There's an old saying, "He who does not learn from history is doomed to repeat it". Turned around, this implies that he who does learn is forearmed—one of the many reasons that paleobiologists want to know everything they can about the conditions of yesteryear. With climatic change upon us, scientists look to the past to clarify future dangers. Unfortunately, when dealing with climate in time and space, the map's a bit blurred.
Packrat middens contain plant remains, are datable, and may last for
10s of thousands of years. Middens from Bishop's Cap, a southern outlier of the
Chihuahuan Desert's Organ Mountains, show that a dry juniper woodland rather than
today's Chihuahuan desertscrub occurred between about 28 and 10 thousand years ago.
Only one site had any Colorado Pinyon—a plant requiring more moisture. But
middens between some 35 to 43 thousand years old showed substantial amounts of the
pine, even though data from elsewhere suggest the older sites should be drier, not
wetter. Once again, different places, different truths—but each truth fills in a
hitherto blank space.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Van Devender, T. R. 1990. Late Quaternary vegetation and climate of the Chihuahuan Desert, United States and Mexico. Pp. 104-133, in Packrat Middens, the Last 40,000 Years of Biotic Change (J. L. Betancourt, T. R. Van Denvender, and P. S. Martin, eds.). Univ. Arizona Press, Tucson.
Van Devender, T. R., and B. L. Everitt. 1977. The Latest Pleistocene and Recent Vegetation of the Bishop's Cap, South-Central New Mexico. The Southwestern Naturalist 22, 337-352.