Evolution

In its broadest formulation, evolution is change over time. Massive evidence—from fossils, biology, morphology, organismal behavior, biogeochemistry, ecology, and cosmology—reveals life evolving since its inception over 3.5 billion years ago. Evolution may be seen as ecology operating over vast periods of geological time (Hutchinson 1965), little of which—less than.00028 of which—has been graced or marred by the presence of humanlike beings. Recent efforts in anthropology to grapple with interspecies communities may in part reflect the doubling of the human population in the last half-century (Sagan 2013; Kirksey 2014). Such growth, tentatively connected to global climate change and more definitively to a human-caused mass extinction (Kaufman and Mallory 1993), has been historically supported by both religious anthropocentrism and secular politics advocating economic growth. However, over the evolutionary long run, very few life forms have grown exponentially and maintained their population numbers. One exception is the cyanobacteria, whose rapid growth some two billion years ago led to an increase of free oxygen from under 1 to 20 percent of Earth’s atmosphere (Margulis and Sagan 1997). Descendants of these organisms are now symbiotic as the green parts, or plastids, of algae and plants. An eco-evolutionary perspective suggests that for humans to survive in the long run we must become more attentive of, and connected to, the planetmates that support us within the long-lived global ecosystem.