[All this week, GS will be covering stories on Marijuana - its traditional uses, basic biology, criminalization, neurological effects and more. Join us all this week for our in depth study of this fascinating, controversial plant!] Cannabis: a word that has undoubtedly struck a different emotional chord with people all around the world since the beginning of recorded history. From being an important component of religious ceremonies to being viewed as downright immoral behavior, the recreational use of marijuana continues to have an aura of controversy around it until this very day (see yesterday’s article).

Interestingly enough, the word cannabis itself comes from Scythian origin, an ancient Iranian people that lived in central Asia whom I trace my own ancestry back to. These ancestors of mine were said to have used this plant not only for the purposes of smoking, but additionally to cleanse themselves in its smoke and weave their clothing using its leaves. As you can observe, then, the use of cannabis is anything but new to human culture.

What made and continues to make this plant of such profound interest to human beings, you may ask? For that, we must look no further than the biology of the plant that has captivated millions if not billions of minds over the millennia.

To understand the intoxicating effects of marijuana, we must first understand the intoxicating component of the plant, namely, tetrahydrocannabinol or THC for short. In its pure form, THC is a glassy solid when cold and a viscid and sticky liquid when warm. Interestingly enough, THC is an evolutionary self-defense mechanism of plants to protect themselves from herbivores (ironically, this has not helped to protect it from the reach of omnivorous humans!).

Preliminary studies have also shown that THC additionally possesses high ultra-violet absorption abilities that may in fact protect the plant from excessive UV radiation from the sun. Viewed in this light, then, THC cannot be thought of as the controversial and often-hated chemical it is made out to be in the rhetoric of today’s political and media commentaries.

So how exactly does THC produce the effects of intoxication in the mind of the user? Well, THC actually binds to a receptor in the central nervous system referred to as the cannabinoid receptor. This begs the question, why exactly does the human central nervous system have a receptor for an exogenous (or outside produced) chemical?

The answer to this question is where marijuana gets really interesting: for there to be a natural receptor for THC in our nervous system, there then must be an endogenous (or self made) chemical within our body that produces the same intoxicating effect as THC does! This revelation led to the eventual discovery of a whole class of substances produced naturally within the human body known as endocannabinoids. In fact, one such endocannabinoid known as 2-arachidonoyl glycerol (2-AG) is even found in human breast milk!

This by no means serves to legitimize the usage of marijuana as a recreational drug. As we all know, there is an awe inspiring homeostasis within the body and therefore, the intentional placement of any outside chemical intoxicant into the body runs the risk of destroying the critical balance at the core of our very being. Even ignoring this, the inhalation of any kind of smoke into the lungs increases the risk of attaining lung cancer exponentially, especially when studies have shown that marijuana smoke contains even more toxic substances than tobacco smoke!

Wherever you stand on this controversial issue, there’s one thing I hope we can all agree upon: one should never associate a plant with the often-irresponsible behavior on the part of humans using the plant. At the end of the day, cannabis was just using THC to defend itself from predators; humans were the ones who decided to smoke it.

Discussion Question: What sort of evolutionary process do you think led to the formation and necessity of endocannabinoids in humans?
Please feel free to comment on anything you may have had questions on about this article.

Source Links:
http://indianmedicine.eldoc.ub.rug.nl/root/O/80265/?pFullItemRecord=ON
http://www.sciencemag.org/cgi/content/abstract/296/5568/678
http://content.nejm.org/cgi/content/abstract/318/6/347
http://grande.nal.usda.gov/ibids/index.php?mode2=detail&origin=ibids_references&therow=585292