If you want a long and detailed answer to this question, check out "The Origins of Political Order" by Francis Fukuyama - the whole book is answering the question of where political organisation came from.

The book goes into various historical examples of where political order came from - even going to pre-history. So I guess it might depend on your definition of "government".

For example, apparently political hierarchy emerged partially biologically (see: primates), but external factors can often force a group of homo-sapiens to form groups in which leaders emerge - such as an outside military threat.

As for how we regard government today though, the argument he makes is that there are three main things that make modern states/governments:

• Strong government (can the government/rulers enforce laws?)
• Accountable government (how is the government held to account?)
• Rule of law (how is government forced to act in a non-arbitrary way, within the constraints of law)

These all emerged at different times and in different places (and arguably are not universal today). For example, he argues that rule of law emerged in Europe thanks in part due to the Catholic church providing an alternative power-base to secular rulers, acting to constrain some actions and legitimate others (the Holy Roman Emperor wasn't truly the Emperor until the Pope had given him the nod). In India it was similar the religious class which lead to the adoption of rule of law. China, he argues, doesn't have a rule of law tradition which is arguably why it experiences totalitarian government today.

Another nice example is in terms of accountable government. Fukuyama notes, for instance, that in most societies throughout history when there has been a transition of power, there has generally been a gathering of elders to legitimate it (these days we have elections, in ancient China all the rich and powerful people got together, in Afghanistan they'd have a loya jirga, etc).

Essentially, its complicated! And depends how you define "government".

Obviously this isn't a complete answer - but I thoroughly recommend the book, even if it'll inevitable receive criticisms for being too teleological.

(nb: not a historian, just an enthusiast here!)