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    This video refers to our study published in the Proceedings of the National Academy of Sciences U.S.A. on March 7, 2011. Here, we show that elephants can cooperate, and learn about the need for a partner in a collaborative task. The elephants learned not only that a partner was needed, but that the partner's actions (pulling a rope) mattered for success. Plotnik et al. 2011. Elephants know when they need a helping trunk in a cooperative task. PNAS Please contact Josh Plotnik at Joshua.Plotnik@gmail.com for further details.