From the science of leaves releasing gases to the link between smell and memory, there’s a reason we love the way fall smells.
The trees are really starting to show off, especially in the mountains. If you’re like me, you know that not only is autumn lovely to look at — it smells good, too.
That musty, earthy smell of nature around us, combined with the crunch of leaves under our feet, is a feast for the senses. Turns out, there’s a reason autumn smells better than summer — or at least has a more distinguishable smell. Rachel Herz, a neuroscientist at Brown University and a leading world expert on the psychological science of smell, says that “in summer, we have just more of a mixture of scent and sort of a wide blend of scent. We smell a lot more of everything around us.
“When it gets cooler and drier, specific scents tend to stand out more. We’re able to kind of pull out the scent of leaves, the scent of bark, the scent of grass in more distinct ways.”
Theresa Crimmins, director of the USA National Phenology Network, agrees, and explains that in fall, scents can be clearer and more prominent due to the changes in weather. (Phenology is the study of cyclical events in nature, like when leaves change color or animals migrate, as well as how they’re influenced by forces like climate.)
The heat — and sometimes humidity — of summer traps smells, creating a “mishmash” for our noses. But, as the days get cooler and crisper, there are fewer volatile organic compounds in the air, and we’re better able to distinguish the ones that are released by dying and decomposing vegetation. As the leaves decompose, various gases are released, and they are responsible for that sweet smell we often associate with fall.
If we are not young children, we probably have specific memories associated with fall. Maybe we raked leaves and then jumped into the giant piles, or took hikes through the mountain splendor. Smelling something familiar is a powerful memory trigger. In fact, smell and memory work differently than seeing or hearing familiar sights or sounds.
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Herz explains, “If you saw something or heard something, you’d think about what that meant first, and you’d analyze it and evaluate it, ‘Oh, this makes me feel such-and-such.’ But with smell, it’s the emotion first and then we try to figure out, ‘Why am I feeling like that? Why am I feeling wistful or nostalgic or excited?’” Additionally, smell and emotion are stored as one memory, according to an article in The Harvard Gazette.
In an academic publication in the journal “Brain Sciences,” she explains further: Studies have now shown that our own “memories triggered by odors feel much more emotional,” activate emotional processing and are more likely to bring us back to the “original time and place of their memories compared to when the same events are recalled” in other ways.
Earlier this year, Harvard Medicine, the magazine of Harvard Medical School, published an article detailing connections between smell, memory and health. Beneficial effects of smells that evoke pleasant memories include mood improvement; stress reduction; slower, deeper breathing; and reductions in markers of inflammation. Losing the ability to smell — a condition called anosmia — can be damaging to our mental health and of course, some smells associated with a traumatic event or events can trigger flashbacks or post-traumatic stress disorder episodes. Recent research with smells and overcoming PTSD show promising results.
So this fall, get out there with your kids and grandkids and inhale some lovely fall aromas. And, if decaying leaves aren’t your thing, there is always pumpkin spice.
Originally published in the Deseret News
