For thousands of years, people have been harvesting the bounty of the natural world. Plants and animals have, of course, provided people with food, but they have also supplied therapeutic remedies for conditions as far ranging as foot fungus and indigestion, snake bites and malaria. In the early part of the 20th century, chemists began unlocking the secrets of many of these substances. They identified them, determined their chemical structures, classified them, and began exploring how to make, or synthesize, the naturally occurring chemicals in the laboratory. So-called "natural products chemistry" was arguably the most important, and potentially most profitable, branch of chemistry of the day.

Two families of compounds — alkaloids and steroids — garnered more attention from early 20th century chemists than any others. Plant compounds called "alkaloids" were notable because of their wide variety and because many were known to have profound physiological and/or psychological effects on humans. Another group of carbon compounds called "steroids" was found to serve important regulatory and developmental functions in many types of organisms, including humans. Steroids, such as testosterone and estrogen, regulated reproduction and development. Other steroids identified at the time were found to be involved in digestion or in the body's response to stress or injury.

In addition to the vital role steroids play naturally in the body, researchers were discovering that they could be effective in treating medical conditions. The reproductive hormone progesterone helped pregnant women carry their babies to full term, while cortisone provided dramatic relief from painful inflammation caused by rheumatoid arthritis. However, stocks of these steroids were agonizingly small and prohibitively expensive. These important compounds would have to be synthesized artificially and in large volumes for significant numbers of people to benefit from their therapeutic effects.

Efforts to isolate human steroids from animal tissues and other raw materials such as urine or bile had proven highly inefficient. However, by this time, chemists knew that plants also produced steroids, and that the structures of these compounds had much in common with animal steroids. Percy Julian and other chemists of the day surmised that plant steroids could likely be chemically transformed into desired animal steroids. In addition, the abundance of plant tissue as compared to animal tissue meant that once they found a way to synthesize steroids, such as progesterone and cortisone from plant steroids, they could do so in volumes sufficient to meet the pressing medical demand for these products. Julian was one of the first and most successful chemists in the effort to increase the supplies of steroids and other important organic compounds.

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