Talk, and the use of hand language by the mute and deaf, more than any other characteristic identifies human beings as human beings. Other species gesture and use body and facial signs which communicate iintention and feeling, and they make noises called "calls." Calls are signs which can be communicated and understood by othe members of the species or community, but they are not language. They are mostly genetic and they are not symbols, not words. Language probably evolved from calls.
We humans have very few calls: laughing, sobbing, groaning, screaming in fear. sighing, and crying with pain.
Did our immediate non-speaking ancestors have more? Probably not many. Primate species have between fifteen and forty calls. Those "most like us:" Bonobos, Chimpanzees, and Gorillas are close to the lower limit-- 14, 15, and 17 respectively. I am guessing that a large number of calls is more useful but prevents learning new ones; small numbers of calls would require the development of other means of communication, more varied gestures or facial expressions, or the invention of speech.
One imaginative anthropologist came up with this suggestion. Suppose a homo-sapient species has a very limited number of calls, one such call warns of peril, another announces the presence of food. A group is very hungry. A member of the group, out of sight of the others, comes upon food, but it is being eaten by predators who also prey on his or her species. If she announces danger the group might not eat, if he announces food some of the group may be eater. Being unusually sapient she ponders her choice. the situation demands both calls or neither; she starts the food call, then breaks it off and starts the danger call. Some equally wise member of the group guesses that this new, strange call might mean "food and danger, approach with great caution." If the group is successful an invention has occured, The call system has been broken open, the new call is not just a call, it is a symbol that was not genetically programmed; it is something like a word, even a sentence.-- a proto-word, a proto-sentence. Having occurred once accidentally with success, it can happen again with deliberation. Evenually a language will evolve, with rules of contruction and thousand, hundred thousand and million word vocabularies
Humans have taught "language" to Bonobos, Chimpanzees, and Gorillas. These have typed or otherwise signaled up to 300 "words," and expressed understanding of over 3000. They have not, as yet, so far as we know, invented a language nor taught a language to another member of their species.
Most of us would agree that the move from call systems to languages was an important innovation
which enriched our lives immensely. A few might disagree. Language makes deception much more possible, it makes lying possible. It transforms the real world into the world of illusions, maya. Perhaps this is why monasteries limit speech and mystics recommend silence.
For Buddhists, the end is the abolishion of suffering; the means is the eightfold path.* An important aspect of the 8-fold path is right speach. I said speech should be useful. Perhaps it would be more Buddhistlike to say that speech should be helpful rather than hurtful. Mother would have had at least one toe on the eightfold path. She said: "if you can't say something good about a person, don't say anything at all." Mom, sadly, was not very good at following her own advice. But i try to imagine what it would be like to follow such advise for a day or a year. I couldn't say: "mom wasn't very good at following her own advice," that was hurtful and unhelpful. Words are tools that can build or destroy.
*The eightfold path includes: Wisdom training (1. Right perspective. 2. Right inention); Ethics training (3. Right speech, 4. Right Action, 5. Right livelihood); and Meditation training (6.Right effort. 7. Right mindfulness, and 8. Right contemplation.