I can’t remember which class I heard it but I once heard a presentation that was so jarring at first and eventually became one of the most romantic stories I was ever told and one of the reasons why I take great offense to people who believe science is without romance or spirituality.
If I remember correctly the presentation started off with, ”What’s the most important thing in human biology? The ocean.”
Quite a hook. The lecturer went on to explain that early life was of course aquatic and once multicellularism arose eukaryotic life started evolving systems that were more and more complex. However at every stage chemical transport was still largely dependent on saltwater bathing the cells of the organism at all times. Additionally seawater is slightly alkaline so it acts as a buffer that maintains protein in a way that pure water cannot.
So how did we move to land and how could Homo sapiens have appeared? The evolution of circulatory systems and blood. You see, blood serves the purposes that the saltwater did when it came to supporting cellular transport and stability. The beautiful and romantic thing the lecturer suggested is that we carry our evolutionary history wherever we go.
The blood in your veins is your body’s remembrance of the sea from which we all came.