... Science Frontiers ONLINE No. 35: Sep-Oct 1984 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Getting The Pouch Right When we think of kangaroos hopping about Australia (which isn't very often), we know that all baby kangaroos are safely "buckled in" their mothers' pouches -- nature's own vehicle restraint system. How fortunate it is that kangaroo pouches open at the top; otherwise, little kangaroos would be falling out all over the place. While some marsupials have pouches opening "up" or "forward" in quite a few others evolution got the directions for pouch manufacture reversed. The koala, the wombat, the thylacine, and the marsupial mole all have backward-opening pouches. Obviously, a forward-opening pouch on the mole would act like a dirt scoop, to the great inconvenience of any occupants. On the other quadrupeds, the backwardopening pouch may protect the young from branches and vegetation. (Marshall, Jeremy H.; "Directional Pouches," Nature, 309:300, 1984.) Comment. This is an example of the socalled Problem of Perfection, where life seems marvelously attuned to its environment; that is, "fittest." Somewhere among the millions of species alive today, there must be one out-and-out failure. Of course, if full-scale nuclear war breaks out, we will know that evolution did make at least one mistake! Evolution gone wrong! Nature's cartoon of a kangaroo with a wrong-way ...
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... -Oct 1990 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Another Anomaly Bites The Dust Some mysterious cultural practice of ancient people all over the world resulted in curious grooves on tooth surfaces. The grooves occur near the cementoenamel junction, mostly on molars and premolars, and usually on males. The diameter of the channel between adjacent teeth varies from 1-4 millimeters. (See SF#61 for an earlier item on the subject.) Proposed solutions to this riddle range from bacterial attack, to gritty saliva propelled through the teeth, to the overenthusiastic use of bone toothpicks. But Australian aborigines have provided a more convincing explanation. When the aborigines want, thin, strong cords for fashioning spears and spearthrowers, they take a pliable, thinned, kangaroo sinew, pull it down between their molars like dental floss and begin "stripping" it, by pulling it back and forth. They get their thin cords this way but also grooved teeth. (Eckhardt, Robert B.; 'The Solution for Teething Problems," Nature, 345: 578, 1990.) Comment. Unless someone comes up with a fatal objection to this theory, we must de-anomalize the grooved-teeth phenomenon. From Science Frontiers #71, SEP-OCT 1990 . 1990-2000 William R. Corliss ...
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