... If a few marks on your bow would help you judge the distance quickly and accurately...
Other organizations still try to maintain the fiction that none of their traditional archers have sights (or brains).
Please explain how a few marks on your bow help to judge distance.
Were this the case, the distance between the knuckles on the hand of your extended arm could be used for the same system. Maybe it was, and that's the answer to your question.
However I suspect that early man would be more reliant on a distance estimation based on experience and other visual clues rather than one requiring a formal distance measurement system and some sort of arithmetic. I think most hunting shots would be taken at 'point on' or closer.
Of course speculation is futile as the only thing we know is that we have no historical evidence for the use of sights in early archery.
Del
BTW, I don't think there is really any question regarding the presence of brains in the skull of even Neolithic man. His skill and intellect is self evident in his artwork, craft and survival even in a ice age.
Please don't fall into the modern trap of thinking that being able to use a mobile phone or credit card is a sign of superior intelligence.