Neanderthal and Denisovan Sense of Smell Studied Using Genomes
When you walk through the woods and come across a beehive, the aroma of honey may fill your senses and bring back fond memories of drinking tea with your grandmother or eating warm biscuits on a lazy Sunday morning.
If you had been taking that walk 300,000 years ago with a Denisovan, a now extinct hominid related to Homo sapiens, by the time you had detected the sweet scent of honey, they might already have been climbing up the tree to get their hands on the sugary treat.
A recent study published in the journal iScience in January indicates that Denisovans might have had an especially acute sense of smell for sweet scents such as honey or vanilla, which could have aided them in locating food.
On the other hand, one group of a related species called Neanderthals underwent a mutation that could have shielded them from the smell of their own body odor.
Humans possess a great deal of genetic diversity in our olfactory receptors that regulate our sense of smell, allowing us to pick up on a wide range of scents.
Scientists believe that the diverse olfactory receptors in humans, which are responsible for detecting different scents, helped our ancestors adapt to new environments as they explored the world. They were able to identify new foods and potential dangers by sensing new scents.
There is a widespread misconception that humans have a weaker sense of smell compared to other animals like dogs, however, this comparison may not be relevant since dogs live in a completely different way.
In order to better understand our own sense of smell, researchers are studying the other Homo species that existed alongside us.
Biological anthropologist Kara Hoover and biochemist Claire de March from the University of Alaska at Fairbanks and the Université Paris-Saclay respectively, reconstructed the odor receptors from the genomes of three Neanderthals, one Denisovan, an ancient human, and a modern human genome database. This research aimed to recreate the noses of our ancient relatives.
Hoover believes that it’s important to understand humans within our own context instead of comparing us to other animals like dogs or mice. She stated that when people view humans as an anomaly, they overlook the fact that humans have a diverse sense of smell and were not so different from other species.
Hoover compared the DNA of Neanderthals, Denisovans, and humans by focusing on 30 olfactory receptors (genes that detect odors).
She found 11 receptors that had unique DNA variations in the extinct species, not present in humans.
De March then constructed these unique receptors by modifying human receptors to match the sequence of the Neanderthal or Denisovan, and tested their responses to different odors.
The study had a limited sample size, as only a few Neanderthals and Denisovans have been genetically analyzed.
Despite this, the study provides valuable insights into the sensory perception of ancient species.
The results showed that the Neanderthal, Denisovan, and human genomes all appeared to have the same range of smells.
However, the Denisovans were found to have a more sensitive sense of smell, while the Neanderthals seemed to have a weaker sense of smell, particularly in detecting their own body odors.
The researchers aimed to study the olfactory receptors of the Neanderthals and Denisovan by comparing their genomes to those of humans.
Hoover found 11 receptors that contained unique DNA variations in the extinct species and de March built those receptors in the lab.
They then exposed the receptors to various odors and measured the responses.
According to Graham Hughes, the study is exciting for the field of sensory perception, but there are limitations since only a few individual Neanderthals and Denisovans have been genetically mapped.
The results showed that all the species had the same repertoire of smells, but the Denisovan had a more sensitive nose for sweet and spicy scents.
One of the Neanderthals had a genetic mutation that diminished its ability to smell androstadienone, which could have been helpful in close proximity with others.
The study provides a bridge from the DNA to the real-world experience of our extinct relatives, but there are limitations in determining their sensory experiences.
The research ultimately showed that all species are more alike than different in terms of smell.