Name: When We First Made Tools
Uploaded: 2021-05-04T02:09:34.000Z
Duration: 10 min 10 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

転換語

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About 2 and a half million years ago, in the Middle Awash Valley of Ethiopia, one of our

ancient human ancestors -- or maybe a group of them -- crouched over a carcass of an

One of these hominins took a sharp stone flake and sliced into the flesh on the inside of

the jaw, grazing the bone and leaving three cut-marks.

These ancestors were after the meaty tongue of the animal, and in trying to remove it,

they left traces of this remarkable moment: the use of a tool by a human ancestor.

They also left behind the technology itself, in the form of a few scattered stone tools.

This site, now known as Bouri, is one of the earliest confirmed locations where a human

ancestor or relative permanently modified some part of the environment around them to

suit their needs - chipping raw stone into a tool.

In the broadest sense, this is what technology is: making tools and using them to interact

These simple stone flakes and the cores of rock they were struck from are what anthropologists

call Oldowan tools - named for Olduvai Gorge in Tanzania, where they were found.

And while these tools don't seem like much when you compare them to the screen you're

watching right now, their creation represents a pivotal moment in the origin of technology

This is when our ancestors first started to make the world around them fit their needs.

But what they didn't know at the time was that this use of technology would change them,

Because the fact is, the use of tools has not only enabled our lineage to take over

the world, it has also shaped our very biology, from our brains to our skeletons.

Of course, hominins didn't invent the use of tools.

The first of our ancestors to make and use technologies like the Oldowan tools were just

expanding on the behavior of our primate ancestors and cousins.

Chimpanzees, our closest living relatives, and capuchin monkeys, a much more distant

branch on our family tree, make and use tools to get at choice foods, like termites and

But hominins - the branch of our family tree that's more closely related to us than to

chimps and bonobos - took things a step further.

They created permanent tools out of carefully chosen materials that were then sometimes

And the Oldowan instruments weren't the first tools that hominins ever made.

In 2011, anthropologists working in West Turkana, Kenya, found evidence of a different type

of stone tool that pre-dates the Oldowan by around 700,000 years.

These tools are even simpler than Oldowan choppers and flakes, they're called

Lomekwian tools, after the site of Lomekwi where they were found.

And they're dated to 3.3 million years ago.

They also seem to have been made in a different way.

Oldowan tools were made by hominins holding rocks in both hands and striking them together.

But Lomekwian tools seem to have been made by holding only one rock and striking it against

another that was sitting on a flat base, or against the flat base itself, to break it

And it seems likely that the tool-makers at Lomekwi were doing this for the same reasons

that the hominins at Bouri were: to try to get hidden foods, like bone marrow or the

But we don't know for sure, because, unlike at Bouri, the Lomekwi hominins didn't leave

Still, in both cases, these tools allowed our early ancestors to get at more nutritious

And this might've kickstarted a feedback loop that affected our bodies forever -- starting

We don't know for sure who the tool-makers at Lomekwi and Bouri were, but they were most likely

australopithecines, members of that early and diverse group of hominins found mostly

And members of this genus typically had smaller brains and smaller bodies than hominins

that followed them: the early members of our genus Homo, who appeared on the scene in eastern

These early members of our genus probably used Oldowan tools, too, like the hominins

And the ancestors that used these tools seemed to do pretty well for themselves.

For example, the earliest known site with clear evidence of long-term and consistent

meat-eating is an Oldowan site called Kanjera South in Kenya, dated to about 2 million years

ago. Over a period of hundreds to thousands of years

the hominins there acquired and butchered many small ungulates, like gazelles, and occasionally

And all that meat and marrow is really high in calories, compared to things like fruits

So regular access to all those calories might've paved the way for our large brains and, in

Now the next phase in the history of our tool use is where things get even more interesting,

Because, this is where we start to find tools outside of Africa … but we're not sure

The traditional story from this point in the anthropological record is that, a little less

than 2 million years ago, we see both a new hominin and a new, more complicated type of

This is when Homo erectus makes its first appearance in Africa, about 1.9 million years

And this species had a larger brain, larger body, and smaller teeth compared to earlier

hominins - all hallmarks of a higher quality diet.

Brains are especially expensive, when it comes to how many calories they require to develop

So it was thought that this might explain why a new, more sophisticated toolkit started

to appear regularly around 1.7 million years ago.

These were large cutting tools, including things like hand-axes, which are made by flaking

hand-sized rocks to a point on both sides, with a rounded end for gripping.

These newer more complex instruments became known as the Acheulean toolkit.

And until very recently, those tools were thought to have first been made by African

members of Homo erectus, and this development was seen as the next pivotal step in our ancestors'

But new finds from China might make this story much more complicated.

In 2018, researchers published their discovery of Acheulean tools from the site of Shangchen,

which were dated to 2.1 million years old.

That date pushes back the appearance of Acheulean technology some 400,000 years.

And it's also 300,000 years before the time when the earliest hominins were thought to