On the Cover
September-October 1999 Volume 87, Number 5
The Niagara Escarpment is a rocky bluff that runs for some 800
kilometers from Lake Huron in Canada, through southern Ontario and into
the U.S. near Niagara Falls. Along the cliff face grow many rare plants
and small trees. In "Cliffs as Natural Refuges," Douglas W. Larson, Uta
Matthes and Peter E. Kelly, botanists from the University of Guelph,
describe their investigation of this unique set of vegetation and
recount their serendipitous discovery that many of the cedars growing on
these cliffs are extraordinarily old. ...
FEATURE ARTICLES
James Nieh
Searching for a proto-dance language reveals possible stages in the evolution of methods by which experienced foragers lead others to food
George Poinar, Jr.
The tools of molecular biology can be used to peer into an organism's genetic future--or its distant past
Steven Krantz
Imaginary numbers are not figments, complex numbers are not difficult, but with such "imaginative mathematics," one can map irregular surfaces precisely
Henry Freudenreich
Astronomers know more about distant galaxies than they do about our own Milky Way
Douglas W. Larson, Uta Matthes, Peter Kelly
Rocky precipices around the world provide a surprisingly sheltered environment for plants and animals
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