You may have read about (or met) people with savant syndrome. Formerly called “idiot savants,” people with savant syndrome have significant learning disabilities but also display exceptional intelligence at times, often to the shock of those who underestimate them. Opossums are the natural world’s own example of savant syndrome!
If you were to look at the brain of a Virginia opossum and didn’t know better, you would assume they were among the least intelligent animals on Earth. Their brains are only one-sixth the size of a raccoon’s and one-fifth the size of a cat’s, giving them one of the lowest brain-to-body ratios of any mammal. An opossum’s brain is also very smooth, lacking the network of folds and grooves seen in most intelligent species.
Interestingly, an opossum’s brain completely lacks the structure known as the corpus callosum, which connects the two halves of the brain and is largest in intelligent animals. In humans, a missing corpus callosum is considered a serious birth defect and is associated with a high rate of learning disabilities (and many noteworthy cases of savant syndrome!).
Because of its unique and primitive brain structure, the opossum does have traits that make it seem unintelligent. They tend to move more slowly than the quick scurriers that dominate the forest, and they don’t always react instantly to changes in their surroundings. Opossums are non-aggressive and not as curious or adventurous as raccoons or coyotes. They also don’t live in social groups or work cooperatively, and mother opossums are notorious for forgetting how many babies they have (something almost no other mammals do).
Despite all this, opossums actually excel in intelligence tests. In one study, scientists tested opossums’ ability to remember where food had been hidden, and they scored even higher than cats, rats, dogs, and rabbits. In another study, opossums demonstrated that they can solve maze puzzles faster than cats and rats. Scientists have also documented the opossum’s ability to recall specific smells a full year after being exposed to them.
Nature is full of surprises, and humans are only just beginning to learn the mysteries of the mind. Perhaps one of the opossum’s gifts to humanity is in showing us that we still have much to learn, and need to respect the sentience and intelligence of every living creature.