Science

The Evolution of Cannabis Through Natural- and Human-Mediated Selection

Loren DeVito, PhD
Written by Loren DeVito, PhD

And what to expect in the cannabis of tomorrow

In 2018, we stand looking into the future of cannabis genetic editing with high hopes of what CRISPR and other tools can do for creating exquisitely tailored cultivars.To appreciate how far the industry has come in both the research and technology that brought us here,we must reflect on where we first started. The cannabis used by our ancestors varied considerably – from color, shape, aroma, taste, and effects – from what currently lines the shelves of dispensaries in legal states. In fact, it may even be difficult to remember a time when unprocessed flower was the only form of cannabis available. So, how exactly did we get here?

As with all plant and animal life, cannabis has been subjected to years of evolution, selecting for the “most fit” traits that survived to the next generation. These traits are governed by alleles, or variant forms of genes, that determine the expression of characteristics like plant color. And the process by which this occurs, either by functional change based on survival or at random in the genome, is known as natural selection.1

But, as humans started domesticating cannabis, human-mediated selection following the principles of Mendelian genetics significantly impacted the future of the plant.2 This process is as simple as crossing red with white roses to get pink ones – but represents a huge shift in the ability to customize plant characteristics for human use.

Breeders began creating hybrids of cultivars to achieve different plant height, form, and color. And, as humans began to migrate, so did the cannabis plant, with different cannabis seeds carried throughout the world.3 Cannabis began to grow in new regions and natural selection again came into play as the traits that allowed it to thrive in difficult environments were selected for in subsequent generations.

Further down the evolutionary road, cannabis science pioneers like Raphael Mechoulam began to dig a little deeper into the cannabis plant and discovered its astonishing array of cannabinoids.4 Plant breeders accordingly began selecting for the genes that produced varying levels of the most popular cannabinoids – THC and CBD – which is how consumers are able to purchase products with specific percentages of certain cannabis compounds today.

And these changes in cannabis composition have occurred very rapidly. A study in 2016 reported that the potency of cannabis increased three-fold from 1995-2014; in addition, the THC:CBD ratio increased nearly seven-fold.5As cannabis continues to go through a “modern evolution” with the availability of highly advanced genetic technology, we will likely see greater customization of cultivars, isolated cannabinoid products (that go far beyond THC and CBD), and additional advances in our understanding of the cannabis genome.

While customization of cannabis products is appealing to recreational users, genetic editing will certainly bring a brighter future to those who use these products for medicinal purposes. By modulating the psychoactive effects of the plant, people with certain conditions will be able to dial up and dial down their symptoms as needed throughout the day.6 And perhaps precise dosing of cannabis to meet these needs may be made possible by genetic editing, as cannabis pharmacokinetics remains a challenge to researchers and clinicians alike.

References

  1. Pickersgill, B., “Domestication of Plants Revisited–Darwin to the Present Day”, Botanical Journal of the Linnean Society, 2009, Volume 161.

(impact factor: 3.124; cited by: 23)

  1. Mendel, G.,“ VersucheüberPlflanzen-hybriden. Verhandlungen des naturforschenden Ver-eines in Brünn”, Bd. IV für das Jahr Abhand-lungen,1865.

(impact factor: not available; cited by: 879)

  1. Clarke, R.C., Merlin, M.D., “Cannabis Domestication, Breeding History, Present-day Genetic Diversity, and Future Prospects”, Critical Reviews in Plant Sciences, 2016, Volume 35.

(impact factor: 6.162; cited by: 8)

  1. Maccarrone, M., Bab, I., Biro, T., et al., “Endocannabinoid Signaling at the Periphery: 50 Years After THC”, Trends Pharmacol Sci, 2015, Volume 36.

(impact factor: 10.148; cited by: 215)

  1. ElSohly, M.A., Mehmedic, Z., Foster, S., Gon, C., Chandra, S., Church, J.C., “Changes in Cannabis Potency over the Last Two Decades (1995-2014)-Analysis of Current Data in the United States”, Biol Psychiatry, 2016, Volume 79.

(impact factor:11.412; cited by: 214)

  1. Bridgeman, M.B., Abazia, D.T., “Medicinal Cannabis: History, Pharmacology, And Implications for the Acute Care Setting”, PT, 2017, Volume 42.

(impact factor: 2.526; cited by: 23)

About the author

Loren DeVito, PhD

Loren DeVito, PhD

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