Creatures That Really Count: Ancients and Moderns on Understanding of Number in Animals

Stephen T. Newmyer

Duquesne University

Many of Aristotle’s attempts to define the human being involve the isolation of some quality or skill that he judges to be unique to our species.  He observes, for example, that one might define “man” as “that which knows how to count” (ti~ to;n oJrivsaito to; ejpistavmenon ajriqmei`n, Topica 142b26).  Aristotle’s assertion of man’s unique understanding of number did not do unchallenged in antiquity.  Moreover, the possibility that other animal species may be capable of counting has in recent years become the subject of intense investigation by cognitive ethologists, those biologists who specialize in the study of animal intelligence.  Modern zoologists have at times reached conclusions that closely mirror those of ancient writers who assert that certain animals can indeed count and have some understanding of the concept of “number.”

Both Plutarch (De sollertia animalium 974E) and Aelian (De natura animalium VII. 1), citing Ctesias as their source, relate that cattle in Susa that are assigned to draw one hundred buckets of water daily refuse to draw even one more, suggesting to Plutarch that each beast “accurately computes and remembers the sum” (ajkribw`~ suntivqhsi kai; katamnhmoneuvei to; kefavlaion, De sollertia animalium 974E).  Particularly intriguing, because his speculations on the nature of the computational skills involved anticipate the findings of modern ethology, is Aelian’s account (De natura animalium IV. 53) of an unnamed animal that divided its food into eleven portions, only ten of which it would consume while leaving the eleventh.  This action suggested to Aelian that the animal, by some “self-taught wisdom” (aujtodivdakton sofivan), understood “the numbers one, two, and successive numbers” (thvn . . . monavda kai; th;n duavda kai; tou;~ eJxh`~ ajriqmou;~ zw/`on oi\den). Some ethologists, corroborating Aelian’s observation, have argued that certain animal species have an innate sense of what they term “cardination,” that is, the ability to understand numbers in succession, as well as the capacity to comprehend the relations “more” and less,” since at least some animals can distinguish correctly between piles containing up to four individual objects. 

Although the accounts of Plutarch and Aelian on the computational skills of animals remain, like many ancient tales of animal wonders, anecdotal and unsubstantiated, their overriding interest in such tales parallels that of at least some ethologists who, like these two Greek writers, ask whether evidence of mental capacities similar in quality, if inferior in quantity, to those of human beings entitles other animal species to entry into the sphere of human moral concern, and might consequently require humans to rethink their treatment of other living creatures.