It is difficult to quantify what the dumbest animal in the world is, simply because there is no universal barometer by which to measure intelligence. However, some animals widely agreed to be dumb include the panda, cane toad, turkey and kakapo.
These four animals are largely considered dumb because of behaviors that could easily lead to their species' extinction. For example, pandas have the physical makeup of a carnivore and eat meat if necessary. However, in the wild they eat exclusively bamboo, which has almost no nutritional value. This makes them extremely lazy, unable to mate regularly and often unable to support newborn cubs.