Word: fossils
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Less familiar is the havoc wreaked on the nitrogen cycle. Through the use of fertilizers, the burning of fossil fuels and land clearing, humanity has doubled the levels of nitrogen compounds that can be used by living things. But those levels are more than can be efficiently absorbed by plants and animals and recycled into the atmosphere. These excess nitrogen compounds wash into fresh- and saltwater systems, where they produce dead zones by stimulating suffocating growths of algae. Since the global food system is based on aggressive use of fertilizer, restoring the balance of the nitrogen cycle poses a daunting...
...only way to slow it down, almost every scientist agrees, is to restructure the way we produce energy. Such stopgap measures as insulation, carpooling and energy-efficient light bulbs are all useful ways to begin curbing the burning of carbon-rich fossil fuels. But in the long run, as the world's population continues to increase and living standards rise, these measures will not be enough...
...life that we know, however wondrous in extent and variety, all proceeds--or so our best inferences tell us--from one single experiment. The biochemical features underlying this amazing variety and the coherent fossil record of 3.5 billion years (implying a single branching tree of earthly life with a common trunk) indicate that every living thing on Earth, from the tiniest bacterium on the ocean floor to the highest albatross that ever flew in the sky, arose as the magnificently diversified evolutionary outcome of one single experiment performed by nature, one origin of life in the early history...
...evidence consists of tiny fossilized ankle and foot bones uncovered in central China beginning in 1995. Painstakingly analyzing their find under a microscope, Daniel Gebo of Northern Illinois University and his colleagues identified features common to both anthropoids and their more primitive forebears. "There's always been a big hole between the earliest fossil anthropoids and prosimians," says Gebo. "The fossils were either true anthropoid or true prosimian; we've never found anything in between until...
Continuing their excavations, Gebo's team hopes that prize may yet turn up at the fossil-rich site in China. But even without it, dawn monkey's tiny feet have given us the best glimpse so far of what our primate forebear might have looked like...