How do we know if they could speak?

When did language evolve?

Because language can not ‘fossilise’, scientists have to rely on purely circumstantial evidence when trying to determine the language and speech capabilities of our ancient ancestors. This has led to continued debates as to when language evolved. There are two main views – some scientists believe language appeared suddenly, and is limited to our own species. Others claim language evolved slowly over the last 2 million years and was not restricted to our own species.

Those who support a sudden development of language focus on archaeological evidence of behaviour that could be connected to language use. Much of this evidence appears only in the last 40,000 years and includes the manufacture of highly complex tools, the production of symbolic art and the existence of widespread trade systems.

By contrast, those who claim language evolved slowly base their argument on skeletal remains and the evidence of structures related to speech production. Certain physical features associated with spoken language, such as the position of the vocal tract, the structure of the brain and the size of the spinal cord, gradually evolved into the modern human form. This evidence is seen to indicate an increasing ability for language and speech over time.

‘Lucy’ - Australopithecus afarensis

Date: 2.8 to 3.9 million years ago
Where lived: eastern Africa
Language ability: commonly thought to have no language or speech abilities. It is likely however, that communication was very important and they may have been as vocal as modern chimpanzees.

Reconstructing the vocal tract

The base of Lucy’s skull was ape-like in shape. This indicates that she, and others of her species Australopithecus afarensis, had an ape-like vocal tract. Chimpanzees, for instance, have a vocal tract with a high larynx and a short pharynx. This limits the range of sounds that they are able to produce. Lucy’s sound range would probably have been restricted in the same way.

Lucy’s spinal cord

The speech of modern humans requires a complex co-ordination of breathing muscles in order to vary pitch and produce long sentences. Lucy’s relatively narrow spinal cord compared to modern humans indicates that she lacked the nerves responsible for this fine control of the muscles that co-ordinate breathing during speech.

Comparing brains

Language is more than just speech and experiments with chimpanzees show that they are able to learn and understand simple sign language. This has been called ‘protolanguage’ because it lacks the syntax and grammar of modern language. Lucy’s brain was similar in size and structure to a chimpanzee’s so she may have been able to use simple protolanguage.

The Turkana Boy - Homo ergaster

Date: 1.5 -1.9 million years ago
Lived: Africa, possibly migrated out into regions of the Middle East and Asia
Language ability: limited speech and language ability. Probably had advanced communication skills and the capability to produce some simple words and communicate to a greater degree than is seen in our closest living relatives, the chimpanzees.

Evidence for this species language ability comes from their fossilised skeletons and from detailed analysis of their tool technology.

Making an impression: Broca's Area

It was initially believed that the ‘Turkana Boy’, and members of his species, Homo ergaster, were capable of language. This was because the inside of the boy’s fossilised skull showed an impression from a part of the brain known as Broca’s Area. Possession of Broca’s Area was once considered to indicate the ability to speak.

New technologies such as Positron Emission Tomography (PET) have now caused this idea to be revised. PET scans highlight areas of the brain that are active during language activities. They have shown that Broca’s Area does not always function during speech and cannot be used as evidence of speech in our ancestors.

Analysing the spinal cord

The vertebrae in the upper part of the Turkana Boy’s backbone showed that his spinal cord was only about half the size of a modern human’s. The speech of modern humans requires a complex co-ordination of breathing muscles in order to vary pitch and produce long sentences. The Turkana Boy’s narrow spinal cord indicates that he lacked the nerves responsible for this fine control of the muscles that co-ordinate breathing during speech.

A simple tool technology
The tools made by Homo ergaster are known as Mode 2 or Acheulian. They are simple and repetitive in design and could have been learnt through imitating the actions of others rather than by spoken language.

Neanderthals - Homo neanderthalensis

Date: 300,000 – 28,000 years ago
Where lived: Europe and the Middle East
Language ability: relatively advanced language abilities, but evidence suggests that they may have had a limited vocal range compared to modern humans. If this were the case, then their ability to produce complex sounds and sentences would be affected.

There has been considerable debate about whether Neanderthals had the capability for fully modern speech. The Neanderthals (Homo neanderthalensis) became extinct about 28,000 years ago and it is often claimed that a reduced language ability compared with modern humans may have been a factor in their extinction.

Evidence for and against their language ability is based on analyses of their skeletal remains and the artefacts that they left behind.

Neanderthal art

Neanderthals left little in the way of symbolic art, an indication that their thought processes, and hence language ability, were unlike that of their modern human contemporaries. Many scientists reached a similar conclusion after comparing Neanderthal vocal tracts to those of modern humans.

Reconstructing sounds from vocal tracts

It is possible to work out how Neanderthals may have spoken by reconstructing their vocal tracts and then comparing them with those of modern apes and modern humans.

The vocal tract’s structure is revealed in the base of the skull. Modern apes, such as chimpanzees, have a flat skull base and a high larynx whereas modern humans have an arched skull base and a low larynx. Our low larynx allows room for an extended pharynx and this structure enables us to produce the wide range of sounds we use in speech. Neanderthal skull bases appear to be less arched than those of modern humans but more arched than those of modern apes. This suggests that the Neanderthals would have been capable of some speech but probably not the complete range of sounds that modern humans produce.

The Neanderthal hyoid bone

The hyoid bone is a small, U-shaped bone that attaches to the larynx at the top of the vocal tract. Fossilised hyoid bones are very rarely found, so this Neanderthal hyoid from Kebara, Israel, was a fascinating discovery. Its similarity to those of modern humans was seen as evidence by some scientists that Neanderthals possessed a modern vocal tract and were therefore capable of fully modern speech. However, recent studies show that hyoid shape is not linked to the structure of the vocal tract. Pig hyoids, for example, are almost identical to those of modern humans.

A language gene?

Researchers studying Neanderthal genes discovered that they shared the same version of a gene FOXP2 with modern humans. FOXP2 is the only gene known so far that plays a key role in language. When mutated, it primarily affects language without affecting other abilities. This gene appears in different forms in other vertebrates where it performs a slightly different function. This suggests the gene mutated not long before the split between the Neanderthals and modern human lines. However, there are plenty of genes involved in language so it takes more than the FOXP2 gene to prove a language ability.

Cro-Magnons - Homo sapiens

Date: 40,000 – 10,000 years ago
Where lived: Europe
Language ability: The Cro-Magnons were members of our own species, Homo sapiens. There is little reason to doubt that these people had the ability to talk and use symbolic language.

Although Cro-Magnon people have left no evidence of written language, they produced symbolic art, performed long distance trade, held ritual burial ceremonies and planned and designed a technologically advanced tool kit.

Art and symbolism
Art is the earliest unambiguous evidence of symbolic behaviour and, like language, requires a shared system of meanings in order to communicate its message. Evidence of art prior to 40,000 years ago is limited and solid evidence of symbolism only occurs after this time.

Complex tools
The earliest tools that appear in the archaeological record 2.6 million years ago are repetitive and could have been learnt through imitating the actions of others rather than by spoken language. By comparison the Cro-Magnon tool kit was complex, varied and innovative. This reflects intentional design and planning which are the basis of complex mental processes and can be associated with language.

Burials and ritual behaviour
Most of the human remains are from deliberate burials and are accompanied with grave goods and covered with ochre. This is evidence for ritual behaviour and interaction with the dead, suggesting some kind of belief in an afterlife. The mental processes associated with such abstract concepts as spiritualism and religion can be associated with the capability for modern language.

The 90,000 year-old double burial from Jebel Qafzeh, Israel is one of the earliest that shows careful placement of the deceased. Burials of modern humans become increasingly complex over time, and Cro-Magnon burials usually include grave goods and other evidence of ritual activity. This pattern of behaviour is also seen at burial sites of other modern human cultures throughout the world.

Cro-Magnon skeletons
The physical features associated with spoken language, such as the vocal tract, the structure of the brain and the size of the spinal cord, are identical between Cro-Magnon people and humans living today. This means that Cro-Magnon people would have been capable of producing the same sounds we use in speech.