Ponderings of a Scientist

Why are oceans important? We modern day Homo sapiens are products of the ocean. Most obviously, we are distant descendants of ocean dwelling organisms. Single celled organisms originally developed (3.7 bya) from inorganic molecules in (or above) the ocean over the course of billions of years. These prokaryotes evolved and branched into bacteria, fungus, plants, fish and amphibians. During this time terrestrial Earth lay barren. Not until 200-400 million years ago did life climb out of the oceans and onto land. Although humans are terrestrial beings, we keep inside of us relics of our wet evolutionary history. First, our blood is a mix of chemicals very similar in composition and salinity to that of the ocean. This is likely because the first organisms to develop circulatory systems had open systems that circulated ocean water in, through, and out their bodies. Eventually our ancestor closed off its circulatory system trapping in the ocean water. That fluid has hence evolved into our blood. Second, “Ontogeny Recapitulates Phylogeny” (the embryonic development of an organism repeats the evolutionary history of it’s species). Embryonic and fetal humans develop in their own personal oceans and as they develop they pass through stages that are very similar to the embryonic and adult bodies of our aquatic ancestors.