Feelings of interconnectedness with nature, of being part of nature, seem to be a primary facet of the psychedelic experience, described over and over again in experience reports, in research surveys and in key historical accounts of early psychedelic experiences. One survey of 150 psychedelic users reported that all reported an increase in nature connection following their psychedelic experiences. There are a number of correlative studies showing that psychedelic users tend to rate highly in nature relatedness, and in a sample of patients with major depression undergoing psilocybin therapy, measures of nature connection remained high 7–12 months post experience. It was interesting to note that the patients with depression did not acknowledge their disconnection from nature until after their psilocybin sessions, when it seems they were reminded of the importance of that connection.

In another study pooling data from healthy participants undergoing psilocybin sessions, an enduring shift in people’s relation to the environment was reported by over a third of study participants 8–16 months later. Interestingly, a follow up of the famous Marsh Chapel Experiment, where Harvard divinity students were given a high dose of psilocybin or placebo, found that when study participants were interviewed 24–27 years later, one of the common themes emerging from interviews was an enduring and deepened appreciation for life and nature following their psilocybin experiences.

One recent large scale study found that lifetime experience with classical psychedelics (but not other consumed substances) was found to strongly predict self-reported engagement with pro-environmental behaviour, and this was largely explained by people’s self-identification with nature, or nature relatedness. Research conducted so far suggests that the long-term increase in nature relatedness reported is tied to the experience of ego dissolution, where a brain network known as the default mode network (which is thought to be a fundamental component of the neural basis of the ego or sense of self) is relaxed and deactivated. This appears to result in perceived boundaries between self and other dissolving, resulting in an expanded perspective of self-nature overlap. It is intriguing that the memory of this perspective shift appears to be enduring, especially given that much of the psychedelic research studies linked to increased nature relatedness among participants are conducted in clinical, nature deprived settings.

One can only wonder at the potential capacity of psychedelics to (re)connect people to nature were monitored psychedelic sessions conducted in natural settings.

The perspective shift catalysed by the experience of psychedelic ego-dissolution appears similar to what is known as the overview effect, a cognitive shift many astronauts report when viewing the earth from space. This has been described as “truly transformative experiences involving senses of wonder and awe, unity with nature, transcendence and universal brotherhood”, with many astronauts becoming passionate environmentalists on their return to earth.

The experience of awe, the emotional response to vast stimuli that transcend current frames or reference, or the feeling of being a “small self” in relation to something much vaster, appears to be an important component of the experience of nature, psychedelic experiences and the overview effect the astronauts report. While not many people are likely to have the opportunity to go to space in the near future to view the earth and experience the overview effect for themselves, it seems that psychedelics may offer an alternative route to a similar transformative vantage point.

Psychedelics have also been found to enhance connectedness in a broader sense…to self, self with others and the world at large. A sense of disconnection is linked to poor mental health, including depression. One study exploring the effectiveness of psilocybin therapy for the treatment of major depression found that of the 17 of 20 people who responded to varying degrees, all independently described feelings of disconnection associated with their experience of depression, and that the psilocybin had worked, at least in part, by enhancing their connectedness to themselves, others and the wider world.

Psychedelics such as psilocybin have found to result in enduring increases in measures of personality trait openness. This is associated with an appreciation for new experiences and aesthetics, imagination, creativity and a hunger for knowledge. Previous to this research personality traits were generally thought to be fixed by the age of 30, and openness was considered to decline with age. In addition, of all the personality traits, openness appears to be one of the strongest predictors of a connection to nature and pro-environmental behaviour.

As Albert Hofmann so eloquently put it, a year before his death at the mighty age of 101:

Reconnecting humans with nature and identifying any means through which we can reverse our disconnection should be considered a common goal and urgent priority shared by all. As a group of ecopsychologists concluded at the Psychology as if the Whole Earth Mattered conference almost 30 years ago: “if the self is expanded to include the natural world, behaviour leading to destruction of the world will be experienced as self-destruction.”

Given the demonstrated capacity of psychedelics to facilitate this increased human-nature connection, it would seem their widespread prohibition is not in the best interests of our species, or the biosphere at large. What if rather than vilifying these compounds, we held them in the same high regard as some indigenous groups do? How different might our global future look if that were the case?

To ensure preservation of the biosphere, we require a fundamental psychological shift at the population level…we need to transcend our sense of separateness and urgently regain a sense of our connection to nature. I can’t think of anything more important.