Cannabis

• 1. Botanical Origins And Taxonomy

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  The genus Cannabis likely split from its closest relative, Humulus, during the mid Oligocene, around 27.8 million years ago according to molecular clock estimates. The centre of origin of Cannabis is likely in the northeastern Tibetan Plateau. The oldest pollen thought to be from Cannabis is from Ningxia, China, on the boundary between the Tibetan Plateau and the Loess Plateau, dating to the early Miocene, around 19.6 million years ago. Cannabis was widely distributed over Asia by the Late Pleistocene. The oldest known Cannabis in South Asia dates to around 32,000 years ago.

  Taxonomists have debated the number of species for well over two centuries. Carl Linnaeus first classified the genus using the modern system of taxonomic nomenclature in 1753. He considered the genus to be monotypic, having just a single species that he named Cannabis sativa L. In 1785, evolutionary biologist Jean-Baptiste de Lamarck published a description of a second species of Cannabis, which he named Cannabis indica Lam. Lamarck based his description on morphological aspects like trichomes and leaf shape, as well as geographic localization of plant specimens collected in India.

  Russian botanist D.E. Janichevsky concluded in 1924 that ruderal Cannabis in central Russia is either a variety of C. sativa or a separate species. In 1929, renowned plant explorer Nikolai Vavilov assigned wild populations of Cannabis in Afghanistan to C. indica Lam. var. kafiristanica Vav. In 1931, Vavilov proposed a three species system, independently reinforced by Schultes et al in 1975 and Emboden in 1974: C. sativa, C. indica and C. ruderalis. However, many taxonomists found these putative species difficult to distinguish.

  In 1976, Canadian botanist Ernest Small and American taxonomist Arthur Cronquist published a taxonomic revision that recognizes a single species of Cannabis with two subspecies. This classification was based on several factors including interfertility, chromosome uniformity, chemotype, and numerical analysis of phenotypic characters. A 2015 analysis of single-nucleotide polymorphisms found a clear divide between the drug/resin and hemp/fiber varieties. A 2020 analysis of SNPs reports five clusters of Cannabis, labeled K1 through K5.

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• 2. Chemical Composition And Pharmacology

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  Cannabis plants produce a large number of chemicals as part of their defense against herbivory. One group of these is called cannabinoids, which induce mental and physical effects when consumed. Cannabinoids, terpenes, terpenoids, and other compounds are secreted by glandular trichomes that occur most abundantly on the floral calyxes and bracts of female plants. There are 483 identifiable chemical constituents known to exist in the cannabis plant, and at least 85 different cannabinoids have been isolated from the plant.

  The two cannabinoids usually produced in greatest abundance are cannabidiol (CBD) and/or Δ9-tetrahydrocannabinol (THC), but only THC is psychoactive. Since the early 1970s, Cannabis plants have been categorized by their chemical phenotype or chemotype, based on the overall amount of THC produced, and on the ratio of THC to CBD. Non-drug plants produce relatively low levels of THC and high levels of CBD, while drug plants produce high levels of THC and low levels of CBD. When plants of these two chemotypes cross-pollinate, the plants in the first filial generation have an intermediate chemotype and produce intermediate amounts of CBD and THC.

  Normal cognition is restored after approximately three hours for larger doses via a smoking pipe, bong or vaporizer. However, if a large amount is taken orally the effects may last much longer. After 24 hours to a few days, minuscule psychoactive effects may be felt, depending on dosage, frequency and tolerance to the drug. Cannabidiol, which has no intoxicating effects by itself, is thought to reduce the anxiety-inducing effects of high doses of THC, particularly if administered orally prior to THC exposure.

  According to Delphic analysis by British researchers in 2007, cannabis has a lower risk factor for dependence compared to both nicotine and alcohol. Everyday use of cannabis may be correlated with psychological withdrawal symptoms, such as irritability or insomnia. Risk of adverse outcomes from cannabis use may be reduced by implementation of evidence-based education and intervention tools communicated to the public with practical regulation measures.

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• 3. Historical Domestication And Cultivation

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  In China, the psychoactive properties of cannabis are described in the Shennong Bencaojing from the 3rd century AD. Cannabis smoke was inhaled by Daoists, who burned it in incense burners. In the Middle East, use spread throughout the Islamic empire to North Africa. In 1545, cannabis spread to the western hemisphere where Spaniards imported it to Chile for its use as fiber. In North America, cannabis, in the form of hemp, was grown for use in rope, cloth and paper.

  The Yanghai Tombs, a vast ancient cemetery situated in the Turfan district of the Xinjiang Uyghur Autonomous Region in northwest China, have revealed the 2700-year-old grave of a shaman. Near the head and foot of the shaman was a large leather basket and wooden bowl filled with 789g of cannabis, superbly preserved by climatic and burial conditions. An international team demonstrated that this material contained THC. This is the oldest documentation of cannabis as a pharmacologically active agent.

  Settlements which date from c. 2200, 1700 BCE in the Bactria and Margiana contained elaborate ritual structures with rooms containing everything needed for making drinks containing extracts from poppy, hemp, and ephedra. Smoking hemp has been found at Pazyryk. Cannabis is first referred to in Hindu Vedas between 2000 and 1400 BCE, in the Atharvaveda.

  The term hemp is used to name the durable soft fiber from the Cannabis plant stem. Cannabis sativa cultivars are used for fibers due to their long stems; Sativa varieties may grow more than six metres tall. However, hemp can refer to any industrial or foodstuff product that is not intended for use as a drug. Many countries regulate limits for psychoactive compound concentrations in products labeled as hemp.

  Cannabis for industrial uses is valuable in tens of thousands of commercial

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• 4. Industrial Hemp Applications

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  products, especially as fibre ranging from paper, cordage, construction material and textiles in general, to clothing. Hemp is stronger and longer-lasting than cotton. It also is a useful source of foodstuffs like hemp milk, hemp seed, and hemp oil, as well as biofuels. Hemp has been used by many civilizations, from China to Europe and later North America during the last 12,000 years.

  In the US, industrial hemp is classified by the federal government as cannabis containing no more than 0.3% THC by dry weight. This classification was established in the 2018 Farm Bill and was refined to include hemp-sourced extracts, cannabinoids, and derivatives in the definition of hemp. Globally, in 2013, 60,400 kilograms of cannabis were produced legally.

  Cannabis is a popular recreational drug around the world, only behind alcohol, caffeine, and tobacco. In the U.S. alone, it is believed that over 100 million Americans have tried cannabis, with 25 million Americans having used it within the past year. As a drug it usually comes in the form of dried marijuana, hashish, or various extracts collectively known as hashish oil.

  In 2014 there were an estimated 182.5 million cannabis users worldwide, representing 3.8% of the global population aged 15,

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• 5. Recreational Use And Social Impact

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  64. This percentage did not change significantly between 1998 and 2014. Cannabis withdrawal symptoms are typically mild and are not life-threatening. Concerns including memory and cognition problems, risk of addiction, schizophrenia in young people, and the risk of children taking it by accident remain significant.

  The plant has been used for medicinal purposes since ancient times, but also as a recreational drug known by several slang terms, such as marijuana, pot or weed. Various cannabis strains have been bred, often selectively to produce high or low levels of tetrahydrocannabinol, a cannabinoid and the plant's principal psychoactive constituent. Compounds such as hashish and hash oil are extracted from the plant.

  Short-term use increases both minor and major adverse effects. Common side effects include dizziness, feeling tired, vomiting, and hallucinations. Long-term effects of cannabis are not clear. Concerns including memory and cognition problems, risk of addiction, schizophrenia in young people, and the risk of children taking it by accident persist among researchers.

  In 1940, CBN was isolated from cannabis extract, and its structure and chemical synthesis were achieved. This was followed by some of the first preclinical research studies to determine the

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• 6. Medical Therapeutics And Research

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  effects of individual cannabis-derived compounds in vivo. The first genome sequence of Cannabis, which is estimated to be 820 Mb in size, was published in 2011 by a team of Canadian scientists.

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