02 Febrero 2017 07:57
It's very unusual for this to happen.
It's hard to watch: the victim suffered horrific injuries and lay on the ground bleeding for hours in the Senegalese savanna. The alpha male, called Foudouko, had been stomped on and beaten with rocks and sticks, before being partially eaten by members of his own troupe.
This is one of only nine known cases in which a gang of chimpanzees have killed a member of their own community.
Usually, chimps live in groups with more females than males, but in this case, the situation was the opposite.
'When you reverse that and have almost two males per every female – that really intensifies the competition for reproduction,' says Michael Wilson from the University of Minnesota. 'That seems to be a key factor here.'
Jill Pruetz, a scientist from Iowa State University, who has been studying Senegalese chimpanzees since 2001, agrees. She also adds that human influence may have skewed the sex ratio, since, in Senegal, female chimps are poached to sell their infants for the pet trade.
Thirteen years ago, Foudouko reigned over the community at the Fongoli Savanna Chimpanzee Project. As alpha male, he was 'somewhat of a tyrant', Pruetz says.
Foudouko achieved his status while he was still an adolescent, and ruled with the help of his 'right-hand man' – a beta male named Mamadou. In 2007, Mamadou was seriously injured and had to live away from his clan for a few weeks. When he returned, he was forced to settle for a lower position in the social hierarchy.
Without the support of Mamadou, Fouodouko was deposed by rivals and was himself forced to live apart from the group. Then, in 2013, Mamadou recovered his beta male position after his brother, David, became alpha.
They accepted Foudouko back into the clan, though some of the other males were not too happy.
'It turned out that there were five young males, all jostling for power, who did not want to let Foudouko back in,' says Pruetz. 'He was trying to come back in at a high rank, which was ultimately a foolish thing to do on his part.'
One morning, Pruetz and her team heard loud screams from the chimps. When they approached the area later, they found Foudouko dead and his body mutilated, with damage to his internal organs and a bleeding anus.
The aggressors continued to attack his corpse, hurling rocks and beating it with sticks. A few of them, in particular the mother of the top two high-ranking young males, cannibalised his body. Pruetz says that since Foudouko's grisly murder, Mamadou has been banished from the group by the same gang of young males.
[Via New Scientist]