One thing that being a scientist has taught me is 

that you can never be certain about anything. 

You never know the truth. 

You can only approach it 

and hope to get a bit nearer to it each time. 

You iterate towards the truth. 

You don't know it.

Evolution is a tightly coupled dance, 

with life and the material environment as partners. 

From the dance emerges the entity Gaia.