In the forests of West Africa, scientists have been observing rock piles next to trees, but have never been too keen on them. But after noticing that the piles of rock appeared in a more symmetric nature. They noted that it was worth looking into.
They placed cameras next to the trees that these occurrences often happened and observed that it was actually the chimpanzees doing it. However, they could not link the activity to any feeding habits nor social behavior.
They noted that the chimps could pick up the stones and thrown them to the tree while uttering some sounds. The occurrences happened too many times just for it to be a coincidence. "This study reports a new chimpanzee behavior, not known previously and highlights the potential of the PanAf project to uncover unknown facets of the life of chimpanzees, our closest living relative," said Christophe Boesch, a lead researcher in the field."The stone accumulation behavior does not seem to be linked to either the abundance of rocks or the availability of suitable trees in an area; it is likely that it has some cultural elements."
It was observed that it was mostly the males who did this, but the females and juveniles sometimes did this as well. However, it is not all the chimps that carried out the activity proving they must have some appointed ritualistic chimp to represent the rest of the clan.