Ancient Maya reservoirs contained toxic pollution: study

History is replete with disappearing ancient dynasties and I highly doubt all the declines of civilizations had identical historic continuums. I am guessing the declines can be due to over population, famine, droughts, wars, and disease.

Interesting read. Not sure I agree, as at the time attributing illness to the water would have been a leap.

So pollution was a problem back then as well.