Evolutionary biology is often posed anthropomorphically in the popular media, as if every form and function had purpose, a result predicated upon an intent, an intent being a rationally contrived solution put together in a process that involves reflection. Given that a lot of evolutionary biologists would reject the notion of a God, it is hard to see this as anything but a kind of intellectual skeuomorph, meant to ease a bitter pill.
But what about the other way of thinking about the purpose of life, as in, what natural laws or universal properties are satisfied by the presence of life? Assuming that life need not exist is easy: we have not seen it anywhere other than here on Earth, and even here we know that extremes of temperature, pressure, and acidity are incompatible with life. But life does exist here, so it is very safe to conclude that in some sense natural laws dictate that life must exist given the conditions reflected in the history of our environment.
People studying complex systems talk about phase transitions at the edge of chaotic regions. Somewhere along the way in this regime we call Earth, conditions went through a phase transition and life took shape as a result.
At that moment, the state of the system was at a fork in the road. One way led to life, and satisfied more laws with less energy or more entropy than the alternative. But which laws?
And life will stop whenever some laws are no longer satisfied, for instance if there is too much energy, or too little. The threshold for continued life is probably different from the original formation, based on environmental changes introduced by the byproducts of living systems, but it is a similar question: what laws are being satisfied by the fact that a living system populates a medium, instead of it remaining sterile?
Edit: in case anyone is so befuddled as to wonder why anyone would ask such a question, the subjects involve autocatalytic chemical reactions, autopoietic structure, and the emergence of order among oscillating parts, among other very fundamental processes.