Alex McColgan

But why?

What really is the difference between a man-made machine and mankind?

Charles Darwin's work on evolution and the origin of species crystallized the idea that life evolves and that all life began from one common ancestor.

Therefore, I should infer from analogy that probably all the organic beings which ever have lived on this earth have descended from some one primordial form into which life was first breathed.

And there it is, emergence, life from chemistry, something different than the sum of its parts.

Darwin understood that life needs no designer.

It is able to be more intricate than a watch without a designer because it is a complex, adaptive system driven by natural selection.

It has the ability to evolve.

A watch is merely complicated.

But before we go back 4 billion years to uncover life's genesis on Earth, we should probably all agree on what it is we're looking for.

What do you think defines life?

What makes something alive?

If you're struggling for an answer, don't worry.

Even NASA can't get three words into their definition without being challenged.

This is science at the bleeding edge.

NASA defines life as a self-sustaining chemical system capable of Darwinian evolution.

Prominent scientists argue that life is not strictly self-sustaining.

Life requires an environment with which it has a dynamic relationship, where life draws its energy and raw materials and expels its waste.

An environment that is full of free energy, an environment that sustains life.

Life's relationship with its environment is crucial to understanding how life is possible.