By studying fossils, scientists have determined that, indeed, prehistoric people probably talked to each other in some form of language.
We can’t say when, exactly, language developed, but 2-millionyear-old fossils of human skulls show the two specific bulges where the brain now controls speech.
The bulges appear in the left side of the brain. One controls the physical movements for speech and the other is necessary for understanding speech.
Specimens of Homo erectus, Homo habilis, and Homo sapiens all show these bulges.