All yeast will produce mostly ethanol with trace amounts of methanol. Its really not an issue with beer becuase the trace methanol is diluted in so much water it won't cause a problem. Even with distilled drinks, its only the first couple jugs that come off the still that has enough methanol to do damage becuase the methanol boils off first. Also the treatment for methanol poisoning is to drink more ethanol becuase it dilutes the methanol in your system.

I'm sure even with whatever weird yeast varieties they were using in Sumer no one got methanol poisoning becuase all they could make was beer mash.