Why were stone handaxes made in the same way for a million years?

Early man made some useful hand tools
And no-one could say they were fools
But the axes they made
They failed to upgrade
‘cause no-one could teach them the rules.

In considering the evolution of human intelligence there is uncertainty about when an effective language first emerged and there is also a mystery of the early stone hand axes, which were made to the same design for about a million years. If the early hominins who made these tools were really that intelligent one might expect that someone in more than 70,000 generations would have found a way of making better stone hand axes.

Chimpanzees choose the best tool for the job

 

A chimp carrying a rock.

 

I was most interested to see the paper When to choose which tool: multidimensional and conditional selection of nut-cracking hammers in wild chimpanzees by Giulia Sirianni, Roger Mundry, and Christophe Boesch which clearly demonstrates that chimpanzees and make some quite sophisticated decisions when choosing stones to use as hammers to crack open nuts.

 

Highlights

• Tool selection by wild chimpanzees was analysed, controlling for tool availability.
• Chimpanzees select nut-cracking tools according to multiple physical properties.
• Selection for weight depends on other tools' properties and on contextual variables.
• Such a sophisticated selection implies quantitatively complex cognitive skills.
• Adjustment of selection to forthcoming transport suggests planning of future actions.

Thanks to EvoAnth for the link.

The Brains of The Great Apes

Mother Chimp showing infant how to break open nuts

The BBC Iplayer is currently showing a program on the brains of the great apes.The summary says "Chris Packham explores the evolution of the great ape's brain to reveal how different parts have been adapted over time by its anatomy, ingenuity and sociability." In practice it says little about the brain except to say that different aspects, such as the development of the hand, has meant that there has been enlargement of the relevant areas of the brain. However there are some excellent wild like photographs illustrating the advanced features of ape behaviours, and I fouind the discussion about the differences between Bono-boos and Chimpanzees particularly interesting. The section on chimpanzees "teaching" their young to crack open nuts showed, in my opinion, how inefficient the chimp teaching techniques are - as it takes 10 years for the young chimp to develop the skill by simply copying the mother.