Advanced communication? Spider monkeys adjust their "whinnies" to regain contact with their group

(Natural News) At least one species of monkey seems to understand that low-frequency sounds travel much further than high-pitched ones. Whenever a Geoffroy’s spider monkey (Ateles geoffroyi) gets separated from its group, the animal deliberately reduces the pitch of its calls. By lowering the frequency of its voice, the isolated monkey makes itself heard over...

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