Our speaker this month, Dr. Carl Johannessen, is a biogeographer interested in understanding how crops and other plants valuable to humans have spread from one culture to another. Because the cultivation of crops predates the beginning of written history by several thousand years (10,000 years vs. 5,000 years, give or take 10%), elucidating exactly where a plant first originated is not easily done. Figuring out patterns of dispersal is even tougher. Archaeological evidence provides considerable insight, but the ancient record is spotty and open to different interpretations. Because of the value of agricultural knowledge, it spread rapidly, as fast as people could migrate. Often it is difficult to distinguish a place of origin from a way station in species dispersal.
One of the major events in human history was the contact between the Old World and the New World. The most widely held view is that this contact was primarily initiated by the voyages of Christopher Columbus. Leif Ericson may have placed a Norse colony on this continent but no cross-oceanic cultural exchange appears to have occurred.
It is common to refer to events as pre-Columbian or post-Columbian, before or after 1492 CE. On the cover is a typical map showing crop origins based on the model of post-Columbian crop dispersal between the Old World and the New World. I use the word "model" deliberately because there are alternate ideas about where crops originated and how they were dispersed. These involve a model that incorporates the notion of pre-Columbian trans-oceanic travel by one or more non-European peoples. Carl is one of those who argues for such an alternate model, often labeled a diffusionist position. Carl's position is not the popular or most widely held view. In this regard it may be considered controversial and this certainly makes it interesting. I am looking forward to hearing Carl making his case.
As a youth I read Kon-Tiki several times, one of the most wonderful true life adventure stories of my generation. Thor Heyerdahl intended to demonstrate that trans-oceanic travel by ancient methods was possible. This he did successfully and I have always been intrigued by the possibility. I confess to adhering to the majority view, however, in thinking that the evidence makes the possibility unlikely.
It is interesting to note that the diffusionist model of crop dispersal is an unpopular but scientific theory, in contrast to popular theories which are not scientific. I'm thinking specifically of the intelligent design and creationist ideas that are popular in some circles. They are popular beliefs but not scientific theories.
One way to understand this is to consider the effort by some state legislatures to require that a sticker be placed in science books stating, "Evolution is a theory, not a fact." Suppose a different legislature, wanting to be balanced about science, suggested requiring that every Bible in public schools and public libraries have a sticker stating, "The existence of God is a theory, not a fact." This is, of course, an absurd notion; no legislature would make any such proposal. The existence of God as a fact is a belief and there's nothing wrong with that. It is not, however, a theory subject to scientific testing.
Evolution is a theory, and that is exactly as it should be because it is subject to scientific inquiry. Intelligent design is a belief, not a theory subject to scientific questioning. This is not to say a scientist as both a thoughtful and religious person might not believe in God as an intelligent designer--Indeed, this appears to be the case as often as not.
It is important to remember that science is a process, a way to learn, and not a set of truths nor necessarily confirmed knowledge. Whether or not Carl "believes" in pre-Columbian dispersal is not the point of his discussion. He wants to try to prove this view by presenting verifiable evidence. We'll evaluate on the basis of our willingness to accept his interpretation of the evidence he presents.