced smarts, Savage cites Kacelnik's 2002 study in the journal Science on a captive New Caledonian crow that bent a straight piece of wire into a hook to fetch a bucket of food in a tube.
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