The 9.2 million research specimens at the San Diego Natural History Museum allow scientists to study our region’s flora and fauna and provide the backbone of evidence for their common descent, perpetual change, and multiplication.
of Natural History
By Bradford D. Hollingsworth, Ph.D., Curator, Department of Herpetology
Darwin is here at the San Diego Natural History Museum. Rest assured, not literally, as he is comfortably at peace in Westminster Abbey, since his death on April 19, 1882. His grave is a few feet away from Isaac Newton and Charles Lyell. Here, on what would have been his 200th year in life, Charles Darwin’s historic journey to the discovery of evolution is detailed in the exhibition Darwin: Evolution|Revolution. And there isn’t a more appropriate place than a natural history museum to celebrate Charles Darwin’s life. In fact, Darwin would have felt perfectly at home in the corridors and collection spaces of our Museum. If not for the distance of the globe, Darwin could have mingled with the likes of Daniel Cleveland, one of the founding members of the San Diego Society of Natural History, which began holding regular meetings in 1874. For the early members of the society, Darwin’s ideas held considerable influence, as the San Diego region was still poorly known to science and its plants and animals had yet to be classified.
The theory of evolution is now 150 years old and its explanatory power is ever increasing. Breaking the theory into five principles, as proposed by the famous 20th century biologist Ernst Mayr, makes it simpler to explain. Mayr argued that Darwinism could be viewed as: 1) perpetual change; 2) common descent; 3) multiplication of species; 4) gradualism; and 5) natural selection. Each of the five principles is in themselves their own theory, with support from different lines of evidence. For example, perpetual change is best documented by our region’s fossil record. A quick walk through Fossil Mysteries and one can observe firsthand the rich history of perpetual change. From the Eocene rainforest to the Pliocene marine environment, the organisms that lived during successive epochs changed. Common descent is documented throughout our collections by connecting the similarity of form, as genealogies are traced back through time. The patterns formed by these similarities follow the simple premise that the daughter and her two parents will be more similar in form than to more distantly related organisms. And as a corollary to descent, the multiplication of species is documented by our ongoing Atlas programs and the study of biogeography. Such studies, firmly grounded in Darwin’s teachings, are today documenting the species diversity and distributional patterns of our region.
One of the one million specimens in the Museum’s Entomology collection is this brown lacewing, a predatory insect related to ant lions. It was collected by Charles Darwin during the voyage of the Beagle. Specifically, it was collected in Hobart, Australia, when Darwin was there in February 1836.
For the San Diego naturalist, these ideas can be readily applied to the collections at the Museum and to observations made in the field. Scientific explorations to remote mountaintops and faraway islands are a part of many evolutionary inquiries. As a current example, the Museum’s researchers have conducted such expeditions to islands in the Gulf of California. The endless variety of plants and animals provide ample opportunity to apply the principles of evolution and scientific study to our region’s natural history. It was Darwin’s careful observations, made in both the laboratory and in nature, which led to the 1859 publication of On the Origin of Species. His most influential experience came when he was a young man and circumnavigated the world onboard the H.M.S. Beagle. Five years of exploration to South America, including visits to the Andes Mountains and Galápagos Islands, provided him the opportunity to observe nature. With few instruments of technology compared to today’s standards, his careful observations and collections were enough to revolutionize thinking.
Today’s natural history museums maintain the same careful diligence that Darwin practiced. The care and maintenance of collections requires painstaking hours of keeping order. Data tied to specimens and notes tied to data—the chain of evidence is preserved to maximize the value of specimens. Each catalogued individual serves as a link to understanding the natural world. The modern evolutionary biologist has additional tools in their research labs. Computers, high-powered microscopes, and DNA sequencing have added new dimensions to natural history research, but the same principles of observation are still at the heart of studying nature. In this respect, today’s evolutionary biologists have much in common with Darwin and the founders of the San Diego Society of Natural History.
Darwin’s vast collections are still in scientific circulation. Many of his specimens are housed in the Natural History Museum in London. Others were delivered to various experts throughout the world and reside in places like the Oxford University Museum of Natural History and Muséum National d’Histoire Naturelle in Paris. Some were deposited in these collections immediately after his voyage or later in life. At the time of their collection, Darwin recorded careful notes on their origin and habit. Many were new to science and yielded surprising alliances once their morphology was studied more carefully. These collections, and natural history collections throughout the world, are repositories of materials from the real world and provide evidence in support of the theory of evolution. The San Diego Natural History Museum holds over 9.2 million research specimens, each contributing evidence to support the principles of perpetual change, common descent, and the multiplication of species.
DARWIN: Evolution|Revolution will be at the San Diego Natural History Museum from November 7, 2009 through February 28, 2010.
Fossil Turritella sea snails from the Pleistocene of the Gulf of California
SAN DIEGO NATURAL HISTORY: FIELD NOTES, December 2009–January 2010