Ancient Humans had Different Smell Sensitivities.
What might this tell us about ourselves?
Hiya!
Our Sapien lifespan once overlapped with at least four other Human species for a few thousand years. However, it’s our cousins, the Neanderthals, that we are drawn to the most — and more recently, the Denisovans. Perhaps it’s because we know more about them than our other Human relatives, and since nearly everyone has some Neanderthal and/or Denisovan DNA, learning about them feels a little more… I don’t know… personal.
We can’t help but wonder how we were the same and how we differed. Well, some researchers at Duke University wondered about the differences between our senses, specifically, our sense of smell. Researchers used genomes and lab-grown olfactory receptors to gauge the sensitivities to different scents. They found that Neanderthals and Denisovans had different smell sensitivities compared to modern-day Humans.
The Power of Smell
Of our five primary senses, I think our sense of smell is the most underrated. Thankfully, researchers have become uniquely interested in it over the last couple of years, and we’re learning all sorts of amazing things. To be honest, the attraction seems to coincide with the pandemic and Covid’s habit of taking people’s sense of smell away. But regardless of what spurred the interest, it’s high time our sense of smell gets the attention it deserves.
After all, we can smell over one trillion scents, and our olfactory system responsible for our ability to smell consists of eight parts within our throat, nose, and brain. Not to mention, unlike our vision, taste, touch, and hearing, which are all directed to our limbic system — responsible for our survival instincts, memories, and emotions — our sense of smell is already part of the limbic system. This means odors are processed differently than the other senses and likely has to do with the strong connection between a scent and our memories and emotions.
Not only do smells trigger emotions, but we also smell emotions via chemosignals, especially powerful emotions like anger. Both mothers and babies can identify each other by smell alone, men can smell when a woman is ovulating, and research suggests scent has a large subconscious part in who we mate with.
So how does our sense of smell compare to our ancient human cousins? This once would have been an unanswerable question — especially considering we can’t examine the brain or any internal tissues from them. But thanks to our technological and scientific advances, we can study their genomes and grow our own olfactory receptors in a lab.
The Study
The recently conducted study by scientists Claire de March of CNRS Paris Saclay University and Hiroaki Matsunami of Duke University published iScience shines a light on certain scent sensitivities the Neanderthals and Denisovans had compared to us today.
The team used previously published genome databases — including 2022’s Nobel Prize winner Svante Pääbo’s impressive ancient DNA collection — to characterize the receptors of Denisovan, Neanderthal, and modern Humans by analyzing their respective genomes.
Though, of course, it’s not exactly easy to predict behavior based on genome sequences, which is why they made 30 lab-grown olfactory receptors from each hominin to measure their sensitivities to specific fragrances.
In an article by Phys.Org about the study, de March said:
 "We had the odorant receptor genomes from Neanderthal and Denisovan individuals and we could compare them with today's humans and determine if they resulted in a different protein."
The Results
They discovered that while our noses appeared to detect the same odors as our ancient cousins, we were sensitive to different fragrances.
The researchers found that Neanderthals were three times less responsive to floral, spicy, or green scents than we are. Otherwise, the odorant receptors of the Neanderthals appear to be pretty much the same as ours. In the same article as before, de March concluded:
"The Neanderthal odorant receptors are mostly the same as contemporary humans, and the few that were different were no more responsive."Â
Meanwhile, the Denisovans were less attuned to florals than we are, but they were acutely good at following their noses to honey, were three times better at sensing balsamic, and four times better and sniffing out sulfur.
Perspective Shift
The tricky thing is that smell isn’t the same for everyone. I might think a fragrance smells good when it makes you turn up your nose. Scent affects each of us differently and changes daily, even throughout the day, based on an array of variables from hormones to hunger. All of this makes it difficult to know for sure how anyone, modern humans or ancient human relatives alike, experience or use smell.
Though one thing I find interesting is that other researchers are finding that our noses — of modern humans — are becoming less sensitive, perhaps it’s because we don’t have to hunt anymore, and the only time our smell comes into play regarding food is to tell whether the milk has gone bad or for the joy of smelling a cooked meal — and less so for smelling food for hunting or gathering purposes.
Then again, our sense of smell is often attributed to food, but as I mentioned before, our noses tell us far more about our surroundings than just whether our produce is ripe. Besides, since our diet isn’t specific — we eat an impressive variety of foods, even before we mass produced them — I wonder, as we learn more about how our subconscious uses scent to gauge our environment if maybe we’ll find that sense of smell is used more for relationships than food sensitivities these days.
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