The Basic Human Tastes

Our society has traditionally recognized four tastes: sweet, salty, bitter and sour. In modern times however we’re better able to get to the root of taste, seeing what molecules are detected by our taste buds, and it has become apparent that there are more basic tastes than we once thought. The most well known one is umami, a savory taste, but LiveScience brings us some other candidates for basic tastes, excerpted below:

1. Calcium

The element calcium is critical in our bodies for muscle contraction, cellular communication and bone growth. Being able to sense it in our chow, therefore, would seem like a handy tool for survival.

Mice seem to have it figured out, kind of. Recent research has revealed that the rodents’ tongues have two taste receptors for calcium. One of those receptors has been found on the human tongue, though its role in directly tasting calcium is not yet settled, said Tordoff.

Calcium clearly has a taste, however, and counterintuitively most mice (and humans) don’t like it. People have described it as sort of bitter and chalky – even at very low concentrations. Tordoff thinks our calcium taste might actually exist to avoid consuming too much of it…

2. Kokumi

That calcium receptor might also have something to do with an unrelated sixth-taste candidate called kokumi, which translates as “mouthfulness” and “heartiness.” Kokumi has been promulgated by researchers from the same Japanese food company, Ajinomoto, who helped convince the taste world of the fifth basic taste, umami, a decade ago.

Ajinomoto scientists published a paper in early 2010 suggesting that certain compounds, including the amino acid L-histidine, glutathione in yeast extract and protamine in fish sperm, or milt – which, yes, they do eat in Japan, and elsewhere – interact with our tongue’s calcium receptors.

The result: an enhancement of flavors already in the mouth, or perhaps a certain richness. Braised, aged or slow-cooked foods supposedly contain greater levels of kokumi…

3. Piquance

Spicy-food lovers delight in that burn they feel on their tongues from peppers. Some Asian cultures consider this sensation a basic taste, known in English as piquance (from a French word). Historically, however, food scientists have not classified this undeniable oral sensation as a taste.

That’s because certain piquant compounds, such as capsaicin from peppers, directly activate our tongue’s touch, rather than taste-bud, receptors. The key piquancy receptor is called TRPV1, and it acts as a “molecular thermometer,” said John E. Hayes, a professor of food science at Penn State….

4. Coolness

At the opposite end of taste sensation from piquance’s peppers is that minty and fresh sensation from peppermint or menthol. The same trick of sensory perception is at work here – activated touch receptors, called TPRM8 in this case, fool the brain into sensing coldness at normal oral temperatures, said Hayes.

As touch sensations, both piquance and coolness are transmitted to the brain via the trigeminal nerve, rather than the three classical nerves for taste. “The set of nerves that carry the burn and cooling sensation are different than from taste sensation,” said Hayes.

Still, there is an argument that temperature sensation, both in the genuine sense and in the confused-brain phenomenon of piquance and coolness, deserves to be in the pantheon of basic tastes. Interestingly, Germanic people dating back to 1500 had considered heat sensation as a taste, Hayes said, and the modern debate over temperature’s status is far from over.

5. Metallicity

… Some Asian cultures place gold and silver leaf, as it’s called, atop curry dishes and candies, while Europeans fancy a bit of these metallic foils on pastries…

Although usually tasteless, such garnishes are sometimes reported as having a distinctive flavor. Researchers have shown that this sensation might have something to do with electrical conductivity, in effect giving the tongue a little zap…

Lab tests have failed to turn up a metallic-taste receptor, Lawless said, and it remains unclear if electrical conductivity or something more is going on for those shiny culinary embellishments. “We’re leaving the door open,” Lawless said.

6. Fat

The jury is still out on whether our tongues can taste fat, or just feel its creamy texture…

Mice can taste fat, research has shown, and it looks like humans can too, according to a 2010 study in the British Journal of Nutrition. The study revealed varying taste thresholds for fatty acids – the long chains that along with glycerol comprise fats, or lipids – in participants.

Intriguingly, the subjects with the higher sensitivities to fat ate fewer fatty menu items and were less likely to be overweight than those with low sensitivity…

7. Carbon Dioxide

Yet another strong sixth taste candidate: carbon dioxide (CO2). When dissolved in liquids, this gas gives soda, beer, champagne and other carbonated beverages their zingy fizz.

That familiar tingling was thought to result from bubbles bursting on the tongue, and had therefore been consigned to the touch category. “It’s tricky because CO2 was always considered a trigeminal stimulus,” said Tordoff.

Researchers presented a strong case for dedicated, taste bud-based carbon dioxide sensors in a Science paper in 2009. They found that an enzyme called carbonic anhydrase 4, which appears on sour taste-sensing cells, specifically detects carbon dioxide in mice…

Pretty interesting stuff. This is another scientific topic where it pays not to get emotionally attached to convention – the fact that there aren’t 5 senses or 9 planets or 4 tastes should be exciting new developments, not scary challenges to our worldview.

It’ll be interesting to see when our culture catches up to these realities; we already acknowledge foods as spicy or minty, but how long will it be before advertisers say their food is more umami or kokumi than their rivals’? 

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Empathy in Rats

A new study has shown that rats will go out of their way to help another rat in distress even with no reward and even if it’s actually costly to them. 

From LiveScience:

In the new study, laboratory rats repeatedly freed their cage-mates from containers, even though there was no clear reward for doing so. The rodents didn’t bother opening empty containers or those holding stuffed rats.

To the researchers’ surprise, when presented with both a rat-holding container and a one containing chocolate — the rats’ favorite snack — the rodents not only chose to open both containers, but also to share the treats they liberated…

In previous studies, researchers found that rodents show the simplest form of empathy, called emotional contagion — a phenomenon where one individual’s emotions spread to others nearby. For example, a crying baby will trigger the other babies in a room to cry as well. Likewise, rats will become distressed when they see other rats in distress, or they will display pain behavior if they see other rats in pain.

For the new study, Mason and her colleagues wanted to see if rats could go beyond emotional contagion and actively help other rats in distress. To do so, the rats would have to suppress their natural responses to the “emotions” of other rats, the result of emotional contagion. “They have to down-regulate their natural reaction to freeze in fear in order to actively help the other rat,” Mason explained…

“When the free rat opens the door, he knows exactly what he’s doing — he knows that the trapped rat is going to get free,” Mason said. “It’s deliberate, purposeful, helping behavior.”

The researchers then conducted other tests to make sure empathy was the driving force in the rats’ behavior. In one experiment, they rigged the container so that opening the door would release the captive rat into a separate arena. The free rat repeatedly set its cage-mate free, even though there was no reward of social interaction afterwards.

That’s pretty fascinating. I think a lot of things are taken for granted as human-only when in fact the world is much more interesting than that, and this may be just such a case. Of course the more similar we find animals to be to humans, the more strict we may become as a society in their uses in research, so this has extra meta-relevance to science.

Anyway, anthropocentrism is a pretty real impediment to science – part of the controversy over evolution, for example – and I think studies like this, finding “human” traits in other animals, chip a bit off of that block and make us face reality a bit more, which is great. Reality is a pretty good place to live in. 

Two New Elements Named, and Some Notes on the Periodic Table

In the thrilling sequel to the naming of darmstadtium, roentgenium and copernicum, two more of the heaviest elements in the periodic table have finally been named: give a warm periodic table welcome to flerovium and livermorium!

From LiveScience:

Element 114, previously known as ununquadium, has been named flerovium (Fl), after the Russian institute’s Flerov Laboratory of Nuclear Reactions founder, which similarly is named in honor of Georgiy Flerov (1913-1990), a Russian physicist. Flerov’s work and his writings to Joseph Stalin led to the development of the USSR’s atomic bomb project.

The researchers got their first glimpse at flerovium after firing calcium ions at a plutonium target.

Element 116, which was temporarily named ununhexium, almost ended up with the name moscovium in honor of the region (called an oblast, similar to a province or state) of Moscow, where the research labs are located. In the end, it seems the American researchers won out and the team settled on the name livermorium (Lv), after the national labs and the city of Livermore in which they are located. Livermorium was first observed in 2000, when the scientists created it by mashing together calcium and curium.

Textbooks are changing before our eyes! This same lab has also synthesized elements 113, 115, 117 and 118, but those have yet to be confirmed so they won’t be named just yet. That leaves the race to elements 119 and 120, which I discussed earlier.

According to different ideas there could be up to 137 or 173 physically possible elements, so element-hunters are eventually going to run out of real estate. Here’s what an extended periodic table might look like, via WikiMedia:

The 8th period (row) would introduce a new block, making the whole table much wider. These blocks represent the type of the highest-energy orbitals occupied by each element’s electrons. The types of orbitals are categorized by the shapes of the areas with the highest probability of an electron being inside. Weird, I know.

For example, pink elements’ most energetic electrons are in the s-orbital, which is shaped like a sphere. That means their outermost (from the nucleus), most energetic, electrons are most likely to be in that sphere (their exact paths are impossible to know due to the Heisenberg uncertainty principle). Each different colour in the periodic table above means that the outermost orbital is a particular shape, and elements over 120 are theorized to have a new orbital shape, which is why they get a new block.

That’s just a quick and dirty summary of course, but if you didn’t before, now you know why the periodic table is blocked off how it is. Those green elements in the extended periodic table above (the f-block) are usually shown separately below the periodic table, so that it’s not as wide. Here’s a standard table for reference, from Jefferson Lab:

In this table the yellow elements are gases at room temperature (ex. hydrogen, oxygen, nitrogen, helium), the greens are solid and the blues are liquid (only mercury and bromine). Notice that block I mentioned, the f-block, at the bottom, keeping the table nice and thin, although out of order. One technicality I have to note though is that elements 71 and 103 on the right end, lutetium and lawrencium, are actually part of the d-block, not f-block, but they’re still grouped with the bottom series, called the lanthanide and actinide series. 

Since I’m getting into the periodic table, I might as well explain why there is a periodic table in the first place: a scientist named Dmitri Mendeleev realized that if you organized atoms by their mass, they fell into a repeating pattern in terms of chemical properties, like helium, neon and argon having similar properties, for example. With what I’ve explained above, it should be easier to understand just why: the periodic table is effectively organized by the properties of the outermost electron orbital, which is generally what interacts in chemical reactions. Every element in a particular column has the same thing going on in its outermost electron orbital, so it’ll have similar chemical reactions compared to the elements above and below it.

Since you’re all up on your science news, you’ve probably heard of the idea of silicon- instead of carbon-based life, which makes sense when you see that silicon is directly below carbon in the periodic table. You may have also heard of the recent report on bacteria that possibly incorporated arsenic into their DNA instead of phosphorous (although that story should be taken with a pound of salt); arsenic is also directly below phosphorous in the table. The table is magic, is what I’m trying to tell you.

In summary: flerovium and livermorium, and I’m easily distracted, but I hope you learned (or at least remembered) something!

Babies With a Sense of Justice

I always find articles about cognitive development in babies to be fascinating, because they show the threshold of what we consider to be quintessential human traits. Now a study out of the University of British Columbia shows that somewhere between 5 and 8 months old, babies go from always preferring helpful individuals to preferring individuals who are helpful or not according to the behaviour of the recipient.

The research is pretty well described by LiveScience:

So the researchers set up a series of experiments using puppets to act out scenarios of helping and harming while each of 32 5-month-olds and 32 8-month-olds watched separately. After each experiment, the infants indicated their preference for the puppets’ behaviors by picking their favorite puppet to hold.

The puppets — a series of cheerful characters, including moose, elephants and a yellow duck — were first shown interacting in either nice or mean ways. One puppet would struggle to open a box containing a toy, while another either jumped in to help or cruelly slammed the lid shut.

Next, the infants watched as the puppet that had helped or hindered played with a ball and dropped it. A third puppet then came into the scene, either to take the puppet’s ball away or to hand it back…

The researchers wanted to know if the babies would prefer the ball-giving puppet or the one that took the ball away. They found that 5-month-olds always preferred the ball-giver, no matter whether the puppet that had dropped the ball had been mean or helpful in the previous scene. At this young age, the babies simply liked puppets to be nice in the moment.

But 8-month-olds were more discerning. They liked it when the third puppet gave the ball back to a previously helpful puppet. But they didn’t like it when the third puppet helped out a previously unhelpful puppet. In scenarios involving the mean, toy box-slamming puppet, 8-month-olds favored a third puppet taking its ball away by 13 to three.

The researchers then repeated the experiments with 32 toddlers ages 19 months to 23 months, this time adding a twist. The toddlers got to watch puppets being nice or mean to each other and then got to play the role of rewarder or punisher. Some toddlers were shown one nice puppet and one mean puppet and asked which they’d like to share a treat with. Others were shown a nice puppet and a mean puppet, both with treats, and were asked to take a treat away from one.

In all cases, the toddlers meted out justice according to the puppets’ earlier actions. Thirteen of 16 gave a treat to a nice puppet, while 14 of 16 took treats away from a mean puppet.

LiveScience also has a video of the puppet show and the babies choosing a puppet – it’s kind of adorable.

This finding is pretty cool. I wonder what the physical switch is that enables babies to be more discerning, if there is one distinct switch? For some small context, here’s a graph of a person’s change in brain weight over time, where blue is male and red is female:

Data from Dekaban, A.S. and Sadowsky, D., Changes in brain weights during the span of human life: relation of brain weights to body heights and body weights, Ann. Neurology, 4:345-356, 1978, via University of Washington

Notice that babies at the ages used in this experiment (5 or 8 months) have brains less than half the size of an adult, and maybe half that of a 3-year-old. They have a long way to go before everything clicks.

This study, to me, raises the question of which behaviours are learned, and which are ingrained. It seems clear here that a sense of justice, in the sense shown, is probably inherent, or at least the capability to learn it is. I’m also kind of surprised that the babies could distinguish between different puppets who were only distinguished by the colour of their clothes. It’s never caught my interest as a field of study, but I’m starting to understand why people might like developmental biology… 

What Casual Climate Science Deniers Don’t Understand About Science

I’m really averse to writing about the political controversy around climate science because it’s beaten to death in every kind of media already, and there are plenty of blogs revolving around it. Without it, though, I might not have started this blog in the first place, since that and the political controversy over evolution are the biggest symptoms of a society that doesn’t know enough about science.

You may have heard about what the media gleefully called “Climategate 2.0”, a release of more stolen emails from climate scientists. Here’s Scientific American and LiveScience discussing the leak, and Life’s Little Mysteries addressing the scientific complaints against anthropogenic climate change. 

In my opinion, the controversies over evolution and climate science stem largely from a sheer lack of understanding of how science works. As I see it there are a few main misunderstandings:

1) Nothing is 100% certain. Deniers demand 100% certainty in scientists’ claims, which is literally impossible. There is always room for error and misinterpretation, in every kind of science. Scientists know this and so they tend to talk about their findings cautiously. This doesn’t translate well in the public sphere; we’re used to people in everyday life making certain claims, especially when those claims are relevant to politics. What kind of politician would say “My plan is to do this, because such-and-such is probably the problem with our economy, and such-and-such will probably help”? That would be honest, but it wouldn’t sell, and that politician’s dishonest opponent would come off much more convincingly.

This creates a conflict when science is dragged kicking and screaming into politics. There’s pressure to put things into certain terms – it’s technically bad science, but good politics. From what little I’ve seen excerpted from the hacked emails, it looks like this is what these scientists are discussing – how to remain scientifically accurate while trying to get across an important public message. Does glossing over the science in this way make them liars or frauds? No, it makes them roughly as inaccurate as everyone else in the public sphere. It’s regrettable that science has to be dumbed down for public presentation, but the dumbing down is obviously not a conspiracy. 

2) There will always be internal disagreement between scientists on smaller issues. Deniers will point out any and every sign of disagreement between scientists when it comes to climate science or evolution, and use this to claim that the science isn’t settled. There will probably always be differing hypotheses when it comes to the details of the matter, but that has no bearing on whether the field as a whole is valid. There’s tons of uncertainty in climate science, and personally I don’t like it at all when bold predictions about 100 years into the future are made, because it seems obvious that those predictions are so error-prone as to be meaningless. However, there’s negligible uncertainty when it comes to the facts of the Earth gradually warming over the last century, and the human release of greenhouse gasses as a significant contributing factor.

Do we know how all of this will pan out? No, not at all. I summarized a New Scientist article earlier showing just how little we know about the magnitude of the problem. This kind of subtlety can be confusing to the public – if we don’t know, then why should we take such dramatic and costly steps to respond? Science doesn’t work strictly by knowing though, as should be clear by the fact that nothing is 100% certain. Everything is a matter of probability. If curbing greenhouse gas release is very likely to be beneficial, then it makes sense to do it, whether or not we can know for sure – which we really can’t, ever. Doing nothing is making an active choice to act on the much less probable future scenario, which doesn’t make any sense. 

3) Science is not an opaque, elite clubhouse. The fact that e-mails from a small group of scientists are being used to smear an entire field betrays a profound misunderstanding of, everything. Science is a global pursuit. Even if these fantasies about these emails being incriminating were true, it would have virtually no implications for climate science, since different groups of scientists have independently come to the same conclusions anyway. Individual scientists can’t just make things up or conspire with impunity. They’re accountable to everyone – anyone can debunk their claims, and if they’re caught forging data or being incredibly dishonest in any way, it’ll probably mean the end of their careers. Science is not like politics – you can’t just lie and move on. If you’re a bad scientist, you’re done, for the rest of your life. There’s no way one particular group of scientists would just decide to make enormous lies about something that’s being investigated all over the world. 

I think the faster-than-light neutrino story is a great example for understanding science better in this context. Were the CERN scientists shunned for going against the overwhelmingly dominant consensus theory? No, quite the opposite. Is there a possibility that the theory of relativity is incomplete? Yes, anyone will admit to that. Does that mean we should ignore all of the findings brought to us by assuming that relativity was completely correct for the last hundred years? No, that would be ridiculous. 

In sum: even the best of theories can be challenged, even the best of theories can be incomplete, but it makes sense to act on what information we have even if it’s not perfect (which, again, it never will be). This alone should be enough to finally move past this political misunderstanding.

All of that being said, another reason why I’m averse to writing about topics like this is because I get the impression that facts and reason are not what’s driving the discussion. I have no idea what will convince most deniers to jump on the modernity bandwagon and trust the global institution of science, but it’s probably not posts like this. 

Three New Elements Named

If you remember your periodic table (and why wouldn’t you?), you may remember some oddly named elements at the highest numbers – ununnilium, unununium, and ununbium, for example. These were placeholder names simply describing their atomic number, but now they’ve finally got names of their own. 

From LiveScience:

The periodic table of elements just got a bit heftier today (Nov. 4), as the names of three new elements were approved by the General Assembly of the International Union of Pure and Applied Physics.

Elements 110, 111 and 112 have been named darmstadtium (Ds), roentgenium (Rg) and copernicium (Cn).

Temporarily called ununbium, copernicium, the new element 112, was named for Polish astronomer Nicolaus Copernicus (1473-1543), who first suggested that the Earth revolves around the sun, not the other way around, and starting the “Copernican Revolution.” In a statement released in July 2009, Sigurd Hofmann, head of the discovery team at GSI Helmholtz Centre for Heavy Ion Research in Germany, said they named the element after Copernicus “to honor an outstanding scientist, who changed our view of the world.”

… Element number 111, officially renamed roentgenium by the General Assembly, was originally discovered in 1994 when a team at GSI created three atoms of the element, about a month after their discovery of darmstadtium, on Dec. 8…

Roentgenium was named after German physicist Wilhelm Conrad Roentgen (1845 – 1923), ridding itself of its temporary name unununium, Roentgen was the first to produce and detect X-rays, on Nov. 8 1895. He won the Nobel Prize in physics in 1901 for the work.

Darmstadtium, the new element 110, which took the temporary name ununnilium, was first synthesized on Nov. 9, 1994, at the GSI facility near the city of Darmstadt…

None of these exist in nature; they can only be created, with great difficulty of course, in a lab, and they’re so large that they quickly come apart into smaller elements. Thanks to these names the periodic table got a little less weird, but we still have ununtrium, ununquadium, ununpentium, ununhexium, ununseptium and ununoctium in need of names. Newtonium, anyone? Maybe some Canadium? No?

“5 Ways the World Will Change Radically This Century”

LiveScience presents us with a brief overview of changes we can expect this century as a result of our population explosion. The article is relatively brief so you should feel safe popping over to check it out, but in any case here’s my excerpt of the highlights:

According to the United Nations Population Division, our population will hit 7 billion on Oct. 31, and though fertility rates have begun to decline across much of the globe, we’re still projected to reach 9 billion by mid-century and level off at around 10 billion by 2100…

Shifting people

… According to Joel Cohen, a population biologist at Columbia University and the keynote speaker at Monday’s conference, India’s population will overtake China’s around 2020, and sub-Saharan Africa’s will overtake India’s by 2040. Furthermore, “In 1950, there were three times as many Europeans as sub-Saharan Africans. By 2100, there will be five sub-Saharan Africans for every European. That’s a 15-fold change in the ratio,” Cohen said…

Jean-Marie Guehenno, former UN Under-Secretary General for Peacekeeping Operations and director of the Center for International Conflict Resolution at Columbia University’s School of International and Public Affairs, said the migration of people from Africa to Europe will present a major challenge in the near future. “You can look at it as an enormous potential from a European standpoint … or you can say, ‘[Africa] is a continent that still has 15 percent that are not going to school,’ and that can be seen as a threat,” Guehenno said. “How are you going to manage that immigration so that this aging continent of Europe benefits from it while managing it? That is going to be a huge question.”

Urbanization

Globally, the number of people living in urban areas matched and then overtook the number of rural people sometime in the past two years. The trend will continue. According to Cohen, the number of people living in cities will climb from 3.5 billion today to 6.3 billion by 2050. This rate of urbanization is equivalent to “the construction of a city of a million people every five days from now for the next 40 years,” he said…

Water wars

… No resource is more precious and vital than water, and, according to economist Jeffrey Sachs, director of the Earth Institute at Columbia, there are already parts of the world that, because of the rapidly changing climate, are at a severe crisis point. “Take the Horn of Africa for example: Somalia’s population has risen roughly fivefold since the middle of the 20th century,” Sachs said. “Precipitation is down roughly 25 percent over the last quarter century. There’s a devastating famine under way right now after two years of complete failure of rains, and [there is] the potential that this is entering a period of long-term climate change.”

Conflicts over water shortages will probably play out as class warfare, said Upmanu Lall, director of the Columbia Water Center. “Wealth inequality tends to grow as a country’s population grows, and this is a very important point to note because per capita consumption of resources has been increasing dramatically. Couple that with inequity in income and couple that with [the issue of] the availability of water,” Lall said…

Future energy

… “Energy is the basic resource which underlies every other,” said Klaus Lackner, director of the Lenfest Center for Sustainable Energy. “And actually, technology is not quite ready to solve the [energy] problem. We know there’s plenty of energy in solar, in nuclear, in carbon itself — in fossil carbon — for probably 100 or 200 years (if we are willing to clean up after ourselves and pay the extra to make that happen). But none of these technologies are quite ready. Solar has its problems and is still too expensive.”

… In short, the future will match one of these two pictures: Either some new, superior form of energy extraction (such as highly efficient solar panels) will be widespread, or the technology, or its implementation, will fail, and humanity will face a major energy crisis.

Mass extinctions

… Aside from the lack of land and resources left for other species, we’ve also caused rapid changes to the global climate, with which many of them cannot cope. Some biologists believe that with the current rate of extinction, 75 percent of the planet’s species will disappear within the next 300 to 2,000 years. These disappearances have already begun, and extinction events will become more and more common over the course of the century.

These are all very troubling concerns, but I can’t help but feel that any predictions into the progress of the next 100 years are bound to be naive. Technology is advancing so rapidly – and its advance is accelerating so rapidly – that I feel like it’s always too early to make doomsday predictions. For example, every day there are new articles on advances in energy generation, a small fraction of which I’ve discussed here; just one breakthrough could radically change our energy outlook. 

A real-life example of an advance allowing unforeseen population growth is the Green Revolution, which overthrew mainstream predictions of widespread famine by revolutionizing agriculture in the developing world. That’s not to say, of course, that we can lie back and trust someone else to technology our way out of these problems, but I think it’s important – in terms of being realistic – to keep an open mind to completely unexpected circumstances that will defy our predictions.

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