Why Liberty?

I prefer the philosophical angle when thinking about liberty, starting with the clarification that comes from distinguishing a Liberty from a Right: A Right is paired with an obligation; a Liberty is not. On the other hand, perhaps there is something to be said for looking into the utility of liberty. It may be that, ultimately, the utility of Liberty and the philosophical basis of Liberty are two sides of the same coin - as Einstein expressed wonder at the utility of mathematics in explaining the behaviour of the physical universe. Who'd a thunk it? A relatively recent theory of the development of the human race came out of the discovery that the Rift Valley in Africa, where humans are thought to have first appeared, underwent a rapid (in geological/evolutionary time) series of drastic climate changes during that initial era of human development. Most evolutionary developments are thought to arise from the need to adapt to particular environments, but what development is needed to adapt to a rapidly changing environment? The answer is 'intelligence'. It is expensive to support a big brain, and quite unnecessary when the environment is relatively steady - slow physical adaptations will do the job. The only circumstance where a big brain pays off is when coping with rapid change is required.