Artist's rendering of an Australopithecus afarensis

When archaeologists hear whispers of humanity's past, it's through the painstaking work of piecing together a story from artifacts and fossilized remains: The actual calls, grunts, and other sounds made by our evolutionary ancestors didn't fossilize. But working backward from clues in ancient skeletons, Dutch researcher Bart de Boer

has built plastic models of an early hominin

's vocal tract---and, by running air through the models, recreated the sounds our ancestors may have made millions of years ago. Non-human primates have an organ called an air sac, a large cavity that connects to the vocal tract. The air sac links onto an extension on the hyoid bone

known as the hyoid bulla. Modern humans have neither an air sac nor an extension on the hyoid bone. But Australopithecus afarensis

---a hominin species that roamed Africa approximately 3.9 million to 2.9 million years ago---had a hyoid bulla, the fossil record shows, meaning it's highly likely it had an air sac, too. Using plastic tubing, de Boer built models of the human vocal tract both without an air sac, like modern humans, and with one, like A. afarensis would have had. By pushing air through the models, he could hear what various vowels sounded like with and without the air sac. Charles Harvey at New Scientistdescribes the sounds that resulted

:

The air sacs acted like bass drums, resonating at low frequencies, and causing vowel sounds to merge; [an Australopithecus] would have had a greatly reduced vocabulary. Even simple words - such as "tin" and "ten" - would have sounded the same to her. ... What, then, might our ancestors' first words have been? With air sacs, vowels tend to sound like the "u" in "ugg". But studies suggest it is easier to produce a consonant plus a vowel, and "d" is easier to form with "u". "Drawing it all together, I think it is likely cavemen and cavewomen said 'duh' before they said 'ugg'," says de Boer.

Read more---and listen recordings of the vocal simulations---at New Scientist

.

Image courtesy of 1997 / Wikimedia Commons