In 2007, scientists devised a memory test and pitted chimpanzees against university students. They found that young chimpanzees consistently outperformed the humans, while older chimps performed at about the same or slightly worse levels.

Watch a video of a young chimpanzee acing the test here: https://www.youtube.com/watch?v=nTgeLEWr614.

During each trial, the chimp or human watched a touch screen where the numbers 1 through 9 flashed briefly all at once, then were replaced by white boxes. The task was to touch each white box in the order of their now-hidden numbers. Thus, the subject had to remember the location of all 9 numbers (which were present on screen for only 650, 430, or 210 milliseconds. (And obviously, the chimpanzees had to be trained to recognize the distinct shapes of the numbers 1 through 9, and in what order they go.) The results clearly demonstrated that young chimpanzees have outstanding memories, far better than those of adult humans.

Indeed, this test is evidence that young chimpanzees have photographic memories; some young humans have this trait (although it fades with age), and it is likely that our early human ancestors also had photographic memories. But researchers suggest that this skill disappeared over evolutionary time, as we acquired newer and more valuable cognitive skills (such as hierarchical representation).

Perhaps in the early years of human evolution, when threats such as predation loomed over our every step, the ability to glance at a scene and instantly remember it was more valuable than the ability to stitch together sounds and symbols to represent ideas, places, and things. With increased sociality, greater defense from predators, and better access to food sources, perhaps we stopped needing photographic memories and developed a new skill, the skill that would launch us to global prominence: language.

This study also prompts us to swallow a bit of our species-wide pride as the Rulers of Earth, Superior in All Ways of Intellect. Chimpanzees beat us at memory tasks, whales and dolphins are better than us at communicating, elephants outwit humans trying to test their intelligence, and likewise sharks would beat us at electromagnetic sensing tasks, birds would beat us at ultraviolet vision tasks, wolves would beat us at smelling tasks, and so on and so forth.

How much of the gulf between human and animal cognition can be explained by mere difference?