Science News - April 10, 2010

In the report on Ardi (“Evolution’s bad girl,” SN: 01/16/10, p. 22), the artist’s illustrations show her in fur. The fact that her purported descendants are relatively hairless has been popularized by Desmond Morris ( The Naked Ape, 1967) and Elaine Morgan ( The Descent of Woman, 1972). What is the paleoanthropologists’ evidence that Ardi had not yet shed her fur coat and gained the advantage of superior heat loss in tireless pursuit of game? Walter J. Freeman, Berkeley, Calif.

Hairiness made sense for an early
hominid species that lived in forests,
had infants that could hang on to
mothers with grasping toes, and, despite
walking upright, couldn’t go anywhere
fast in tireless pursuit of anything, says
anthropologist and Ardi researcher
Owen Lovejoy of Kent State University
in Ohio. Long-distance hunting did
not emerge as a regular practice until
several million years after Ardi’s time
and played no major role in hominid
hair loss, in Lovejoy’s view. Significant
hair loss probably occurred once Homo
sapiens developed cultural means for
controlling body temperature, such as
clothing and water containers, he
contends. — Bruce Bower

Midwestern cool-down The article “Irrigation could be cooling Midwest” (SN: 2/13/10, p. 15) says that the average global temperature rose 0.74 degrees Celsius during the past century and then shows the number of 90 degree-plus [Fahrenheit] days for the past 80 years. Why the difference in time scales? What was the temperature for the past 80 years? Richard A. Kroc, Batavia, Ill.

The graph of 90 degree-plus days that
you refer to shows data only from Chi-
cago. Northern Illinois University
scientist David Changnon’s research
focused on meteorological data gath-
ered between 1930 and 2009, because
the longest set of weather data from a
site in the Chicago area comes from a
weather station at Midway Interna-
tional Airport, where meteorologists
first began collecting data in 1928.
For the 80-year period that Changnon
studied, global average temperature
increased by about 0.65 degrees Cel-
sius, according to data compiled by
NASA’s Goddard Institute for Space
Studies in New York City.

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