Summation by Asian Elephants (Elephas maximus).
Recent empirical evidence for complex cognition in elephants suggests that greater attention to comparative studies between non-human primates and other animals is warranted. We have previously shown that elephants possess the ability to judge the difference between two discrete quantities, and unlike other animals, their choice does not appear to be affected by distance or overall quantity. In this study, we investigated Asian elephants' ability to perform summation, as exemplified by the ability to combine four quantities into two sums and subsequently compare them. We presented two discrete sums (3-7) to the elephants by baiting two buckets; they were loaded sequentially with two discrete quantities (1-5 pieces) of food per bucket. All three elephants selected the larger grand sum significantly more often than the smaller grand sum. Moreover, their performance was not affected by either distance to the bait or the overall quantity evaluated. Studies report that the performance of other animal species on similar tasks declines as distance to the bait decreases and as the overall quantities evaluated increase. These results suggest that the numerical cognition of Asian elephants may be different from that of other animals, but further study is required to elucidate the differences precisely.
Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, 1560-3 Kamiyamaguchi, Hayama, Miura 240-0193, Japan.
Naoko
N
Irie
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan.
Toshikazu
T
Hasegawa
elephants; numerical cognition; relative quantity judgment; summation