Life in the Beginning

What is Life

Carbon

When Did Life First Appear on Earth

How did Life First Appear

The First Inhabitants

Building blocks of life are in space

Essential Elements of Life

Window of Opportunity has increased

Panspermia, Comets the Galactic Taxis

Window of opportunity for life to evolve is larger than once thought
So we can see that the bio-molecules, the building blocks of life, most likely existed in the clouds of material, massive molecular clouds, from which the Earth and the rest of the solar system was formed, since we see them across our galaxy in similar massive molecular clouds. They exist in comets. And meteorites have also been found to contain amino acids, implying that the building blocks of proteins were present in the material from which the Solar System formed thus making the case for the cosmic origin of Earth's amino acids. Carboxylic acid and sugars have also been found in meteorites further strengthening the cosmic origin of life's building blocks.

So these distant molecular clouds, or stellar nuseries, thousands of light years away from us, which may eventually form more solar systems contain sugar and amino acids. So the chemical precursors of life must actually form in clouds long before planets develop in a solar system. But the build up of complexity can only proceed so far in molecular clouds. To proceed further would require a terrestrial planet in a habitable zone of a solar system. But how do they get to the surface of a planet in a habitable zone like Earth? Comets appear to be the most likely suspect.

So the time available for chemistry to take the step from non-living to living has dramatically increased. It was thought that this must have happened from the formation of the Earth 4.5 billion years ago to 3.8 billion years ago when the first signs of life were identified. But now this could have happened billion of years before the solar system was formed since the universe is approximately 14 billion years old.

So did life originate on Earth or on the icy materials of molecular clouds, the materials from which the stars and planets are formed. If the latter, life is likely to be common across the universe. Does this mean that all life stems from the same basic components, amino acids and sugars? Although not necessarlily the ones we are made of.

And it should be noted, that the fact that all living things are made up of combinations of the same 20 amino acids, as distinct from the more numerous remaining amino acids is strong evidence that all life has descended from a common ancestor.