Orangutans have a rather unusual warning signal: it is similar to the sound of a kiss. Scientists believe that using this signal, orangutans inform their relatives about the danger, but it is assumed that the signal can be used to notify the predator that it has been discovered. In the new work, the researchers decided to see if orangutans are really able to transmit information about something that is not represented in the present, or about past or future events.
Experiments experts conducted in the depths of the forest on the Indonesian island of Sumatra. They dressed in special “costumes”, painted like the color of a predator, in particular in tiger stripes; female orangutans with calves at the same time (within two minutes) were to be on a tree nearby.
It is noted that in half of these “meetings” the animals gave a warning signal. And in most cases the signal was “postponed” – on average for seven minutes, and in one case – even for 20 minutes. “She stopped doing the same thing, took her cub, defecated (a sign of stressful experience) and slowly climbed up the tree,” says Adriano Reis e Lameira, one of the authors of the work, describing the latter case. “At the same time, she behaved very quietly.” And only twenty minutes later, as the researcher notes, she finally gave a warning signal – and it lasted more than an hour.
Although the fact that orangutans give a signal only after a while can be explained, for example, by the fact that they are very scared, the researchers are not inclined to this version. Experts believe that females are waiting, probably, in order to protect their young, which indicates developed cognitive abilities.
The results of a new study suggest that orangutans, like people, are capable of “talking” about the past. However, further research is required to verify this conclusion.
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