I know it's not really a history question, but i've always wondered why there is this definite point in time where human societies began to form. We have a hundred thousand years old registers of humans using tools and trying out agriculture, but there is a lack of anything society worthy, no architecture or anything.
And then, it looks like there is a suddenly rush of civilizations emerging from nomads and bands of hunter-gatherers everywhere in the world that takes place 10 thousand years after the last iceage (what is not that much comparing with how long humans have been around.), i am pretty sure all major cultures we know do not date to far before that but i don't know why.
So, first thing first, but archaeologists don't use terminology and phrasing like "civilization", "major cultures", or "lack of anything society worthy" because they have implied value judgement. The implication is that sedentary-agricultural and state societies (what you are calling "civilization") are somehow superior to hunter-gatherer societies. Whether or not that is intended, it is implied and that value judgement doesn't help us understand human societies.
This is important in answering your question, because the answer is that for the majority of human history there wasn't an good reason to develop sedentary agricultural societies or state societies. For the majority of human history living in hunter-gatherer societies was very effective (in terms of survival) and so there was no necessity to develop an alternative.
The short answer to why did these sedentary agricultural and state societies develop all at once around 10,000 years ago is that the environmental and climate changes caused by the transition from the Pleistocene (the "ice age") into the Holocene at about that time both made agriculture (and consequently, state societies) both more necessary and more viable.
Take a look at this question from about a month ago that had a long discussion about the issue in more detail.