For years, the instruments mounted on the steel towers above the Amazon canopy read zero for a particular family of molecules. The Amazon Tall Tower Observatory, rising out of the forest roughly 150 kilometers northeast of Manaus, samples the air exactly where the trees release it. And in that air, a certain class of sesquiterpene alcohols — heavier, stickier relatives of the volatile compounds that give a forest its green, resinous smell — simply weren’t there. Flat zero, visit after visit.
Then came the drought.
The 2023–2024 El Niño brought the most severe drought ever recorded in the Amazon basin. Rivers fell. Vegetation strained at every level. And the forest did what stressed organisms do: it reached for its chemistry. The trees ramped up their production of sesquiterpenes — the reactive, short-lived molecules plants make as distress signals and protective agents — by 122 percent across the span of the El Niño. That part, on its own, would have surprised no one. Stressed trees make more defensive compounds. The pattern is old and well documented.
What happened next had no precedent in the measurement record.
The drought peaked. The rains returned. And in the wet season that followed, three compounds appeared in the open air above the canopy that had never been recorded there before — beta-eudesmol, alpha-eudesmol, and gamma-eudesmol. The instruments that had read zero for years suddenly registered them at levels rivaling the forest’s main stress compounds. Stranger still, they surfaced after the emergency rather than during it, and they lingered for weeks.
The researchers, publishing this June in Communications Earth & Environment, read the appearance of these molecules as an adaptation to oxidative stress — the forest shifting its metabolism toward lower-volatility, more reactive compounds to mitigate the kind of internal damage that extreme heat and water shortage inflict. They are careful to note that they measured the air, not the inside of the trees; the metabolic shift behind the emissions is an inference, not a direct reading. And the change is not permanent. Between El Niño events, which recur every two to seven years, the forest’s chemistry returns to its unstressed baseline.
There is even a loop folded into the story. Because these eudesmol alcohols are heavier and less volatile, they are more likely to form the microscopic particles that seed clouds — which means the forest’s stress chemistry may feed back into the rainfall it depends on. The defense reshapes the very environment that conditions the next response.
I have spent the better part of four decades thinking about molecules rather than labels, and I will admit this finding stopped me. Not because a stressed forest defends itself — that is the oldest story in biology — but because of the shape of the tale. The defense outlasted the threat. The protection kept running well past the moment that called for it.
We carry it in us as well.
When human tissue is injured or pushed past its limits, the initial insult is often a flood of reactive oxygen species — unstable molecules that tear at cells from within. It is, in miniature, the same category of damage drought visits on a tree. And the body answers with a protective program that is every bit as inducible, every bit as on-demand, as the forest’s. A regulator called Nrf2, ordinarily held in check, is released and travels into the nucleus, where it switches on the body’s antioxidant machinery: glutathione synthesis, protective enzymes, the cellular tools for absorbing oxidative damage. Heat-shock proteins rise to chaperone strained tissue through the crisis. This is chemistry produced in response to harm, for the purpose of limiting harm — a protective and regulatory act, exactly as you might describe one.
But the part worth dwelling on is not how the body turns defense on. It is how the body turns it off.
The word resolution comes from the Latin resolvere — to loosen, to release, to dissolve. We tend to hear it as a synonym for ending, as though inflammation simply burns down to nothing. It doesn’t. Inflammation is brought to a close by a dedicated class of molecules the body manufactures for that single purpose — the specialized pro-resolving mediators, built from the fatty acids in our tissues, whose entire job is to loosen and dissolve the response once it has done its work. The stress axis behaves the same way. Cortisol rises to meet a threat, and then, through its own feedback, instructs the brain to stop producing the signals that summoned it. The off-switch is not an absence. It is an active, manufactured event. The body spends real resources to stand down.
This is the symmetry I keep returning to: defense is regulated in both directions. The capacity to respond is only half of a healthy system. The capacity to complete the response — to release it, to return to baseline — is the other half, and it is no less active, no less biochemical, no less essential.
Which is why the lingering tale in the Amazon data reads, to me, less like a curiosity and more like a warning we already understand in our own bodies. When the off-switch fails — when cortisol will not fall, when inflammation will not resolve, when the protective program keeps running after the threat has passed — physiology has a name for the result. It is allostatic load: the wear that accumulates not from the stressor itself but from a defense that cannot stand down. The very chemistry that protected the tissue in the acute moment becomes, in its persistence, the source of injury.
So the forest does not only mirror the body’s defense. In that weeks-long tale, it mirrors the body’s central vulnerability. A response that outlives its reason stops being protection and becomes cost.
There is a question hiding in all of this, and it is the one I am asked most often: if a plant manufactures protective compounds under stress, can its chemistry lend anything to ours? The honest answer is yes — but rarely in the way the wellness shelf implies, and the difference is the whole point.
The popular story holds that plant “antioxidants” enter the body and mop up our free radicals directly. Redox biologists have spent two decades taking that picture apart. At the concentrations that actually reach our tissues, direct scavenging is far too slow to matter against our own enzymatic defenses. What many plant compounds do instead is more interesting, and more in keeping with everything above: they act as mild stressors. A great number of them are phytoalexins — the very toxins a plant builds to defend itself — and taken in at low doses, they nudge our cells with a small, survivable oxidative or electrophilic signal. That signal trips the switch we already met: Nrf2 slips its leash, enters the nucleus, and turns on our own antioxidant and detoxifying enzymes. The plant does not hand us its defense. It teaches ours to wake up.
Biologists call this xenohormesis — xeno, foreign; hormesis, the benefit of a small stress: one organism reading the chemical distress signals of another and provisioning itself accordingly. Stated in our terms, the plant compound is a cue, not a cure. It works precisely by engaging the body’s capacity for self-regulation rather than standing in for it.
Which returns us, fittingly, to the three molecules the Amazon released — because they make a quiet case for why the constituent, not the plant, is the right unit of attention. The eudesmols are one sesquiterpene skeleton in three arrangements, alpha, beta, and gamma, differing by little more than the placement of a bond. One might expect them to behave alike. They do nothing of the kind.
Beta-eudesmol provides the most direct human-cell evidence on exactly this theme: when applied to human skin fibroblasts before an oxidative insult, it protected them against hydrogen peroxide damage and quieted their inflammatory signaling. And yet the same molecule, inside cancer cells, does the reverse — it suppresses an Nrf2-controlled detoxifying enzyme to leave those cells more exposed to treatment. Same compound, opposite role, entirely by context.
Alpha-eudesmol protects as well, but through a different door altogether: it is a presynaptic calcium-channel blocker that dampens the excitatory glutamate release which injures neurons during a stroke, and the neuropeptide release tied to migraine — and it does so without disturbing blood pressure.
Gamma-eudesmol, meanwhile, has scarcely been studied in mammals; its documented life remains mostly antimicrobial and insect-deterrent, on the plant’s side of the ledger. I will not claim a human benefit for it that the literature has not yet earned.
Three isomers, three different stories, one of them still largely unwritten. This is biochemical individuality at the scale of a single molecule — and it is why I have never trusted reasoning that stops at the name on the bottle.
The wider family of aromatic constituents bears the principle out. The phenolic terpenoids — thymol and carvacrol from thyme and oregano, eugenol from clove — can trap radicals directly in a beaker, but in living tissue their more meaningful work is the xenohormetic one: prompting Nrf2, calming the inflammatory NF-κB signaling, lowering the cytokines that keep a response running too long. They do, at the molecular level, what this whole essay is circling: not forcing an outcome, but helping the body find its own way back to baseline.
One restraint belongs here, and it is the same one the cancer cells insist upon. Nrf2 is not a dial that turns only toward health. Held too low, cells go undefended; driven too high for too long, the very same pathway can shelter disease and blunt its treatment. It follows a hormetic curve — helpful in measure, harmful in excess — which is only the molecular restatement of what the forest already showed us: a protective response is a good thing exactly to the degree that it knows when to stop.
I want to be precise about what is and isn’t being claimed here, because precision is the whole point of working at the level of the molecule. The compounds are not the same. A tree’s eudesmol and a human’s resolving mediators are different chemistry doing different work in different kingdoms of life. What they share is not substance but strategy — the underlying logic of a living system under threat. And that logic, stated plainly, is this: turning the defense on is the easy half. Turning it off is the achievement.
We are fluent, culturally, in activation. We know how to summon the stress response; many of us live in a near-permanent state of having summoned it. What we have largely forgotten is the other half of the design — that the body is built not only to rise to a threat but to release it, and that health lives in the off-switch as surely as it lives in the on. To partner with the body’s own logic is to honor its capacity to stand down, not merely its capacity to respond.
The Amazon, in the worst drought of its recorded life, reached for a protective chemistry and then could not quite let it go. It is a stunning thing to have caught on instruments above the canopy. It is also, if we are willing to read it that way, a question posed back to us — about what we are still holding, long after the rain has returned, that it might finally be time to dissolve.
And there is one more reading, the most human one, that I have saved for last.
A drought is a season, not a climate. The lean stretches — in a marriage, in the bank account, in the body’s own reserves — arrive, and they are real, and the mistake is rarely the drought itself. The mistake is what we build to survive it. In scarcity we tell ourselves a story — there is not enough, it will not return, I must brace — and that story is not a flaw. It is a defense. It does for the heart what the eudesmols did for the forest: it protects something vulnerable through a hard passage.
But notice the shape, because we have already seen it. The danger was never the protection. It was the protection that would not stand down — the chemistry the forest kept exhaling for weeks after the rain came back. The scarcity story does precisely this. It earns its keep in the dry season and then, unwatched, keeps narrating into the wet one, pricing every new moment by the terms of a drought that has already broken.
This is not a call to be rid of our stories. Some of them will be needed again; a story that has known real scarcity can become wisdom the next time the sky goes quiet. The work is gentler than erasure and harder than it sounds — to loosen a story’s grip on the present, to stop letting a season dictate a life, to let it dissolve when its work is done, the way the body dissolves an inflammation it no longer needs.
Consider the cry, then, as the body’s own version of what the forest did.
For weeks the Amazon held its protective chemistry and kept releasing it long after the rain returned. We do something stranger and more merciful. When a stress has been carried too long — braced against, narrated, held in the jaw and the shoulders and the breath — the body, at a threshold it chooses for us, finds the tears and sets the whole thing down. A cry is not a leak. It is a release: the nervous system tipping out of its guard and back toward rest, the held thing allowed, at last, to move.
We have been told that weeping flushes some toxin from us, and the chemistry does not really bear that out. The relief is quieter, and truer, than a purge. Relief comes from the Latin relevare — to lift, to lighten, to raise the weight off — and that is the actual event: not a substance expelled, but a load set down, the body lowering itself out of defense.
Tears, in the end, are the human rain. Not the drought’s chemistry lingering, but the return of water to a ground that has held too long — the season changing inside a single face.
Here is where a daily practice earns its place, and why I am careful about how I say it. Scent is the one sense wired almost directly into the brain’s seats of memory and feeling, which makes a deliberate, genuine aroma less a remedy than a doorway — a reliable way to step out of the narrating mind and back into the sensing body, out of the appetitive reach for more and into the plain registration of this. The oil does not delete the story. It returns you, for a breath, to the present the story was talking over. Practiced daily, that small return becomes its own kind of weather: not the absence of drought, but the steady knowing that rain is not a memory. It is a season. It comes back.
References
Byron, J., et al. (2026). Intense El Niño provokes production of new reactive volatiles as stress defences in Amazon rainforest. Communications Earth & Environment, 7, 419. https://doi.org/10.1038/s43247-026-03597-7
Howitz, K. T., & Sinclair, D. A. (2008). Xenohormesis: sensing the chemical cues of other species. Cell, 133(3), 387–391.
Surh, Y. J. (2011). Xenohormesis mechanisms underlying chemopreventive effects of some dietary phytochemicals. Annals of the New York Academy of Sciences, 1229, 1–6. https://doi.org/10.1111/j.1749-6632.2011.06097.x
Anti-inflammatory and ECM gene expression modulations of β-eudesmol via the NF-κB signaling pathway in normal human dermal fibroblasts. Biomedical Dermatology (2018). https://doi.org/10.1186/s41702-017-0014-3
Effect of β-eudesmol on NQO1 suppression-enhanced sensitivity of cholangiocarcinoma cells to chemotherapeutic agents (2018). PMC6006851.
The nonpeptide α-eudesmol from Juniperus virginiana Linn. (Cupressaceae) inhibits ω-agatoxin IVA-sensitive Ca²⁺ currents and synaptosomal ⁴⁵Ca²⁺ uptake. Brain Research (1999); and the companion study, ω-agatoxin IVA-sensitive Ca²⁺ channel blocker, α-eudesmol, protects against brain injury after focal ischemia in rats (2000).
Terpenoids in essential oils: chemistry, classification, and potential impact on human health and industry (2024) — review of constituent-level activities, including thymol, carvacrol, and eugenol.
Master Clinical Neuroaromatherapist | Founder, Aromagenomics
Developer of the ANIS™ Methodology | Author | Consultant
This essay is educational and reflective in nature. It describes endogenous physiology and published research, and is not intended as medical advice or as a claim regarding any product.