When and where did atheism first start ?

[Belacqua]

Yeah, the default for human beings is definitely thinking about the world in terms of non-human spirits..... 

I think I was clear that I wasn't talking about modern humans. I think the concepts were still fuzzy for very early humans, and the ideas of what was alive, and what had emotions, and what needed to be cooperated with, was nowhere near what it is for us on this forum. 

That is why theism is not a learned behaviour, we're all definitely born with theistic tendencies, and no faith is required.

I think we have built in desires to explain how the world works. Maybe it works like a language -- the desire and the basic structure is built in, but the specifics are learned from whatever society the child finds herself in. In a religious society, she learns religion as the explanation. In a logic-only society, she learns logic as the explanation. 

If we take the term "faith" in its simplest sense, to mean "I'm pretty sure it's true,"  then a child raised in a logical household will have faith in logic. 

Just because our ancestors were too sodding thick to work out what thunder was, doesn't mean that woo is hard wired into us.

That particular woo isn't hardwired into us. The general desire to find explanations probably is. Some explanations will be a lot better than others.