| CHIMPANZEES BOSSOU AND NIMBA

Mother

Acquiring a taste for nuts

Mother

Observing closely

Showing an interest in stones

Stealing her sibling

Experiencing every step  in Learning-nut-cracking process

Selecting one

Trying to crack the mother

The challenge of combining the stones and the nuts

Education by master-apprenticeship

Putting several nuts on the anvil stone

Never give up

First success

Accidentally hitting her foot

The adults who cannot use stone tools

Young chimpanzees who cannot use stone tools