（続）石器作りとセンテンス作りは同じ

Scientific Americanの4月号が昨年ブログで取り上げた内容を特集していましたね。特集記事を書いたDietrich Stoutが動画の人物です。

COGNITION
Tales of a Stone Age Neuroscientist
By honing ax-making skills while scanning their own brains, researchers are studying how cognition evolved
By Dietrich Stout on April 1, 2016

こちらは定期購読者しか読めない内容なので以下の昨年のインタビューを紹介します。内容的にはブログの過去記事や上記の動画やこのインタビューをより詳しく説明したものなので、大枠はインタビューの中で十分です。

Learning to Make a Stone Age Axe Gives Clues to How the Brain Evolved
For many decades, scientists have tried to understand the past by doing as our forebears did. One important endeavor in what is called experimental archaeology involves moderns crafting Stone Age tools by chipping away at rocks.
STAFFBy Gary Stix on April 17, 2015

3. What did you find? Did it in some way provide hints of the evolution of higher mental functions?
We found that strategizing about how to make a tool was associated with activation of prefrontal cortex associated with the “executive” control of cognition–that is, holding information in mind while manipulating it. More specifically the pattern of activity suggested “mental time travel,” a complex cognitive ability to run mental simulations by projecting into the future or past. Think for example of planning out a home improvement project by mentally running through the steps and trying to identify problems before they happen. We found that this was necessary for the handaxe technology but not the earlier Oldowan, meaning that these artifacts can help us trace the timing and context for the emergence of this important human ability. It even suggests that the demands of learning to make stone tools may have been part of what drove the evolution of this capacity.

4. How important was toolmaking as a driver of evolution? Is it possible that it had something to do with the development of language?
Well, we don’t know for sure but our research has provided evidence suggesting it may have been quite an important driver. It’s not in this paper but my other publications have looked quite a bit at the link with language. There is increasingly strong evidence that an underlying mental ability to construct and understand complex, hierarchically structured sequences is important for both language and tool-making, so that selection on tool-making ability could have provided a “preadapted” base from which language later emerged.