石器作りとセンテンス作りは同じ

（１分あたりから）
In particular, for this kind of a relatively refined tool, surely a hand ax, it was both important for you to very accurately strike the stone and understand where the stone breaks but also to formulate a plan of how you are going to achieve the shape, particularly how you are going to make the tool mason in thin and cross-sectioned.
And that was associated with activity in parts of the brain. People associate it with something called Mental Time travel that is projecting yourself into the future in order to make plans.
特に、この種の比較的洗練された道具、ここでは、手斧ですが、重要になるのが２点あり、非常に正確に石を打ち、どこで石が割れるか理解することと、どのような形を生み出すか計画を立てること、どのように道具を薄く、断面を作り上げるのかが重要です。これは脳の部位での活動と関連があります。「メンタルタイムトラベル」と呼ばれるものと結びつけるのです。自分自身を未来に投影して計画を立てるのです。

『大英博物館展―100のモノが語る世界の歴史』を見に行ってきたのですが、まず気になったモノは「オルドヴァイ渓谷の握り斧」です。石器作りと言語の獲得との関連に興味を惹かれました。以下の説明が冒頭の動画の研究のことを指しているのかは不明ですが、同じような点を指摘しています。

オルドヴァイ渓谷の握り斧
石　140万～120万年前　タンザニア　オルドヴァイ渓谷
長さ:23.8cm　幅:10cm　厚さ:5cm
道具にやどる言語の息吹
大英博物館が所蔵する人類最初期の道具のひとつ。左右対称のしずくの形で、完成形をイメージして計画的に作られたとみられる。近年、CTスキャンで人の脳を調べたところ、計画的に物を作る時に使われる脳の部位が、言語を話す時の脳の部位と重なることがわかったため、手斧の存在は、言語が発達し始めたことの手がかりになるとみられる。

BBCの番組では、It now seems very likely that if you can shape a stone you can shape a sentence.（石器を作れるならば、文章も作れる可能性が高いようです）と説明していました。

Episode Transcript - Episode 3 - Olduvai Handaxe
Olduvai handaxe (made 1.2 - 1.4 million years ago) found in Olduvai Gorge, Tanzania, East Africa

Recently, scientists have looked at what happens inside the brain when a stone tool is being made. They've used modern hospital scanners to see which bits of the brain are used when a knapper is working with stone - and surprisingly the areas of the modern brain activated when you're making a handaxe overlap considerably with those you use when you speak. It now seems very likely that if you can shape a stone you can shape a sentence.
最近、科学者たちは石器作りの最中での脳内の活動を調べてみました。病院の最新スキャナーを使って石器作りをしている人の作業中に脳のどの部位が使われているか確認したのです。驚くことに、手斧を作っている時に現代人の脳が活性化している部位は話している時に使う部位とかなり重複していました。石器を作れるならば、文章も作れる可能性が高いようです。

６分１５秒あたりから
But as well as great manual dexterity, what's important for our story is the conceptual leap required - to be able to imagine in the rough lump of stone the shape that you want to make, in the way a sculptor today can see the statue inside the block of marble.

This particular piece of supreme hi-tech stone is between 1.2 and 1.4 million years old. Like the chopping tool we were looking at in the last programme, it was found in East Africa, at Olduvai Gorge, that great split in the savannah in Tanzania. But this comes from a higher geological layer than the chopping tool, and there's a huge leap between those earliest first stone tools and this handaxe, because I think it's in this tool that we find the real beginnings of modern humans. The person that made this is, I think, a person we would have recognised as someone like us.

All this carefully focussed and planned creativity implies an enormous advance in how our ancestors saw the world and how their brains worked. But this handaxe may contain the evidence of something even more remarkable. Does this chipped stone tool hold the secret of speech? Was it in making things like this that we learned how to talk to one another?

Recently, scientists have looked at what happens inside the brain when a stone tool is being made. They've used modern hospital scanners to see which bits of the brain are used when a knapper is working with stone - and surprisingly the areas of the modern brain activated when you're making a handaxe overlap considerably with those you use when you speak. It now seems very likely that if you can shape a stone you can shape a sentence.

Of course we've no idea what the maker of our handaxe might have said, but it seems probable that he would have had roughly the language abilities of a seven-year-old child. But whatever the level, this early speech would clearly have been the beginnings of a quite new capacity for communication - and that would have meant that people could sit down to exchange ideas, plan their work together or even just to gossip. If you can make a decent handaxe like this one, it's a good bet that you're well on the way to something we would all recognise as society.

自分で石器を作ってみる研究があるのですね。下記の動画で自分で作った石器を見せてくれれています。石器作りというのは原始的な営みに思えましたが、非常に知的な活動であることがわかりました。