For a long time it was believed that only people can evaluate their past. However, this theory was refuted ... by orangutans.
In the course of observations, scientists at the University of Zurich found that female orangutans wait about 7 minutes after the predator disappears from view to signal an alarm to their relatives. Moreover, this signal is very specific, it is somewhat reminiscent of the sound of a human kiss.
The experiments were carried out in the Ketamba forests of the Indonesian island of Sumatra. To imitate predators, the scientists had to put on a "camouflage" with the color of a tiger, in which they were in the field of view of seven female orangutans for several minutes.
However, only one female reacted with a characteristic sound to the "provocation" while the predator was in the field of view. The reaction of the others followed in the time range from 7 to 20 minutes. According to scientists, the reason for this behavior may be fear for the life of their young, inherited by female orangutans from distant ancestors.
The impressive intelligence shown by the orangutans may help us better understand the evolution of our own language abilities.
Scientist imitates a tiger