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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

  • antelope on the shore of a lake.

  • 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

  • with the world around you.

  • 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 youre

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

  • and in the evolution of our lineage.

  • 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,

  • too.

  • 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

  • nuts.

  • 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

  • carried around and re-used.

  • 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, theyre called

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

  • And theyre 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 create a sharp edge.

  • 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

  • insides of hard-shelled nuts.

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

  • behind butchered bones .

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

  • foods more often.

  • And this mightve kickstarted a feedback loop that affected our bodies forever -- starting

  • with our brains.

  • 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

  • in eastern and southern Africa.

  • 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

  • Africa around 2.4 million years ago.

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

  • at Bouri.

  • 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

  • larger antelope,.

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

  • and tubers.

  • So regular access to all those calories mightve paved the way for our large brains and, in

  • turn, further technological innovation.

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

  • and more complicated.

  • Because, this is where we start to find tools outside of Africabut were not sure

  • who made them.

  • 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

  • tool emerge.

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

  • ago.

  • 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

  • and to maintain.

  • And so are larger, more muscular bodies.

  • 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

  • use of tools.

  • 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

  • have made it out of Africa.

  • The earliest known fossils of human ancestors that weve found outside of Africa belong

  • to a population of Homo erectus, found at a site called Dmanisi in the Republic of Georgia,

  • dated to 1.8 million years ago.

  • But who made the tools found in China is still unknown.

  • The general consensus is that it was probably Homo erectus.

  • Because, fossils of Homo erectus have been found at another site in China that are 1.7

  • million years old, so we know they made it there at some point.

  • But other researchers have suggested that maybe it was an earlier member of genus Homo

  • that made the tools, like maybe Homo habilis.

  • Itll take more research to figure out what exactly is going on here, but that’s part

  • of what makes paleoanthropology so interesting: New discoveries are made all the time.

  • And all of these technological innovations - from the very simplest to the more complex

  • stone tools - were major breakthroughs for our lineage.

  • For our australopithecine ancestors, the use of tools meant they could incorporate more

  • animal resources, like meat and bone marrow, into their diets, consuming more calories

  • than they’d been able to get before.

  • And more calories meant more available energy, allowing those early hominins to develop and

  • maintain larger brains and bodies over time, leading to taxa like Homo erectus.

  • And the very circuitry of our brains might also have started to change when we began

  • making and using tools.

  • In 2008, researchers at a medical school in Indiana used PET scans to study the brains

  • of modern expert stone toolmakers while they made Oldowan and Acheulean tools.

  • And the scans showed that toolmaking activated parts of the brain associated with visual-motor

  • coordination and planning.

  • Demands in those parts of the brain also grew as the toolmaking became more complex.

  • So the researchers concluded that these neural signatures of tool-making may suggest that

  • our brains and our technological capabilities may have co-evolved.

  • And of course, the act of toolmaking may also have had an effect on what we use to make

  • them: our hands.

  • In 2018, a team of anthropologists conducted an experiment to learn more about how the

  • biomechanical stresses of tool making might have shaped our anatomy.

  • Their study subjects wore special gloves with sensors in them and then did things like nut-cracking,

  • breaking bones for marrow, and making stone tools, to see how much stress these things

  • placed on each of their fingers.

  • And the research showed that the two activities that created the most stress were breaking

  • bones for marrow and making stone flakes using hammerstones.

  • So, these two activities might have been especially important in driving the evolution of our

  • hands.

  • Because, using tools in these ways would have exerted powerful selective pressure on things

  • like increased stability and better gripping ability, and maybe even having bigger, stronger

  • thumbs.

  • From the size of our bodies to the wiring of our brains and the capabilities of our

  • hands, we owe some incredibly important aspects of our modern anatomy to stone tools.

  • But of course, they were only the beginning of our capacity for technology.

  • Their legacy continues to this day, and the reason you can watch me talk to you right

  • now is because our always-evolving ability to create new things to help us interact with

  • the world around us.

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  • by forces you might not have thought of -- not just our biology, but also the physics, geology,

  • and chemistry of the natural world.

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  • Thanks for joining me today in the newly named Konstantin Haase studio!

  • And extra big thanks to our current Eontologists, Jake Hart, Jon Ivy, John Davison Ng and STEVE!

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当我们第一次制作工具时(When We First Made Tools)

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    joey joey 發佈於 2021 年 05 月 04 日
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