Final answer:
Evidence from reconstructing a Neanderthal throat and studying the larynx placement suggests that Neanderthals lacked the necessary anatomy for humanlike speech. The presence of a hyoid bone implies some capacity for tongue muscle anchoring, but it remains unclear if they could produce complex language. Modern humans, on the other hand, have a lower-placed larynx and possess the FOXP2 gene, which is linked to complex language understanding.
Step-by-step explanation:
Evidence supporting the idea that australopithecines were unable to speak comes from various sources. Philip Lieberman, a cognitive scientist, argues that Neanderthals lacked the anatomy necessary for humanlike speech. He reconstructed a Neanderthal throat and found that their vocal apparatus couldn't fit in the neck like it does in modern humans. Additionally, the placement of the larynx in Neanderthals was high in the throat, limiting their ability to produce certain sounds.
Furthermore, the presence of a hyoid bone in Neanderthals suggests some ability to anchor tongue muscles, but it is still unclear whether they had the capacity for complex language production. In comparison, Homo sapiens, or modern humans, have a lower-placed larynx and possess the FOXP2 gene, linked to complex language understanding. The ability to produce complex speech likely gave Homo sapiens an advantage over Neanderthals.