Ancient humans had the same sense of smell, but different levels of sensitivity, according to a new study.
If you have the grooming habits of a Neanderthal, perhaps it’s a good thing that your nose isn’t as sensitive to urine and sweat as a modern human’s.
If you had adopted the hunter-gatherer lifestyle of a Denisovan in the Asian steppes, your strong nose for energy-rich honey would definitely give an advantage.
While we don’t know exactly what these two endangered human species sensed or preferred to eat, a new study by Duke University scientists has revealed a bit more about what they might have been able to smell.
Using a technique that allows them to test olfactory sensitivity on olfactory receptors grown in a laboratory dish, the researchers compared the scent-ability of three types of humans.
Drawing on published databases of genomes, including ancient DNA collections collected by 2022 Nobel Prize laureate Svante Pääbo, and looking at the genes involved, the researchers were able to characterize the recipients of each of the three human species.
March said “It is quite challenging to infer a behavior solely from the genetic sequence. We have the olfactory genomes of Neanderthals and Denisovans. We can compare these to modern humans and determine if they formed a different protein.”
How did you find out that you have the same sense of smell?
The researchers then tested the responses of each hominin’s 30 lab-grown olfactory receptors against a set of scents to measure how sensitive each receptor type was to a particular odor.
Laboratory tests have shown that modern and ancient human receptors detect basically the same odors, but their sensitivities differ.
It showed that Denisovans, who lived between 30,000 and 50,000 years ago, were less sensitive to scents that modern humans perceive as floral, but were four times better at detecting sulfur and three times better at balsamic. And they were very compatible with honey.
Matsunami, a professor of molecular genetics and microbiology at the Duke School of Medicine said, “We don’t know what Denisovans eat, but there is some reason this receptor should be susceptible.” Honey is very important to modern hunter-gatherers, the Hadza tribe of Tanzania.
Neanderthals, who still existed about 40,000 years ago and who apparently changed a few of their genes to modern humans, used almost the same receptors we have today, and were three times less responsive to green, floral, and spicy scents. “Although their sensitivity may vary, their selectivity is constant,” Matsunami said.
“Neanderthal olfactory receptors were mostly the same and different from modern humans, a few that were no longer sensitive,” de March said.
Odor receptors are associated with ecological and nutritional needs in many species. It probably evolves as a species changes habitats and diets.
Matsunami said “Each species must evolve olfactory receptors to maximize its suitability for foraging. In humans, it’s more complicated because we eat so much. We don’t really focus on a single area.”
The lab also used the cell-based olfactory tester to see the genetic variation among modern humans. Matsunami says, “Some individuals can smell certain compounds but not others. Functional changes explain this situation.”
Duke University. January 5, 2023.
Article: Claire A. de March et al. (2022). Genetic and functional odorant receptor variation in the Homo lineage. iScience.