Here's why:
* Brain size: Australopithecus had relatively small brains compared to modern humans. Language requires complex brain structures and cognitive abilities that likely weren't present in these early hominins.
* Vocal anatomy: While some Australopithecus species may have had the physical capacity for basic vocalizations, their vocal tracts were likely not as flexible as modern humans, making complex speech production unlikely.
* Lack of evidence: There's no archaeological or fossil evidence to suggest that Australopithecus had any form of language.
It's important to remember that language is a complex evolutionary development. While early hominins may have had some form of communication, it's highly unlikely to have been anything resembling the sophisticated language we use today.