Around 430 million years ago, in the Silurian period, the first terrestrial plants appeared. There are now about 391,000 plant species, divided into four main groups: mosses, ferns, gymnosperms (such as conifers) and angiosperms (flowering plants).
The last important transition in the history of plants is from pines and spruces to flowering plants such as oak trees and rose bushes. Leaves adapted to make all the reproductive organs of the plant appear in a single special structure, better known as the flower. This transformation allowed flowering plants to become the most important plant group on earth. They now make up over 90% of all the plants alive today and are vital to humans and animals as a source of food — think fruits, vegetables, nuts, grains, and seeds. Whether we notice it or not, these plants are vital for the survival of humans and animals.
There is currently a lot of discussion and debate over cannabis and its use in healthcare. But what is often left out of the dialogue is over 6000 years of documented experience people have had with the cannabis plant. Historically, cannabis’ medical applications appear to have been realised by most cultures, however, it appears that much of our modern-day cultural perspective on cannabis is based neither on historical evidence nor recent discovery. As with many scientific disciplines, much can be learned from our collective history.
One of the earliest evidence of cannabis cultivation comes from China in the form of pollen deposits found in the village site of Pan-p’o that are dated to 4000 BCE. At the time, cannabis was regarded among the ‘five grains’ and was farmed as a major food crop in addition to its significant role in the production of textiles, rope, paper, and oil. The first record of its use in medicine comes from the Pen-ts’ao ching, the world’s oldest pharmacopoeia. Although compiled between 0- 100 AD, the Pen-ts’ao has been attributed to Emperor Shen-nung, who ruled during 2700 BCE. It recognizes cannabis as being useful for more than 100 ailments, including rheumatic pain, gout, and malaria. The Pen-ts’ao ching also mentions the psychoactive effects of cannabis, stating that “ma-fen (fruit of cannabis), if taken over the long-term, makes one communicate with spirits and lightens one’s body”. Between 117-207 AD, Hua T’o, a physician of the time and the founder of Chinese surgery, described cannabis as an analgesic. He is reported to have used a mixture of cannabis and wine to anesthetize his patients before surgery. As cannabis use increased in China, it spread westward, reaching India by 1000 BCE.
Cannabis spread quickly throughout India and was used extensively, both recreationally and medicinally. It was also adopted and integrated into religious practices, earning a mention in the Atharva Veda, one of the Vedic scriptures of Hinduism, as being among the five sacred plants of Hinduism, and teaching that a guardian angel lives within its leaves. Cannabis is mentioned within the Vedas as a “source of happiness,” a “joy-giver,” and a “bringer of freedom”. The Raja Valabba states that the gods created cannabis out of compassion for humans. In Hinduism, cannabis was smoked during the daily devotional service. Due to religious use in India, it was possible to explore the medicinal benefits of cannabis, which led to the discovery that cannabis can be used to treat a plethora of diseases and ailments. The general uses in India included use as an analgesic, anticonvulsant, anaesthetic, antibiotic, and anti-inflammatory. These properties allowed for the treatment of many diseases, including epilepsy, rabies, anxiety, rheumatism, and even respiratory conditions such as bronchitis and asthma. Cannabis use continued to spread throughout the world and was adopted by many diverse cultures.
The Assyrians were aware of cannabis’ psychotropic effects since at least 900 BCE. By 450 BCE, cannabis had reached the Mediterranean, as evidenced by a first-hand account from Herodotus. Herodotus writes of a Scythian funeral ceremony, where cannabis seeds were burned ritually for their euphoric effects. In Tibet, cannabis was sacred, used extensively in medicine and in Tantric Buddhism to facilitate meditation.
In Persian medicine, cannabis’ biphasic effects were clearly noted, emphasizing the distinction between cannabis’ initial euphoric effects and the dysphoric effects that follow. The Persian physician Avicenna (980 – 1037 AD), one of the most influential medical writers of the medieval period, published ‘Avicenna’s Canon of Medicine’, a summary of all medical knowledge of the time. His canon was widely studied in western medicine from the thirteenth to the nineteenth century, having a lasting impact on western medicine. Avicenna recorded cannabis as an effective treatment for gout, Edema, infectious wounds, and severe headaches.
In Arabic medicine, cannabis was regarded as an effective treatment for epilepsy. Recorded first by al-Mayusi, between 900-1000 AD, followed by al-Badri, in 1464 AD, who wrote of the chamberlain’s epileptic son who was cured using cannabis leaves.
In the 1300s, Arab traders brought cannabis from India to Africa, where it was used to treat malaria, fever, asthma, and dysentery.
The 1500s saw cannabis reach South America via the slave trade, which transported Africans along with seeds, from Angola to Brazil. In Brazil, cannabis was used extensively in the African community, including in religious rituals such as the ‘Catimbo,’ which used cannabis for magical and medical purposes. From Brazil, cannabis travelled north to Mexico where it was used recreationally by individuals of low socioeconomic class.
Cannabis’ therapeutic uses were first introduced to Western medicine in 1839, when the Irish physician William O’Shaughnessy published ‘On the preparations of Indian hemp, or gunjah’. In the first paragraph of his work, he highlights that “…in Western Europe, [cannabis’] use either as a stimulant or as a remedy is equally unknown,” indicating British unfamiliarity with the drug. O’Shaughnessy first encountered cannabis while working as a physician in India with the British East India Company. Interested, he studied the existing History and cannabis literature on cannabis and conferred with elders and healers to understand the recreational and medicinal uses of cannabis in India. O’Shaughnessy then proceeded to test the effects of different forms of cannabis on animals to evaluate the toxicity of the drug. Confident that the drug was safe, he provided extracts of cannabis to patients and discovered it had both analgesic and sedative properties. The immediate results impressed him enough to begin prescribing the drug and he was rewarded with positive results. His greatest success came when he managed to calm the muscle spasms caused by tetanus and rabies. O’Shaughnessy’s initial results, followed by those of other physicians, led cannabis to spread rapidly through Western medicine in both Europe and into North America.
In 1860, the Committee on Cannabis Indica of the Ohio State Medical Society reported success for the use of cannabis to treat many ailments including gonorrhoea, asthma, rheumatism, and intense stomach pain. Cannabis’ use in medicine continued to grow, peaking in the late eighteenth/early nineteenth century when it could be readily found in over-the counter pharmaceuticals such as “Piso’s cure” and the “One day cough cure”. This rapidly increasing popularity of the new medication sparked the publication of more than 100 papers on its therapeutic uses. In 1924, Sajous’s Analytic Cyclopedia of Practical Medicine summarized what, at the time, were believed to be the main therapeutic uses of cannabis. They concluded that cannabis was useful in the treatment of migraines, coughing and inflammation, along with diseases such as tetanus, rabies, and gonorrhoea.
Following this rapid rise of use within 1900s medicine, cannabis use began to decline due to a variety of factors. Vaccines for diseases such as tetanus made cannabis’ previous role in treating these diseases obsolete. Furthermore, development of synthetic analgesics such as chloral hydrate, antipyrine and aspirin filled some of the demand for analgesics. However, it was the development of the hypodermic needle and its application to opiates that could be considered the greatest factor to the decline of cannabis use. These factors led to an overall decrease in the prevalence of cannabis and its necessity as an analgesic, making it more susceptible to the political influences to follow.
At the beginning of the 1900s, cannabis’ recreational use in the United States of America was in large restricted to Mexican and African minority groups who had immigrated into the country. By the 1930s there was an increase in recreational use among all US citizens, leading narcotics officers to push for restrictive legislation on both the recreational and medicinal use of cannabis. The American Medical Association advised that cannabis remains a medical agent, citing its medicinal use, low toxicity and absolutely no evidence “…to show that its medicinal use is leading to the development of cannabis addiction”. However, despite the protests, in 1937 the Marijuana Tax Act was enacted, ending the already diminished use of cannabis as a therapeutic. In 1941, cannabis was removed entirely from the American pharmacopeia.
Over the next couple of decades, cannabis use in medicine was almost non-existent, and it was not until the 1970s that medical interests were revived. The prevalence of recreational cannabis use rose significantly in the early 1970s, spiking from only 5% of people reporting to have used cannabis in 1967, to 44% in 1971. This massive increase in recreational use brought cannabis into the spotlight, and with the discovery of cannabis’ active component (Δ9-THC) by Gaoni and Mechoulam in 1964, it became possible to isolate the principal component, making the study and quantification of its effects possible. In 1988, the receptor CB1 was identified. It was found to be the binding site of THC and to be the most abundant neurotransmitter receptor in the central nervous system. This discovery was followed by the identification of a second cannabinoid receptor, CB2, localized primarily in the peripheral nervous system and on immune cells. The presence of cannabinoid receptors, concentrated in neural and immune cells, alluded to a mode of action that could be the source of cannabis’ analgesic, sedative and immunoregulatory properties.
Over the past few thousand years many distinct cultures have been exposed to cannabis and often realised its medicinal application. When cannabis was introduced to Western medicine, its medicinal applications were swiftly recognised, and its use spread rapidly. The decline of cannabis use in the west was due to a variety of factors and as a result its medicinal use was forgotten. The discovery of the active constituent Δ9-THC, as well as endogenous receptors for cannabinoids, stimulated research into the drug showing that cannabis does, in fact, have a direct effect on the body.
Cannabis use both culturally and medically has had a long and well-documented history. Cannabis has been used medicinally in many diverse cultures, and upon exposure to western medicine in the 19th century, it quickly gained popularity as an analgesic, anticonvulsive, and hypnotic. These medical properties are innately part of cannabis biology, and over time selective breeding projects have amplified these traits. The medical properties of this plant combined with an understanding of the effective methods of consumption help make cannabis the powerful medication it is today. Much can be learned from this historical record, but what is most salient is that the use of cannabis to treat clinical symptoms is not new. The challenge is education and policy changes to incorporate the nature of cannabis’ atypical consumption requirements into modern clinical methodology.