Want to see an enduring source of scientific dispute and perplexity? Go to your refrigerator, open a carton of eggs, and look at their speckles. Bird-egg coloration has been studied for more than a century. In a review in the Journal of Avian Biology, biologists Golo Maurer and Phillip Cassey present no fewer than seven possible explanations for eggshell color. Each focuses on how colors might shape an embryo's fate by modulating sunlight hitting its shell.
Their ideas stand in contrast with most earlier explanations, the fates of which were shaped by a late-19th century debate between biologist Alfred Russel Wallace and little-known naturalist Alexander M'Aldowie. According to M’Aldowie, eggshell pigment shielded embryos from harmful radiation. According to Wallace, they provided camouflage from predators.
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