Below I note that sex matters when it comes to evolution, specifically in the case of how sexual reproduction forces the bits of the genome to be passed back and forth across sexes. In fact, the origin of sex is arguably the most important evolutionary question after the origin of species, and it remains one of the most active areas of research in evolutionary genetics. More specifically the existence of males, who do not bear offspring themselves but seem to be transient gene carriers is a major conundrum. But that’s not the main issue in this post. Let’s take the existence of males as a given. How do sex differences play out in evolutionary terms shaping other phenotypes? Consider Bateman’s principle:

Bateman’s principle is the theory that females almost always invest more energy into producing offspring than males, and therefore in most species females are a limiting resource over which the other sex will compete.

Female ova are energetically more expensive, and scarcer, than male sperm. Additionally, in mammals and other live-bearing species the female invests more time and energy after the point of fertilization but before the young exhibit any modicum of organismic independence (the seahorse being the exception). And, often the female is the “primary caregiver” in the case of species where the offspring require more care after birth. The logic of Bateman’s principle is so obvious when its premises are stated that it easily leads to a proliferation of numerous inferences, and many data are “explained” by its operation (in Mother Nature: Maternal Instincts and How They Shape the Human Species the biological anthroplogist Sarah Hrdy moots the complaint that the principle is applied rather too generously in the context of an important operationally monogamous primate, humans).

But the general behavioral point is rooted in realities of anatomy and life-history; in many dioecious species males and females exhibit a great deal of biological and behavioral dimorphism. But the direction and nature of dimorphism varies. Male gorillas and elephant seals are far larger than females of their kind, but among raptors females are larger. If evolution operated like Newtonian mechanics I assume we wouldn’t be theorizing about why species or sex existed at all, we’d all long ago have evolved toward perfectly adapted spherical cows floating in our own effluvium, a species which is a biosphere.

Going beyond what is skin deep, in humans it is often stated that males are less immunologically robust than females. Some argue that this is due to higher testosterone levels, which produce a weakened immune system. Amtoz Zahavi might argue that this is an illustration of the ‘handicap principle’. Only very robust males who are genetically superior can ‘afford’ the weakened immune system which high testosterone produces, in addition to the various secondary sexual characteristics beloved of film goers. Others would naturally suggest that male behavior is to blame. For example, perhaps males forage or wander about more, all the better to catch bugs, and they pay less attention to cleanliness.

But could there be a deeper evolutionary dynamic rooted in the differential behaviors implied from Bateman’s principle? A new paper in The Proceedings of the Royal Society explores this question with a mathematical model, The evolution of sex-specific immune defences:

Why do males and females often differ in their ability to cope with infection? Beyond physiological mechanisms, it has recently been proposed that life-history theory could explain immune differences from an adaptive point of view in relation to sex-specific reproductive strategies. However, a point often overlooked is that the benefits of immunity, and possibly the costs, depend not only on the host genotype but also on the presence and the phenotype of pathogens. To address this issue we developed an adaptive dynamic model that includes host–pathogen population dynamics and host sexual reproduction. Our model predicts that, although different reproductive strategies, following Bateman’s principle, are not enough to select for different levels of immunity, males and females respond differently to further changes in the characteristics of either sex. For example, if males are more exposed to infection than females (e.g. for behavioural reasons), it is possible to see them evolve lower immunocompetence than females. This and other counterintuitive results highlight the importance of ecological feedbacks in the evolution of immune defences. While this study focuses on sex-specific natural selection, it could easily be extended to include sexual selection and thus help to understand the interplay between the two processes.

The paper is Open Access, so you can read it for yourself. The formalism is heavy going, and the text makes it clear that they stuffed a lot of it into the supplements. You can basically “hum” through the formalism, but I thought I’d lay it out real quick, or at least major aspects.

This shows the birth rate of a given genotype contingent upon population density & proportions of males & females infected with a pathogen

These equations takes the first and nests them into an epidemiological framework which illustrates pathogen transmission (look at the first right hand term in the first two)

And these are the three models that they ran computations with

There are many symbols in those equations which aren’t obvious, and very difficult to keep track of. Here’s the table which shows what the symbols mean….

If you really want to understand the methods and derivations, as well how the details of how they computae evolutionarily stable strategies, you’ll have to go into the supplements. Let’s just assume that their findings are valid based on their premises.

Note:

- They assume no sexual selection
- They assume unlimited male gametes, so total reproductive skew where one male fertilizes all females is possible
- Fecundity is inversely correlated with population density
- Total population growth is ultimately dependent on females, they are the “rate limiting” sex
- Total population growth is proportional to density
- There is no acquired immunity
- There is no evolution of the pathogen in this model

Basically the model is exploring a quantitative trait which exhibits characteristics in relation to resistance of acquiring the pathogen and tolerance of it once the pathogen is acquired. In terms of the “three models,” the first is one where there is resistance to the pathogen, individuals recover from infection and decrease pathogen fitness. The second is one of tolerance, individuals are infected, but may still reproduce while infected. Note that the ability to resist or tolerate infection has a trade off, reduced lifespan (consider some forms of malaria resistance). The third model shows the trade off of tolerance and resistance.

The “pay off” of the paper is that they show that the male evolutionarily stable strategy (ESS), that is, a morph which can not be “invaded” by a mutation, may be one of reduced immune resistance in certain circumstances of high rates of infection. There is an exploration of varying rates of virulence, but there was no counterintuitive finding so I won’t cover that. In any case, here’s the figure:

The text is small, so to clarify:

1) The two panels on the top left are for model 1, and show variation in male and female recovery from infection left to right (resistance)

2) The two panels on the bottom left are for model 2, and show variation in male and female fecundity when infected left to right (tolerance)

3) The four panels on the right are for model 3, and show variation in recovery in the top two panels and fecundity in the bottom two, with male parameters varied on the left and female on the right

The vertical axis on all of the panels are male infection rate, the horizontal the female infection rate. Circled crosses (?) indicate regions (delimited by solid lines) where females evolve higher immunocompetence than males. The lighter shading indicates a higher value of the trait at ESS (recovery or fecundity). Note that the two top left panels show a peculiar pattern for males, the sort of counterintuitive finding which the model promises: when infection rates among males are very high their resistance levels drop. Why? The model is constructed so that resistance has a cost, and if they keep getting infected the cost is constant and there’s no benefit as they keep getting sick. In short it is better to breed actively for a short time and die than attempt to fight a losing battle against infection (I can think of possible explanations of behavior and biological resistance in high disease human societies right now). It is at medium levels of infection rates that males develop strong immune systems so that they recover. The bottom right portion of panel which shows variation in male resistance illustrates a trend where high female infection results in reduced immune state in males. Why? The argument is simple; female population drops due to disease result in a massive overall population drop and the epidemiological model is such that lower densities hinder pathogen transmission. So the cost for resistance becomes higher than the upside toward short-term promiscuous breeding in hopes of not catching the disease. Another point that is notable from the panels is that males seem to be more sensitive to variation in infection rates. This makes sense insofar as males exhibit a higher potential variance in reproductive outcomes because of the difference in behavior baked into the model (males have higher intrasexual competition).

One can say much more, as is said in the paper. Since you can read it yourself, I commend you to do so if you are curious. Rather, I would like a step back and ask: what does this “prove?” It does not prove anything, rather, this is a model with many assumptions which still manages to be quite gnarly on a first run through. It is though suggestive in joint consideration with empirical trends which have long been observed. Those empirical trends emerge out of particular dynamics and background parameters, and models can help us formalize and project abstractly around real concrete biological problems. The authors admit their model is simple, but they also assert that they’ve added layers of complexity which is necessary to understand the dynamics in the real world with any level of clarity. In the future they promise to add sexual selection, which I suspect will make a much bigger splash than this.

I’ll let them finish. From their conclusion:

We assessed the selective pressures on a subset of sex-specific traits (recovery rate, reproductive success during infection and lifespan) caused by arbitrary differences between males and females in infection rate or virulence (i.e. disease-induced death rate). In so doing, we covered a range of scenarios whereby sex-specific reproductive traits such as hormones and behaviour could plausibly affect the exposure to infection…r the severity of disease…First, we showed that changes in the traits of either sex affect the selective pressures on both sexes, either in the same or in opposite directions, depending on the ecological feedbacks. For example, an increase in male susceptibility (or exposure) to infection favours the spread of the pathogen in the whole population and therefore tends to select for higher resistance or tolerance in both sexes if the cost of immunity is constitutive. However, above a certain level of exposure, the benefit of rapid recovery in males decreases owing to constant reinfection (we assume no acquired immunity). This selects for lower resistance in males, ultimately leading to the counterintuitive situation where males with higher susceptibility or exposure to infection than females evolve lower immunocompetence…A similar pattern arises if the cost of immunity is facultative, in the form of a trade-off between rate of recovery and relative fecundity during infection (model (iii)): if males happen to be more susceptible (or exposed) to infection than females, they are predicted to evolve a longer infectious period balanced by higher sexual activity during infection than females.

Restif, O., & Amos, W. (2010). The evolution of sex-specific immune defences Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2010.0188

National Geographic is running a series called Known Universe. The series consists of six-parts and the first one premieres Thursday, April 1st at 10 pm ET/PT

From how to find micro-meteors on your roof (yes I am going to try it) to the collision between the Milky Way and Andromeda, the first episode looks at cosmic collisions of all sorts.

The part about gravity waves I found to be too short, but that’s just because I am fascinated by them. You will find out how gravity waves are produced. Oh and the measurement of gravity waves suing LIGO are briefly explained – accurate to 1/1000th of a proton.

Be sure to check it out, record if you have to it’s good stuff.

The last-minute repairs, friendly competition, racing out to the track to get in that last run that might just be the one—that’s all over. And the dancing of the “Electric Slide” in the awards banquet hall has begun.

It was an up-and-down day. Penn State’s hydrogen fuel cell, HFV, drove like a champ and achieved the equivalent of 1,803 miles per gallon. But they couldn’t quite claim the number one spot. “We kept going back and forth with Cicero” says team member John Bearer, referring to the fuel cell champion Cicero North-Syracuse High School. Bearer wasn’t too disappointed, though, as the competition is far from cutthroat: At the very end, Northern Arizona gave up its final spot in line to Cal Poly, whose crew yearned to take a last shot at a better mileage number.

The fuel cell car from Missouri, however, never managed to finish the 10-lap race and get a number on the board. They were on pace for 300 MPG equivalency, but halfway through runs, the computer system registered errors and the car shut down. In a nice nod, though, the Tigers took home the “perseverance in the face of adversity” award.

Canadian team Université Laval won the overall prize for all the cars, excluding solar, with 2,488 MPG. One of the cars by team Rose-Hulman, who we profiled earlier, won third in prototype combustion engines with just more than 1,800 MPG. But the Purdue Polaris, which we profiled yesterday, achieved a best result of 4,548 MPG equivalency. It also took home the People’s Choice Award with nearly 100,000 votes, and the design and communication awards.

You can see all the results here. And tomorrow we’ll be bringing you a slideshow of the best images from Shell Eco-marathon 2010.

Time is short. Only two windows of urban concept racing time remain, and though Louisiana Tech’s last run in its blue car jumped the score from 173 miles per gallon up to 251, they still lag behind leader Mater Dei High School of Evansville, Indiana. So it’s time to pull out all the stops.

In the “garage,” Tech crew members count down the time until they must be back out on the track. In the waning minutes, crew member Beau Downey tells me all they can do to try to close the gap on the MPG leaders is streamline how air flows around the car. First, he says, they’re trying to smooth out the car’s undertray. While the overall carbon fiber body cuts through the air nicely, he thinks the air coming under the car gets caught and causes drag.

Louisiana Tech has sheets of plastic they brought down in case they needed to redo the car’s tinted windows. But in these last few moments it’s time to forget about that and cut the sheets into shells that cover the wheel wells, with the idea that passing air won’t be able to get in there, either.

Missouri, too, is feeling the heat. As we mentioned in our first post yesterday, the Tigers had quite an ordeal just getting a working car to Houston. During test runs yesterday, however, a connection came loose after just five of the 1o laps. Back in the shop, they’ve found the faulty connection, and race to repair so they can hit the road this afternoon and get a score on the board before competition ends in the evening.

These Shell Eco-marathon cars are aiming for ultra-high mileage, so to be frank, driver comfort takes the backseat. Or, rather, it would if these cars had a backseat.

Having a car come high up off the ground raises air resistance, so the prototypes are low and sleek. Blaine Castongia of Rose-Hulman Institute of Technology in Terre Haute, Indiana, whose transparent car in seen here, says suspension gets the ax, too: It’s just wasted energy.

As a result, Rose-Hulman drivers Bethany Brisco and Barbara Arrowsling get a rough ride. The steering controls are right by their hips, so moving right or left means swaying one’s hips out of the way to make room. The two women say it’s easy to see where they’re going despite the low angle, unless they’re sitting still.

What’s not easy, they say, are the race conditions. The team is accustomed to testing its cars on closed courses with smooth surfaces. This year’s Shell Eco-marathon, however, forces them to drive the on Houston streets, which can be a little unpleasant even if you had suspension and were more than a few inches off the ground. The two Rose-Hulman drivers also say that racing with other cars on the track reflects more of the haphazard nature of real driving. You might have a desired route in mind to reduce mileage, but if another car cuts you off and forces you outside, too bad.

Danica Patrick caused a flurry of excitement when she entered the high ranks of professional racing, but here at the eco-marathon, female drivers are the norm. Women get the glamor spot in the cockpit of many if not most of the cars, as teams seek to reduce as much weight as possible.

So Brisco and Arrowsling are the ones putting Rose-Hulman’s driving strategy in place. The team’s two cars, running on lawn string trimmer’s engines and using only 15 mL of fuel per run, are among the best in the field. One has exceeded 1,800 MPG. Castongia says he hopes to break the team’s own record of 1,972 MPG, though that might be a long shot. With another 20 MPG in the afternoon run, though, Rose-Hulman could break back into second place.

If they get better, the drivers probably deserve the thanks. Louisiana Tech driver Joseph Nealy says he got the team’s blue car up from 173 MPG to 251 by using a better driving strategy: ditching the preconceived plan of when to accelerate, and ignoring the speedometer, which lags a few seconds behind anyway. “This time it was driven completely by ear,” he says.

Racing finishes in the late afternoon. We’ll keep you updated when the final scores come in.

The fourth-to-last Space Shuttle launch has been scheduled by NASA for April 5. Discovery will be on a 13 day mission to the space station, where it will bring various supplies and swap out some station hardware. Discovery will be using the Leonardo multi-purpose logistics module to carry those supplies.

The launch is planned for 06:21 EDT (10:21 GMT), so the sky will still be relatively dark but getting lighter (sunrise is a little after 07:00). It should be very pretty!

Given that they make up 40 of the 50 cars in the fields, the vehicles in the prototype category ruled the road course here Houston for much of yesterday. But as day one rolled on, the urban concept cars—which look a little less like futuristic bobsleds on wheels and little more like what you’d recognize as a car—cruised around the track.

The car above is Concept Zero, by the crew from the Polytechnic Institute of NYU. (They’d be DISCOVER’s home team, as we’re based in New York.) Team members Jonathan Sorocki and Michael Choi say that besides the challenge of trying to build their own car within the span of just months, they ran into another problem: They weren’t allowed to weld on campus.

As it turned out, that minus became a plus. With some funding from Time Warner and Nordan Composites, Sorocki and Choi’s team built Concept Zero from carbon fiber. With only one weld in the car, it weighs in at a slim 227 pounds, Sorocki says, and much of that weight comes from the swank rims they procured from Vespa Soho in Manhattan. Thus, despite the fact that Concept Zero isn’t much smaller than a Volkswagen Beetle, it putters around the track powered by a 1.1 horsepower engine.

NYU made a full run with 144 MPG yesterday. However, shortly thereafter the axle shifted and the disc brake started rubbing against other parts. After a night of little sleep and spare part runs to Home Depot, the car is back together and the crew is shooting for 200 MPG today. And if they don’t win any mileage awards, the team members have their other bases covered: NYU is the most active team lobbying for the people’s choice award. That piece of paper you see on the window lists texting instructions for voting.

At the other end of the funding spectrum lies Durand High, the ethanol-powered Wisconsinites we covered yesterday. After the team repaired the bent bike wheels that car #50 suffered in a morning accident, the vehicle—which contains less than $1,000 of materials and runs on a 5.5 HP Honda engine donated to the school eight years ago—cruised to a 345 MPG run yesterday. Now coach Bill Rieger says the team plans to let the driver give a little more fuel in bursts and do more coasting, to see if strategy can get them up to 500 MPG.

Durand’s 5.5 HP is more than most teams brought to the Shell Eco-marathon, so it’s worth a shot. “We got overkill,” Rieger says. “We’re going to dig in today.”

Thanks to artist Samantha Brooke for contributing this week's stunning watercolor to The Science of Kissing Gallery featuring affectionate behavior among giraffes. Submit your original photograph or artwork for consideration by emailing me at srkirshenbaum@yahoo.com.

“To examine the means whereby dragons produce fire and steam, we have studied a related species, the desert-lizard Lacerta pyrophorus. Morphological studies showed that there were in the snout three distinctive features: (1) a dorsal swelling in the pharynx, the Organ of Feuerwerk, consisting of brown adipose tissue with an extensive sympathetic innervation; (2) greatly enlarged lachrymonasal ducts, the Ducts of Kwentsch; and (3) asbestos deposits in the nasal skin, the Bestos Bodies. Physiological studies show that the Organ of Feuerwerk can, when the animal is excited, produce extremely high temperatures. We discuss how these mechanisms can produce steam and fire, and how the snout is protected. We also discuss and offer a solution to the problem of how, since dragons are invariably male, the species can be propagated.”

“Fig. 2. Laboratory photograph showing S.T.G. performing an experiment on a specimen of L. pyrophorus. The microthermistor is in position. Note S.T.G.’s protective clothing (courtesy of Amourplating plc, UK), and his macromanipulator (especially developed by Equus Probes Ltd., UK). The demure appearance of the technician (Miss Virginia Young) may not be typical; at the time she was into bondage, and shortly afterwards left to marry S.T.G. Photograph by courtesy of U. Cello.”

Thanks to Per for today’s ROFL!

Image: flickr/Beverly & Pack

Related content:
Discoblog: NCBI ROFL: Does garlic protect against vampires? An experimental study.
Discoblog: NCBI ROFL: Phase 1: Build army of alligators that can run on land. Phase 2: Take over the world!
Discoblog: NCBI ROFL: Study proves dolphin tattoos lame.

Update and reboot: Sam Harris has responded to my blog post reacting to his TED talk. In the initial version of this response-to-the-response-to-the-response-to-the-talk, I let myself get carried away with irritation at this tweet, and thereby contributed to the distraction from substantive conversation. Bad blogger.

In any event, Sam elaborates his position in some detail, so I encourage you to have a look if you are interested, although it didn’t change my mind on any issue of consequence. There are a number of posts out there by people who know what they are talking about and surely articulate it better than I do, including Russell Blackford and Julian Sanchez (who, one must admit, has a flair for titles), and I should add Chris Schoen.

But I wanted to try to clarify my own view on two particular points, so I put them below the fold. I went on longer than I intended to (funny how that happens). The whole thing was written in a matter of minutes — have to get back to real work — so grains of salt are prescribed.

First, the role of consensus. In formal reasoning, we all recognize the difference between axioms and deductions. We start by assuming some axioms, and the laws of logic allow us to draw certain conclusions from them. It’s not helpful to argue that the axioms are “wrong” — all we are saying is that if these assumptions hold, then we can safely draw certain conclusions.

A similar (although not precisely analogous) situation holds in other areas of human reason, including both science and morality. Within a certain community of like-minded reasoners, a set of assumptions is taken for granted, from which we can draw conclusions. When we do natural science, we assume that our sense data is more or less reliable, that we are not being misled by an evil demon, that simpler theories are preferable to complicated theories when all else is equal, and so forth. Given those assumptions, we can go ahead and do science, and when we disagree — which scientists certainly do — we can usually assume that the disagreements will ultimately be overcome by appeal to phenomena in the natural world, since as like-minded reasoners we share common criteria for adjudicating disputes. Of course there might be some people who refuse to accept those assumptions, and become believers in astrology or creationism or radical epistemological skepticism or what have you. We can’t persuade those people that they’re wrong by using the standards of conventional science, because they don’t accept those standards (even when they say they do). Nevertheless, we science-lovers can get on with our lives, pleased that we have a system that works by our lights, and in particular one that is pragmatically successful at helping us deal with the world we live in.

When it comes to morality, we indeed have a very similar situation. If we all agree on a set of starting moral assumptions, then we constitute a functioning community that can set about figuring out how to pass moral judgments. And, as I emphasized in the original post, the methods and results of science can be extremely helpful in that project, which is the important and interesting thing that we all agree on, which is why it’s a shame to muddy the waters by denying the fact/value distinction or stooping to insults. But I digress.

The problem, obviously, is that we don’t all agree on the assumptions, as far as morality is concerned. Saying that everyone, or at least all right-thinking people, really want to increase human well-being seems pretty reasonable, but when you take the real world seriously it falls to pieces. And to see that, we don’t have to contrast the values of fine upstanding bourgeois Americans with those of Hitler or Jeffrey Dahmer. There are plenty of fine upstanding people — you can easily find them on the internet! — who think that human well-being is maximized by an absolute respect for individual autonomy, where people have equal access to primary goods but are given the chance to succeed or fail in life on their own. Other people think that a more collective approach is called for, and it is appropriate for some people to cede part of their personal autonomy — for example, by paying higher taxes — in the name of the greater good.

Now, we might choose to marshall arguments in favor of one or another of these viewpoints. But those arguments would not reduce to simple facts about the world that we could in principle point to; they would be appeals to the underlying moral sentiments of the individuals, which may very well end up being radically incompatible. Let’s say that killing a seventy-year-old person (against their will) and transplanting their heart into the body of a twenty-year old patient might add more years to the young person’s life than the older person might be expected to have left. Despite the fact that a naive utility-counting would argue in favor of the operation, most people (not all) would judge that not to be moral. But what if a deadly virus threatened to wipe out all of humanity, and (somehow) the cure required killing an unwilling victim? Most people (not all) would argue that we should reluctantly take that step. (Think of how many people are in favor of involuntary conscription.) Does anyone think that empirical research, in neuroscience or anywhere else, is going to produce a quantitative answer to the question of exactly how much harm would need to be averted to justify sacrificing someone’s life? “I have scientifically proven that if we can save the life of 1,634 people, it’s morally right to sacrifice this one victim; but if it’s only 1,633, we shouldn’t do it.”

At bottom, the issue is this: there exist real moral questions that no amount of empirical research alone will help us solve. If you think that it’s immoral to eat meat, and I think it’s perfectly okay, neither one of us is making a mistake, in the sense that Fred Hoyle was making a mistake when he believed that conditions in the universe have been essentially unchanging over time. We’re just starting from different premises.

The crucial point is that the difference between sets of incompatible moral assumptions is not analogous to the difference between believing in the Big Bang vs. believing in the Steady State model; but it is analogous to believing in science vs. being a radical epistemological skeptic who claims not to trust their sense data. In the cosmological-models case, we trust that we agree on the underlying norms of science and together we form a functioning community; in the epistemological case, we don’t agree on the underlying assumptions, and we have to hope to agree to disagree and work out social structures that let us live together in peace. None of which means that those of us who do share common moral assumptions shouldn’t set about the hard work of articulating those assumptions and figuring out how to maximize their realization, a project of which science is undoubtedly going to be an important part. Which is what we should be talking about all along.

The second point I wanted to mention was the justification we might have for passing moral judgments over others. Not to be uncharitable, but it seems that the biggest motivation most people have for insisting that morals can be grounded in facts is that they want it to be true — because if it’s not true, how can we say the Taliban are bad people?

That’s easy: the same way I can say radical epistemological skepticism is wrong. Even if there is no metaphysically certain grounding from which I can rationally argue with a hard-core skeptic or a Taliban supporter, nothing stops me from using the fundamental assumptions that I do accept, and acting accordingly. There is a weird sort of backwards-logic that gets deployed at this juncture: “if you don’t believe that morals are objectively true, you can’t condemn the morality of the Taliban.” Why not? Watch me: “the morality of the Taliban is loathsome and should be resisted.” See? I did it!

The only difference is that I can only present logical reasons to support that conclusion to other members of my morality community who proceed from similar assumptions. For people who don’t, I can’t prove that the Taliban is immoral. But so what? What exactly is the advantage of being in possession of a rigorous empirical argument that the Taliban is immoral? Does anyone think they will be persuaded? How we actually act in the world in the face of things we perceive to be immoral seems to depend in absolutely no way on whether I pretend that morality is grounded in facts about Nature. (Of course there exist people who will argue that the Taliban should be left alone because we shouldn’t pass our parochial Western judgment on their way of life — and I disagree with those people, because we clearly do not share underlying moral assumptions.)

Needless to say, it doesn’t matter what the advantage of a hypothetical objective morality would be — even if the world would be a better place if morals were objective, that doesn’t make it true. That’s the most disappointing part of the whole discussion, to see people purportedly devoted to reason try to concoct arguments in favor of a state of affairs because they want it to be true, rather than because it is.

As heated global warming debates continue, scientists are also investigating ways to get our planet to cool off if the politicians can’t figure out how to reduce greenhouse gas emissions. The latest geoengineering scheme involves turning the world’s oceans into a giant bubble bath, with hundreds of millions of tiny bubbles pumped into the seas. This would increase the water’s reflectivity and bring down ocean temperatures, according to Harvard University physicist Russell Seitz. As the creative physicist said to the assembled crowd at an international meeting on geoengineering research: “Since water covers most of the earth, don’t dim the sun…. Brighten the water.”

Seitz explained that micro-bubbles already occur naturally, with bubbles under the ocean’s surface reflecting sunlight back into space and mildly brightening the planet. What Seitz imagines doing now is artificially pumping many more bubbles into the sea. These additional micro-bubbles would each be one five-hundredth of a millimeter and would essentially serve as “mirrors made of air.” The scientists say they could be created off boats by using devices that mix water supercharged with compressed air into swirling jets of water. “I’m emulating a natural ocean phenomenon and amplifying it just by changing the physics—the ingredients remain the same” [ScienceNOW], Seitz said.

Using a computer model that simulated how air, light, and water interacted, Seitz found that the micro-bubbles could have a profound cooling effect on our planet–suggesting that temperatures could cool as much as 5.4 degrees Fahrenheit. Along with the reflectivity of the added bubbles, previously published reports show that they may improve fuel efficiency of cargo ships, allowing them to virtually float on air [Treehugger]. Seitz has submitted a paper on the concept he calls “Bright Water” to the journal Climatic Change [ScienceNOW].

While Seitz is excited at the possibility of creating “bubble patches” to reduce the effects of global warming, it still needs to be seen what sort of infrastructure would be required to create these giant bubble baths. And as with all geoengineering schemes, there’s that pesky question of whether hacking planet-wide systems will have any pesky side effects.

Related Content:
80beats: Study: Climate Hacking Scheme Could Load the Ocean With Neurotoxins
80beats: With $4.5M of Pocket Change, Bill Gates Funds Geoengineering Research
80beats: If We Can’t Stop Emitting CO2, What’s Our Plan B?
80beats: Fighting Global Warming: Artificial Trees and Slime-Covered Buildings
DISCOVER: 5 Most Radical Ways to Squelch a Climate Crisis (slide show)

Image:Flickr/gog1_1gog

I found this incredible film by Cristobal Villa (via Eterea Studios) at Cocktail Party Physics. There's also a terrific list featuring some of Jennifer's favorite math books for popular audiences so go visit!

The Hive Overmind has assimilated two new blogs: Gene Expression by Razib Khan and Not Exactly Rocket Science by Ed Yong. The former focuses on the squishy science (though, like the rest of us, isn’t afraid to post strong opinions), and the latter covers science in general.

Please welcome these blogs to our collective brain!

Do you often feel the need for a sweet sugar rush or a moment of bacon-induced bliss? A new study offers evidence that that surge of pleasure is similar to a heroin high, and that eating junk food regularly can significantly change the brain’s chemical make-up, creating junk food addicts who are driven to overeat.

Lead researcher Paul Kenny says it had previously been unclear whether extreme overeating was initiated by a chemical irregularity in the brain or if the behavior itself was changing the brain’s biochemical makeup. The new research by Kenny and his colleague Paul Johnson, a graduate student, shows that both conditions are possible [Scientific American].

For the study, published online in Nature Neuroscience, Kenny and colleagues headed to the grocery store. “We basically bought all of the stuff that people really like — Ding-Dongs, cheesecake, bacon, sausage, the stuff that you enjoy, but you really shouldn’t eat too often,” he said [Reuters]. One set of lab rats was allowed unfettered access to these high-calorie foods, while another rat group was allowed just one hour of access to the junk food per day. Both sets of rats also had the option of eating standard healthy lab rat fare. Finally, a control group of rats were kept on a healthy diet.

Scientists found that rats with unlimited access to junk food quickly became addicted. They constantly munched on the junk food through the day, becoming substantially overweight and turning into compulsive overeaters. Meanwhile, the rats with limited access to the food held their hunger, preferring to binge-eat in a limited time than consume healthy rat food. These rats gorged for 60 minutes, consuming 66 percent of their daily calorific intake in just one hour and soon developed a pattern of compulsive binge eating.

The researchers found that rats that overate had altered brain chemistry. Initially, each time they ate a Ding-Dong or rasher of bacon, they got a shot of the feel-good chemical dopamine. But just like human drug addicts, they soon had to increase their dosage to get the same dopamine rush. As the pleasure centers in the brain became more and more blasé, and less responsive, the rats quickly turned into compulsive overeaters. They were motivated to keep eating to get their fix [The Vancouver Sun]. Specifically, Kenny and his colleagues found that overeating decreased levels of the dopamine 2 receptor in the rats’ brains; human drug addicts have also been showed to have reduced levels of dopamine 2 receptors.

The altered brain chemistry also seemed to make it difficult for the rats to switch away their unhealthy eating habits–in other words, they were hooked. When the rats were eventually barred from eating junk food and given only what researchers called “the salad bar option,” they took an average of 14 days before they would even consider eating healthy food. “I was really shocked at the magnitude of the effect,” Kenny says. “They basically don’t eat anything. If that translates over to us as a species, that’s a major problem” [Scientific American].

The findings in a study of animals cannot be directly applied to human obesity, but may help in understanding the condition and in developing therapies to treat it [Reuters]. But Kenny says it’s possible that some people may be born with a predisposition to have lower D2 levels. “That may be why they’re more likely to gain weight. They’re already halfway down that road, if you will” [The Vancouver Sun].

Related Content:
80beats: Cheesecake Is Like Heroin to Rats on a Junk-Food Diet
Not Exactly Rocket Science: Making Sense of Obesity Genes
Cosmic Variance: Cheap, Crappy Calories
Discoblog: Just Like Humans, Crows Embrace Junk Food… and Pay the Price

Image: Wikimedia

High school and college engineers can do a lot with a lawn trimmer engine, bicycle wheels and a few wires—like build prototype cars that get in the thousands of miles per gallon. Here we bring you the best images from this weekend’s Shell Eco-marathon Americas competition.

A Powerful Prototype

All weekend long, prototype cars built by students around the country and shipped down to Texas battled it out. They ran 10-lap races around the 0.6 course of city streets in downtown Houston, striving to be top dog in miles per gallon.

The cars in the prototype division, like this one from Loyola-Marymount University, didn’t have many of the luxuries of the normal cars driving by and wondering what was going on. But those normal cars also don’t run at more than 1,000 miles per gallon, as many racers achieved.

The winning team in the prototype category, from Universite Laval in Canada, achieved nearly 2,500 MPG. (See a full list of winners here.)

We here at DISCOVER have managed to score 9 Blu-ray DVD copies of the recent Warner Bros production of Sherlock Holmes. (Let’s just say they fell off a truck.) Anybody out there want ‘em? We’re going to post a tweet in mere moments about the giveaway; the first 9 people to comment here or retweet our message will find themselves the lucky—and fast—winners. Here’s the official description of this Holmes re-boot:

The action-adventure mystery “Sherlock Holmes” is helmed by acclaimed filmmaker Guy Ritchie. Robert Downey Jr. brings the legendary detective to life, and Jude Law stars as Holmes’ trusted colleague, Watson. Revealing fighting skills as lethal as his legendary intellect, Holmes will battle as never before to bring down a new nemesis and unravel a deadly plot that could destroy the country.

Buy it on Blu-ray™ Combo Pack, DVD and For Download 3/30

Sherlock Holmes © 2009 Warner Bros. Entertainment Inc. All rights reserved.

Are spring allergies making you feel a little stuffed up? No problem–a small outlay of cash and a lot of faith in crackpot science should soon set you straight. Just invest in one of the new “healing ringtones” available in Japan; then the next time your phone rings, stick your cell phone close to your nose and let the ringtone work its magic.

According to Japan Ringing Tone Laboratory, each downloadable therapeutic ringtone can heal a certain ailment. From weight loss to hay fever, creator Matsumi Suzuki is confident that his ringtones can perk you up. (His previous innovation was the “Bow-lingual,” a device that he claimed could translate dog barks into human-speak.)

Explaining how a healing ringtone can fight hay fever, for example, Suzuki said the sound waves produced by the ringing phone dislodge stuck pollen in the nose, thus clearing the airway and making the allergen-crazed individual feel better.

While healing ring tones sound entertaining, it seems pretty obvious that they won’t save you a trip to the doctor. The BBC cautions:

Index, the mobile phone content provider which markets the therapeutic ring tones, admits the technology behind them is perhaps a little unproven but insists the number of downloads suggests they may be working.

Related Content:
Discoblog: Can an iPhone App Clear up Your Acne?
Discoblog:: Worst Science Article of the Week: Use a Cell Phone, Damage Your Baby
Discoblog: In Hospitals, If Your Disease Doesn’t Kill You, a Cell Phone Might
80beats: Surprise! Study Suggests Cell Phone Use Could Actually Fight Alzheimer’s

Image: iStockphoto

I swear, Zach is reading my mind. Click to read the punch line.

But I imagine what would really happen is that this would only get fully funded as long as the LHC had an abstinence-only provision on daughter particles.

Last week’s meeting of the Convention on International Trade in Endangered Species (CITES) put the spotlight on marine species like the bluefin tuna and some endangered sharks, as the meeting failed to protect them from being overfished to extinction. But a new survey published in the UK journal Mammal Review reminds us that it’s not just marine animals that are endangered by humans, but also primates.

The survey showed that despite CITES’ tight trade regulations for primates, more than a hundred primate species, from gorillas to monkeys to tiny lorises, are endangered by traditional medicine. The survey found that animals across the world were being hunted and killed for their perceived magical or medicinal values–of the 390 species studied, 101, or more than a quarter, are regularly killed for their body parts, with 47 species being used for their supposed medicinal properties, 34 for use in magical or religious practices, and 20 for both purposes [BBC].

The survey found that people still use primate parts to treat a wide variety of ailments. In Bolivia, spider monkey parts are used to cure snake bites, spider bites, fever, coughs, colds, shoulder pain, and sleeping problems; in India, the survey found that many people believe that macaque blood is a cure for asthma. Other monkeys or lorises have their bones or skulls ground up into powder administered with tea, or have their gall bladders ingested or blood or fat used as ointments [BBC]. Monkeys are also valued in Sierra Leone, where a small piece of chimpanzee bone is tied to a child’s waist or wrist, as parents believe it will make the child stronger as he grows older.

But even as primate body parts are considered valuable, local customs and beliefs can sometimes be instrumental in helping save the species, the survey found. In parts of Asia, Hindu beliefs help protect species such as long-tailed macaques (Macaca fascicularis) in Bali or grey langurs (Semnopithecus spp) in India. While in the village of Bossou in the Republic of Guinea, the Manon people consider chimpanzees sacred [BBC].

Apart from the indiscriminate hunting, the survey noted that other pressures like loss of habitat, subsistence hunting, and trade in bush meat are also leading to the decline in primate numbers. Of the 101 primate species studied in detail, the researchers found that 12 were classified by the International Union for the Conservation of Nature as being critically endangered, 23 as endangered, and 22 as vulnerable.

The survey comes even as the World Federation of Chinese Medicine Societies (WFCMS) issued a statement this month urging its members not to use tiger bone or any other parts from endangered wildlife, as they had no proven medicinal value. The use of tiger bones was also removed from the traditional Chinese medicine pharmacopeia in 1993 when China instituted a domestic trade ban on tiger parts. But despite, the internal ban, the survey notes, trade in tiger bones still continued.

Related Content:
80beats: It’s Hard Out Here for a Tiger, World Bank Says
80beats: Bushmeat Debate: How Can We Save Gorillas Without Starving People?
80beats: New Threat to Primates Worldwide: Being “Eaten Into Extinction”
DISCOVER: Extinction—It’s What’s for Dinner

Image: iStockphoto

There used to be a Twitter account called Best of Wikipedia — it was a wonderful source for quirky things you might not have chanced upon in your normal browsing. Alas, it’s been quiet since November, so we’re left to our own devices. For some reason or another I was reading about Scholasticism, the dominant approach to teaching and learning in medieval Europe. Its early days came to pass during the Carolingian Renaissance in the late 700’s under Charlemagne.

Besides uniting Central Europe, Charlemagne was also a patron of learning, and used his influence to bring scholars from across the continent to his court. Most importantly, he recognized that the decline of literacy and the splintering of Latin into mutually incomprehensible regional dialects caused difficulties for the administration of an empire, so he ordered that every abbey in his domain should start a school. The idea of widespread schooling was a novel one at the time, and the long-term impact of this decision is probably incalculable. Sure, most of the scholarship may have been devoted to the interpretation of classic texts rather than the production of new knowledge, but you have to think that all that learning helped lay the groundwork for the eventual climb out of the Dark Ages. Start people thinking, and you never know where they will go.

So I was especially fascinated to read about Alcuin of York, one of Charlemagne’s greatest scholars. He was a respected teacher in Northumbria before being brought to court, where he had an enormous effect on the scholarship — establishing the liberal arts (the trivium and quadrivium) as the basis for the curriculum, and convincing Charlemagne not to put pagans to death if they refused to convert. He also produced a textbook of math problems with solutions, from which we learn that medieval word problems were more colorful than those we have today — these include the problem of the three jealous husbands and the problem of the wolf, goat and cabbage.

But it’s clear to me what Alcuin’s greatest achievement really was: he’s the guy who invented lower case letters. Can you imagine a world in which everything was written in ALL CAPS? Every time we read a crazy person ranting on the internet, we should give thanks to Alcuin that not everybody sounds like that.