Canadian researchers released a study yesterday comparing the genetic sequences of over 120 different cannabis strains. The largest study of its kind, it looks at three key points; genetic differences between hemp and marijuana*, the genetic relationships between Indica and Sativa types, and genetic stability within commonly-used strain names.
Unsurprising, the study confirmed a clear distinction between ‘hemp’ cultivars and it’s more THC-endowed ‘marijuana’ types, but the more noteworthy finding is the lack of distinction between varieties labeled as “Indica” or “Sativa”, especially in terms of their purported therapeutic effects.
Because prohibition has pushed breeding practices for cannabis largely into the black market, names and distinctions between varieties has become difficult to verify. While hemp has long been known as distinct from more psychoactive varieties sold for recreational and medical use, there is a great deal of rumour and folklore attached to strain names and indica and sativa varieties and their alleged difference in therapeutic effects.
For example, it is a commonly held belief that Indica strains are a sedative ‘body’ high and Sativa strains are an energizing ‘head’ high. The available data from this study, as well as one conducted in 2013 by a researcher in California seems to show that these common distinctions may not always be accurate.
The inaccuracy of reported ancestry in marijuana likely stems from the predominantly clandestine nature of Cannabis growing and breeding over the past century. Recognizing this, marijuana strains sold for medical use are often referred to as Sativa or Indica “dominant” to describe their morphological characteristics and therapeutic effects. Our results suggest that the reported ancestry of some of the most common marijuana strains only partially captures their true ancestry. ~The Genetic Structure of Marijuana and Hemp
Jonathan Page, President and CEO of Anandia Labs and an Adjunct Professor at the University of British Columbia who co-led the research project in collaboration with several Canadian researchers, spoke about their findings in an interview recently with Lift.
“It goes without saying that we found differences between hemp and marijuana,” explained Page. “What was startling about that was the degree of genetic difference between them. That’s really the first evidence of the widespread genetic changes in cannabis as the result humans domesticating it and cultivating it for different purposes.”
The differences in strains of ‘marijuana’ types was less predictable.
“Within the 81 marijuana samples we also looked at their reported ancestry - whether it was indica, sativa or hybrid,” Page continues. “We asked the question ‘Is there a correlation between their reported ancestry and what we were able to obtain using the genomic analysis?’. In fact, what we found is there is only a moderate correlation. People generally don’t know what they really have in terms of indica or sativa. It’s not really based on a strong scientific foundation”.
The study gives an example of a 100% reported C. sativa strain (Jamaican Lambs Bread) and found it was “nearly identical” to a reported 100% C. indica strain from Afghanistan. Whether the often-held belief in the therapeutic distinction between sedative indica highs and invigorating sativa highs is at least partially a placebo effect or if there are other factors at play will require further research.
“We want patients consuming medical cannabis to know what they are using and that they can trust batch to batch, type to type, that it’s going to be accurately labeled. This work doesn’t mean we can’t trust any of the products available, but it does mean that we can improve on the situation we are in now.” ~Dr. Jonathan Page
Lastly, the study looked at marijuana strain names and the genetic variations within. It compared samples with identical names to each other as well as other samples and found that 6 of 17 comparisons samples were more “genetically similar” to samples with different names than to samples with the same name. So the Purple Kush you buy from Producer A may not be all that similar to the Purple Kush sold to you by Producer B. and more importantly, there are currently few options to accurately understand that distinction.
“Strain naming conventions are very confused at this point,” said Page. “We don’t have a good way of making sure that a strain has a particular name is actually that strain. There is no real ability to do that in the industry right now, and with the indica sativa split, this distinction is fraught with uncertainty.
“We want patients consuming medical cannabis to know what they are using and that they can trust batch to batch, type to type, that it’s going to be accurately labeled. This work doesn’t mean we can’t trust any of the products available, but it does mean that we can improve on the situation we are in now.”
All of the sequencing data is available publicly, freely accessible for researchers worldwide, as is Page’s 2011 sequencing of the cannabis genome.
*(Editors note: The distinction ‘hemp and ‘marijuana’ are used here to distinguish between cultivars traditionally bred for seed and fibre with those traditionally bred for medicine)