Is there any reason to think that Neandertals (or other near-homo sapiens predecessors) did not have out-of-control ZZ Top/Duck Dynasty facial hair? They're nearly always pictured as clean-shaven, but why?
Unfortunately historians can't answer this sort of a question. If there was ever a time that was "pre-historic" you've found it.
You might have better luck over at /r/AskAnthropology or perhaps even over at r/AskScience
I dabble in early human history and can tell you that it was a matter of hygiene and health. Early man was not stupid, he knew the dangers of keeping a beard which could make himself prone to infections and infestations as well as catching on fire or being pulled by another in a fight. However, early man also did not have the great antibacterial cleaning agents those Duck Dynasty fellows call shampoo.