In this portrait of Earth, at just about the midpoint of its probable lifespan*, a biologist discusses the evolution* of the network of life and the key role played by humans in determining* the future of our world.

    Unlike most books on earth history, which present the story of life on our planet in terms of one chronological* period after another, the author discusses Earth’s rich diversity* in terms of important evolutionary developments. Among these he explains the importance of symbiosis*, sex, and altruism* as the reason for Earth’s biodiversity. When single cells began working together, it sparked the sudden appearance of complex animals. Much later symbiotic relationships led to flowering plants that depended on animals for pollination* and seed dispersal*. With sexual selection, there developed a surprising world of complex behaviors and a huge array* of life forms.

    In humans, sexual selection had a great influence on the development of our large brains.

    When species learned to work together, this resulted in even greater variety and complexity. In early humans, altruism gave rise to ever-widening social circles and the spread of culture.

    The author also discusses the role of photosynthesis* in establishing and maintaining life on earth; the evidence for ancient natural disasters, which caused extinctions*; and the importance of religion and the recent use of scientific reasoning in the development.

    This panoramic* perspective is well presented to arouse* in readers an appreciation for life on Earth and to encourage wise command of the natural world on which our future depends.

    (SD-Agencies)