Links for Keyword: Chemical Senses (Smell & Taste)

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By SINDYA N. BHANOO Mosquito sperm have a sense of smell, researchers are reporting, in a finding that could suggest ways to help control the spread of disease-carrying insects. The sperm carries a set of chemical sensors identical to the olfactory receptors on the mosquitoes’ antennas, according to a study in Proceedings of the National Academy of Sciences. Mosquitoes mate just once in their lifetime, and the female stores the male’s sperm in an organ called a spermatheca. Before the eggs mature, the female seeks out blood using the receptors on her antennas. Soon after, chemical signals cause the sperm tails to beat rapidly and start the fertilization process. “The sperm may need a chemical signal to become ready for fertilization,” said Jason Pitts, a researcher at Vanderbilt University and an author of the study, which was supported by the Gates Foundation as part of its efforts to improve global health. Another author, Laurence Zwiebel, also a Vanderbilt researcher, called the dual use of the olfactory receptors a clear and clever example of convergent evolution: The mosquitoes, he said, “found something that works and use it in multiple ways.” The scientists think olfactory receptors may exist on the sperm of many other insects, and they are developing chemical compounds that can be applied to breeding grounds to block the receptors. “You can effectively confuse the sperm or make them inactive,” Dr. Zwiebel said. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 19241 - Posted: 02.12.2014

by Bob Holmes Midnight fridge raids are part and parcel of a late-night marijuana smoking session. A study in mice has provided the most complete explanation yet for why a spliff triggers intense hunger pangs. The findings, which elucidate the role of smell, also suggest that we might eventually be able to treat common disorders such as obesity and loss of appetite with a simple nasal spray. We know that the active ingredient in cannabis, THC, binds to cannabinoid receptors in the brain called CB1s. This binding inhibits chemical signals that tell us not to eat, and so make us feel hungry. But this isn't the end of the story. Since smell plays such a central role in making us feel hungry, it must be part of the explanation - but no one knew exactly how it fit. To find out, Giovanni Marsicano of the French research agency INSERM in Bordeaux and his colleagues genetically modified mice to make it possible to turn on and off the CB1 receptor in particular nerve cells within the smell, or olfactory, system. The key proved to be a group of nerve cells that carry signals from the cerebral cortex down to the olfactory bulb, the primary smell centre of the brain. When the team switched off CB1 on these cells, they found that hungry mice no longer ate more than their well-fed counterparts. Conversely, activating CB1 in the same cells by injecting THC caused hungry mice to eat even more. THC-treated mice also responded to less-concentrated food smells than untreated mice, a sign that the chemical had enhanced their sense of smell. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 19230 - Posted: 02.10.2014

Ask a group of people to describe the color of a sheet of paper, a cloud, or a glass of milk, and chances are they’ll all say “white.” But ask the same group to describe the smell of cinnamon, and you’ll likely get a potpourri of answers, ranging from “spicy” to “smoky” to “sweet,” and sometimes all three. When it comes to naming smells, humans struggle to find concise, universal terms. Indeed, scientists have long thought the ability was out of our reach. But a new study indicates that the inhabitants of a remote peninsula in Southeast Asia can depict smells as easily as the rest of us pick colors. The study concerns the Jahai, nomadic hunter-gatherers who live in the mountain rainforests along the border between Malaysia and Thailand. Smell is very important to this society. Odors are often evoked in illness, or medicine, for example, and it is one of the few cultures to have words devoted exclusively to smells. “For example, the term pʔus (pronounced ‘pa-oos’) describes the smell of old huts, day-old food, and cabbage,” says Asifa Majid, a psychologist at the Centre for Language Studies at Radboud University Nijmegen in the Netherlands. This suggests, she says, that the Jahai can isolate basic smell properties, much like we can isolate the color white from milk. To find out if the Jahai are better at naming smells than the rest of us, Majid and colleagues asked native Jahai speakers and native English speakers to describe 12 different odors: cinnamon, turpentine, lemon, smoke, chocolate, rose, paint thinner, banana, pineapple, gasoline, soap, and onion. The Jahai easily and consistently named the odors, whereas English speakers struggled, the team reports in the February issue of Cognition. © 2014 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 19129 - Posted: 01.14.2014

Brian Owens Fruitflies know exactly how much alcohol will be good for their young. Larvae living on a food source with the right concentration of ethanol will grow into heavy, healthy adults and will be protected against parasites — which explains why the insects are attracted to rotting fruit or the crate of empty beer bottles in your kitchen but not to the vodka or gin. Now researchers have uncovered the neural mechanism that allows the fruitfly Drosophila melanogaster to choose the best place to lay its eggs. The work is published today in Proceedings of the National Academy of Sciences1. A team led by Ulrike Heberlein, a molecular biologist at the Howard Hughes Medical Institute’s Janelia Farm Research Campus in Ashburn, Virginia, found that clusters of neurons, working in opposition to each other, help the flies to choose the place with the most beneficial concentration of ethanol in which to lay their eggs. The neurons all release the neurotransmitter dopamine, a key player in the brain's reward circuitry. Neurons of the PAM and PPM3 clusters encourage the flies to seek out ethanol, whereas PPL1 neurons apply the brakes, preventing the flies from laying their eggs on food containing high levels of ethanol that could harm the larvae. “They can discriminate among ethanol concentrations that are very similar — 3% versus 5% — so the system evolved to have great sensitivity,” says Heberlein. Their favourite booze strength is 5%, similar to that of a typical beer. Heberlein's team also traced the neurons involved in ethanol preference to specific brain regions. Both the pro-ethanol PAM and anti-ethanol PPL1 neurons were active in the mushroom body, whereas the pro-ethanol PPM3 ones were active in the ellipsoid body. Both of these brain structures are involved in decision-making and memory, and mushroom body neurons also play a part in ethanol-reward memory. © 2013 Nature Publishing Group,

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 19013 - Posted: 12.10.2013

By Julia Calderone As we sat in my car outside a silent movie theater in Los Angeles, my friend anxiously opened a plastic bag containing a white T-shirt she’d slept in for the past three nights. “Does it smell like me?” she asked nervously, gesturing the open end toward my face. I stuck my nose into the bag and inhaled. We were about to attend a pheromone-based speed dating party with the following rules: 1. Find a clean white T-shirt. 2. Sleep in only that shirt for three consecutive nights. 3. Bring the shirt to the party sealed in a bag. As we walked into the theater, coordinators assigned each of our bags a unique color-coded sticker (pink for female, blue for male), and tossed them into a pile. A pack of hipsters nursing PBRs sat in the wooden theater seats, slightly amused by the bizarre 70s Egyptian-themed silent porn projected onto the screen. In the courtyard, 20-somethings mingled by the outdoor bar. Did they think alcohol would make us okay with sniffing strangers’ dirty laundry? Mounds of bags sat on two long tables – beckoning our nostrils. We were instructed to sniff as many T-shirts of the sex we were attracted to, and select shirts that innately smelled the sexiest. I came across bag number 166, which shockingly smelled exactly like my grandmother’s house – a delightful mix of Christmas and chicken parmesan. The point was to trust our instincts, right? I went with it. © 2013 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 19005 - Posted: 12.06.2013

by Erika Engelhaupt When I was in graduate school, I once gassed out my lab with the smell of death. I was studying the products of plant decomposition, and I had placed copious quantities of duckweed into large tubs and let the mix decompose for a few weeks. Duckweed is a small floating aquatic plant; it looks harmless enough. But when I dragged my tubs into the lab and set up a pump and filtration system, all hell broke loose. The filter clogged, the back pressure threw the hose off the pump, and a spray of decomposed mess flew all over a poor professor who had come in to help. For the rest of the day, he smelled like a pile of dead raccoons. That day, I learned about cadaverine and putrescine. These two molecules are produced during the decomposition of proteins, when the amino acids lysine and ornithine break down, and they are largely responsible for the smell of rotting flesh. My mistake in the lab was to think that rotting plants are more innocuous than rotting animals. Duckweed, it turns out, has such high protein levels that it’s used as animal feed, and those proteins, like any proteins, can create a deathly stench. The smells of cadaverine and putrescine tend to provoke a strong reaction (as I learned once the duckweed stench subsided and my labmates were able to return to the lab). But not every animal finds the odors disgusting. Carrion flies, rats and other animals that eat or lay eggs in dead things are attracted to the molecules. So researchers have started to look for exactly how animals tune in to these smells. Pinning down animals' odor detectors gives researchers a way to study aversion or attraction to certain objects. And understanding how these behavioral responses work will, I believe, help researchers clarify why humans feel the distinct emotion known as disgust. © Society for Science & the Public 2000 - 2013.

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18939 - Posted: 11.16.2013

Brian Owens The hordes of microbes that inhabit every nook and cranny of every animal are not just passive hitchhikers: they actively shape their hosts’ well-being and even behaviour. Now, researchers have found evidence that bacteria living in the scent glands of hyenas help to produce the smells that the animals use to identify group members and tell when females are ready to mate. Kevin Theis, a microbial ecologist at Michigan State University in East Lansing, had been studying hyena scent communication for several years when, after he gave a talk on the subject, someone asked him what part the bacteria might play. “I just said, ‘I don’t know’,” he says. He started investigating. He found that for 40 years, scientists had wondered whether smelly bacteria were involved in animals' chemical communication. But experiments to determine which bacteria were present had been inconclusive, because the microbes had to be grown in culture, which is not possible with all bacteria. However, next-generation genetic sequencing would enable Theis to identify the microbes in a sample without having to grow them in a dish. Using this technique, Theis and his colleagues last year published a study1 that identified more types of bacterium living in the hyenas’ scent glands than the 15 previous studies of mammal scent glands combined. In both spotted hyenas (Crocuta crocuta) and striped hyenas (Hyaena hyaena), most of the bacteria were of a kind that ferments nutrients exuded by the skin and produces odours. “The diversity of the bacteria is enough to potentially explain the origin of these signals,” says Theis. Now, they have found that the structure of the bacterial communities varied depending on the scent profiles of the sour, musky-smelling 'pastes' that the animals left on grass stalks to communicate with members of their clan. In addition, in the spotted hyenas, both the bacterial and scent profiles varied between males and females, and with the reproductive state of females — all attributes that hyenas are known to be able to infer from scent pastes. The work is published this week in Proceedings of the National Academy of Sciences. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 18915 - Posted: 11.12.2013

By Cheryl G. Murphy Is it possible that our vision can affect our taste perception? Let’s review some examples of studies that claim to have demonstrated that sometimes what we see can override what we think we taste. From wine to cheese to soft drinks and more it seems that by playing with the color palette of food one can trick our palates into thinking we taste things that aren’t necessarily there. © 2013 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 7: Vision: From Eye to Brain
Link ID: 18854 - Posted: 10.30.2013

by Laura Sanders When I started to get out and about with Baby V, I occasionally experienced a strange phenomenon. Women would approach and coo some pleasant little noises. After an appropriate amount of time had passed, these strangers would lean in close and ask to smell my baby. I’m the first to admit that this sounds creepy. Truth be told, it is a little creepy. But now I completely get it. The joy from a single whiff of newborn far outweighs any trifling social conventions about personal space and body odors. So when women approach looking for a little hit of eau de bebe, I get sharey. By all means, ladies, lean in and smell away. Tiny babies smell very, very good. So good that I’m getting a little high from just thinking about how good babies smell. So good that people attempt to bottle and sell this scent (like this baby-head-scented spray— pleasant, but pales in comparison). So good that scientists really want to know why some women find this smell irresistible. Scientists recently studied the brains of women as they sniffed new baby scent. Two-day-old babies delivered the good stuff by wearing the same pajamas for two nights. Women then sniffed the odor extracted from the outfit while brain scans assessed neural activity. Overall, the 30 women in the study (who weren’t told what they were sniffing, by the way) rated the scent as mildly pleasant. As the intoxicating scent of newborn wafted into their brains, neural activity increased in areas of the brain linked to good feelings, called neostriate areas. In the brains of the 15 women who also happened to be mothers, the brain activity seemed stronger. (No word yet on what new baby smell does to dads’ brains.) © Society for Science & the Public 2000 - 2013.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 18746 - Posted: 10.05.2013

By Michelle Roberts Health editor, BBC News online The thousands of aromas humans can smell can be sorted into 10 basic categories, US scientists say. Prof Jason Castro, of Bates College, and Prof Chakra Chennubhotla, of the University of Pittsburgh, used a computerised technique to whittle down smells to their most basic essence. They told the PLoS One journal they had then tested 144 of these and found they could be grouped into 10 categories. The findings are contentious - some say there are thousands of permutations. Prof Castro said: "You have these 10 basic categories because they reflect important attributes about the world - danger, food and so on. "If you know these basic categories, then you can start to think about building smells. "We have not solved the problem of predicting a smell based on its chemical structure, but that's something we hope to do." He said it would be important to start testing the theory on more complex aromas, such as perfumes and everyday smells. In reality, any natural scent was likely to be a complex mix - a blend of the 10 different categories, he said. Prof Tim Jacob, a UK expert in smell science at Cardiff University, said: "In the 1950s a scientist called John Amoore proposed a theory which involved seven smell categories based upon molecular shape and size. BBC © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18671 - Posted: 09.19.2013

By Caitlin Kirkwood Do NOT EAT the chemicals. It is the #1 laboratory safety rule young scientists learn to never break and for good reason; it keeps lab citizens alive and unscathed. However, if it hadn’t been for the careless, rule-breaking habits of a few rowdy scientists ingesting their experiments, many artificial sweeteners may never have been discovered. Perhaps the strangest anecdote for artificial sweetener discovery, among tales of inadvertent finger-licking and smoking, is that of graduate student Shashikant Phadnis who misheard instructions from his advisor to ‘test’ a compound and instead tasted it. Rather than keeling over, he identified the sweet taste of sucralose, the artificial sweetener commonly known today as Splenda. Artificial sweeteners like Splenda, Sweet’N Low, and Equal provide a sweet taste without the calories. Around World War II, in response to a sugar shortage and evolving cultural views of beauty, the target consumer group for noncaloric sweetener manufacturers shifted from primarily diabetics to anyone in the general public wishing to reduce sugar intake and lose weight. Foods containing artificial sweeteners changed their labels. Instead of cautioning ‘only for consumption by those who must restrict sugar intake’, they read for those who ‘desire to restrict’ sugar. Today, the country is in the middle of a massive debate about the health implications of artificial sweeteners and whether they could be linked to obesity, cancer, and Alzheimer disease. It’s a good conversation to have because noncaloric sweeteners are consumed regularly in chewing gums, frozen dinners, yogurts, vitamins, baby food, and particularly in diet sodas. © 2013 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 18614 - Posted: 09.07.2013

Josh Howgego When it comes to our sense of smell, we are all experiencing the world in very different ways. Scientists already know that humans' sensitivity to smelly molecules varies considerably from person to person (see: 'Soapy taste of coriander linked to genetic variants'). But evidence that genetic variations — as opposed to habit, culture or other factors — underlie these differences has been hard to come by. Geneticist Richard Newcomb of the New Zealand institute for Plant and Food Research in Auckland and his colleagues searched for olfactory genes by testing 187 people’s sensitivity to ten chemicals found in everyday food, including the molecules that give distinctive smells to blue cheese, apples and violets. They found that, as expected, the smelling abilities of their subjects varied. The team then sequenced the subjects’ genomes and looked for differences that could predict people’s ability to detect each chemical through smell. For four of the ten chemicals, the researchers identified clusters of genes that convincingly predicted smelling ability, as they report today in Current Biology1. The study could not conclude whether similar genetic associations exist for the other six compounds, or whether factors other than genes play a role in those cases. Previously, only five regions of the genome had been shown to affect olfactory ability when they undergo mutations, so Newcomb’s study has nearly doubled the number of genetic associations known to influence smell. And because there is nothing special about the chemicals they studied, Newcomb says that it is logical to think the findings would extend to lots of scents, meaning that people experience the plethora of chemicals surrounding them in endlessly different ways. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18454 - Posted: 08.03.2013

By Scicurious Sometimes, funny stories really bring out the wonder of the human body. You can get orgasms triggered in your feet, because of overlap in the sensory cortex. Receptors that are involved in narcolepsy are also involved in how much you eat. And knocking out receptors that regulate taste…can make you sterile? Who knew? Let’s start with taste. We taste because the chemicals in foods hit receptors on our tongues. Receptors for sweet, salt, bitter, sour, and umami (which can commonly be thought of as “savory”). Now, a receptor isn’t just a single protein, it’s actually several protein subunits working together to function. So, for example, the receptor subunit TAS1R3 is a subunit that can play two different tasting roles. When combined with one other subunit, it helps to sense sweet (like saccharin), and when combined with another, if helps you taste umami (like MSG, which is definitely umami flavored). If you get rid of the gene for TAS1R3, you end up with an animal that can’t detect either sweet or umami very well. There’s another subunit that is covered in this paper as well, GNAT3. GNAT3, instead of being specific for something like sweet or bitter, instead plays a role in “basic taste“. But these two protein subunits are not JUST expressed on the tongue and in the gastrointestinal tract. They are expressed elsewhere in the body…and especially in the testicles. © 2013 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 18336 - Posted: 07.02.2013

David Derbyshire Every year Robert Hodgson selects the finest wines from his small California winery and puts them into competitions around the state. And in most years, the results are surprisingly inconsistent: some whites rated as gold medallists in one contest do badly in another. Reds adored by some panels are dismissed by others. Over the decades Hodgson, a softly spoken retired oceanographer, became curious. Judging wines is by its nature subjective, but the awards appeared to be handed out at random. So drawing on his background in statistics, Hodgson approached the organisers of the California State Fair wine competition, the oldest contest of its kind in North America, and proposed an experiment for their annual June tasting sessions. Each panel of four judges would be presented with their usual "flight" of samples to sniff, sip and slurp. But some wines would be presented to the panel three times, poured from the same bottle each time. The results would be compiled and analysed to see whether wine testing really is scientific. The first experiment took place in 2005. The last was in Sacramento earlier this month. Hodgson's findings have stunned the wine industry. Over the years he has shown again and again that even trained, professional palates are terrible at judging wine. "The results are disturbing," says Hodgson from the Fieldbrook Winery in Humboldt County, described by its owner as a rural paradise. "Only about 10% of judges are consistent and those judges who were consistent one year were ordinary the next year. © 2013 Guardian News and Media Limited

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 14: Attention and Consciousness
Link ID: 18319 - Posted: 06.29.2013

By Helen Briggs BBC News Our perception of how food tastes is influenced by cutlery, research suggests. Size, weight, shape and colour all have an effect on flavour, says a University of Oxford team. Cheese tastes saltier when eaten from a knife rather than a fork; while white spoons make yoghurt taste better, experiments show. The study in the journal Flavour suggests the brain makes judgements on food even before it goes in the mouth. More than 100 students took part in three experiments looking at the influence of weight, colour and shape of cutlery on taste. The researchers found that when the weight of the cutlery confirms to expectations, this had an impact on how the food tastes. For example, food tasted sweeter on the small spoons that are traditionally used to serve desserts. Colour contrast was also an important factor - white yoghurt eaten from a white spoon was rated sweeter than white yoghurt tasted on a black spoon. Similarly, when testers were offered cheese on a knife, spoon, fork or toothpick, they found that the cheese from a knife tasted saltiest. "How we experience food is a multisensory experience involving taste, feel of the food in our mouths, aroma, and the feasting of our eyes," said Prof Charles Spence and Dr Vanessa Harrar. BBC © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18315 - Posted: 06.26.2013

by Paul Gabrielsen Take a whiff, men. A chemical component of other guys' sweat makes men more cooperative and generous, new research says. The study is the first to show that this pheromone, called androstadienone, influences other men's behavior and reinforces the developing finding that humans are susceptible and responsive to these chemical signals. Pheromones are everywhere in the animal world. Bugs in particular give off these chemicals to sound an alarm, identify a food source, or attract a mate. And smitten animals may indeed have "chemistry" together—pheromone signals are a subconscious part of their communication. Scientists didn't know if humans played that game as well. But in the last 30 years, they've identified both male and female putative pheromones that are linked to mood and reproductive cycles. Some fragrancemakers have even incorporated them into their products, hoping to add an extra emotional punch to colognes and perfumes. Real-life pheromones don't smell so nice, however: The specialized glands that produce these chemical compounds are located near the armpit, where they mix with sweat. Previous investigations focused on the chemicals as sexual attractants—studying a male pheromone's effect on female mood and behavior, for example. Turns out that women aren't the only ones susceptible to the power of male pheromones. Evolutionary biologist Markus Rantala of the University of Turku in Finland crafted an experiment in which 40 men in their mid-20s played a computer game in which two players decided how to share €10. One player offers a possible split, and the other decides whether to accept or reject it. Each participant took a turn making or deciding on offers. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 18217 - Posted: 06.01.2013

By Susan Milius Cockroaches that don’t fall for traps’ sweet poisons have evolved taste cells that register sugar as bitter. In certain groups of the widespread German cockroach (Blattella germanica), nerve cells that normally detect bitter, potentially toxic compounds now also respond to glucose, says entomologist Coby Schal of North Carolina State University in Raleigh. The “bitter” reaction suppresses the “sweet” response from other nerve cells, and the roach stops eating, Schal and his colleagues report in the May 24 Science. Normally roaches love sugar. But with these populations, a dab of jelly with glucose in it makes them “jump back,” Schal says. “The response is: ‘Yuck! Terrible!’” This quirk of roach taste explains why glucose-baited poison traps stopped working among certain roaches, Schal says. Such bait traps combining a pesticide with something delicious became popular during the mid-1980s. But in 1993, Jules Silverman, also a coauthor on the new paper, reported roaches avoiding these once-appealing baits. “This is a fascinating piece of work because it shows how quickly, and how simply, the sense of taste can evolve,” says neurobiologist Richard Benton of the University of Lausanne in Switzerland. What pest-control manufacturers put in their roach baits now, and whether some still use glucose, isn’t public, Schal says. But humankind’s arms race with cockroaches could have started long ago, “in the caves,” he says. In this back-and-forth struggle, it’s important “to understand what the cockroach is doing from a molecular basis.” © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18193 - Posted: 05.25.2013

by Meera Senthilingam Malaria parasites give mosquitoes a keener sense of smell, it seems. A small-scale study in the lab finds that mosquitoes infected by the parasite are three times as likely as uninfected mosquitoes to respond to human odours. If the same results are seen in malaria-carrying mosquitoes in the wild, it could lead to new ways to combat the disease. Female anopheles mosquitoes are attracted to the chemicals in human odours, which help them find the source of blood they need to grow their eggs. When these mosquitoes carry Plasmodium falciparum – the most lethal form of malaria parasite – the likelihood that they will target humans rises. "We knew already that mosquitoes bite more often when they're infected. They probe the skin more frequently," says James Logan from the London School of Hygiene and Tropical Medicine. To quantify the effect – and try to work out its cause – Logan and his colleagues infected some lab-grown Anopheles gambiae mosquitoes with Plasmodium parasites, while leaving others uninfected. They then tested how both groups were attracted to human smells. Mosquitoes are particularly attracted to foot odours, so Logan's team used nylon stockings containing the volatile chemicals produced by our feet. Over a period of three minutes, Plasmodium-infected mosquitoes landed and attempted to bite the stockings around 15 times on average. By contrast, the uninfected mosquitoes attempted to bite only around five times on average during that time. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18160 - Posted: 05.16.2013

Published by scicurious I love salt. It's just delicious. I wrote this post while noshing on deliciously salty popcorn, after a dinner which I put salt on. I crave salt so much that my parents used to joke about getting me a salt lick. And I'm not alone. Sodium is an incredibly important part of life, which means it's also an important part of what we eat. To make sure we get enough salt, animals have evolved salt-sensing systems, and low levels (below 100 mM of NaCl) of salt are very attractive. But there IS such a thing as too much salt. High levels of salt (>300 mM NaCl) are really aversive (from personal experience, I wonder if Carrabba's restaurant has concentrations of salt in their food over 300 mM). Most animals will quickly turn up their noses at a high salt concentration. You probably know that you have classes of receptors on your tongue for taste (though they are not clustered into areas of your mouth, like front for sweetness, as previously thought). You have sweet, umami (savory), bitter, sour, and salt. In most animals, sweet and umami are always attractive, while bitter and sour are nasty (except where we have overcome the aversion to enjoy things like coffee and beer). Salt, though, is the only one that goes two ways, with low levels being attractive and high levels being aversive. Now we know how low salt works. The salt receptors that are currently known are good for detecting low salt. But high salt, that's more difficult. First of all, our aversion to high salt concentrations is not very selective. While low salt detection is limited to good old NaCl, high salt detection is non-specific, working for many salts including NaCl, but others as well (like KCl). Neurotic Physiology Copyright © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 18025 - Posted: 04.13.2013

Published by scicurious Today's post comes to you courtesy of Mary Roach (aka, the person I want to be when I grow up). I have a copy of her latest book, Gulp: adventures in the alimentary canal that I am reading for review, and a weird science connoisseur such as myself of course spends half her time in the bibliography section, wherein I located this paper. This paper may thus be taken as a pre-review of the book. Spoiler: so far, the book is FABULOUS, but should never be read while eating. Ah, goat milk. When I think of goat milk, I think of places like farmer's markets, Whole Foods, and little Heidi dancing through the alps. I'll admit to never having drunk raw goat milk (though I do LOVE goat cheese). But after having read this paper, I'm afraid that I do not WANT to try raw goat milk. Why? I'm afraid of the taste...the goaty taste...that is potentially hot, sexy goaty hormones. Hot sexy goat hormones sprayed around in hot, sexy goaty URINE. So, goat milk doesn't usually taste...well, goaty. Usually it tastes pretty much like cow milk (whole fat cow milk, that is). But sometimes, you'll get a bad batch. Nothing's WRONG with it, per se, it's still healthy and not bad, but it's...goaty. The flavor and smell are musky and weird, and not at all tasty. So obviously you want to find the source of that problem. For years, people who raise goats have pinpointed the MALE goat as the source of the issue. Male goats smell very goaty indeed, particularly during the goat mating season (the rutting season). Some of the odors they emit are so strong they can be smelled several hundred meters away. The odors are very volatile, so they will spread easily, and the idea has long been that if your male goat is around the ladies, his manly odors will get on them and in them, and thus in their milk, resulting in goaty milk (which, if the male goat is the cause, means that goaty milk is really just...MANLY). So goat farmers usually keep their male goats at a good distance from the females during the rutting season, to keep the males from getting their...manliness in the milk. Manliness is just not very tasty. Copyright © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 17969 - Posted: 03.30.2013