The Fragrance of Thriving
Coming to Ground #9
On the first really warm, sunny day of spring, I planted pansies in a couple of pots by my front door. As I dug into the soil to fill the pots, I closed my eyes and inhaled the fresh, earthy scent of moist dirt. It was so good that I lingered there for a moment breathing it in, and wondered: Why is the smell of moist soil so wonderful?
The aroma of fresh soil is recognized as a pleasant smell by people all over the world. Inhaling it can even usher in feelings of wellbeing. The fragrance is partially emitted by an organic compound that has been given the name geosmin by scientists, which means “earth smell” in Greek. We humans have plenty of helpful assets, like thumbs and speech, but we’re not blessed with a keen sense of smell like many of our other earthly kin. Even so, we are astonishingly good at distinguishing the musky scent of damp soil, detecting geosmin in concentrations as minute as five parts per trillion.1 That would be the equivalent of one drop of water in four Olympic sized swimming pools combined. To put this in perspective, a shark who is incredibly good at zeroing in on the scent of blood, detects blood at one part per million,2 the equivalent of one cup of water in one of those Olympic pools.
Scientists have known for quite some time that microbes in the soil produce geosmin, but its ecological significance wasn’t known until 2020 when researchers discovered that the scent was an agent of connection between two very different soil organisms in a mutually beneficial relationship that has existed for nearly 500 million years. Streptomyces bacteria dispersed within the soil make geosmin when they sporulate to reproduce, their last “gasp” before they die. This is precisely when help is needed to spread those spores for reproduction. The springtail, a tiny wingless insect-like animal, smells its favorite meal as the odor radiates from the soil, enticing it to dig down to find it. Professor Mark Buttner, one of the scientists who studied these organisms, summed up the relationship in an interview:
The springtails eat the [dead] Streptomyces, so the geosmin is attracting them to a valuable food source. And, the springtails distribute the spores, both stuck on their bodies and in their feces, which are full of viable spores, so the Streptomyces get dispersed. This is analogous to birds eating the fruits of plants. They get food but they also distribute the seeds, which benefits the plants.3
This earthy fragrance is especially pungent on days when rain falls upon dry earth. The aroma is so captivating that another word was fabricated to describe the specific alchemy of a soil smell that arises from the earth when rain falls after a prolonged drought. In dry soil, plant roots produce oils that mix with the microbial geosmin when rain soaks in. The scent wafts up from the damp ground and mingles with ozone in the air from a spring or summer thunderstorm, and becomes even more pungent and complex. The resulting fragrance is now known as petrichor thanks to a couple of Australian chemists. Petrichor is a melding of two Greek words: pétrā for “rock,” and īchōr, which is a unique and ancient Greek word for the ethereal golden fluid that flowed through the ancient Greek mythic gods and graced them with immortality.4 A poetic etymology for the scent of wet soil and green things, punctuated by lightning, that now attracts mortal beings with a promise of sustenance.
Microbial creatures just might be metaphorically akin to those ancient Greek deities as they are also primordial entities. Microbes are the oldest and most numerous lifeforms on Earth, and they are intricately woven into every kind of ecology. Evolutionary microbiologist Lynn Margulis referred to us and all other earthlings as “symbionts” because of the way our survival is intricately embedded in relationship.5 Margulis asserted that we all “abide in a symbiotic world”6 and this has become ever clearer over time.
The discovery of our absolute dependence upon the trillions of microbes that make up the microbiome within and upon every human body, is relatively recent. Another astonishing finding about complex interdependence that recently came to light are the symbiotic entanglements of fungal mycelium, tree roots and microbes that are integral to the life of forest ecosystems. As these examples of interspecies mutuality have come to light, they have inspired awe and expanded our consciousness of what it means to be alive here on this small planet nestled within an inconceivable vastness.
Australian cultural anthropologist Diana Young has been learning from the Pitjantjatjara people of Southern Australia for many years. In her work we can find a glimmer that points toward possibilities for why people are so sensitive to and attracted by the aroma of damp soil: ancestral memory. This olfactory experience is deeply embedded in people because of a strong sense of wellbeing associated with the ability to find food and water. When it rains after a period of dryness, the scent of soil intensifies. Water is a blessing, enabling plants to grow. Plants can be eaten and animals that humans like to hunt also eat plants. Consequently, the Pitjantjatjara people describe the earthy smell of geosmin as the color green. This is a pattern of perception that was laid down by ancient ancestors, and has been passed on for countless generations of living on a desert land.7
The scent of geosmin may trigger a feeling of wellbeing in many of us because of an ancient bodily memory of its connection to survival. It is the scent of water and fertility, a powerful elixir. It’s a clue that camels follow in the desert, tracking the scent of geosmin for up to 50 miles to locate water.8 For someone like me, with north-western European ancestry, who lives in a northern climate in Michigan, the aroma signals a very welcome return to warmth after winter. This fragrance connects with a desire to flourish and as such may evoke hope. Can the semiotic presence of an iconic scent that stimulates a sense of wellbeing and hope also be a kind of symbiosis? It is a meaningful signal that arises out of interspecies relationship originally recognized as important to basic survival, perhaps now poetically woven into the body and psyche, as a mysterious greening forth of a sense of wellbeing.
The entwinement of kinship can be found wherever life is found. Deep within we know and mysteriously respond to it even if we haven’t consciously attended to that inner awareness yet. We encounter it when we catch a whiff of living soil on a warm spring day after the rain has fallen and we pause to appreciate it. A glimmer of recognition shimmers through us in any moment when we behold what Andreas Weber calls “the world’s deep aliveness,”9 wherever and whenever we perceive it.
(Please see the footnotes at the end of this post for sources.)
Thank you for reading—or listening!
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Spring Creature Spotlight:
Every year I know that it’s officially spring with the Peepers are singing! In the short video below, Spring Peepers, aka Chorus Frogs (Pseudacris crucifer) are now whooping it up among the Skunk Cabbage in the woodland pond near my home. They’re celebrating new beginnings by fervently serenading potential mates. (April 14 2024) These tiny tree frogs are only about .75-1.5 inches long, but WOW are they loud!
For more on Spring Frog behavior,
’s latest piece will fill you in on what’s happening with Wood Frogs in ponds in the northeast US :
Joseph Stromberg, “What Makes Rain Smell So Good?” Smithsonian Magazine, April 2, 2013, https://www.smithsonianmag.com/science-nature/what-makes-rain-smell-so-good-13806085/
Alex Fox, “How Rain Evolved Its Distinct Scent—and Why Animals and Humans Love It,” Smithsonian Magazine (April 17, 2020), https://www.smithsonianmag.com/smart-news/smell-rain-explained-180974692/
John Innes Centre, “Research unearths the science behind the smell of spring,” Press Release, April 6, 2020. https://www.jic.ac.uk/press-release/research-unearths-the-science-behind-the-smell-of-spring/
Dictionary.com entry: “Petrichor- noun a distinctive scent, usually described as earthy, pleasant, or sweet, produced by rainfall on very dry ground.” “Petrichor is an uncommon word used in mineral chemistry or geochemistry to describe the pleasant scent of rain falling on very dry ground. Petrichor is a compound of the Greek nouns pétrā “rock, stone” (as in petroleum “rock oil”) and īchṓr, the juice or liquid—not blood!—that flows in the veins of the Olympian gods. About 60 percent of ancient Greek words have no satisfactory etymology; īchṓr is one of them. Petrichor was coined by two Australian chemists, Isabel “Joy” Bear and Richard Grenfell Thomas, in 1964.” https://www.dictionary.com/e/word-of-the-day/petrichor-2019-02-28/
Lynn Margulis, Symbiotic Planet: A New Look at Evolution (New York: Basic Books, 1998), 5.
Ibid., 9.
Diana Young, “The Smell of Greenness: Cultural Synaesthesia in the Western Desert,” Etnofoor, Vol. 18, No. 1, SENSES (2005), pp. 61-77 (17 pages) “synesthesia” is a phenomenon in which something that is perceived by one sense is experienced through another, like the scent of soil being described visually as a color. NOTE: I feel that the use of the term “synesthesia” in this paper feels a bit too “objective” when the Pitjantjatjara are expressing a visceral experience of the color green as they smell what brings the green into their lives—that is embodied poetry, not to be dismissed by a scientific word.
Paul Simons, “Camels Act On a Hump,” The Guardian, March 3, 2003, https://www.theguardian.com/science/2003/mar/06/science.research.
Andreas Weber, Enlivenment: Toward a Poetics for the Anthropocene, (Cambridge, MA: MIT Press, 2019), 9.
This piece was drawn from a much longer essay that is part of a thematically interconnected collection of 11 essays with the working title, “Rooted in the Kindom: A Call to Rejoin the Living,” submitted to the faculty of Earlham School of Religion in spring of 2023 for the fulfillment of Master of Arts in Theopoetics and Writing. From time to time I may pull out more of that work and share it here.
I love this essay! The smell of rain and earth is the smell
of spring, something else l'm missing so much right now
during a sojourn in the city, away from my home in the
country and all the sensory harbingers of spring that
usually mark the season. There is earth here for sure,
but all the other urban smells seem to obscure it's scent
and I'm also spending most of my time indoors. Thanks
for such a great explanation of why l've always loved that
scent of green so much. l'm anxious to get back home
and stick my nose in the earth
Thanks for this. All sorts of things fire in these sensing words. Good note on synesthesia as a stunting concept of a much larger networking of the senses that we have become alienated from. I wonder if the clean compartments of the sensual is a left brain thing and synesthesia a right hemisphere way and an earlier natural resting face of the sensual. That parts per trillion business on the scent of wet earth is fascinating. We are all dowsing with the fork of our souls every moment, well-chasers like the camels. Will look up that work by Young for sure.