IMO, this is why some contemporary science gets such a bad reputation. You state an estimate range going back perhaps as much as 500,000 years. But not 600,000? Not 700,000? No, no, but 500,000 is a definite possibility (more recent is more likely, of course, but the range of informed estimates goes back as much as 500,000 years).
And with all that, exactly how much evidence do you have for gestural communication within this timeframe? Any fossilized one-finger salutes?
Answer: You're guessing, conjecturring, and supposing. And you're calling it science.
Your alternative is exactly what? That {poof} something happened by a process that no one knows about?
That {poof} there was a talking snake? Never one seen ever since.
I agree with you that it is impossible to know how language started, but it seems to me understandable in terms of development of brain capacity, use of symbols, evolutionary development of the vocalization apparatus in our throats, and an obvious benefit for early humans in family/ tribal societies. It is interesting that writing is only about 8,000 years old.
"Contemorary Science" (I have to guess at what you mean by that) has a great reputation amongst educated people. What makes you think it has a bad reputation? I don't think the Global Warming pimps have undone the mapping of the Genome.
You state an estimate range going back perhaps as much as 500,000 years. But not 600,000? Not 700,000? No, no, but 500,000 is a definite possibility (more recent is more likely, of course, but the range of informed estimates goes back as much as 500,000 years).
Scientific estimates of what happened a long, long time ago tend to point to magnitude. 1/4 million, 1/4 million, it ain't billions.
When a chemist measures the concentration of a substance in the laboratory or a physicist predicts the orbit of a comet, their results are likely to be accurate to within tiny fractions of a percent. This is because they can repeat their experiments and observations again and again, until they get accurate models, with which they confidently make predictions. During the past few centuries we've used the very accurate results of experimental scientists to make lots of useful things that almost always work the way we expect them to. That has given 'science' the reputation it has, so almost everyone agrees that its a good thing to make decisions based on science.
When a geologist says something is 72 million years old, or an anthropologist says a stage of human development took place 250,000 years ago, no one is particularly suprised if the same people come back five years later and say they were off by 25%. That's because there is only one earth, and they can't go back and repeat all of history a few more times to make sure their observations were correct. Their work is interesting because over time it gives us a clearer picture of the history of our world; however earth science is not usually useful as a basis for policy decisions, because it is simply based on collections of observations rather than repeatable experiments.
It is ironic then, that the groups of people clammoring for policy decisions based on 'science' are not experimental scientists whose work is verifiably accurent, but the 'earth scientists' whose results may well be off by 25%, 50% or an order of magnitude. Skeptics who question the wisdom of policy decisions based on observations of unrepeatable events are not Luddites who reject science. They simply understand the importance of repeatibility to the scientific method.