When and where did atheism first start ?

[Belacqua]

Some people say that everything was just atheist until some guy invented the concept of god. 
That's a lazy excuse to avoid real thinking.

No it isn't. How would you label early humans in a time before we invented Gods, and everyone had a lack of belief? Okay the word atheist isn't a perfect fit but it's close enough for me. 

When you say "before we invented gods," it sounds as if we were going along with no notion of gods and then came up with the idea out of whole cloth. 

That strikes me as too simple, and as projecting modern thinking backwards where it doesn't belong. 

People tried to figure out how the world worked. They attributed various events to various kinds of forces and agents. Some of these are what we would now call natural, and some weren't. Some were anthropomorphized, and some weren't. 

Gawdzilla and other lazy thinkers act as though people used to be honest empiricists until some guy had a fantasy. That suits the general anti-religion ideology around here, but it's a comic book view of history.

You are sounding like someone who is pushing the idea of some sort of intentional design, like we were destined to invent Gods through an 'inbuilt need'. I'm not buying it.

This is your interpretation, but it's not what I'm saying.

I'm saying that when early humans tried to explain the world, it was natural and understandable that they would picture causal agency, other-than-human powers, and thinking agents that reflected the way they themselves thought. If early humans were at all thinking beings, offering the very earliest explanations for how things work, it is close to a default premise for them to assume that other things work the way we do. Only bigger, in the case of volcanoes, for example. 

Before any such explanations occurred to early primates, it makes sense to call them atheist in the sense that dirt is atheist, or the empty space in a box is atheist: it lacks belief because it has no belief. It has no belief because it has no abstract thought or the capacity to try to explain.