For millennia, the San and Khoikhoi peoples of Southern Africa knew something Western pharmacology is only beginning to confirm. The story of Sceletium tortuosum — what kanna is, what it does, and what it means — changes entirely when we start where it actually begins.

Most articles about Sceletium tortuosum begin with the alkaloids. They tell you about mesembrine, about serotonin reuptake inhibition, about the standardized extract Zembrin and its clinical trial results for anxiety and cognition. That information is real and worth knowing.

But it is not where the story begins.

The story begins in the semi-arid scrublands of Southern Africa’s Northern and Western Cape, where the San and Khoikhoi peoples — the oldest continuous inhabitants of the continent — had already developed a sophisticated, multigenerational relationship with this small succulent long before any European ship appeared on the horizon. They fermented it. They chewed it. They used it in ceremony, as a social bond, as medicine for long hunts and difficult days. The knowledge of how to prepare it, when to use it, and what it meant was not incidental — it was transmitted across generations as living wisdom, not written instruction.

What happened next — the colonial encounter, the century of confusion, the eventual pharmacological vindication — is one of the more instructive stories in the history of plant medicine. It is a story about what gets lost when context is stripped from a plant, and what becomes possible when it is restored.

The Botany: A Succulent Built for Survival

Sceletium tortuosum belongs to the family Aizoaceae — the same family as ice plants and living stones — and it is shaped by the same uncompromising environment. The genus name, Sceletium, comes from the Latin for skeleton, a reference to the distinctive latticed appearance of the dried lower leaves, which look as though the plant has been partially dissolved back into itself. The species name, tortuosum, refers to the plant’s characteristically twisted stems.

It grows in the rocky, semi-arid regions of South Africa’s Northern Cape, Western Cape, and Eastern Cape provinces — landscapes that are beautiful and merciless. The plant has evolved to thrive under conditions that would desiccate most species: it stores water in its thick, fleshy leaves, manages its chemistry in ways that may discourage predation, and produces a set of alkaloids whose ecological function is still only partially understood.

There are approximately nine species within the genus Sceletium, but tortuosum has been the primary focus of both traditional use and modern research — a convergence that is itself worth noting. Traditional healers did not choose their plants at random. The San and Khoikhoi’s specific interest in this species, documented across centuries and across different community contexts, anticipated what phytochemical analysis would eventually confirm.

The Chemistry: What the Plant Actually Contains

The pharmacological interest in kanna centers on a group of alkaloids — nitrogen-containing compounds that interact directly with the human nervous system. The primary active compounds are mesembrine, mesembrenone, and mesembrenol, each with distinct and complementary profiles of activity.

The PDE4 inhibitory activity of mesembrenone is particularly interesting to researchers because PDE4 inhibitors are an active area of pharmaceutical development for conditions including anxiety, depression, and cognitive decline — yet the San people were working with a natural PDE4 inhibitor long before the biochemical target was even named.

This is a pattern that appears repeatedly in ethnobotanical research: traditional knowledge pointing, sometimes centuries in advance, toward mechanisms that Western pharmacology later arrives at through the formal drug discovery process. It is one of the most compelling arguments for taking traditional knowledge systems seriously as a form of scientific inquiry — not a precursor to it, but a parallel practice with its own rigor and its own accumulated evidence base.

The History: 400 Years of Being Misunderstood

The written history of kanna in European accounts begins in 1610, with the logs of a Dutch ship called The Globe, docking in what is now Saldanha Bay near Cape Town. The ship’s crew documented their search for a local root called “kanna,” comparing it favorably to ginseng — a medicinal root already valued across Asia. It is a small, telling detail: the Dutch understood enough to know this plant was worth seeking, but not enough to understand what it actually was or why.

That dynamic — recognition without comprehension — would persist for nearly four centuries.

What the timeline makes visible is the gap — the centuries between the San and Khoikhoi peoples’ sophisticated use of this plant and the moment Western science finally developed the tools and the willingness to take that use seriously. That gap is not merely historical. It shaped what knowledge was preserved, what was lost, what was commercialized without consent, and what had to be painstakingly reconstructed through fieldwork.

The closing of that gap, in large part, is the work of one researcher.

The Researcher Who Retraced the Route

In 1995, Dr. Nigel Gericke did something that no modern botanist had done: he followed the historic Dutch expedition route through Namaqualand, the way the early colonial naturalists had traveled, and he went looking not for specimens but for people.

He found them. Traditional healers including Gert Dirske and Jap-Jap Klaasse, and shepherds including Lodewyk Mories, who still held living knowledge of how kanna was prepared, used, and understood within the Khoikhoi tradition. Gericke documented what he found with the rigor of a scientist and the respect of someone who understood what he was being given access to.

The significance of Gericke’s approach is worth dwelling on. He did not arrive extracting samples and leave. He documented the cultural practice – how kanna was fermented, how it was used socially versus medicinally, what the traditional understanding of its effects and its appropriate uses actually was. And he built commercial relationships that included indigenous healers as partners, not sources. Phyto Nova, the company he co-founded, had two indigenous healers among its founding partners — a model that anticipated the ethical frameworks the broader industry is still catching up to.

From the field – Gert Dirske, Khoikhoi traditional healer, Namaqualand, 1995

“We ferment the plant for several days before using it. It is not the same plant after fermentation — it becomes something different, something the body can receive. The raw plant is too sharp. You must know how to prepare it. This knowledge was given to us by our grandparents, and their grandparents before them.”

– Documented by Dr. Nigel Gericke during ethnobotanical fieldwork, Namaqualand, 1995

From the field – Jap-Jap Klaasse, Khoikhoi traditional healer, Namaqualand, 1995

“Kanna is for when a man’s heart is heavy. When there is worry, or the work is long, or there has been grief — you take a little and the weight lifts. Not like being drunk. It is more like the sun coming through. You are still yourself, but the heaviness is gone. We have always known this.”

“It is also for the children who cannot settle, and for the old ones who cannot sleep. We know the amounts. We know when to use it and when not to. It is not something you take carelessly.”

– Documented by Dr. Nigel Gericke during ethnobotanical fieldwork, Namaqualand, 1995

These accounts are not anecdotal colour. They are primary source data — the result of fieldwork that took seriously the idea that Khoikhoi healers had developed, over generations, a form of pharmacological knowledge that was precise, contextual, and transmissible. Gericke treated what he heard as evidence, not folklore.

Dr. Nigel Gericke

Ethnobotanist · Physician · Leading researcher on Sceletium tortuosum

Dr. Nigel Gericke is a medical doctor and ethnobotanist with 25 years of experience in botanical R&D and innovation, specializing in psychoactive plants. He trained in traditional African medicine under senior healers, including Tsonga healer Ncindani Maswanganyi of Mbokota Village, Limpopo (1987–1989). Dr. Gericke has led interdisciplinary research on Sceletium tortuosum, spanning ethnobotanical fieldwork, crop development, neuropharmacology, and preclinical and translational clinical studies. He is a peer reviewer for the Journal of Ethnopharmacology, co‑author of two books and two book chapters, and author of 25 peer‑reviewed papers.

The significance of Gericke’s approach is worth dwelling on. He did not arrive extracting samples and leave. He documented the cultural practice — how kanna was fermented, how it was used socially versus medicinally, what the traditional understanding of its effects and its appropriate uses actually was. And he built commercial relationships that included indigenous healers as partners, not sources. Phyto Nova, the company he co-founded, had two indigenous healers among its founding partners — a model that anticipated the ethical frameworks the broader industry is still catching up to.

That Gericke is an Advisor to the McKenna Academy is not incidental. It reflects the Academy’s commitment to building a community where the people who did the work — in the field, with the knowledge holders, over decades — are at the table.

The Clinical Picture: What the Research Shows

Between 2013 and 2017, Zembrin — the standardized extract developed from Gericke’s foundational research — became the subject of the first rigorous clinical trials ever conducted on Sceletium tortuosum. Four randomized, double-blind, placebo-controlled studies, published in peer-reviewed journals, produced results that were carefully limited in their claims but significant in what they demonstrated:

Zembrin was found to be safe when taken daily over three months. An fMRI study showed a measurable reduction in amygdala reactivity to negative emotional stimuli — a finding consistent with the plant’s traditional use for anxiety and emotional regulation. A cognitive study showed pro-cognitive effects. A six-week clinical trial demonstrated a significant reduction in HAMA-A anxiety scores at a 50mg daily dose.

These are not dramatic results. They are carefully bounded, preliminary, and appropriately qualified. But they matter — because they represent the formal scientific beginning of an evidence base for what Khoikhoi and San communities had observed across generations. The traditional knowledge did not wait for the clinical trials. The clinical trials caught up to the traditional knowledge.

WHAT THE RESEARCH DOES NOT YET TELL US

There is a significant gap between the clinical literature on Zembrin — a standardized, isolated extract — and the traditional whole-plant preparations the Khoikhoi and San used. Fermentation, for example, changes the alkaloid ratios in ways that are not fully understood. The social and ceremonial context of traditional use is absent from a clinical trial by design, but it may not be pharmacologically irrelevant. The interaction between the plant’s alkaloids and set, setting, and intention — questions that psychedelic research has become increasingly attentive to — have barely been asked in the kanna literature.

This is where ethnobotany and clinical pharmacology need each other. The clinical trials validate the direction. The ethnobotanical record contains dimensions of the picture that clinical trials, by their nature, do not capture.

The Broader Conversation: Kanna in the Context of African Plant Traditions

The story of Sceletium tortuosum is not only a story about one plant. It is a story about what happens when plant knowledge travels — across time, across cultures, across the ocean — and what is preserved or lost in that journey.

The Khoikhoi and San peoples’ relationship with kanna is one thread in a much larger fabric of African plant knowledge: knowledge systems that survived colonial disruption, forced migration, and centuries of deliberate suppression. Much of this knowledge was maintained not through institutions but through people — healers, elders, shepherds, farmers who kept the preparation methods, the dosing knowledge, the understanding of context alive across generations simply by continuing to practise them.

What Gericke’s fieldwork demonstrated — and what the clinical research has begun to confirm — is that this kind of knowledge is not romantic or symbolic. It is pharmacologically precise. The Khoikhoi healers who described fermentation as essential were describing a real biochemical process. The descriptions of emotional regulation, of dosing appropriate to age and condition, of the difference between social and medicinal use — these are not folk wisdom awaiting scientific translation. They are observations accumulated through rigorous multigenerational practice.

The work of restoring full credit to that practice — to Gert Dirske, Jap-Jap Klaasse, Lodewyk Mories, and the long line of knowledge holders before them — is ongoing. So is the science. And so is the conversation about what it means to study plants ethically, in genuine partnership with the communities whose knowledge has always been at the centre of the story.

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