History

Evidence of the inhalation of cannabis smoke can be found as far back as the Neolithic age, as indicated by charred cannabis seeds found in a ritual brazier at an ancient burial site in present day Romania. The most famous users of cannabis were the ancient Hindus of India and Nepal, and the Hashshashins (hashish eaters) of present day Syria. The herb was called ganjika in Sanskrit (ganja in modern Indian and Nepali languages).The ancient drug soma, mentioned in the Vedas as a sacred intoxicating hallucinogen, was sometimes associated with cannabis.
Cannabis was also known to the Assyrians, who discovered its psychoactive properties through the Aryans. Using it in some religious ceremonies, they called it qunubu (meaning "way to produce smoke"), a probable origin of the modern word. Cannabis was also introduced by the Aryans to the Scythians and Thracians/Dacians, whose shamans (the kapnobatai—“those who walk on smoke/clouds”) burned cannabis flowers to induce a state of trance. Members of the cult of Dionysus, believed to have originated in Thrace, are also thought to have inhaled cannabis smoke. In 2003, a leather basket filled with cannabis leaf fragments and seeds was found next to a 2,500- to 2,800-year-old mummified shaman in the northwestern Xinjiang Uygur Autonomous Region of China.
Cannabis has an ancient history of ritual use and is found in pharmacological cults around the world. Hemp seeds discovered by archaeologists at Pazyryk suggest early ceremonial practices like eating by the Scythians occurred during the 5th to 2nd century BCE, confirming previous historical reports by Herodotus. Some historians and etymologists have claimed that cannabis was used as a religious sacrament by ancient Jews and early Christians. It was also used by Muslims in various Sufi orders as early as the Mamluk period, for example by the Qalandars. In India and Nepal, it has been used by some of the wandering spiritual sadhus for centuries, and in modern times the Rastafari movement has embraced it as a sacrament. Elders of the modern religious movement known as the Ethiopian Zion Coptic Church consider cannabis to be the Eucharist, claiming it as an oral tradition from Ethiopia dating back to the time of Christ, even though the movement was founded in the United States in 1975 and has no ties to either Ethiopia or the Coptic Church. Like the Rastafari, some modern Gnostic Christian sects have asserted that cannabis is the Tree of Life. Other organized religions founded in the past century that treat cannabis as a sacrament are the THC Ministry, the Way of Infinite Harmony, Cantheism, the Cannabis Assembly and the Church of Cognizance.
Cannabis was introduced to the Americas in the mid-19th century by Indian laborers under the Indian indenture system implemented by the British Empire after the end of African slavery in the British West Indies. In the Caribbean, cannabis is still known as ganja (the Sanskrit word for marijuana), Indian or Coolie weed. The plant eventually spread into Mexico, U.S., Canada and the rest of the Americas.
The production of cannabis for drug use remains illegal throughout most of the world through the 1961 Single Convention on Narcotic Drugs, the 1971 Convention on Psychotropic Substances, and the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, while simple possession of small quantities is either legal, or treated as an addiction rather than a criminal offense in a few countries.

Medical use

A synthetic form of one chemical in marijuana, Delta-9 Tetrahydrocannabinol (THC), is a controversial treatment for medical use. The American Marijuana Policy Project, a pro-cannabis organization, contends that cannabis is an ideal therapeutic drug for cancer and AIDS patients, who often suffer from clinical depression, and from nausea and resulting weight loss due to chemotherapy and other aggressive treatments. A recent study by scientists in Italy has also shown that cannabidiol (CBD), a chemical found in marijuana, inhibits growth of cancer cells in animals.
FDA and comparable authorities in Western Europe including the Netherlands, have not approved smoked marijuana for any condition or disease. A common view is that if there is any future of marijuana as a medicine, it lies in its isolated components, the cannabinoids and their synthetic derivatives.
A synthetic extract of cannabis has been shown to relieve symptoms of anorexia in elderly Alzheimer's patients.
Glaucoma, a condition of increased pressure within the eyeball causing gradual loss of sight, can be treated with medical marijuana to decrease this intraocular pressure. There has been debate for 25 years on the subject. Some data exist, showing a reduction of IOP in glaucoma patients who smoke marijuana, but the effects are short-lived, and the frequency of doses needed to sustain a decreased IOP can cause systemic toxicity. There is also some concern over its use since it can also decrease blood flow to the optic nerve. Marijuana lowers IOP by acting on a cannabinoid receptor on the ciliary body called the CB receptor. Although marijuana is not a good therapeutic choice for glaucoma patients, it may lead researchers to more effective, safer treatments. A promising study shows that agents targeted to ocular CB can reduce IOP in glaucoma patients who have failed other therapies.
Medical marijuana is used for analgesia, or pain relief. “Marijuana is used for analgesia only in the context of a handful of illnesses (e.g., headache, dysentery, menstrual cramps, and depression) that are often cited by marijuana advocates as medical reasons to justify the drug being available as a prescription medication.” It is also reported to be beneficial for treating certain neurological illnesses such as epilepsy, and bipolar disorder. Case reports have found that cannabis can relieve tics in people with OCD and/or Tourette syndrome. Patients treated with tetrahydrocannabinol, the main psychoactive chemical found in cannabis, reported a significant decrease in both motor and vocal tics, some of 50% or more. Some decrease in obsessive-compulsive behavior was also found. A recent study has also concluded that cannabinoids found in cannabis might have the ability to prevent Alzheimer's disease. THC has been shown to reduce arterial blockages.
Another use for medical marijuana is movement disorders. Marijuana is frequently reported to reduce the muscle spasticity associated with Multiple Sclerosis, this has been acknowledged by the Institute Of Medicine, but it noted that these abundant anecdotal reports are not well-supported by clinical data. Evidence from animal studies suggests that there is a possible role for cannabinoids in the treatment of certain types of epileptic seizures. The marijuana will numb the nervous system slightly so the body won’t go into shock. A synthetic version of the major active compound in cannabis, THC, is available in capsule form as the prescription drug dronabinol (Marinol) in many countries. The prescription drug Sativex, an extract of cannabis administered as a sublingual spray, has been approved in Canada for the treatment of multiple sclerosis. Dr. William Notcutt states that the use of MS as the disease to study “had everything to do with politics”.

New breeding and cultivation techniques
Main article: Cannabis (drug) cultivation
It is often claimed by growers and breeders of herbal cannabis that advances in breeding and cultivation techniques have increased the potency of cannabis since the late 1960s and early '70s. However, potent seedless marijuana such as "Thai sticks" were already available at that time. In fact, the sinsemilla technique of producing high-potency marijuana has been practiced in India for centuries. Sinsemilla (Spanish for "without seed") is the dried, seedless inflorescences of female cannabis plants. Because THC production drops off once pollination occurs, the male plants (which produce little THC themselves) are eliminated before they shed pollen to prevent pollination. Advanced cultivation techniques such as hydroponics, cloning, high-intensity artificial lighting, and the sea of green method are frequently employed as a response (in part) to prohibition enforcement efforts that make outdoor cultivation more risky. These intensive horticultural techniques have led to fewer seeds being present in cannabis and a general increase in potency over the past 20 years. The average levels of THC in marijuana sold in United States rose from 3.5% in 1988 to 7% in 2003 and 8.5% in 2006.
"Skunk" cannabis is a potent strain of cannabis, grown through selective breeding and usually hydroponics, that is a cross-breed of Cannabis sativa and C. indica. Skunk cannabis potency ranges usually from 6% to 15% and rarely as high as 20%. The average THC level in coffeehouses in the Netherlands is about 18–19%.
The average THC content of Skunk #1 is 8.2%; it is a 4-way combination of the cannabis strains Afghani indica, Mexican Gold, Colombian Gold, and Thai: 75% sativa, 25% indica. This was done via extensive breeding by cultivators in California in the 1970s using the traditional outdoor cropping methods used for centuries.
In proposed revisions to cannabis rescheduling in the UK, the government is considering scheduling the more potent cannabis material as a separate, more restricted substance. Many cannabis proponents are vehemently opposed, reasoning that if one can smoke less cannabis to achieve the same effect, then it is safer in the long run than smoking a less potent product.
A Dutch double-blind, randomized, placebo-controlled, cross-over study of male volunteers with a self-reported history of regular cannabis use aged 18–45 years concluded that smoking of cannabis, with higher THC reflecting the content levels of netherweed (marijuana with 9–23% THC) as currently sold in coffee shops in the Netherlands, may lead to higher THC concentrations in serum (the internal dose). Smoking of cannabis with higher THC concentrations leads to an increase of the occurrence of effects, particularly among younger or inexperienced cannabis smokers, who do not adapt their smoking to the higher THC. Smoking of cannabis with higher THC concentrations was associated with a dose-related increase of physical effects (such as increase of heart rate, and decrease of blood pressure) and psychomotor effects (such as reacting more slowly, being less concentrated, making more mistakes during performance testing, having less motor control, and experiencing drowsiness).
What was well observed in the Dutch study was that the effects based from a single dose—the smoking of one piece of a joint for 20–25 minutes—lasted for more than eight hours. The reaction time was still significantly slower about five hours after smoking. At that time, the THC serum concentration was low, but still present. This means that even when individuals have the impression that their state has returned to baseline and that they can smoke another piece of joint, the effect of the first joint may be still present. When subjects smoke on several occasions per day, accumulation of THC may occur.
Another study showed that 15 mg THC result in no learning whatsoever occurring over a three-trial selective reminding task at two hours. In several tasks, delta(9)-THC increased both speed and error rates, reflecting “riskier” speed–accuracy trade-offs.
There are two recognized types of herbal cannabis, sativa and indica. So-called sativa strains are reputed to induce a noticeably more "cerebral" high, while indica strains induce more of a body high. These two drug types are often hybridized or crossed with early-maturing (but low in THC) ruderalis strains to increase the range in desirable characteristics.