How Long Have We Used Psychoactive Plants?

Psychoactive plants have been a part of the human story for thousands of years. From ceremonial rituals to medicinal remedies and spiritual experiences, plants with mind-altering properties have shaped cultural, religious, and healing practices across the globe. But how long exactly have we been using these plants and what do recent discoveries tell us about our ancient connection to them?

A groundbreaking archaeological study published in 2025 has revealed the earliest known evidence of psychoactive plant use in the Arabian Peninsula, pushing the timeline back nearly 2,700 years. This new research not only expands our understanding of ancient ethnobotanical practices, but it also invites us to reexamine the depth of humanity’s long-standing relationship with nature’s pharmacopoeia, including staples like cannabis.

Let’s explore what makes a plant psychoactive, how long humans have been using cannabis, and what the latest discovery in Iron Age Arabia tells us about our ancestral knowledge of plant medicine.

What Makes a Plant Psychoactive?

Before we delve into the timeline, it’s important to understand what “psychoactive” means. A psychoactive compound is any substance that, when consumed, alters brain function, resulting in changes in perception, mood, consciousness, cognition, or behavior. These effects can be subtle or profound, and they vary greatly depending on the plant, the dose, and the context of use.

Psychoactive plants include:

• Cannabis, particularly THC
• Peganum harmala (Syrian rue), which contains harmala alkaloids like harmine and harmaline
• Psilocybin mushrooms, containing psilocin and psilocybin
• Ayahuasca vines, rich in DMT
• Opium poppies, containing morphine and codeine

Such plants have been used not just recreationally, but ritually, medicinally, and spiritually. Their psychoactive properties have played key roles in religious ceremonies, shamanic journeys, and traditional healing systems for millennia.

Cannabis: One of the Oldest Known Psychoactive Plants

Cannabis is one of the most extensively documented psychoactive plants in human history. Scientific and archaeological findings have traced its use back over 2,500 years, with some suggesting even older applications. Some examples of cannabis being used throughout the years include:

Ancient Central Asia (circa 500 BCE)

Archaeologists found braziers containing cannabis residue in burial sites in the Pamir Mountains, suggesting it was burned for inhalation during ritual ceremonies.

China (as early as 2,700 BCE)

Traditional Chinese medicine texts attribute the use of hemp to Emperor Shen Nong, who recorded its therapeutic potential.

India (Vedic Period)

The sacred text Atharvaveda refers to cannabis as one of the “five sacred plants,” with uses tied to religious rites and healing.

Middle East and North Africa

Cannabis was used in Islamic medicine, and hashish was a common preparation by the 10th century.

These records show cannabis as more than a plant; it was a tool for healing, introspection, and transcendence. And despite modern prohibition efforts in the 20th century, today’s research continues to validate many of these traditional uses.

Rediscovering Our Psychoactive Past: The Peganum Harmala Breakthrough

In May 2025, a team of international researchers led by Dr. Barbara Huber and Prof. Marta Luciani published a landmark study documenting the earliest known use of Peganum harmala as a fumigated psychoactive plant. The discovery came from the Iron Age site of Qurayyah in northwestern Saudi Arabia, dating back nearly 2,700 years.

Using advanced metabolomic profiling techniques, researchers analyzed the chemical residues in ceramic fumigation devices found in domestic and communal settings, such as kitchens, courtyards, and cellars. They confirmed the presence of β‑carboline alkaloids (harmine and harmaline), and related compounds found in Peganum harmala, also known as Syrian rue.

These alkaloids are known for their:

• Psychoactive effects, particularly when combined with other plants like DMT
• Medicinal properties, including antimicrobial, antiparasitic, and antispasmodic uses
• Mood-enhancing potential, possibly used for mental clarity, emotional wellness, or spiritual focus

While the precise purpose of the fumigation remains unknown, the context suggests a multifunctional role combining health, ritual, pest control, and spiritual well-being.

Cultural Significance of Psychoactive Plants

While many today associate psychoactive plants with recreational or countercultural use, they were once respected as tools of knowledge and healing in ancient societies. From the ayahuasca rituals of the Amazon (AMZN ) to the cannabis-smoking shamans of Central Asia, these plants were considered gateways to other realms of consciousness and were used deliberately and often with ritual guidance.

The Qurayyah findings further support the idea that ancient humans had an intimate and informed relationship with their environment, particularly with the mind-altering plants it offered. Their usage was likely embedded in:

• Spiritual ceremonies
• Disease treatment and prevention
• Space purification (e.g., fumigation for hygiene or sacredness)
• Mood and mental health support

What’s striking is how the lines between medicine, ritual, and daily life were far more blurred in ancient contexts than they are in our modern pharmacological frameworks.

What the Past Teaches Us About the Future

As science continues to rediscover the healing and psychoactive properties of plants long known to ancient cultures, we are witnessing a resurgence in interest in plant-based medicine and ethnobotany. Cannabis legalization, the psychedelic renaissance, and growing support for integrative medicine are all part of this modern reawakening.

The Qurayyah study is more than a historical footnote; it’s a reminder that our ancestors were deeply aware of the medicinal and psychological powers of plants, and that modern science is just beginning to catch up.

Final Thoughts: Rediscovering Ancient Wisdom in Modern Times

The curiosity of how long we have used psychoactive plants opens the door to a deeper understanding of human culture, consciousness, and healing. As we uncover more about our ancestors’ relationship with these potent botanical allies, we begin to reclaim a part of ourselves that modern society has long forgotten.

In many ways, the future of plant-based medicine lies not just in innovation but in rediscovery.