The first Genetic Elucidation of Human Hyperosmia to Isovaleric Acid from PLOS Biology is about human differences in smell. Basically this article invesitgated a person's ability to smell four different odors: 1) isovaleric acid (sweat),:2) isoamyl acetate (think pears or bananas), 3) carvone (spearmint), and 4) cineole (eucalyptus). While most of the olfactory receptor genes in humans are now pseudogenes, we still maintain the ability to detect 10,000 different odors (bet you didn't know that). They conclude that downstream polymorphisms may have an impact on how we smell. Why is this important well think about odors and what you like to smell and it may also relate to how you odor is perceived my members of the opposite sex (ala this article from 2003).
Genetic Elucidation of Human Hyperosmia to Isovaleric Acid
Abstract: The genetic basis of odorant-specific variations in human olfactory thresholds, and in particular of enhanced odorant sensitivity (hyperosmia), remains largely unknown. Olfactory receptor (OR) segregating pseudogenes, displaying both functional and nonfunctional alleles in humans, are excellent candidates to underlie these differences in olfactory sensitivity. To explore this hypothesis, we examined the association between olfactory detection threshold phenotypes of four odorants and segregating pseudogene genotypes of 43 ORs genome-wide. A strong association signal was observed between the single nucleotide polymorphism variants in OR11H7P and sensitivity to the odorant isovaleric acid. This association was largely due to the low frequency of homozygous pseudogenized genotype in individuals with specific hyperosmia to this odorant, implying a possible functional role of OR11H7P in isovaleric acid detection. This predicted receptor–ligand functional relationship was further verified using the Xenopus oocyte expression system, whereby the intact allele of OR11H7P exhibited a response to isovaleric acid. Notably, we also uncovered another mechanism affecting general olfactory acuity that manifested as a significant inter-odorant threshold concordance, resulting in an overrepresentation of individuals who were hyperosmic to several odorants. An involvement of polymorphisms in other downstream transduction genes is one possible explanation for this observation. Thus, human hyperosmia to isovaleric acid is a complex trait, contributed to by both receptor and other mechanisms in the olfactory signaling pathway.Here is a second article on how other animals relate to us and know when to hold and when to fold them so to speak
Abstract: Animals can benefit from classifying predators or other dangers into categories, tailoring their escape strategies to the type and nature of the risk. Studies of alarm vocalizations have revealed various levels of sophistication in classification [1, 2, 3, 4, 5]. In many taxa, reactions to danger are inflexible, but some species can learn the level of threat presented by the local population of a predator [6, 7, 8] or by specific, recognizable individuals [9, 10]. Some species distinguish several species of predator, giving differentiated warning calls and escape reactions; here, we explore an animal's classification of subgroups within a species. We show that elephants distinguish at least two Kenyan ethnic groups and can identify them by olfactory and color cues independently. In the Amboseli ecosystem, Kenya, young Maasai men demonstrate virility by spearing elephants (Loxodonta africana), but Kamba agriculturalists pose little threat. Elephants showed greater fear when they detected the scent of garments previously worn by Maasai than by Kamba men, and they reacted aggressively to the color associated with Maasai. Elephants are therefore able to classify members of a single species into subgroups that pose different degrees of danger.
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