Stebbins, Ledyard G.
Ledyard G. Stebbins is a botanist. He is also the author of Processes of Organic Evolution, 3d ed.
The evolution of species is not caused by the urge of individual organisms toward something better, nor is it a series of trends from the simple to the complex. Darwin to DNA, Molecules to Humanity, 1982.The theory of evolution aims to explain the processes underlying phenomena as diverse as the grandeur of a giant redwood, the intricacy of an orchid, the complex society of a beehive or anthill, the efficiency of a tiger spring at its prey, and the capacity of human beings to create masterpieces of art. music, and literature. Ibid.
Most physicists, chemists, and biological evolutionists agree that the evolution of organic molecules began about 4 billion years ago. The first living cell appeared about 3.5 billion years ago, and the first simple many-celled animal appeared roughly 600 million years ago. Ibid.
The common ancestor of apes and humans appeared some 6 million years ago, and the beginning of recorded history was about 6,000 years ago. Ibid.