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Equid evolution; talking Neanderthals
Not strictly topical but no doubt of interest to many:
Two stories from the Science section of today's New York Times.
Paper's copyright acknowledged.
Ancient Horses' Secrets
By HENRY FOUNTAIN
The true age of a horse, common wisdom holds, can be told by looking
in its mouth. The teeth hold few mysteries.
The fossilized teeth of ancient horses, it turns out, hold few
mysteries either. A team of researchers from the Florida Museum of
Natural History and other institutions, taking a close look at the
dental remains of six species dating from five million years ago, has
cast doubt upon a widely accepted model of horse evolution.
Under that model, until about 20 million years ago horses had
short-crowned teeth and were primarily browsers, eating leafy and
soft-tissue plants. Then, as patterns of climate and vegetation
changed, horses underwent a rapid and widespread adaptation,
developing long teeth more suited to grazing on grasses and other
The researchers, reporting in a recent issue of Science, examined the
isotopic composition of tooth enamel in the six fossilized species,
all of which were found in central Florida. Depending on whether the
horse had a browsing or grazing diet, the enamel contains different
proportions of particular carbon isotopes.
The six species all have high-crowned teeth and should, under the
evolutionary model, be grazers. But the isotopic analysis, coupled
with examination of microscopic pits and scratches on the tooth
surfaces, showed that not all of the six species were grazers: Some
were browsers, and some had a mixed diet.
It was big news last year: Researchers at Duke University had
concluded that Neanderthals and other human ancestors might have been
able to talk.
Now, three graduate students at the University of California at
Berkeley are disputing that idea. In a paper in The Proceedings of the
National Academy of Sciences, they asserted that the anatomical
feature the Duke anthropologists said was a predictor of vocal ability
-- a hole in the base of the skull through which nerves run from the
brain to the tongue -- is no predictor at all.
The Duke researchers had argued that a larger hole, or hypoglossal
canal, meant larger nerves and more complex tongue function. And they
noted that the canal in Neanderthals and other Homo ancestors was
close in size to those of modern humans.
But the Berkeley researchers pointed out that many speechless monkeys
and apes have human-sized canals. They also examined human cadavers
and found no correlation between size of a canal and the number of
nerve fibers running through it.
"Language is a virus from outer space."
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