An event as simple as the world’s first bite may have sparked an ancient “explosion” of life 500 million years ago that led to the rise of the broad groups of animals that are still alive today.
The cause of what is known as the “Cambrian Explosion” — which occurred during the Cambrian Period 542 million to 490 million years ago — has puzzled scientists for years. Theories about the event’s cause include an increase in the amount of atmospheric oxygen, a recovery from a global glaciation, and key genetic changes in precursor animals that allowed the development of bilateral symmetry, hard shells and bones, and rapid locomotion.
Harvard Professor of Biology and of Geology Charles Marshall presented his alternate theory Tuesday (April 29), suggesting that it was an increase in interactions between species, such as predation, that drove an escalating evolutionary process that led to the development of teeth and claws and the wide variety of characteristics that we see among Earth’s animals today.
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