BBC NEWS | Science/Nature | Wild gorillas seen to use tools

BBC NEWS | Science/Nature | Wild gorillas seen to use tools: "'We've been observing gorillas for 10 years here, and we have two cases of them using detached objects as tools,' said Thomas Breuer, from the Wildlife Conservation Society (WCS), who heads the study team in Nouabalé-Ndoki National Park in the Democratic Republic of Congo.

'In the first case, we had a female crossing a pool; and this female has crossed this pool by using a detached stick and testing the water depth, and trying to use it as a walking stick,' he told the BBC.

The second case saw another female gorilla pick up the trunk of a dead shrub and use it to lean on while dredging for food in a swamp.

She then placed the trunk down on the swampy ground and used it as a bridge."

1. Even if this is tool use, tool use has nothing to do biological change.
2. If it was tool use, why would there only be two observations in 10 years?