Dendral - History

History

During mid 20th century, the question "can machines think?" became intriguing and popular among scientists, primarily to add humanistic characteristics to machine behavior. John McCarthy, who was one of the prime researchers of this field, termed this concept of machine intelligence as "artificial intelligence" (AI) during the Dartmouth summer in 1956. AI is usually defined as the capacity of a machine to perform operations that are analogous to human cognitive capabilities. Much research to create AI was done during the 20th century.

Also around mid 20th century, science, especially biology, faced a fast-increasing need to develop a "man-computer symbiosis", to aid scientists in solving problems. For example, the structural analysis of myogoblin, hemoglobin, and other proteins relentlessly needed instrumentation development due to its complexity.

In the early 1960s, Joshua Lederberg started working with computers and quickly became tremendously interested in creating interactive computers to help him in his exobiology research. Specifically, he was interested in designing computing systems that to help him study alien organic compounds. As he was not an expert in either chemistry or computer programming, he collaborated with Stanford chemist Carl Djerassi to help him with chemistry, and Edward Feigenbaum with programming, to automate the process of determining chemical structures from raw mass spectrometry data. Feigenbaum was an expert in programming languages and heuristics, and helped Lederberg design a system that replicated the way Carl Djerassi solved structure elucidation problems. They devised a system called Dendritic Algorithm (Dendral) that was able to generate possible chemical structures corresponding to the mass spectrometry data as an output.

Dendral then was still very inaccurate in assessing spectra of ketones, alcohols, and isomers of chemical compounds. Thus, as seen in figure 1, Djerassi "taught" general rules to Dendral that could help eliminate most of the "chemically implausible" structures, and produce a set of structures that could now be analyzed by a "non-expert" user to determine the right structure. Figure 2 shows how Dendral operates without an expert, after all the general rules were entered into Dendral's knowledge base.

The Dendral team recruited Bruce Buchanan to extend the Lisp program initially written by Georgia Sutherland. Buchanan had similar ideas and interests as Feigenbaum and Lederberg, but his special interests were scientific discovery and hypothesis formation. As Joseph November said in Digitizing Life: The Introduction of Computers to Biology and Medicine, "(Buchanan) wanted the system (Dendral) to make discoveries on its own, not just help humans make them". Buchanan, Lederberg and Feigenbaum designed "Meta-Dendral", which was a "hypothesis maker". Heuristic Dendral "would serve as a template for similar knowledge-based systems in other areas" rather than just concentrating in the field of organic chemistry. Meta-Dendral was a model for knowledge-rich learning systems that was later codified in Tom Mitchell's influential Version Space Model of learning.