Geology and Evolution: Partners in Science

Evolutionary theory focuses on the mechanisms of change in organisms but evolution’s history is critically dependent on various earth science disciplines.  These provide a framework for how the physical and biological environments, changing through time, interacted with those mechanisms through selection to produce the historical and present biodiversity at all levels from species to ecosystems.  The earth has always changed in many ways over many time frames—tectonically through plate motions, mountain building, island construction and destruction; paleoclimatically through changes in the way heat is trapped and distributed over short and long times; oceanographically through changing current (surface and deep) patterns, nutrient supplies, and habitats; extraterrestrial through the changes induced by impacts from outer space that increased habitat destruction and reduced biodiversity; volcanism through isolating and destroying populations, creating new habitats and destroying existing ones; paleontologically through the documentation of life forms from nearly 4 billion years ago to the present; among others.  These geological processes have resulted environmental changes over time that enhanced natural selection in one or another way.  They resulted in species, biodiversity and biogeographic changes affecting more or less all organisms including humans, and they still do.  These changes in geology and evolution are calibrated using the latest geochronological methods, thus relating them to each other in a time sequence.  All of this arises from scientific data and hypothesis testing.  Biologic evolution is solidly based on good science in general and earth sciences in particular.  Indeed the evolutionary history of life on Earth cannot be understood without reference to the paleoenvironments created by geologic events.  A good example is the evolution within the human lineage where molecular biology shows the relationship of modern humans to chimpanzees but the fossil record shows the intermediate steps, the climatic and biotic changes associated with their evolution, and the dispersal of ancient and modern humans throughout the world.  These concepts can be taught at most levels by emphasizing changes in the physical and biotic world resulting in new circumstances, hence natural selection, for particular common or popular animals and plants that produced evolutionary changes.