Is human evolution inevitable?

"Darwin's Compass: Why the evolution of humans is inevitable" will be the title of a lecture by Cambridge University Professor Simon Conway Morris at 3 p.m. January 29, 2010, in Dallas Hall's McCord Auditorium on the SMU Campus.

Morris is speaking at SMU as part of the University's series of lectures commemorating the publication of Charles Darwin's On the Origin of Species 150 years ago. His lecture is sponsored by the University's Scott-Hawkins Lecture Series and he was co-invited by SMU's Departments of Mathematics and Biological Sciences.

Morris's Lecture Abstract: Nobody disputes the reality of evolution, nor the primacy of the Darwinian explanation. So is the end of the matter? I suggest not, and for several reasons. First, in contrast to any other science, evolutionary biology appears to have entered closure with the extraordinary idea that because evolution happens it is thereby self-explanatory. Second, and linked to the first point, almost without exception neo-Darwinians insist evolution is entirely open-ended and thereby unpredictable. I suggest the exact opposite. In fact evolution is like any other science and has significant predictabilities, including the evolution of intelligence. Evidence for this is available from both evolutionary convergence and molecular inherency. The former is the unremarkable observation that from different starting points in the tree of life very much the same structures evolve. The camera eye of the octopus and human is a classic example. Molecular inherency is simply drawing attention to the fact that complex structures, such as the nervous system, have many components that evolved long before the simplest nerve appeared. Third, neo-Darwinians are in denial about the reality of consciousness, and the much vaunted "explanations" are not matched by telephone calls from the Nobel Committee. So, relax, there is much to play for.

Morris is Professor of Evolutionary Paleobiology at the University of Cambridge, a Fellow of the Royal Society and an expert in soft-bodied mid-Cambrian fauna. This very important period in Earth’s history saw what has been termed the Cambrian Explosion when in a relatively short period of geologic time most of the major groups of animals appeared. Morris’ conclusions from his studies of the Burgess Shale deposits of British Columbia, his in-depth knowledge of biology and the evolutionary history of life has led him to propose a provocative and important hypothesis that is central to our understanding of the evolution of life.

Morris proposes that evolution runs in specific directions and to specific ends that are determined by the restraints imposed by the physical world in which life exists. Morris argues that many evolved characteristics of life, the evolution of sight for example, seem limited by the physics and chemistry required by the processes, and as a consequence, only a few possible "solutions" are available for evolution to take advantage of and eventually be employed by life.

According to Morris, these physical limitations result in repeated events of “convergent” evolution of very similar systems over and over again, often-times resulting in multiply independent, convergent “rediscoveries” of the same structures for the same functions - camera eyes, sense of smell, balancing organs, saber teeth - right up through the over all “look and feel” of whole organisms. Morris claims there is an inevitability to evolution that will, given the proper conditions on the proper planet, drive the process to similar ends – similar eyes, similar organisms and even similar intelligences.

This inevitability hypothesis is almost diametrically opposed to the propositions of Stephen Jay Gould and others that contingency is all-important in determining the direction in which evolution will run. The late Gould popularized this concept in his book, Wonderful Life, when he likened life’s history to a video tape, that if re-wound and played again, would most assuredly take us to an unrecognizably alien world without humans and perhaps without any intelligence what-so-ever. The contingency hypothesis is perhaps best exemplified by the historical event responsible for the extinction of the dinosaurs. Had the meteor missed the Earth, it is claimed, mammals would not have become dominant, and humans would not have evolved.

Morris’ thinking spans not only these great questions in paleontology, biology and Earth history, but also encompasses cosmology. He postulates that while human-like intelligence is inevitable, the probability of finding a planet and conditions that would allow the trajectory to be completed is so small as to be infinitesimal. Hence, he concludes, we are inevitable humans in a lonely universe.

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