title: Seed size variability: from carob to carats.
abstract: The seeds of various plants were used as weights because their mass reputedly varies so little. Carob (Ceratonia siliqua), which has given its name to the carat, is particularly famous in this regard. But are carob seeds unusually constant in weight and, if not, how did the myth arise? The variability of seeds sampled from a collection of carob trees (CV=23%) was close to the average of 63 species reviewed from the literature (CV=25%). However, in a perception experiment observers could discriminate differences in carob seed weight of around 5% by eye demonstrating the potential for humans to greatly reduce natural variation. Interestingly, the variability of pre-metrication carat weight standards is also around 5% suggesting that human rather than natural selection gave rise to the carob myth.
authors.affiliation: Institute of Environmental Sciences, University of Zürich, Winterthurerstrasse 190, Zürich 8057, Switzerland. lindsayt@uwinst.unizh.ch
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Turnbull
authors.forename: Luis
authors.initials: L
authors.lastname: Santamaria
authors.forename: Toni
authors.initials: T
authors.lastname: Martorell
authors.forename: Joan
authors.initials: J
authors.lastname: Rallo
authors.forename: Andy
authors.initials: A
authors.lastname: Hector
mesh_terms: D007887:Fabaceae / Q000235:genetics*; D014644:Genetic Variation; D008954:Models, Biological; D018521:Plant Physiological Phenomena; D012639:Seeds / Q000737:chemistry*; D013045:Species Specificity; D014197:Trees