Environmental Problems, Their Causes, and Sustainability 1

Modern humans(Homo sapiens sapiens)appear about2 secondsbefore midnight530 million years 370 millionyearsFirst fossilrecord ofanimals225 million yearsInsects andamphibiansinvadethe land6965 millionAge ofreptilesPMyearsAge ofmammalsmidnight12Recorded humanhistory begins1/4 secondbefore midnightOrigin of life(3.6–3.8 billionyears ago)AM36570 million years39Plants begininvadinglandEvolution andexpansion of life12noon780 million years1 billion yearsFigure 5-3 Natural capital: greatly simplified overview of the biological evolution of life on the earth,which was preceded by about 1 billion years of chemical evolution. Evidence indicates that microorganisms(mostly bacteria and, later, protists) that lived in water dominated the early span of biological evolution on theearth, between about 3.7 billion and 1 billion years ago. Plants and animals evolved first in the seas. Fossil andrecent DNA evidence suggests that plants began moving onto land about 780 million years ago, and animalsbegan invading the land about 370 million years ago. Humans arrived on the scene a very short time ago. Wehave been around for less than an eye blink of the earth’s roughly 3.7-billion-year history of biological evolution.Although we are newcomers we have taken over much of the planet and now have the power to cause the prematureextinction of many of the other species that travel with us as passengers on the earth as it hurtlesthrough space.http://biology.brookscole.com/miller1489