As COVID-19 peaks for the third time in America, with no signs of slowing, the news of Pfizer’s vaccine has stirred up quite a bit of excitement. With an efficacy rate of 90% far exceeding scientists’ expectations, this potential vaccine holds tremendous promise.
But how did pre-modern cultures, without our present-day knowledge of immunology and medicine, find cures for ailments ranging from coughs to heart palpitations? How did they realize that certain herbs could cure certain diseases?
The answer seems simple: the doctrine of signatures. According to the NY Times, this principle states that “plants have a ‘signature’ — color, texture, shape, scent and even the environment in which they grow — that resembles the body parts and diseases they heal.” So for example, since bloodroot produces a red extract when sliced open, it was once used to treat blood diseases. The doctrine of signatures has influenced traditional medicine practices of many major civilizations, including the Romans, Native Americans and Indians.
Despite this widespread adoption of the doctrine of signatures, however, there is no sign of its scientific accuracy. A 2007 study states, “There is no evidence that morphological plant signatures ever led to the discovery of medicinal properties.” This makes intuitive sense — a plant with heart-shaped leaves can’t necessarily cure cardiac disease.
The study’s author, Dr. Bradley C. Bennett of Florida International University, also postulates that the doctrine of signatures might have evolved as a memory device: as humans discovered the medical uses of certain plants, they preserved this knowledge by pointing out similarities to human organs.
Further complicating things is the fact that the doctrine of signatures does appear to work in a few cases. Purslane, a wormlike grass, does actually help fight parasitic infections. Walnuts, appearing similar to a human brain, help boost memory.
Regardless of the veracity of the doctrine of signatures, however, it’s certainly a fascinating look into the history of medicine. These glimpses into the past provide a temporary cerebral escape from today’s pandemic realities while also reminding us of the long path towards progress.
Article By Isabella Fan of Montgomery Blair High School
Photo Courtesy of Pexels Images
Edited by Arts & Culture Editor Vainavi Gambhir