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wrote:
On 1 Oct 2004 07:46:23 -0700, (Bruce Jackson) wrote: wrote in message . .. Okay, you asked for it. A zebra is a black animal with white stripes. Occasionally, you get a zebra whose white stripes fail to form properly and are dashed, white dots and blotches instead of solid white stripes. How do we know that such zebras suffer from white stripes failing to form vs. black strips that grew together? Dear Bruce, The white blotches, dots, and dashes on the oddball zebra appear to be partially formed white stripes on a black background. There is no apparent narrowing of the white stripes consistent with the alternate theory of expanding black stripes, just the look of dashed white highway stripes. So in zebras, white stripes are caused by inhibition of dark pigment. The whole essay in "Hen's Teeth and Horse's Toes" is worth a look. (The preceding essay is also about zebras.) If nothing else, you'll learn that there are three species whose striping patterns differ according to when the striping begins during fetal development. Zebra striping is most notably different on the rump, which expands markedly during the fifth week of fetal development. So if the stripes are laid down before this expansion, they expand into big stripes, but if the striping occurs after the fetal rump has expanded, they will be narrower and more numerous. Gould lacked the courage to speculate about whether female fetal zebras worry about the stripes making their butts look big, but I think that we may reasonably infer that this is one of the causes of the notorious irritability of the creatures. Carl Fogel I think I better take my zebra back to the paint shop and have them reshoot it. |
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