Current scientific evidence indicates that life first appeared on Earth 3.6 billion years ago. To put this evolutionary span in perspective, it is helpful to telescope the entire process into a single year. By doing so, 1 day represents 10 million years, 1 hour covers 417,000 years, 1 minute spans 6950 years and 116 years flash by in 1 second.
Using this condensed calendar of life, chemoautotrophic bacteria, feeding on sulfides and other organic chemicals, develop along the mid-oceanic ridges early on January 1. By January 10, stromatolites of photosynthetic cyanobacteria appear in shallow bays across the globe. Eukaryotic cells, which contain cytoplasmic organelles, turn up by mid June and multicellular algae have evolved by late September. Complex, soft-bodied organisms, such as sea worms, jellyfish and soft corals evolve in late October and, by November 1, shelled marine life has appeared.
Early in November, star fish, mollusks, sea urchins and trilobites scour the ocean floor and jawless fish evolve by the middle of the month. Around November 20, plants and animals colonize the shore for the first time, a momentous event in the course of evolution. Sharks, boney fish, primitive arachnids, early amphibians and ferns grace the scene by November 24 and flying insects take to the air by the end of the month.
Horseshoe crabs and primitive reptiles are the newcomers on December 1, followed by frogs, lizards, modern corals and modern conifers on December 6. Turtles, crocodiles and the earliest dinosaurs appear by December 9 while the first mammals turn up on December 11. Flowering plants first adorn the Earth on December 16 and, 5 days later, ants and early marsupials make their appearance. Social bees and snakes evolve by December 23 while the dinosaurs become extinct on the next day (of course, some dinosaur lines live on as birds).
Primates first appear on December 25, followed by bats, whales, canids, ancestral horses, early ruminants and true monkeys on the 26th. Pigs and mastadons roam the land on December 28 and both apes and pinnipeds turn up the following day. Gorillas evolve in the early hours of December 31, followed by the first hominids at 7 AM, mammoths at 12 noon and polar bears at 11:15 PM. Modern man finally graces the planet at 11:42 PM and all humans living today have been present for less than a second!
