科学美国人60秒:Ancient Human Ancestors Heard Differently

Imagine the evolutionary advantage of being able to hear a predator rustling in the tall grass nearby—or in the ability to hear a comrade making a (make a titch sound, like calling a horse) sound to warn you about that predator. Now a study finds that early human species may have had sharper hearing in certain frequencies than we enjoy. The finding is in the journal Science Advances. [Rolf Quam et al, Early hominin auditory capacities]

“We’ve been able to reconstruct an aspect of sensory perception in a fossil human ancestor known as Australopithecus africanus and Paranthropus robustus from South Africa.”

Binghamton University anthropologist Rolf Quam.

“Both of these fossil forms lived about two million years ago and represent early human ancestors. We took CT scans of the skulls. We created virtual reconstructions on the computer of the internal structures of the ear that will predict how an organism hears based on these measurements of its ear.”

And the reconstructed physiology reveals that those early hominins likely heard differently than both modern chimps and modern humans.

Specifically, the hominins were probably more sensitive to frequencies associated with sounds like t, k, f, and s.

“We’re not arguing they had language, but we think our results do have implications for how they communicated. And the finding is that this hearing pattern would have been beneficial if you were engaging in short-range vocal communication in an open environment.”

The estimation of the hearing abilities of the hominins complements previous research suggesting that these species spent more time in open environments such as the savannah—where a hasty, short-range consonant from a comrade might convey important information—than they spent in  dense rainforests, where sound travels farther. Could be that (make a few consonant sounds) were survival tools that also paved the way for the evolution of full-fledged human language. Even if we can’t hear those sounds quite as well as those ancient hominins did.

—Cynthia Graber

[The above text is a transcript of this podcast]

Quam audio provided by Casey Staff