ABSTRACT

Charles Darwin first coined the term “living fossil” to describe archaic forms, including lungfishes and horseshoe crabs, which seem not to have changed since their appearance in the fossil record hundreds of millions of years ago. As Darwin explained, evolution is not merely a chronicle of historical events but an ongoing process that is the fundamental basis of all life on Earth. Given that evolution is all about species changing over time, how can we explain such species as the coelacanth, tuatara, or chambered nautilus, which certainly appear to violate the central rule of constant change? To what extent have these species truly stopped changing? Can we best explain this phenomenon by internal (genetic) or external (environmental) processes?

More broadly, what do “living fossils” tell us about species? What is a species, and how do we recognize distinct species? Is it possible to distinguish ancient species from recent species? Can we connect them in a continuum over the grand sweep of deep geologic time? Why is the modern species concept (based on reproductive compatibility) problematic for paleontologists? Is it worth fixing this problem or should we construct a new model to define and distinguish species? Finally, what can “living fossils” tell us about basic patterns and processes of life, including what we might find in the extraterrestrial life of other worlds?

About the Speaker:

Alexander J. Werth is Venable Professor of Biology at Hampden-Sydney College in Virginia. He earned his BS in zoology from Duke University (1985) and AM and PhD in organismic and evolutionary biology from Harvard University (1987, 1992), then was a postdoctoral fellow with the North Slope Borough (Alaska) Department of Wildlife Management. He has been a Fulbright Scholar with the Ministry of Fisheries, Agriculture, and Marine Resources in the Republic of Maldives and a visiting scientist at marine laboratories in Maine, Alaska, and Iceland.

His research focuses on two areas: 1) evolutionary complexity, particularly why some features of organisms tend not to change over time (e.g., vestiges, atavisms, “living fossils”); and 2) biomechanics and functional morphology of feeding in toothed and baleen whales, especially the material properties of the whale’s oral filter and how flow and drag affect these dynamic processes. He is working with international teams of biologists, engineers, and physicists to construct and test 3D printed models so that we can better understand the filter feeding of whales and design more effective industrial filters.