“A close look at Neanderthal dental records has shown that the ancient humans used a plant-based “aspirin” to treat pain and illness.”
That was around 180,000 years ago and the leaves they were chewing did actually contain the active ingredient in aspirin..
Evidence of opium use has been found in humans since 4300 BC apparently.
Then there was the small matter of the American Civil War and use of morphine on the battlefields for the first time..
that Neanderthal was chewing poplar tree leaves which contain the pain killer salicylic acid (the active ingredient of aspirin)