How Do We Know They Could Talk?

From Snake Jazz by Dave Baldwin:

Many years ago, I attended one of Professor Frederick Hulse’s anthropology seminars at the University of Arizona. There, a student asked Dr. Hulse how we might know, from archeological evidence, that people were capable of speech. Dr. Hulse replied, “We can be sure of this, at least, when we find graves containing old people.” His reasoning was that old people aren’t much good for doing anything but talking. If they are found in graves, they must have been kept alive for many years because they had some value to their society. They were given the opportunity to get old because they had something to say that was deemed worth listening to.