A few items with summat to do with this forum:
** The 22nd coded-for amino acid. Two research articles and a "perspective" in the 24 May 2002 issue of
Science talk of the discovery that the RNA word UAG, usually a "stop" codon, can code for an amino acid named pyrrolysine in some methanogenic archaea and bacteria. The "new" amino acid is like lysine, but with some extra baggage on its sidechain. This joins selenocysteine, another "noncanonical" amino acid coded by a different stop codon in certain cases, which was discovered some years back.
Watch for AiG to crow about "how little biologists know!" with this news. I would suggest, though, that using a code for two meanings just shows sloppy design.
**The same issue has an article:
Quote:
Excavation of a Chimpanzee Stone Tool Site in the African Rainforest
Julio Mercader, Melissa Panger, and Christophe Boesch
Science 2002 296: 1452-1455.
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which reports on tool use by chimps in The Ivory Coast. The abstract:
Quote:
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Chimpanzees from the Taï forest of Côte d'Ivoire produce unintentional flaked stone assemblages at nut-cracking sites, leaving behind a record of tool use and plant consumption that is recoverable with archaeological methods. About 40 kilograms of nutshell and 4 kilograms of stone were excavated at the Panda 100 site. The data unearthed show that chimpanzees transported stones from outcrops and soils to focal points, where they used them as hammers to process foodstuff. The repeated use of activity areas led to refuse accumulation and site formation. The implications of these data for the interpretation of the earliest hominin archaeological record are explored.
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The authors suggest that these "used, but not manufactured" chimp tools might be useful to paleo folks looking for very early hominid tools: what might the very first tools really look like?
**Third, and maybe more comfortable in a real philosophy forum than here, is a piece in the previous issue:
Quote:
Is Face Processing Species-Specific During the First Year of Life?
Olivier Pascalis, Michelle de Haan, and Charles A. Nelson
Science May 17 2002: 1321-1323.
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The abstract:
Quote:
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Between 6 and 10 months of age, the [human]infant's ability to discriminate among native speech sounds improves, whereas the same ability to discriminate among foreign speech sounds decreases. Our study aimed to determine whether this perceptual narrowing is unique to language or might also apply to face processing. We tested discrimination of human and monkey faces by 6-month-olds, 9-month-olds, and adults, using the visual paired-comparison procedure. Only the youngest group showed discrimination between individuals of both species; older infants and adults only showed evidence of discrimination of their own species. These results suggest that the "perceptual narrowing" phenomenon may represent a more general change in neural networks involved in early cognition.
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Interesting stuff, and it appears to this complete outsider to throw a lot of very cold water on many of the models used for "how humans learn."
05-26-2002, 03:28 PM
News of some relevance...
