Name: 当我们第一次说话时（When We First Talked）
Uploaded: 2021-05-03T04:03:46.000Z
Duration: 12 min
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Usually, I'd start an episode of Eons  by telling you about the discovery of some

strange fossil or setting the scene for a world-changing event like an ice age or an

But today, I want to try something a little different.

Instead of thinking about a story, I want you to stop and think about the thing I'm

doing here - literally, that I'm standing here and telling you a story.

Because, the evolution of our ability to speak is its own epic saga - and it's worth pausing

It's taken several million years to get to this moment where I can tell you about

how it took several million years for us to get here.

And, yes, there are other animals alive today that communicate in sophisticated ways - like

whales, elephants, and crows, to name a few.

Still, our vocal abilities as a species are pretty unique.

From the anatomy of one particular bone in our throats and the proportions of our vocal

tract, to the morphology of our ears, paleoanthropologists are piecing together the puzzle of when and

And while speech itself doesn't fossilize, the fossil record of our ancestors and relatives

can still give us important clues about the time when we first talked.

Now, this story could start between 400 and 360 million years ago, when the first ancient

tetrapods transitioned from life in the water to life on land, and evolved lungs and a movable

Controlling both of these with precision is important for creating the many different

Or it could start between about 8 and 6 million years ago, when our lineage - the hominins

- split off from the ancestors of our closest living relatives, chimpanzees and bonobos.

While there's no question that they can communicate with vocalizations, gestures,

and expressions, they can't speak like us - despite decades of effort to teach them

And our earliest hominin relatives probably couldn't talk like us, either.

The first piece of fossil evidence that can be used to reconstruct hominin vocalization

comes from the skeleton of a juvenile Australopithecus afarensis dated to 3.3 million years ago.

It's a U-shaped bone that sits in your neck just below the level of your jaw and it doesn't

Instead, it's held in place by muscles and ligaments.

In humans, the hyoid is an important attachment point for the muscles of the tongue.

But, in chimps - and in most other living apes - it also helps support structures called

Now, we don't know exactly what these things do.

Some research has suggested that they might help make vocalizations louder and help primates

call for longer or more often without hyperventilating.

But they also seem to introduce new, lower resonances to vocalizations and reduce the

differences between higher-pitched sounds.

Both of which would make human speech sounds harder to understand.

And, here's the thing, the hyoid of Australopithecus afarensis looked more like those of chimps

Which means that this hominin likely had air sacs attached to their hyoid.

So, her species probably couldn't speak like we do.

And that one hyoid is the only one we have from any species of australopithecine.

The hyoid is a small, fragile bone, so it's one of the least well-known bones in the hominin

In fact, the next oldest hyoids we've ever found come from a site that's almost three

In that span of time, the australopithecines disappeared, and our own genus, Homo, evolved,

with some populations even making their way out of Africa to Asia and Europe.

And a cave site in northern Spain called the Sima de los Huesos - or the Pit of Bones - is

where those next-oldest hyoids were found.

They've been dated to around 450,000 years old and belonged to members of the species

This species may be the common ancestor of Neandertals and our own species, Homo sapiens,

or it might just be a close relative of both.

And while both of the hyoids from this site are incomplete, what is preserved looks a

lot more like our hyoid than like the hyoid of Australopithecus afarensis or a chimp.

So, these hominins probably didn't have laryngeal air sacs.

But that doesn't necessarily mean they could talk like us - at least, not based on their

See, along with a lack of laryngeal air sacs, members of our species also have unique vocal

You can split the vocal tract above the larynx, or voice box, into two basic parts.

The mouth makes up the horizontal part and the pharynx makes up the vertical part - the

In adult humans, these two parts are about the same length.

This allows us to make three of the different vowel sounds - a, i, and u - and to make them

And almost all human languages have at least three vowels - and they tend to be these three.

This might be because they sound the most different from each other, so  they're less

But some anthropologists don't think that other hominins had these same proportions.

For example, researchers previously suggested that Neandertals had much shorter vertical

parts of their vocal tracts and longer horizontal parts.

Human infants and chimpanzees also have short vertical segments of their vocal tracts, and

can't make those distinct vowel sounds as a result.

But that fossil site in Spain can also give us clues about this piece of the puzzle.

Because, there's one individual with a nearly-complete skull and all seven neck vertebrae that researchers

have used to estimate the lengths of the two parts of the upper vocal tract.

They found that the horizontal part was actually only a little bit shorter than the vertical

This makes the fossil's proportions more like those of a 10 year old human child than

And 10 year olds can still make those same distinct vowel sounds, meaning this almost

half-a-million-year-old hominin probably would've been able to do it, too.

Some of our more recent relatives also seem to've had vocal tract proportions similar

When anthropologists reconstructed the vocal tract length of one adult Neandertal from

France dated to between 50,000 and 70,000 years ago, they found that the horizontal

section of his upper vocal tract was slightly shorter than the vertical section.

So, he, too, could probably make the full range of sounds found in human speech.