Recent research shows some species make tools, or exhibit planning and logic.
Many animals exhibit smart behaviors. But do any of them show what humans would call "intelligence?" Some recently reported lines of research cautiously suggest that the answer is "yes."
Chimpanzees have surprised a research team by making wooden spears for hunting. It's the first known example of weaponmaking by a nonhuman.
Western scrub jays have shown future planning – rather than instinctive actions – in their food-caching behavior. Ravens have demonstrated logical thinking in solving a food-retrieval puzzle.
Such revelations are beginning to enable scientists to make the crucial distinction between genetically hard-wired behavior or trial-and-error learning and "intelligent" thinking.
Jill Pruetz of Iowa State University in Ames and Paco Bertolani at England's University of Cambridge reported the chimpanzee's surprising behavior earlier this month in the journal Current Biology. They observed it in southeastern Senegal.
Chimps have often been seen to use sticks to retrieve insects such as termites for food. This time, a chimp carefully sharpened a stick to make a spear. It then thrust the spear into a hole in a tree to skewer a bush baby – a small primate that chimps regularly eat. The researchers saw 22 instances of such spear hunting. Scientists know that chimps make tools, including stone tools. Now they are seen to be making weapons. The more closely chimps are studied, the more humanlike traits they display.
So, too, do some birds.
Reporting their work in Nature last month, Nicola Clayton and colleagues, also at Cambridge University, showed how western scrub jays plan for the future.