Kara C. Hoover and Julia Feuer-Cotter
4 March 2016. Anthropology Colloquium in Bunnell 405 from 3-4:30
Consider Smell: Smelling Imagined Geographies through Time and Space
4 March 2016. First Friday at Ursa Major Distillery from 5-8pm
Join us for a multi-sensory experience that opens the nose to engage deeply across the senses via multisensory molecular cocktails with locally produced spirits, neurogastronomical foods, and interactive art that imagines other geographies. Art pieces range from molecular rendering of olfactory signaling, photography enhanced with bespoke smells, interactive sculptures, crowd sourced smell maps, and smell masks which explore another person’s reality through the nose. This series of works explores the synergy of art and science via the sense of smell. Kara C Hoover uses the nose as an environmental probe to explore smelling across time and space. Julia Feuer-Cotter explores how this environmental perception is enacted in Alaska’s recent past through cultural practices along the Dalton Highway.
14-17 March Arctic Perspectives at the UAF Gallery
Visit “Exploring the past with the sense of smell: circumpolar narratives and the creation of place: at the art show “Arctic Perspectives” at the Fine Arts Complex/UAF Art Gallery. An opening reception for the exhibit will be held on 14 March 2016 and all are welcome to attend. Art will be on display 12–17 March during regular Gallery hours, 9am – 5pm. The Gallery is located in the Art Department wing of the Fine Arts Complex, Room 313. On the left side of the Great Hall, the Gallery is the first door to the left immediately upon entering the wing.
Tomorrow, my colleagues and I will engage members of the public to consider smell from the molecular level to the streets of London! Following two events in Nottingham, tomorrow’s event will focus on a workshop format in the morning where Zoologist/Behavourial Geneticist Matthew Cobb of the University of Manchester and I will give an interactive lecture/workshop on the molecular level of smell from odorants to perception with an evolutionary spin. We’ll talk about our recent paper showing how one gene linked to smell may have been selected in Eurasian populations and contemplate what the evolutionary setting for smell selection may have been. After a small tastes multisensory lunch, our group will take a smell walk led by Designer Kate McLean of Canterbury Christ Church University (sensorymaps.com) and Geographer Julia Feuer-Cotter of the University of Nottingham. For more info see: www.considersmell.com
My recent research has had a little news coverage today which is lovely. My esteemed colleague, Dr. Matthew Cobb of the U of Manchester (@matthewcobb), fronted for our team today on BBC4 Inside Science (What Neandertals Smelt). The piece begins at 15:38 and runs for about 8 minutes.
The University of Manchester did a nice PR piece on our paper in Chemical Senses today as well. In short, we found a signature of natural selection acting on OR7D4, a gene that controls the receptor for androstenone. Androstenone is found in all mammals but male pigs have it in spades because it makes female pigs receptive to sex. Eurasians have a higher probability of desensitization to the compound based on their genetic code. We speculate a bit broadly that perhaps the decreased sensitivity to this compound made boar (which reeks of androstenone, among other things) more appealing as a food choice to our Neolithic ancestors. After all, pigs were first domesticated in Asia, where they have an evolutionary origin.
Perhaps the most fun part of this paper was the work done by my also esteemed colleague at Duke University (Dr. Hiroaki Matsunami) wherein his lab made the androstenone receptor based on sequence data from the Denisova paleogenome. My study of the ancient genes suggested that Altai Neandertal was similar to humans but Denisovans had a unique variant. This mutation did not make a real difference in the mutated gene’s functional response to the odor but the fact that we were able to demonstrate this was a big breakthrough.
Now, we are rebuilding about 30 more ancient olfactory receptors to see how different those were!
As I prepare the first half of my Science of Smell online class, I am having fun looking for various examples of all things biomolecular, biochemical, and genetic related to olfaction. If I were a taste and flavour chemist or a molecular gastronomist, I’d probably be interested in somehow exploiting the chirality of biomolecules in food and drinks!
Chirality refers to the non-symmetrical nature of some molecules. Non-symmetrical molecules are like our right and left hands: they appear the same in reverse but you cannot superimpose the image of one over the other in the mirror nor can a left-handed glove fit a right hand. In the pharmaceutical industry, chirality is very important because the enantiomer of a biomolecule that produces a positive outcome (like reducing morning sickness using thalidomide or hyperactivity using Ritalin) may cause a harmful effect (birth defects) or no effect. The handedness is determined by the stereocenter of a molecular. Those with ‘right’ handed stereocenters are ‘R’ or + enantiomers and those with ‘left’ handed stereocenters are ‘S’ or – enantiomers (the S comes from sinister, Latin for left).
Our olfactory receptors are clever things: they can tell the difference between the right and left hands! The two most common examples are of carvone and limonene. The R-carvone/(-) carvone is recognized as mint and its enantiomer as carraway. R-limonene/(+) limonene smells ‘orange’ and its enantiomer is lemon (see image to the right). So next time you smell oranges and lemons at the same time, recognize the power of your nose to be ambidextrous by distinguishing between the two biomolecules!
Olfactory receptor genes have more variation than most gene families in the human genome. The only family with greater diversity is the major histocompatibility complex (MHC). Both families also exhibit high heterozygosity. Due to its association with disease, the MHC is well-studied. The explanation for the maintenance of MHC diversity is pathogen-driven selection–either through heterozygote advantage or frequency-dependent selection (see here for a review); a small number of papers (here’s two: 1 and 2) have also argued for divergent allele advantage. A diversity of pathogens will result in a diversity of MHC genes over time; as a species develops resistance to a disease, an evolutionary respones occurs in the disease-causing agent. The common analogy is the evolutionary arms race, also called the Red Queen Hypothesis.
If we apply that same model to olfaction in light of a few recent findings. there might be something worth pursuing. We know we can smell millions of odors. Such a diversity of odorants in the environment that vary from region to region may result in incredible diversity in the human olfactory receptor subgenome–especially if we look at it from the perspective of divergent allele advantage.
A study from 2013 that documented sex differences in sleep needs (based on inflammatory markers) turned my thoughts to stress susceptibility. I recently wrote about allostatic load, a measure of elevated cortisol (a stress hormone) in living human populations. While attempts to transfer the concept of allostatic load to the bioarchaeological record are lacking robusticity, there is a rich history of people writing about odonto-skeletal stress markers and variation within and among populations in the frequencies of these markers.
A commonly cited expectation is that male physiological vulnerability results in higher levels of stress markers unless otherwise culturally buffered by sex-biased investment in offspring. The assumption of sex-based differences in one stress marker (enamel hypoplasias) was reviewed and mostly dismissed by Guatelli-Steinberg and Lukacs (though read the paper to understand the weak effect sex may have in some cases, the data analyzed to make this conclusion, and other subtle findings). Instead, they find that the big effect in the development of sex differences is from culturally based sex-biased investment in children. The sex-bias is hard to show in the archaeological record: in other words, while the biological data may show a sex difference, determining if the differences are from sampling error (burials most often are small in sample size and non-representative) or cultural biases (interpretable often through the material culture record) is extremely challenging.
According to a growing body of research (perhaps stemming from high rates of heart disease in modern females–number one killer), females have more inflammatory markers in their body and higher rates of inflammation. Inflammation is part of the native immune system and a basic sign of physiological stress. These findings, if they can be applied to past populations, suggest that females are not buffered biologically and archaeological data suggest that more often than not, females are also not buffered culturally.