When We First Talked

Summary

This episode of Eons explores the evolution of human speech, a unique trait that sets us apart from other animals. It delves into the anatomy of our vocal tract and ears, using fossils like the hyoid bone to trace the development of speech capabilities. The show discusses how early hominins like Australopithecus afarensis likely couldn't speak as we do, while later species like Homo heidelbergensis and Neandertals show evidence of vocal tracts and hearing abilities similar to ours, suggesting they might have been able to produce and comprehend human-like speech.

Takeaways

• 🗣️ The evolution of human speech is a complex process that took millions of years to develop, involving unique anatomical features.
• 🦜 Other animals like whales, elephants, and crows communicate in sophisticated ways, but human vocal abilities are distinct.
• 🦴 The hyoid bone, a U-shaped bone in the neck, is crucial for human speech and differs significantly between humans and our closest relatives like chimps.
• 🕰️ Fossil evidence suggests that the ability to produce human-like speech sounds may have evolved around 450,000 years ago with Homo heidelbergensis.
• 👶 The vocal tract proportions of modern humans, with similar lengths of the horizontal and vertical parts, allow for distinct vowel sounds, a feature that may not have been present in early hominins.
• 🧬 Neandertals had vocal tract proportions and hyoid bones similar to modern humans, suggesting they could potentially produce a range of speech sounds.
• 👂 Changes in ear anatomy and hearing ability over time have been linked to the development of human language, with later hominins showing increased sensitivity to higher frequencies important for consonant sounds.
• 🧬 The debate continues over whether Neandertals and other early hominins had language, but there's no anatomical reason they couldn't make and hear human-like speech sounds.
• 🎭 The script highlights the importance of storytelling in human evolution, suggesting that our extinct relatives may have also been capable of storytelling.
• 🔬 The study of fossils, particularly those related to the hyoid bone and ear anatomy, provides crucial insights into the evolution of speech and hearing in human ancestors.

Q & A

What makes human speech unique compared to other animals?

Human speech is unique due to our vocal abilities, which are part of what makes us human. This includes the anatomy of our throats, the proportions of our vocal tract, and the morphology of our ears, which allow for the creation of a wide range of distinct sounds.

What is the significance of the hyoid bone in the context of human speech evolution?

The hyoid bone is significant because it is an important attachment point for the muscles of the tongue in humans, which is crucial for speech. Fossil evidence of the hyoid bone in early hominins like Australopithecus afarensis suggests that they likely had air sacs attached to their hyoid, indicating they could not speak like modern humans.

How does the presence of laryngeal air sacs in early hominins affect their ability to produce human-like speech sounds?

Laryngeal air sacs, present in early hominins like Australopithecus afarensis, introduce lower resonances to vocalizations and reduce the differences between higher-pitched sounds, making it harder to produce and understand the distinct speech sounds characteristic of human language.

What is the relationship between the vocal tract proportions and the ability to produce distinct vowel sounds?

In humans, a vocal tract with roughly equal lengths of the horizontal (mouth) and vertical (pharynx) parts allows for the production of distinct vowel sounds like 'a', 'i', and 'u'. Early hominins may have had different proportions, affecting their ability to produce these sounds.

How do the vocal tract proportions of Homo heidelbergensis compare to those of modern humans?

The vocal tract proportions of Homo heidelbergensis, as estimated from a nearly-complete skull and neck vertebrae, were more similar to a 10-year-old human child than an adult, suggesting they could produce distinct vowel sounds similar to modern humans.

What evidence suggests that Neandertals might have been capable of human-like speech?

Evidence from Neandertal hyoid bones and vocal tract reconstructions indicates that they had similar anatomy to modern humans, suggesting they could make a full range of human speech sounds. Additionally, their hearing abilities, as modeled from ear anatomy, were similar to ours, which is important for both producing and understanding speech.

How do the ear structures of early hominins like Australopithecus africanus and Paranthropus robustus differ from those of modern humans?

Early hominins had ear structures that were intermediate between modern humans and chimpanzees, with some features more similar to humans, such as a slightly shorter and wider eardrum passage, but other features like the incus and stapes were more chimp-like, affecting their hearing abilities.

What is the significance of the changes in ear anatomy and hearing ability in the Homo genus?

The changes in ear anatomy and hearing ability in the Homo genus, such as the expansion of maximum sensitivity to higher frequencies, suggest an adaptation for hearing consonants, which is a key feature of human language.

What is the 'Pit of Bones' and how does it contribute to our understanding of human speech evolution?

The 'Pit of Bones', or Sima de los Huesos, is a cave site in Spain where some of the oldest hominin hyoids were found. These fossils provide crucial evidence for the evolution of speech by showing changes in the hyoid bone over time.

What is the debate surrounding the presence of language in extinct hominin species like Neandertals?

The debate centers on whether the anatomical evidence of speech capabilities in Neandertals indicates the presence of language. While they could potentially make and hear human-like speech sounds, there is not enough evidence to definitively say whether they had language as we understand it.

Outlines

00:00

🗣️ The Evolution of Human Speech

The paragraph discusses the unique vocal abilities of humans and how they evolved. It highlights that while other animals communicate, human speech is distinct due to our anatomy, including the hyoid bone, vocal tract, and ear morphology. The journey begins with the transition of ancient tetrapods to land and the evolution of the movable tongue, and continues with the divergence of hominins from chimpanzees and bonobos around 8 to 6 million years ago. The first piece of evidence for hominin vocalization is the hyoid bone of Australopithecus afarensis, suggesting that early hominins could not speak as we do. The paragraph also touches on the significance of the hyoid bone's structure in relation to the presence of laryngeal air sacs, which are not present in modern humans and would have affected the clarity of speech.

05:01

🦜 Vocal Tract Proportions and Speech Sounds

This section delves into the proportions of the human vocal tract and how they enable us to produce distinct vowel sounds. It contrasts the vocal tract anatomy of modern humans with that of Neandertals and other hominins. The discovery of a nearly-complete skull and neck vertebrae from the Sima de los Huesos site in Spain provides evidence that early Homo heidelbergensis may have had vocal tract proportions similar to modern humans, suggesting the potential for distinct vowel production. The paragraph also discusses the findings from the reconstruction of a Neandertal's vocal tract and the discovery of hyoid bones resembling those of modern humans, indicating a capacity for human-like speech sounds. Additionally, it explores the evolution of ear anatomy and hearing abilities in hominins, which are crucial for both producing and perceiving speech.

10:03

👥 Speculations on Language and Communication in Extinct Hominins

The final paragraph ponders whether extinct hominins like Neandertals had language, acknowledging the ongoing debate and the lack of definitive evidence. It points out that while Neandertals and other members of the genus Homo possess the necessary anatomy for producing and hearing human-like speech, this does not conclusively prove the existence of language. The paragraph also notes the human-like behaviors observed in Neandertals, hinting at their potential for complex communication. It concludes by emphasizing the responsibility of modern humans to piece together the puzzle of our ancestors' speech abilities and to share this evolutionary narrative.

Keywords

💡Evolution

Evolution refers to the process by which species of organisms change over time through genetic variation and natural selection. In the context of the video, evolution is central to understanding how humans developed the ability to speak, a unique trait among animals. The script discusses the evolutionary journey from early tetrapods to hominins, highlighting the gradual changes that led to the sophisticated communication abilities of Homo sapiens.

💡Hominins

Hominins are members of the taxonomic family Hominidae, which includes humans and their ancestors. The script uses this term to discuss the divergence of human lineage from that of chimpanzees and bonobos, approximately 8 to 6 million years ago. This divergence marks a significant point in the evolution of speech capabilities, as hominins are the precursors to the anatomical adaptations necessary for human speech.

💡Hyoid bone

The hyoid bone is a U-shaped bone located in the neck that plays a crucial role in speech by anchoring the tongue and other muscles involved in vocalization. The script discusses the hyoid bone's importance in the evolution of speech, noting that the hyoid of Australopithecus afarensis resembled that of chimpanzees, suggesting an inability to speak like modern humans. In contrast, the hyoids of Homo heidelbergensis and Neandertals were more similar to humans, indicating a potential for speech.

💡Vocal tract

The vocal tract is the part of the anatomy involved in speech production, including the mouth, throat, and nasal passages. The script explains that the proportions of the vocal tract are critical for producing distinct vowel sounds. It contrasts the vocal tract proportions of early hominins, which were different from humans, with those of Homo sapiens, which allow for a wide range of speech sounds.

💡Laryngeal air sacs

Laryngeal air sacs are structures found in some primates, including chimpanzees, that may aid in vocalization. The script suggests that these sacs could have limited the vocal capabilities of early hominins by introducing lower resonances and reducing the distinctness of higher-pitched sounds, which are essential for human speech.

💡Pharynx

The pharynx is the muscular tube that connects the mouth and nasal cavity to the esophagus and larynx. In the context of the video, the pharynx is part of the vocal tract, and its length relative to the oral cavity is important for producing distinct vowel sounds. The script notes that in humans, the pharynx and oral cavity are roughly equal in length, which is essential for clear speech.

💡Neandertals

Neandertals, or Homo neanderthalensis, are an extinct species of humans that lived in Eurasia. The script discusses the anatomical evidence suggesting that Neandertals had vocal tracts and hyoid bones similar to modern humans, implying they might have been capable of speech. This raises questions about the complexity of their communication and culture.

💡Homo heidelbergensis

Homo heidelbergensis is an extinct species of hominin that may be a common ancestor to both Neandertals and modern humans. The script mentions that the hyoids found in this species were more similar to humans than to earlier hominins, suggesting a potential for speech capabilities. This species is significant in the narrative of human evolution and the development of speech.

💡Hearing range

Hearing range refers to the span of frequencies that an organism can perceive as sound. The script explores how the hearing range of early hominins differed from that of modern humans, with later hominins showing a greater sensitivity to higher frequencies, which is crucial for distinguishing consonants in speech. This change in hearing ability aligns with the anatomical adaptations for speech production.

💡Consonants

Consonants are speech sounds that are produced by obstructing the airflow in some way. The script emphasizes the importance of being able to hear and produce consonants like 't', 'k', 'f', and 's' for clear speech communication. The evolution of hearing abilities in hominins, particularly sensitivity to higher frequencies, is linked to the capacity for producing and understanding consonants.

Highlights

The evolution of human speech is an epic saga that took millions of years.

Other animals communicate sophisticatedly, but human vocal abilities are unique.

Paleoanthropologists study the anatomy of our throats, vocal tracts, and ears to understand the evolution of speech.

The first ancient tetrapods evolved lungs and a movable tongue, crucial for human speech.

Hominins, our lineage, split from chimpanzees and bonobos 8 to 6 million years ago.

Australopithecus afarensis, 3.3 million years old, provides the first fossil evidence for hominin vocalization.

The hyoid bone's structure in Australopithecus suggests they couldn't speak like humans.

Homo heidelbergensis, dated to 450,000 years ago, had hyoids more similar to humans, indicating a possible lack of laryngeal air sacs.

Homo sapiens have unique vocal tract proportions, unlike other hominins.

A nearly-complete skull from Sima de los Huesos suggests Homo heidelbergensis could make distinct vowel sounds.

Neandertals had vocal tract proportions and hyoid bones similar to modern humans, suggesting speech capability.

Neandertals' hearing abilities were modeled to be similar to Homo sapiens, important for language.

Homo erectus fossils show human-like ear features, suggesting advanced hearing abilities.

The debate on whether extinct relatives had language is ongoing, with evidence suggesting they could make and hear human-like speech sounds.

Neandertals exhibited human-like behaviors, hinting at potential for language and storytelling.

Modern humans are left to piece together the puzzle of our ancestors' speech abilities.

Transcripts

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

extinction.

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

to appreciate that.

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.

They’re part of what makes us human.

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

how this adaptation arose.

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

tongue.

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

sounds that make up human speech.

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

how.

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

Because!

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.

This special bone is called the hyoid.

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

connect to any other bone.

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.

It does that in chimps, too.

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

laryngeal air sacs.

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

and gorillas than it does like ours.

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

fossil record.

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

million years younger.

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

Homo heidelbergensis.

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

hyoid bones alone.

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

tract proportions.

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

bit between the mouth and the voice box.

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

sound really distinct from each other.

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

likely to be misheard.

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

part.

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

an adult.

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

to that individual.

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.

And there’s more anatomical evidence for speech in Neandertals than just one reconstructed

vocal tract.

Bringing it back to the hyoid bone, we’ve found two from these extinct relatives of

ours.

One is from another cave site in Spain and dates to around 43,000 years ago.

It’s incomplete, but was described as being “almost indistinguishable” from a modern

human hyoid.

The second is a little older, dating to around 60,000 years ago, and comes from a site in

Israel called Kebara Cave.

It also looks a lot like our hyoid bones.

The scientists who worked on this bone even CT-scanned it to see if its internal structure

was a match for a human hyoid.

See, bone can actually change or remodel its microscopic architecture over time, based

on how it’s being used.

So if a Neandertal was using the muscles and ligaments that attach to its hyoid the same

way we do, CT scans of our hyoids should look similar, too.

And they did!

Which means that both the outside and the inside of the hyoid of this Neandertal suggest

that he was capable of making human-like speech sounds.

But!

Being able to make human-like speech sounds is only half the story - the other half is

being able to hear them.

While paleoanthropologists haven’t found very many fossil hyoids, they have found a

lot of skulls.

These allow them to study things like the size and shape of the ear canals - and sometimes

even the tiny bones of the ear themselves - because they’re contained within the temporal

bones of the skull.

And by comparing the fossils to the anatomy of living primates and humans, they can model

the hearing ranges of our extinct relatives.

Early hominins, like Australopithecus africanus and Paranthropus robustus, have some features

of their ears that look more like ours than like a chimpanzee.

For example, they have a slightly shorter and wider passage leading from the outside

of the skull to the membrane of the eardrum.

And they have a malleus - one of the bones of the middle ear - that looks human-like.

But the other two bones of the middle ear - the incus and stapes - are more chimp-like

in size and shape.

And when their hearing abilities are modeled, they’re not quite like ours or like those

of a chimp.

These early hominins seem to have been more sensitive to mid-range frequencies than modern

humans or chimps are.

More human-like ear anatomy and hearing abilities seem to originate in our genus, Homo.

Homo erectus fossils from Asia have some human-like features, and the hominins from Sima de los

Huesos and the Neandertals are even more similar in ear anatomy to Homo sapiens.

The same hearing model used for the early hominins predicts that the later members of

our genus probably had hearing abilities like ours.

They lost a little bit of the mid-range frequency sensitivity seen in early hominins, but expanded

their range of maximum sensitivity to include higher frequencies.

It’s been suggested that greater sensitivity to those higher frequencies is important for

hearing consonants, especially t, k, f, and s.

And the use of consonants is a key feature that distinguishes human language from most

animal communication.

These changes in ear anatomy and hearing ability go along with the changes in the hyoid bone

over time - early hominins were more similar to our closest living relatives and the members

of our genus Homo are more similar to us.

And by the time we get to the Sima de los Huesos hominins and the Neandertals, we seem

to have all the anatomy in place for distinct vowel and consonant sounds -- which is pretty

incredible!

Now, we don’t know if this means these extinct relatives had language.

This is still a big topic of debate and we don’t have enough evidence to say either

way.

It might just come down to how we define language.

But what we can say is that there’s no anatomical reason they couldn’t make and hear human-like

speech sounds.

And we know the Neandertals were capable of very human-like behavior, like caring for

injured members of their groups and using objects for personal ornamentation.

So maybe they were storytellers, too.

As the only hominins left, it’s up to us to piece together the puzzle of our ancestors’

speech abilities — and use our own to tell this evolutionary story.

Hey if you wanna learn more about all the ways in which Neandertals were similar to

us...as well as what happened to them, be sure to check out our episode, “When We

Met Other Human Species”.

Now I have to say this month’s Eontologists are : Sean Dennis, Jake Hart, Annie & Eric

Higgins, John Davison Ng, and Patrick Seifert!

By becoming an Eonite at patreon.com/eons you’ll get fun perks including submitting

a joke for us to read like this one...

from my friend Matty Dahman.

Why did the T Rex need a nap?

Because he was wiped out.

I need a nap after this script!

Thanks Matty for submitting your joke.

And as always thank you for joining me in the Konstantin Haase studio.

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