Which hominid could speak a language?

This is a tricky question, as we don't have direct evidence of language use in any extinct hominid species. We can only infer based on their brain size, anatomy, and archaeological evidence.

Here's what we know:

* Neanderthals had brains comparable in size to modern humans and some evidence suggests they may have had a form of language, perhaps even with a grammar system.

* Homo erectus had a smaller brain than Neanderthals, but still larger than earlier hominids. They created sophisticated tools, used fire, and likely had some form of communication.

* Australopithecines had much smaller brains and likely had more limited communication abilities.

Therefore, it's impossible to say definitively which hominid could speak a language. The ability to speak a complex language is likely a gradual development over time. We may never know for sure, but research continues to shed light on the evolution of language and its origins.