The few foreign visitors who came to my ancestral home Dali in Yunnan in the 1980s broadly fell into two types. The first ones were people who dressed in formal suits and stayed at the most luxurious hotels – always accompanied by an English-speaking guide and driven around in chauffeured cars. The second type, however, was more interesting: carefree, young hippies clad in colourful clothes with unkempt long hair. They holed up in cheap guest houses, mingling with locals and venturing into the hills and woodlands, seemingly looking for something.

With my curiosity piqued, one day I summoned enough courage to ask one of them what they were doing. A man, said to be from California, gave me a mysterious grin and said: “We are looking for the magic plant ‘faiyezi’ (flying leaves).” I asked my botanist uncle what ‘faiyezi’ was. He laughed hard but never gave me a straight answer.

Many years passed before I realised what those visitors were searching for: marijuana. While peoples in Yunnan began to cultivate cannabis some 6,000 years ago, the modern marijuana industry started in the land where my visitor came from: the United States. It was no coincidence that he and hundreds of others travelled halfway around the world to Dali in search of the magic plant. Unbeknownst to either of us at the time, their journeys would lead to an intriguing evolution of the plant that is still unfolding today.

On April 20 when pot smokers around the world celebrate their hallowed “Weed Day”, the mood this year would be quite upbeat. In recent years, there has been a sea change in public attitudes towards cannabis in the West. More and more countries have legalised or decriminalised the recreational use of marijuana.

Ironically, in Asia where cannabis cultivation first began, cannabis laws remain the strictest. China will probably be the last country to relax such laws because of its painful history with drug use. But even here, the story is not straightforward. China is by far the world’s largest cultivator of industrial cannabis, or hemp, and a leading researcher on the medicinal use of cannabis, accounting for more than half of the patents filed globally last year.

Let’s go back to the evolution of marijuana in America for a minute.

Few policies have backfired as spectacularly as the White House’s war on cannabis in the 1980s.

Smoking marijuana was always illegal in the US, but the law was loosely implemented throughout the 1960s and 1970s. Cannabis culture spread fast and wide thanks to the hippie movement and was on the verge of social acceptance. In 1972, US president Jimmy Carter even proposed to decriminalise marijuana. His point man on drug policy, Peter Bourne, openly smoked it.

Things took a sudden turn when Ronald Reagan came to power. Reagan and his wife Nancy crusaded passionately against marijuana, making it the focal point of America’s war on drugs. Marijuana was listed together with heroine and cocaine as the most dangerous drugs – even though there was no evidence suggesting that its effect could be anywhere as hazardous as the other two.

To this day, there is no single proven case of death caused by marijuana overdose. The drug dependency rate of marijuana is low. Only 9 per cent of marijuana users will develop withdrawal syndromes after they quit, on par with caffeine. By comparison, the dependency rate for tobacco is 32 per cent, alcohol 15 per cent and cocaine 17 per cent, according to a study by the US National Institute on Drug Abuse based on samples of 8,000 people.

Yet throughout the 1980s till 2000, the lion share of the US government’s anti-drug efforts was spent on battling marijuana use. Nearly 50,000 American citizens were jailed solely for marijuana-related crimes – higher than any other drug offence. Doctors were told they could not even talk about the potential medicinal use of the plant. Today, many are still puzzled by the intensity and single-mindedness in demonising cannabis. Some believe that its close identification with the hippie culture made it a trophy target for political conservatives who resented against the liberal 1960s.

Before 1981, most of the marijuana smoked in America was grown in Mexico. These were seeds of cannabis sativa, an equatorial species that could not set flowers north of the 30th parallel, meaning that it was difficult to grow in most parts of the US. Reagan’s war on marijuana, and Mexican drug cartels’ discovery that cocaine and heroin had much higher profit margins, stopped the flow of marijuana across the border.

Thousands of American hippies embarked on the “hashish quest” through Asia to search for a type of cannabis that would flower farther north. My first encounter with an American was a by-product of this big adventure.
Rule number one of marketing marijuana: Avoid stoner clichés

Eventually they found their holy grail in Afghanistan and returned with seeds of cannabis indica – a stout, frost-tolerant species that can flower as far north as Alaska. The indica is exceptionally potent, although its taste is harsher and its highs more physically debilitating than those of sativa. Many growers soon started crossing the two in the hope of producing something that would combine the most desirable traits of each plant. The result was a great revolution in cannabis genetics.

The new sativa/indica hybrids have the smoother taste associated with the best sativa and the powerful potency and hardiness of an indica. Today, these hybrids – including Northern Lights, Skunk #1, Purple Haze, California Orange and Pineapple Express – are regarded as the benchmarks of modern marijuana breeding.

Despite the sweeping ban by Reagan’s government, the growth of the plant expanded in the US. In 1982, the White House was embarrassed to find that the amount of domestic marijuana was bigger than its official estimate of total American crops. The US government began to fly aerial reconnaissance missions to spot marijuana farms. This forced the growers to move indoors. There, they kick-started a second revolution in cannabis genetics.

By growing cannabis in greenhouses, growers could precisely manipulate water, nutrients, light, carbon dioxide and heat. This made it possible to produce “Frankenstein” species that are small in stature but have extremely high yield and potency. The concentration of Tetrahydrocannabinol (THC), the principle psychoactive compound in marijuana, ranged from 2 per cent to 3 per cent before the crackdown in 1980s. Most of the natural cannabis species found in Yunnan, for instance, has a THC level between 1.5 per cent and 3 per cent. But in the greenhouses, growers started breeding marijuana with THC levels above 15 per cent.