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Science 26 January 1996:
Vol. 271. no. 5248, p. 448
DOI: 10.1126/science.271.5248.448
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Research News

Virginia Morell

Using a "protein clock," researchers have dated a basic split in the tree of life, between prokaryotes--cells without nuclei--and eukaryotes, to 2 billion years ago. The results, reported on page 470 of this issue, are at odds with some other studies, which have placed this division anywhere from 3.5 billion to 1.6 billion years ago. The scientists have also used this clock, based on differences among 57 different enzymes found in 15 groups of organisms from bacteria to baboons, to date the origins of all major groups of organisms on the planet.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Determining divergence times with a protein clock: Update and reevaluation.
D.-F. Feng, G. Cho, and R. F. Doolittle (1997)
PNAS 94, 13028-13033
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