Spring Recapitulates Evolution

First the leaves come back, photosynthesizing to produce the energy the animals will consume for life as well.

Spring provides a kind of annual recapitulation of the evolution of life on Earth, an opportunity to celebrate anew the greening of the planet three and a half billion years ago by the first photosynthesizing bacteria. All life—the whole glorious parade along the path—depends upon the photosynthesizers. As spring dresses the deciduous woodlands in its Easter best, the nonphotosynthesizers get moving too. Suddenly the woods are skittering, fluttering, munching. singing. From rock-hard seed cases, from underground burrows, from twiggy nests high in the trees. from behind the bark of trees they come, to eat plants, or to eat the creatures that eat plants, or to eat the creatures that eat the creatures. . . . With the invention of photosynthesis, life plugged into a star. and the battle against entropy was won. The universe continues to run down, as it must, but on the surface of the Earth there spreads out a film of highly ordered matter of marvelous complexity and resourcefulness. The one-celled organisms that ruled the Earth 3 billion years ago were no more advanced than the scum that lives on our shower curtains, but that scum had evolved the ability to make carbohydrates with sunlight. These sunlight-trapping bacteria later lent their talents, as chloroplasts, to the first time plant cells; every cell in every tree in the wood lands contains these organelles that were once bacteria living on their own. Animals developed along a different branch of the evolutionary tree, and it seems unlikely that you and I had photosynthesizers among our ancestors. But the tree of life is a web of interdependence. Green leaves are our necessary link to our yellow star.