Chapter 13 Advent of the Eukaryotes 300 About 1.5 billion years ago, after 2 billion years in which bacteria had the world to themselves, a far more complex type of organism arose, the eukaryote. Chapter 14 Evolution of Multicellular Life 320 Fungi are perhaps the most unusual of all multicellular organisms, as their cells share cytoplasm and nuclei. Chapter 15 Evolution of Plants 336 Plants successfully colonized the land in partnership with symbiotic fungi. The evolution of plants has been marked by the appearance first of vascular plants, then seeds, and finally flowers. The plant body is basically a vertical tube that grows in length at its tips and, in trees, also in girth.
Water is drawn up into the plant shoot from the soil when water vapor evaporates from the leaves.
The evolution of the animal body plan has been marked by a series of innovations that are reflected in the characteristics of the major phyla. Chapter 19 History of The Vertebrates 436 Vertebrates first evolved in water, where more than half of vertebrate species still live. The move onto land involved many changes in physiology and body structure. How Humans Evolved 460 Humans evolved from australopithecines in Africa only a few million years ago. The genus Homo appears to have spread from Africa several times.