Tuesday, 2 May 2006
Aren’t you glad you don’t have a craving to eat stumps?
Modern humans may consume too much sodium, but modern gorillas often find it hard to get enough. Tropical soils tend to be deficient in the mineral and, as a result, these and other forest-dwelling primates don’t get much in the plants they eat.
So they supplement their diet in different ways. Lowland gorillas, for instance, are known to hang out in swampy areas in forest clearings where there are more sodium-rich plants. But mountain gorillas have been found to have a stranger source of sodium: rotting wood.
In addition to their regular diet of leaves, stems, bark and fruits, mountain gorillas for years have been observed to eat decayed stumps and logs. Other primates, including chimpanzees and mountain monkeys, are known to eat them, too.
Rotting wood doesn’t have much protein or sugar, so the behavior puzzled. Jessica M. Rothman and her colleagues at Cornell University set out to see if there was a nutritional reason for it. They studied mountain gorillas in the Bwindi Impenetrable National Park in Uganda.
As reported last week in the journal Biology Letters, the researchers found that the gorillas ate decayed wood at least once a month. The pieces eaten contained much higher amounts of sodium than the usual components of their diet, and logs and parts of stumps that the gorillas avoided had far less sodium than those that were consumed.
This from the NY Times.
Also, doncha just love two and three sentence paragraphs ad infinitum?
Today’s vocabulary: Mahalanobis distance. This is a statistical means of comparing an unknown sample with an known dataset to see how similar they are, a kind of multivariate analysis, at least as I understand it. That link is NOT a Wikipedia entry, ’cause the Wiki-freaks have composed an entry is all formulae and not helpful for me, or, I’m guessing, you! BTW, I encountered this stat in a series of articles that comprise a spat about Early Formative Mesoamerican pottery sourcing chemical analyses. So, unanswerable question: how many of those co-authors knew/know what Mahalanobis distance is and how to use it appropriately!