以下轉載普羅斯教授的研究報告。他指出：現代人類因為種種原因(包括飲料食物)，演化到能夠控制發音器官的階段；於是在大約70,000年前發展出第一個語音(可戲稱為「打啵音」；請參看所附「中、英術語對照」提供的連接)。大約50,000年前發展出「語音」，然後發展出「語言」、「語句」、「句型」、和「文法」等等。他區分「發聲」和「語音」；強調基因和人體器官在語言演化過程中的關鍵角色。

普羅斯教授在文章第一段中指出，其它研究報告認為：人可能從20萬年到200萬年前開始就使用語音或語言。他表示不以為然。此處可參看Human Ancestors May Have Evolved the Physical Ability to Speak More Than 25 Million Years Ago。

我看到的另一篇研究報告中作者指出：人類「移民出非洲」是個大規模和極其複雜的活動，如果沒有語言來溝通協調，完成這項工作的機率很小。這可以反證或支持：至少在70,000年前左右(上下一萬年？)，人類就有溝通的媒介和機制。因為這是最近一次的「出非洲記」。

但是，也有學者認為：200萬年前現代人類始祖就開始「出非洲」；50萬年前海德堡人也曾「出非洲」。那麼，這是說50萬年前人類祖先就使用語音和語言？

不過，造成「出非洲」的重要因素是自然環境(包括氣候、地理、和生態)改變。在求生存壓力下，或許溝通協調不一定是必要條件。另一方面，由於地球史上冰河時代阻斷了人類的發展過程，人類進化史上可能有好幾次重起爐灶的經歷。語言使用也就未必是線性式發展。總之，普羅斯教授的報告雖然嚴謹，但還不能稱為定論。

請參看 2022年人類演化領域的14個重大發現 一文。


When did humans first start to speak? How language evolved in Africa

George Poulos, Professor Emeritus, University of South Africa, 12/26/22

When did humans first begin to speak, which speech sounds were uttered first, and when did language evolve from those humble beginnings? These questions have long fascinated people, especially in tracing the evolution of modern humans and what makes us different from other animals. George Poulos has spent most of his academic career researching the phonetic and linguistic structures of African languages. In his latest book, On the Origins of Human Speech and Language, he proposes new timelines for the origins of language. We asked him about his findings.

When and where did human speech evolve?

Research carried out for this study indicates that the first speech sounds were uttered about 70,000 years ago, and not hundreds of thousands or millions of years ago, as is sometimes claimed in the literature.

While my research has been primarily based on phonetic (speech sounds) and linguistic (language) analyses, it has also taken into account other disciplines, like palaeoanthropology (the study of human evolution), archaeology (analysing fossils and other remains), anatomy (the body) and genetics (the study of genes).

The transformation of Homo sapiens (modern humans) from a “non-speaking” to a “speaking” species happened at about the same time as our hunter-gatherer ancestors migrated out of Africa.

When those early adventurers migrated beyond the African continent, they took with them the greatest gift ever acquired by our species – the ability to produce speech sounds, enabled by the creation of a “speech” gene.” It was that ability, more than anything else, that catapulted them into a world in which they would dominate all other species.

Which speech sounds were first uttered?

The very first speech sounds ever produced were not just random involuntary sounds. Underlying these speech sounds was a fledgling network that connected certain areas of the brain to different parts of the vocal tract. Various anatomical and environmental factors contributed to Homo sapiens’ ability to produce speech sounds for the first time ever.

Another interesting factor was an apparent change in the diet of our early ancestors and the possible effect it might have had on the human brain. The change to what was essentially a marine diet rich in omega 3 fatty acids occurred when those early humans migrated from the interior to the coastlines of the continent.

The vocal tract developed gradually over a long period, and the different stages in its development determined the types of sounds that could be produced. At the time of the “out of Africa” migration, the only part of the vocal tract that was physiologically developed to produce speech sounds was the oral cavity (mouth area).

The only speech sound that could be produced entirely in the mouth at the time was the so-called “click” sound. The airstream could be controlled within the mouth. Clicks are the only known speech sounds that behave in this manner. They still occur today in a few African languages – predominantly in the Khoisan languages spoken in parts of Botswana, Namibia and South Africa.

Clicks occur in less than 1% of the languages of the world. They also occur in a few isolated instances in East Africa and in certain languages of South Africa that adopted the clicks when they came into contact with the Khoisan. Clicks have also been noted in one instance outside the African continent, in an extinct ceremonial language register known as Damin in Australia.

An example of a click speech sound is the so-called “kiss” (or bilabial) click where the lips are brought together, and the back part of the tongue is raised against the back of the mouth. The lips are then sucked slightly inwards, and when released a click sound is produced.

The production of the alveolar click. Courtesy George Poulos (示意圖，請至原網址觀看)

My research suggests that the “kiss” click was probably the first speech sound ever produced by Homo sapiens. As time moved on, the various parts of the tongue became more and more maneuverable (容易控制), making it possible for other click sounds to be produced in the mouth as well.

So, when did the other speech sounds evolve?

This study demonstrates that the production of all the other human speech sounds (the other consonants, as well as all the vowels) began to take place from approximately 50,000 years ago. This was dependent on the gradual development of a well-proportioned vocal tract which included the mouth, the area behind the mouth (the pharynx), the nasal passages, and the all-important larynx with its vocal cords. Three airstream mechanisms evolved for the production of all speech sounds, and they evolved gradually in successive stages.

How did humans communicate before clicks?

Before this, the only sounds humans could produce were the so-called “vocalisations” or vocal calls. Those were imitations or mimics of various actions or sounds that humans were exposed to in their environment.