Cannabis, the marijuana plant, offers an enthralling lens as a means to learn about the natural world. Cannabis is only one species of the billions of organisms that have ever lived on this planet. And like all of the billions of species that are alive or have lived (about 99.9 percent of all life on this planet has gone extinct in the past), cannabis is beautiful, whether you use it or not.

You might be wondering, Does this guy believe that every living thing is beautiful? Yes, I do, in some way or another, for the most part. The beauty is there mostly because of the sheer strangeness of all life, and more so because of the ways in which life has taken over this once sterile blob of chemicals and minerals we call Earth. Nothing that is living should be taken for granted! Even the lowliest of bacteria are amazing. The strangeness, improbability, vastness, and interconnectedness of Earth’s ecological systems are what make them so beautiful, and also hard to explain.

How life on this planet got the way it is is one of those wonders of existence that is probably best pondered in one’s more amiable states of mind. But we can find a lot of explanations logically. Science is the realm for doing this, and the challenge for scientists is to figure out the best explanations for the phenomena we see around us. It’s tricky, because we are never going to know whether we are completely right about anything. We can convince ourselves we are right about something, but we are never going to be sure, because as the great philosopher of this problem, Karl Popper, realized, there is no final arbiter of truth in science; no one thing or person can tell us we are correct. But Popper did realize that we can determine when something is wrong or false—a scientific process he called falsification. Therefore, explaining cannabis is really an endeavor of identifying what is false or inconceivable about it, and using that as fodder for explanation. There are other ways to philosophize about this problem, but Popper’s theory of empirical falsification has been quite helpful to me as a way of sifting through the information in the natural world.

I have found the biology of cannabis to be particularly astonishing. Its closest relatives (hops) and its place in the botanical tree of life might surprise you. Though poorly understood until recently, it has a rich taxonomic history. Over a dozen different scientific names have been used for this plant species, which is in reality probably only one species.

Throughout this book I refer to cannabis by several names. For the most part I use only “cannabis” and “marijuana” as interchangeable terms for this amazing plant. Occasionally I slip into the vernacular and use “pot” or “grass,” and when appropriate I will use the term “hemp.” Hemp is an interesting name for cannabis, which usually refers to the plant’s role as a fiber. It took on a different meaning in the United States when the national Agriculture Improvement Act of 2018 defined it as cannabis with less than 0.3 percent tetrahydrocannabinol (THC) content. I also alternate between using scientific names such as Cannabis sativa or the genus Cannabis, which I italicize. When I refer to the vernacular cannabis, I do not italicize or capitalize the word unless at the beginning of a sentence or in a title. The name marijuana is also vernacular, so I neither italicize nor capitalize it.

The sex life of cannabis lies at the heart of its utility, leading to the wholesale slaughter of male plants in marijuana fields. Males will pollinate the females, leading to a lot of seeds, which detracts from the production of the coveted chemicals tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA). Although cannabis is often called a “weed,” the variations it shows in outward physical appearance (phenotype) and its internal biochemistry are astonishing. For example, some marijuana plants are giants, growing to over ten feet tall, whereas others reach only a foot or two. As a consequence, there are over a thousand different strains. Cannabis plants make a thousand or more different chemicals that are stored in their tissues for a variety of evolutionary reasons, and these chemicals are the basis of marijuana’s psychoactive and medicinal utility.

How did cannabis evolve the different pathways for the more than one thousand compounds it makes? How did it develop the sex system it uses to reproduce? Why are its floral structures the way they are? These questions require that we take a close look at its biology and genome (an organism’s complete set of DNA), of which there are at least ten full genomes sequenced to date. An equally interesting question is, How did the many strains of this plant develop? Answering this question involves understanding the complicated genealogy of the strains. Because so much of the development of cannabis was accomplished surreptitiously, teasing apart its breeding history is more daunting than understanding wine grape genealogy, or even human genealogy.

Many readers will have their own anecdotes about their experience and encounters with cannabis, be they recreational or medicinal, exemplifying one of the major effects of THC on the brain. It prompts the release of dopamine (the feel-good receptor of the brain) and induces an overall feeling of euphoria. Because it influences the brain’s receptors to be more active, it also heightens sensory perception and changes both the way you communicate and how you process incoming information. It also impairs your judgment.

Just as vivid as my pleasant memories of collegiate use of marijuana are my less mellow memories of the first time I saw the “This Is Your Brain on Drugs” televised public service announcement and heard Nancy Reagan’s motto, “Just Say No.” Both of these antidrug campaigns were representative of the backlash against marijuana use in the 1980s and the war on drugs of the 1980s and 1990s, much of which focused on cannabis use. These are important aspects of the maturation of marijuana use in modern society and its eventual partial legalization. They are also a reminder that there are negative connotations of marijuana use.

Not everyone is convinced that cannabis is nonaddictive. Some researchers have examined the role of marijuana smoking in the onset of schizophrenia, whereas others note the health problems associated with smoke inhalation and secondary smoke contact involved with marijuana use.

Although cannabis became a huge part of the counterculture of the 1960s and 1970s, it was already embedded in many other cultures. These cultural phenomena represent an important part of the plant’s natural history. Its use in various rituals and religions is important for a full disclosure of its utility and history of usage.

If the patterns of use of cannabis by humans are any indication of its impact on culture and society, then the noble weed should be on everyone’s mind. Over 60 percent of college students surveyed in 2020 said they have used marijuana at least once, with 16 percent of those imbibing at least once a day. Surprisingly, 60 percent is also the same frequency with which college students said they have used alcohol at least once. Younger people of high school age use marijuana and alcohol at half the rate of those who are of college age. Although use of cannabis has slightly dropped in adults, it is estimated that on average 20 million adults (around 10 percent of all adults) in the United States used marijuana in the past year. More surprisingly, it appears that over 60 percent of all Americans surveyed approve of some degree of legalization of marijuana. Indeed, over the past decade or so cannabis has been legalized in several states in the United States and in various other countries.

Legalization of cannabis has been slow and deliberate. As of this writing, twentythree states and the District of Columbia allow fully legalized marijuana use and another twenty-three states have mixed-use laws, leaving only four states (Georgia, Kansas, Idaho, and Wyoming) where it remains fully illegal. It is difficult to generalize about the various degrees of legalization of cannabis use, because each state has its own laws, but it is clear that there is a move nationally toward legalization. The picture globally is a bit different, as in most countries marijuana use is still illegal. But many of the countries where it is illegal either have decriminalized it or do not enforce the laws they have on the books.

Recreational cannabis use is a cultural phenomenon that most users were forced to keep clandestine until recently. And its medicinal uses, although implied and in many

ways anecdotal in the past, are only recently being quantified and seriously touted as legitimate medical phenomena.

Marijuana is also big business today. Several cannabis companies trade stock publicly, and it appears that the global COVID-19 pandemic has not been a hindrance to the growth and monetary value of these companies. It is not unusual to see IIPR, EGOV, SSPK, or GWRG (all ticker symbols for cannabis-based companies), to name a few, stream across the tickers on financial news channels.

As a full-time evolutionary biologist, part-time botanist, recreational user, and more than likely a future medicinal user, I find cannabis one of the most fascinating of all plants on our planet. I hope this book invites as much curiosity in you as it does in me—not only in cannabis but in science.

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Contents

Preface