Humanity language is the result of some dramatic evolutionary changes over the last few million years, which have reshaped our old primate vocal organs into the more sophisticated organs we use today. So what did all this change sound like?
That's the question University of Amsterdam researcher Bart de Boer attempted to find out, using some plastic tubes and puffs of air to recreate how our distant hominid ancestors sounded like millions of years ago. a key shift in the last three million years has been the loss of the air sac, a balloon-like organ that all the other primates need to make deep booming noises. In humans, this air sac has become a vestigial organ like tonsils or the appendix, and freeing up that space in our vocal organs has allowed us to create a much richer mix of sounds.
Conversely, old hominids still had the air sac, such as the specimen "Lucy's baby", named for the more famous specimen Lucy and much like her an Australopithecus afarensis girl from 3.3. million years ago. This would have meant they had a much more limited repertoire of sounds they could make. We know she still had the air sac because of the presence of the hyoid bulla, a skeletal feature to which the air sac anchors itself.
To mimic the air sac, de Boer created artificial vocal tracts using the plastic tubes, half of which featured an extra chamber where the air sac would be. He then could force air down the tracts and, depending on how he arranged the tracts, they would create different vowel sounds. He recorded these vowel sounds and then played them for 22 people, asking them to identify the various vowel sounds they heard.
De Boer added and subtracted noise over the recordings based on how well the subjects could identify the different sounds. He found that those listening to the more modern vocal tracts could identify vowel sounds through far more noise than those who wee listening to the air sac tracts. Basically, the air sacs were like bass drums, which created low frequency resonance and, in turn, made the vowel sounds combine and become indistinguishable.
This means that Lucy and her people would have had tremendous difficulty distinguishing between even the most basic of words - something like "tin" and "ten" would sound essentially the same to her, meaning their potential vocabulary would be greatly, greatly reduced. The air sacs also limited the ability to create consonants, making lengthier words with several different sounds in it all but impossible to say.
As for the first word spoken by our ancient ancestors, de Boer has come up with a rather amusing possibility. He says that most vowels tend to sound like the "u" sound in words like "ugg" - which makes cartoon depictions of cavemen where they make sounds like that surprisingly accurate. However, cavemen probably didn't say "ugg", because it was easier to form words with the consonant first followed by a vowel. And the easiest consonant to put before the vowel "u" happens to be "d." Yes, before any other word, it's possible our ancestors were just saying, "Duh." Seems so obvious now, doesn't it?