Orangutans (Pongo pygmaeus) Remember Old Acquaintances

• Yuki Hanazuka ,

  * E-mail: yuki.hanazuka@gmail.com

  Affiliation Department of Psychology, Graduate School of Letters, Chuo University, 742-1 Higashi-nakano, Hachioji, Tokyo, Japan

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• Naoki Shimahara,

  Affiliation Tama Zoological Park, 7-1-1 Hodokubo, Hino, Tokyo, Japan

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• Yukie Tokuda,

  Affiliation Tama Zoological Park, 7-1-1 Hodokubo, Hino, Tokyo, Japan

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• Akira Midorikawa

  Affiliation Department of Psychology, Faculty of Letters, Chuo University, 742-1 Higashi-nakano, Hachioji, Tokyo, Japan

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