Origin of speech

The origin of speech differs from the origin of language because language is not necessarily spoken; it could equally be written or signed. Speech is a key part of how humans talk to each other. It helps us share thoughts, feelings, and ideas. It lets us connect with others and work together.

Scientists have tried to understand how speech began in humans, but they have not yet found a single answer that everyone agrees on.

Animals, including primates like monkeys and apes, can make sounds to talk to each other. However, they do not use their tongues the way humans do. Humans use their tongues, lips, and other parts of the mouth in special ways to create speech. This makes the development of human speech a fascinating question for many researchers.

Modality-independence

The word modality means the way we share information, like talking, writing, or signing. Human language is special because it can work in any of these ways. If a child cannot hear or speak, they can still learn and use language by signing. Sign languages for people who are deaf work just like spoken languages, even though they use hand movements instead of sounds. This shows that the parts of our brain for language can work well, no matter how we choose to share our thoughts.

Unlike animals, humans can switch between different ways of communicating while still sharing the same message. For example, we can talk on the telephone without needing to see each other’s faces, or we can write an email without using any sounds. Some Australian Aboriginal cultures have traditions where people use signing instead of speaking for certain times, and then switch back to speaking when they can. This shows how flexible and powerful human language really is.

Evolution of the speech organs

Speaking is the main way people share their thoughts and feelings. To do this, we use our lips, tongue, and other parts of our mouths very well.

Our speech organs first developed for basic things like eating and breathing. Animals have similar organs, but they don't use them to make sounds the same way humans do. Humans are special because we can use our breathing and eating systems to make clear speech sounds.

Tongue

The word "language" comes from the Latin word for "tongue." Experts say the tongue is the most important part for making speech sounds, followed by the lips. The human tongue is shaped differently from most animals. It sits lower in the throat, which helps us make many different sounds. This special shape lets us change the shape of our mouth and throat to make vowels and other sounds that animals can't make.

Lips

In humans, the lips help make certain sounds. Even though lips aren't made just for speech, they changed over time as humans started to see more and rely less on smell. This allowed the lips to move more and help with facial expressions. Thicker lips and a smaller mouth space also help us make different sounds.

Respiratory control

Humans have better control over our breathing when we talk compared to other animals. We can stretch out breaths and make quick sounds, which helps us speak clearly. Special muscles in our chest and belly help us control this breathing.

Larynx

The larynx, or voice box, sits lower in humans than in other animals. This gives us a longer space in our throat that helps make our voice clearer and louder. Animals often have a shorter or no space like this, so their voices sound different. Some animals can lower their voice boxes temporarily, but humans do it all the time.

Experts don't all agree on how special the human voice box is. Some say only humans have a voice box that stays low and works with the tongue to make many sounds. Others think speech might not be the main reason for this change. They wonder if making deeper voices for showing strength might have been more important at first.

At least one orangutan has shown it can control its voice box.

The size exaggeration hypothesis

Making the voice box lower can make the voice sound deeper, which can make an animal seem bigger and stronger. Some experts think this was the main reason human voices got lower, not just for talking. They say that even though women have higher voice boxes, they still do better at speaking than men.

Neanderthal speech

Most experts think Neanderthals could speak almost as well as modern humans. Their tools and hunting skills suggest they needed some way to share ideas. We also found a gene in Neanderthals that helps with mouth movements for speech.

In the past, people thought Neanderthals couldn't make certain sounds because of their voice box, but we now know they likely could make a wide range of sounds. Scientists found a Neanderthal voice box that looked like modern humans', suggesting they had similar speech abilities.

The shape of Neanderthal ears also suggests they could hear many speech sounds clearly.

Hypoglossal canal

The hypoglossal nerve helps control the tongue. Scientists once thought the size of a canal in the skull could show how well ancient humans could move their tongues, but we now know this isn't a good way to tell.

Distinctive features theory

Some experts think our speech system works like a digital keyboard, where each sound is a combination of simple "on" or "off" settings. For example, the voice either makes a sound or it doesn't. This theory started with a Russian scientist and was later used to understand language structure.

Self-organisation theory

Some scientists believe speech sounds naturally organize themselves through use. When people talk and listen, they adjust sounds to be easier to say and understand. Computer models show how groups of people can create shared sound systems just through talking to each other.

Gestural theory

Some theories suggest that early humans used hand gestures before they could speak. Over time, as they gained control over their voices, speech developed. Research shows that sign language and spoken language use similar brain areas, supporting this idea.

Critics wonder why early humans would give up easy-to-see gestures for harder-to-hear sounds, but some suggest tool use made hand gestures difficult, leading to speech.

Possible semi-aquatic adaptations

Some ideas suggest that early humans living near water might have developed better breath control and mouth movements from diving for food, which helped them speak better later on.

Timeline of speech evolution

We do not know exactly when humans first began to speak. Unlike writing, speech leaves no traces behind. Scientists study body features and genes to guess when our ancestors might have been able to talk. Even then, we cannot be sure if they used speech.

Some researchers believe that languages began to change and spread at least 100,000 years ago. Others look at the different sounds in languages today to estimate when speech might have started. They suggest that languages could date back to between 350,000 and 150,000 years ago in Africa, around the time when modern humans evolved.

However, these ideas are debated. Some experts say that comparing sounds in languages to genes is not accurate. They believe the patterns we see today are due to more recent contacts between groups of people rather than showing us the deep history of language.