Hammer of the Chimps?
Julio Mercader, an archaeologist at the University of Calgary, has unearthed stone hammers that he says chimps used 4,300 years ago to crack nuts.
If the findings hold up, it's another example in widening body of work that shows that other primates developed tools.
The hammers were discovered in the Tai rainforest in modern-day Ivory Coast. The tools, according to Mercader, show distinctive signs of wear and are thus not likely the product of natural forces.
The tools, however, wouldn't be the kind humans would make. The cantaloupe-size stones are too large to be wielded by a human hand. Farmers didn't live in the region at the time, so it is unlikely the chips picked it up through watching villagers.
In addition, the stones contain starch residue from several types of nuts known to be staples in the chimp diet. These nuts were not part of the human diet.
"Some of the nuts require a compression force of more than a thousand kilograms to crack. And the idea is to crack the shell but not smash it--it's not a simple technique," said Mercader in a prepared statement.
Modern chimps teach each other nut cracking techniques, but it generally takes an animal seven years to learn the appropriate techniques.
Many may shrug and say: So what? The media in shows such as Lance Link Secret Chimp has shown how chimps can drive miniature Rolls Royces and wear neckties. Many of these scenes, however, are likely staged.
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Archaeologist Julio Mercader at the University of Calgary has discovered hammer-like tools dating back 4300 years.  The tools are thought to have been used by non-human primates to crack nuts.

The large size of the stones are of too great a weight to have been favoured as tools by humans.  Further, humans are not believed to have been in that area at that time for the primates to have learned from them by observation.

Mercader suggests that this implies the primates learned to use the tools either independently of humans or else by a common ancestor (of common descent). 

Further evidence supporting the hypothesis that the hammers were not used by humans includes that the nut residue on the tools are of nuts which were not regularly a part of a human diet.

Mercader elaborates in a prepared statement: “Some of the nuts require a compression force of more than a thousand kilograms to crack. And the idea is to crack the shell but not smash it — it’s not a simple technique.”  Editorial correction: force is a vector while mass is a scalar. By context, the force is approximately 10KN (10 KiloNewtons).

Social and Political implications follow from the findings also.  Anthropologist Agustín Fuentes (at Indiana’s University of Notre Dame) said, “It puts the nail in the coffin on those who say chimp tool use is atypical.”

This parallel of human evolution may also lead to further debate on the legal rights of primates.