Where did life come from?
One of the common questions asked about evolution is ‘where did life come from?’ While the question is a fair one, the direct connection isn’t. Evolution explains how life adapts, not where it came from. Your mechanic doesn’t need to explain how steel is refined to fix your car: they’re different areas of science.
We know evolution occurs and have a broad understanding of it. The origins of life are somewhat more speculative. This doesn’t invalidate what we do know. Disagreement and challenges are what drives science forward. Theories that work are kept, theories that don’t are either refined or discarded. Such as...
Spontaneous generation.
This belief, that complex life rises fully formed, existed from ancient Greece well into the 1800’s. Essentially people believed that rotting meat spawned maggots, grain stores birthed mice and so on. It may seem ludicrous now but without modern knowledge of micro-organisms or reproduction, their logic is understandable. Careful experimentation and application of the scientific method eventually disproved the theory.
Does this mean that life cannot come from non-life? No. It means that complex life cannot spontaneously come into existence. But at a basic level, life is just chemicals. And chemistry happens all the time.
Abiogenesis.
At its core ‘natural selection’ means simply ‘there will be more of that which is better at making more of itself’. What follows here is my rough description of abiogenesis, the rise of organic life from basic elements.
Imagine, long ago, before any life on earth, an ocean vent, heat rising up from the earth’s core. You have lots of elements and energy. Elements form chemicals. Some of these can be self replicating, in a similar way to crystals ‘growing’. Amino acids can form in this environment. Some will break down but over time, those ‘better’ at building more of themselves become more common. These can become very long molecule chains. Amino acids can form proteins. They can form RNA then DNA. Like evolution this process takes time, many small steps accumulating.
The rise of life may seem improbable, but consider the vastness of our planet and the times scales involved. And remember, it only needed to happen once.
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