{"id":11257,"date":"2026-10-29T00:38:00","date_gmt":"2026-10-29T00:38:00","guid":{"rendered":"http:\/\/cannabis.net\/blog\/opinion\/why-cannabis-makes-thc-the-17millionyearold-genetic-secret-revealed"},"modified":"2026-10-29T00:38:00","modified_gmt":"2026-10-29T00:38:00","slug":"why-cannabis-makes-thc-the-17-million-year-old-genetic-secret-revealed","status":"publish","type":"post","link":"https:\/\/cannitrol.com\/blog\/why-cannabis-makes-thc-the-17-million-year-old-genetic-secret-revealed\/","title":{"rendered":"Why Cannabis Makes THC: The 17-Million-Year-Old Genetic Secret Revealed"},"content":{"rendered":"<div id=\"wp_fb_like_button\" style=\"margin:5px 0 5px 5px;float:right;height:100px;\"><script src=\"http:\/\/connect.facebook.net\/en_US\/all.js#xfbml=1\"><\/script><fb:like href=\"https:\/\/cannitrol.com\/blog\/why-cannabis-makes-thc-the-17-million-year-old-genetic-secret-revealed\/\" send=\"true\" layout=\"standard\" width=\"450\" show_faces=\"false\" font=\"arial\" action=\"like\" colorscheme=\"light\"><\/fb:like><\/div><p><img src=\"https:\/\/cannitrol.com\/blog\/wp-content\/uploads\/2026\/10\/why-cannabis-makes-thc-the-17-million-year-old-genetic-secret-revealed.jpg\"><\/p>\n<h3><img alt=\"why cannabis makes thc\" src=\"https:\/\/cannitrol.com\/blog\/wp-content\/uploads\/2026\/10\/why-cannabis-makes-thc-the-17-million-year-old-genetic-secret-revealed-1.jpg\" \/><\/h3>\n<h3>Seventeen Million Years in the Making<\/h3>\n<p>Every so often I like to remind myself that the plant I write about was not designed by a <a href=\"https:\/\/cannabis.net\/blog\/opinion\/what-to-look-for-in-a-dispensary-characteristics-of-reputable-locations\">dispensary marketing team<\/a>. Long before anyone rolled a joint, named a strain after a dessert, or argued about <a href=\"https:\/\/cannabis.net\/blog\/strains\/what-is-the-difference-between-sativa-and-indica-marijuana\">indica versus sativa<\/a> on the internet, cannabis was simply a weedy little plant somewhere in Asia, doing whatever it needed to survive.<\/p>\n<p>Which raises a question I&#8217;ve been chewing on for years: why does this one plant make THC at all? Its closest relatives don&#8217;t. Hops, cannabis&#8217;s cousin and beer&#8217;s best friend, doesn&#8217;t get anybody high. So where did this chemistry come from, and when?<\/p>\n<p>A new study published October 22 in <em>Plant Biotechnology Journal<\/em> gets us closer to an answer than we&#8217;ve ever been. And the answer starts roughly 17 million years ago.<\/p>\n<h2>The mother cannabinoid and her three children<\/h2>\n<p>A quick refresher, because the chemistry matters here. Cannabis doesn&#8217;t make THC directly. The plant first builds a precursor called <a href=\"https:\/\/cannabis.net\/blog\/medical\/exploring-cbga-the-mother-of-all-phyto-cannabinoids\">CBGA<\/a>, often nicknamed the &#8220;mother cannabinoid.&#8221; Specialized enzymes called cannabinoid synthases then reshape CBGA into different molecules. One enzyme makes <a href=\"https:\/\/cannabis.net\/blog\/medical\/what-is-thca\">THCA<\/a>. Another makes <a href=\"https:\/\/cannabis.net\/blog\/medical\/cbda-a-cannabinoid-acid-with-therapeutic-promise\">CBDA<\/a>. A third makes CBCA. Heat later converts those acidic forms into the THC, CBD and CBC most of us have heard of.<\/p>\n<p>Those three enzymes are the whole ballgame. Whether a plant is a <a href=\"https:\/\/cannabis.net\/blog\/history\/what-does-it-mean-to-be-couchlocked\">couch-locking THC<\/a> monster or a non-intoxicating CBD hemp variety comes down largely to which synthase genes it carries and how active they are. If you want to understand where cannabis&#8217;s personality came from, you have to trace where those genes came from.<\/p>\n<h2>Seventeen million years ago, a gene got copied<\/h2>\n<p>The new study, by researchers at the Chinese Academy of Agricultural Sciences, Huazhong Agricultural University and Yangzhou University, did exactly that. According to The Marijuana Herald&#8217;s report on the paper, the team found that the story began with a gene duplication that happened <em>before<\/em> cannabis and hops split into separate lineages, an event they estimate at roughly 17 million years ago.<\/p>\n<p>After the split, the two plants went their separate ways with that inheritance. Cannabis kept two related gene lineages, now located on chromosomes 2 and 7. Hops kept only a version resembling the chromosome 2 genes.<\/p>\n<p>The chromosome 7 lineage in cannabis is where things got interesting. It went through additional rounds of duplication and mutation, and over time those copies specialized into the enzymes that produce THCA, CBDA and CBCA. The chromosome 2 lineage, by contrast, stayed closer to the ancestral form and never developed the same cannabinoid-making talents.<\/p>\n<p>That neatly explains the hops question. Hops didn&#8217;t lose the ability to make THC. It never kept the branch of the family tree that eventually learned how.<\/p>\n<p>The researchers also mapped the relationships between the three synthases. The THC and CBC enzymes turned out to be closer relatives of each other, while the CBD enzyme branched off earlier. In family-tree terms, THC and CBC are siblings, and CBD is more like a cousin. I find that delightful, given how often THC and CBD are marketed as yin and yang.<\/p>\n<h2>Why it took this long to see<\/h2>\n<p>You might reasonably ask why we&#8217;re only learning this now, given that the cannabis genome was first sequenced back in 2011. The short answer is that the cannabis genome is a mess, in the most scientific sense of the word.<\/p>\n<p>According to the study, about 79% of it consists of repetitive DNA, long stretches that look nearly identical to one another. Imagine trying to reassemble a shredded book in which most of the pages say roughly the same thing. Earlier genome assemblies left gaps in exactly those regions, including parts of chromosome 7 where the cannabinoid synthase genes live.<\/p>\n<p>This team produced two &#8220;gap-free&#8221; genome assemblies from a single <a href=\"https:\/\/cannabis.net\/blog\/medical\/cbddominant-extracts-improve-autism-symptoms-in-children-say-new-medical-studies\">CBD-dominant female<\/a> plant of Chinese origin called Golden Cannabis sativa, which contained around 4% CBD and no detectable THC. The two assemblies represent the two sets of chromosomes that plant inherited, each about 741 to 745 million base pairs long, with all 10 chromosomes fully assembled, more than 99% completeness and roughly 27,000 genes apiece.<\/p>\n<p>With no gaps to hide in, the synthase genes finally came into focus.<\/p>\n<h2>Having the gene isn&#8217;t the same as using it<\/h2>\n<p>Some of the most practically useful findings are less about deep time and more about how messy the genetics of modern cannabis really are.<\/p>\n<p>First, the researchers found many synthase-like sequences scattered around the genome, but most were broken. Mutations had rendered them unable to produce working enzymes. Across the genomes they examined, they found no more than one intact copy of the main THC or CBD synthase gene per set of chromosomes.<\/p>\n<p>Second, the physical layout varies enormously between varieties. In some genomes, the THC and CBD synthase regions sit 10 to 30 million base pairs apart. In others, they are only 4 to 5 million apart. That is evidence of major genomic rearrangement over the plant&#8217;s evolutionary and breeding history, and a warning that one reference genome cannot represent the whole species.<\/p>\n<p>Third, gene activity matters as much as gene presence. In this CBD-dominant plant, the CBD synthase gene was highly active during flowering, the CBC synthase much less so, and the rest were weak or silent.<\/p>\n<p>Put those together and you get a lesson that applies far beyond the lab: a plant&#8217;s cannabinoid profile depends on which genes are intact, where they sit in the genome, and how loudly they&#8217;re being expressed. The genetic recipe is more complicated than the strain name on the jar suggests.<\/p>\n<p>The team also tackled a long-running debate about whether cannabis went through extra rounds of whole-genome duplication. They found no evidence of that. Instead, cannabis shares an ancient genome triplication with many flowering plants, and most of its later diversification came from smaller-scale duplications, mobile genetic elements and rearrangements. In other words, cannabis didn&#8217;t get its chemistry by photocopying its entire genome. It got it by tinkering with one gene family.<\/p>\n<h2>The ancestors were generalists<\/h2>\n<p>This study lands in the same year as another one worth reading alongside it. In December 2025, researchers at Wageningen University &amp; Research in the Netherlands, led by Robin van Velzen and Clo\u00e9 Villard, published work in the same journal using a technique called ancestral sequence reconstruction. Working backward from modern DNA, they calculated what long-extinct cannabinoid enzymes looked like, then rebuilt them in the lab and tested them.<\/p>\n<p>Their finding complements the Chinese study beautifully. The ancestral enzymes were generalists that could produce several cannabinoids at once. Only after gene duplications did their descendants specialize into the dedicated THC, CBD and CBC enzymes we see today. The reconstructed ancestors were also sturdier and easier to produce in microbes like yeast than their modern counterparts. One &#8220;evolutionary intermediate&#8221; proved especially good at producing CBC, a cannabinoid no existing cannabis plant makes in high amounts.<\/p>\n<p>The Wageningen team also found that cannabis evolved this ability independently from distantly related plants, such as some rhododendrons, that make similar compounds. Nature apparently arrived at cannabinoid-style chemistry more than once, which suggests it is useful to plants for reasons of their own. The leading hypotheses involve defense against insects, pathogens and UV radiation, though that question is still open.<\/p>\n<p>One honest disclosure from that story: van Velzen is also affiliated with Bedrocan, a medical cannabis producer, though the company was not involved in the study.<\/p>\n<h2>So what do we actually get out of this?<\/h2>\n<p>I want to be careful not to oversell it, because the researchers aren&#8217;t. The Chinese study was <a href=\"https:\/\/cannabis.net\/blog\/medical\/what-cannabis-strain-has-the-most-complete-genome-meet-pink-pepper-the-weed-culitvar-that-has-s\">genome sequencing<\/a>, comparative genetics and gene expression measurement. It did not create new varieties, and it did not show that its evolutionary map can immediately be used to boost cannabinoid production. The authors themselves say the next step is linking complete genomes to measured gene activity and cannabinoid content in individual plants.<\/p>\n<p>Still, the long-term implications are real.<\/p>\n<ul>\n<li>\n<p><strong>Smarter breeding.<\/strong> Knowing which synthase copies are intact and active, and where they sit, gives breeders better genetic markers than &#8220;this one smelled great last year.&#8221;<\/p>\n<\/li>\n<li>\n<p><strong>Better chemotype prediction.<\/strong> If growers can read a seedling&#8217;s genome and know whether it will lean THC, CBD or CBC, a lot of trial and error disappears.<\/p>\n<\/li>\n<li>\n<p><strong>New cannabinoid profiles.<\/strong> The Wageningen CBC enzyme hints at plants or yeast strains producing cannabinoids that are currently rare and expensive to study.<\/p>\n<\/li>\n<li>\n<p><strong>Biotech production.<\/strong> Sturdier ancestral enzymes could make it cheaper to produce specific cannabinoids in microbes, which matters for pharmaceutical research where purity and consistency are everything.<\/p>\n<\/li>\n<\/ul>\n<p>There&#8217;s also something quietly satisfying about the bigger picture. For most of the last century, cannabis was studied mainly as a problem to be controlled. Now we&#8217;re reconstructing its family history with the same tools used for crops like rice and wheat. That shift says as much about our culture as it does about the plant.<\/p>\n<h2>The plant that kept the right gene<\/h2>\n<p>When I strip it all down, the story is almost poetic. Around 17 million years ago, a single gene got copied. Two plant lineages walked away with the same inheritance. One, hops, kept the boring branch and became beer&#8217;s flavoring. The other, cannabis, kept the branch that tinkered, duplicated and specialized until it could produce some of the most studied, debated and legislated molecules on Earth.<\/p>\n<p>We are still a long way from fully understanding how this plant works. But every gap filled in its genome is a gap filled in our ability to use it wisely, whether that means medicine, agriculture or just knowing a little more about what&#8217;s in the jar.<\/p>\n<p>Not bad for a weed.<\/p>\n<h2>Sources<\/h2>\n<p><a href=\"https:\/\/nltimes.nl\/node\/85572\">NL Times on the Wageningen study and van Velzen&#8217;s Bedrocan affiliation<\/a><\/p>\n<h3><strong>NOT ALL ABOUT THE THC, READ ON&#8230;<\/strong><\/h3>\n<p><strong><a href=\"https:\/\/cannabis.net\/blog\/opinion\/it-isnt-all-about-thc-what-to-look-for-in-quality-weed\"><img alt=\"NOT ABOUT THC\" src=\"https:\/\/cannitrol.com\/blog\/wp-content\/uploads\/2026\/10\/why-cannabis-makes-thc-the-17-million-year-old-genetic-secret-revealed-2.jpg\" \/><\/a><\/strong><\/p>\n<p><a href=\"https:\/\/cannabis.net\/blog\/opinion\/it-isnt-all-about-thc-what-to-look-for-in-quality-weed\"><strong>WHY GOOD WEED IS NOT ALL ABOUT THE THC LEVELS!<\/strong><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Seventeen Million Years in the Making Every so often I like to remind myself that the plant I write about was not designed by a dispensary marketing team. Long before anyone rolled a joint, named a strain after a dessert, or argued about indica versus sativa on the internet, cannabis was simply a weedy little [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[9,1,3,61,1736],"tags":[],"_links":{"self":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/posts\/11257"}],"collection":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/comments?post=11257"}],"version-history":[{"count":0,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/posts\/11257\/revisions"}],"wp:attachment":[{"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/media?parent=11257"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/categories?post=11257"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cannitrol.com\/blog\/wp-json\/wp\/v2\/tags?post=11257"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}