in the replay, we are wiped out of future history—all of us, from shark to robin to orangutan... And so, if you wish to ask the question of the age—why do humans exist?—a major part of the answer, touching those aspects of the issue that science can treat at all, must be: because Pikaia survived the Burgess decimation.This interpretation that the chances of evolutionary products are unpredictable is known as evolutionary contingency. Gould, from this statement, is regarded as "the most famous proponent" of the concept. His idea has inspired many research involving enolutionary contingency from palaeontology to molecular biology. He used Pikaia among the Cambrian animals as an epitome of contingent event in the entire evolution of life; if Pikaia had not existed, the rest of chordate animals might not have evolved, thus completely changing the diversity of life as we know. According to him, contingency is a major factor that drives large-scale evolution (macroevolution) and dictates that evolution has no inevitable destiny or outcome. However, as Gould explained, "The bad news is that we can't possibly perform the experiment." Notes References Further reading Bishop, A., Woolley, A. and Hamilton, W. (1999) Minerals, Rocks and Fossils. London: Phillip's Conway Morris, Simon. 1998. The Crucible of Creation: The Burgess Shale and the Rise of Animals. Oxford University Press, New York, New York. Norman, D. (1994) Prehistoric Life: the Rise of the Vertebrates, London: Boxtree Sheldon, P., Palmer D., Spicer, B. (2001). Fossils and the History of Life. Aberystwyth: Cambrian Printers/The Open University. p. 41-42. External links La evolución de las especies: ¿por qué sobrevivió Pikaia? (Spanish) Fossils of the Burgess Shale - Middle Cambrian Pikaia gracilens Walcott, a stem-group chordate from the Middle Cambrian of British Columbia Cephalochordata Prehistoric chordate genera Cambrian chordates Burgess Shale animals Transitional fossils Fossil taxa described in 1911 Taxa named by Charles Doolittle Walcott Cambrian genus extinctions