Friday, April 29, 2011

On semen

From The Huffington Post
Lazar Greenfield, M.D. is no ordinary surgeon. Until last week, he was the president-elect of the American College of Surgeons. The man is the inventor of the Greenfield Filter, a device that has saved countless lives as a means of preventing blood clots during surgery. He's a professor emeritus of surgery at the University of Michigan. He has written more than 360 scientific articles in peer-reviewed journals, 128 book chapters and two textbooks. He has served on the Editorial Board of 15 scientific journals and was also the lead editor of the Surgery News, the trade publication in which his writing initiated Semengate.

In the February issue, he penned some thoughts on Valentine's Day under the heading of "Gut Feelings." ("But Valentine's Day is about love, and if you remember a romantic gut feeling when you met your significant other, it might have a physiological basis.") Greenfield proceeded to then discuss the mating habits of fruit flies ("It has long been known that Drosophila raised on starch media are more likely to mate with other starch-raised flies"), the mating habits of the rotifer ("Biologists say that it's more advantageous for a rotifer to remain asexual and pass 100 percent of its genetic information to the next generation."). In each case, Dr. Greenfield made sure to reference to the scientific literature. Then he turned his attention to humans.

Dr. Greenfield noted the therapeutic effects of semen, citing research from the Archives of Sexual Behavior which found that female college students practicing unprotected sex were less likely to suffer from depression than those whose partners used condoms (as well as those who remained abstinent).

Presumably it was the closing line that caused the controversy: "So there's a deeper bond between men and women than St. Valentine would have suspected, and now we know there's a better gift for that day than chocolates."

The attempt at Jackie Mason-humor apparently didn't sit well in certain quarters. Dr. Greenfield resigned as editor of the Surgery News and gave up his stewardship of ACS after learning that his article had spurred threats of protests from outside women's groups.

In an interview with the Detroit Free Press last Wednesday, Dr. Greenfield explained:
The editorial was a review of what I thought was some fascinating new findings related to semen, and the way in which nature is trying to promote a stronger bond between men and women. It impressed me. It seemed as though it was a gift from nature. And so that was the reason for my lighthearted comments.
The story has been big in the scientific community, but in all that has been printed, there is one take I thought missing and noteworthy -- that of the three psychologists who authored the peer-reviewed article cited by Dr. Greenfield. So I tracked down Steven M. Platek, Rebecca L. Burch, and Gordon G. Gallup, Jr.

Speaking for the group, Dr. Steven M. Platek, Ph.D, the editor-in-chief of Frontiers in Evolutionary Neuroscience and a co-editor of Evolutionary Psychology, offered this analysis:
Frankly, we think people are over reacting to the comments made by Dr. Lazar Greenfield. There is growing evidence that human semen has the potential to produce profound effects on women. We have replicated the effects showing female college students having sex without condoms are less depressed as measured by objective scores on the Beck Depression Inventory. We've also examined the data as a function of whether the students were using hormonal contraceptives, whether they were in committed relationships, and how long these relationships have lasted. The anti-depressant properties of semen exposure do not vary as function of any of these conditions. It is not a question of whether females are sexually active, since students having sex with condoms show the same level of depression as those who are not having sex at all. We have also received numerous semen testimonials from other women who attest to the anti-depressant effects of semen exposure and these accounts often include the use of control trials (i.e., comparisons generated by switching from condoms to unprotected sex, or vice a versa).
Only 5 percent of the ejaculate is sperm. What's left is seminal plasma, which is a rich concoction of chemicals, including many that have the potential to produce mood-altering effects derived from hormones, neurotransmitters, and endorphins. There are even female sex hormones in male semen. Within a hour or two after insemination, you can detect heightened levels of many of these seminal chemicals in a woman's bloodstream.

But it is also important to acknowledge that there is a dark side to semen chemistry. The vagina is a very hostile environment for sperm. During human evolutionary history women couldn't afford to conceive as a consequence of being inseminated by just any man, and the presence of semen in the female reproductive tract often triggers an immune reaction that treats the sperm as a pathogen. Not surprisingly, semen chemistry has evolved to neutralize vaginal acidity and suppress the woman's immune system. There is even reason to believe that because of the immunosuppressant properties of semen, frequent insemination may compromise the female immune system. Because there are female as well as male sex hormones in human semen, there are other reasons to believe that additional features of semen evolved to promote the reproductive best interests of the donor. The presence of follicle stimulating hormone and leutenizing hormone in semen, implies that semen exposure has the potential to promote induced ovulation.

How can someone be asked to resign for citing a peer-reviewed paper? Dr. Greenfield was forced to resign based on politics, not evidence. His resignation is more a reflection of the feminist and anti-scientific attitudes of some self-righteous and indignant members of the American College of Surgeons. Science is based on evidence, not politics. In science knowing is always preferable to not knowing.

Steven M. Platek
Rebecca L. Burch
Gordon G. Gallup, Jr.

Thursday, April 28, 2011

Health care expenditures

From the Kaiser Family Foundation.

The US government spends more on health care as a percent of GDP (7.4%) than Switzerland, Canada, Italy, Spain, U.K., Norway, Australia, and Japan.

Besides that, except for Switzerland and France we spend at least 50% more in total on health care (again as a percent of GDP) than any other country in the world. (We spend 42% more than Switzerland and 46% more than France.)

(H/T Ezra Klein)

My Anniversary Gift to Lisa

Tuesday, April 26, 2011

IQ scores reflect motivation as well as ‘intelligence’

From Not Exactly Rocket Science | Discover Magazine
[Angela Lee Duckworth from the University of Pennsylvania] looked at the scores of 508 young boys who had taken an IQ test in 1987. The boys were part of the Pittsburgh Youth Study, and researchers kept in touch with them into adulthood, for at least 12 years after the original test. As usual, their scores predicted their eventual academic performance, the number of years they spent in education, their odds of being employed as adults, and their number of criminal convictions.

But there was more. The original tests were all delivered verbally and the sessions were filmed. Duckworth recruited three independent researchers to review the footage for signs of low motivation, such as refusing to take part, or wanting the session to end. The team found that boys with lower IQ scores were also less motivated when they took the test, and their degree of motivation also predicted the course of their lives. Accounting for motivation weakened the link between IQ and life-success, especially for employment and criminal convictions. …

If you think it’s obvious that motivation would confound the results of IQ tests, then Robert Stenberg, who studies intelligence at Oklahoma State University, agrees with you. “D’uh!”, he says. Sternberg thinks that Duckworth has produced a “great research study” but adds, “To almost anyone except some subset of psychologists who study IQ testing, it will come as little surprise that motivation is an extremely powerful determinant of performance in school and in life. Most employers, for example, are at least as eager to know about job applicants’ motivation as they are to know about their cognitive skills. Teachers also know that ability without high motivation typically results in little success in a challenging curriculum.”

Monday, April 25, 2011

How to (spot a) lie with statistics

Paul Krugman finds the hole in the claim that government spending has increased from 19.6 percent of GDP in fiscal 2007 to 23.6 percent in fiscal 2010. There are two causes. (a) GDP itself has grown much more slowly since 2007 as previously, and (b) recession-related government spending (such as unemployment insurance) has grown significantly. These are both what we expect. During a recession the government should both continue its normal operation and increase spending to support people in trouble. Other than these two areas, there are no major increases in government spending.

The gap between sales of new home and existing home

From the always sensible Calculated Risk.
This graph starts in 1994, but the relationship has been fairly steady back to the '60s. Then along came the housing bubble and bust, and the "distressing gap" appeared (due mostly to distressed sales).

The gap is due mostly to the flood of distressed sales. This has kept existing home sales elevated, and depressed new home sales since builders can't compete with the low prices of all the foreclosed properties.

Thursday, April 21, 2011

Mitt Romney Haunted By Past Of Trying To Help Uninsured Sick People

From The Onion (naturally).
BELMONT, MA—Though Mitt Romney is considered to be a frontrunner for the 2012 Republican presidential nomination, the national spotlight has forced him to repeatedly confront a major skeleton in his political closet: that as governor of Massachusetts he once tried to help poor, uninsured sick people.

Romney, who signed the state's 2006 health care reform act, has said he "deeply regrets" giving people in poor physical and mental health the opportunity to seek medical attention, admitting that helping very sick people get better remains a dark cloud hovering over his political career, and his biggest obstacle to becoming president of the United States of America.

"Every day I am haunted by the fact that I gave impoverished Massachusetts citizens a chance to receive health care," Romney told reporters Wednesday, adding that he feels ashamed whenever he looks back at how he forged bipartisan support to help uninsured Americans afford medicine to cure their illnesses. "I'm only human, and I've made mistakes. None bigger, of course, than helping cancer patients receive chemotherapy treatments and making sure that those suffering from pediatric AIDS could obtain medications, but that's my cross to bear."

"My hope is that Republican voters will one day forgive me for making it easier for sick people—especially low-income sick people—to go to the hospital and see a doctor," Romney added. "It was wrong, and I'm sorry."

According to Romney, if he could do things over again, he would do everything he could to make certain that uninsured individuals got sicker and sicker until they died. Promising his days of trying to provide medical coverage to the gravely ill are behind him, Romney said that if elected president, he would never even think about increasing anyone's quality of life or trying to lower the infant mortality rate.

In addition, Romney repeatedly apologized for wanting to help people suffering from diabetes, Crohn's disease, and anemia.

"I don't know what got into me back then," Romney said. "Wanting to make sure people were able to have health insurance if they left their job. Providing a federally funded website so individuals could compare the costs of insurance providers. Making certain that somebody who earns less than 150 percent of the poverty level can receive the same health care coverage as me or any government official. All I can say is that I was young and immature, and I am not that person anymore."

"The only solace I can take is in the hope that some of the folks I helped were terminally ill patients who eventually withered away and died," Romney added.

Though Romney has apologized profusely, Beltway insiders said he would need to distance himself from his I-tried-to-help-sickpeople image. Sources noted that Romney's current promise to take away health care from anyone who can't afford it is a step in the right direction, but might not be enough.

"The major strike against Mitt Romney is that he not only tried to help people get medical care, he actually did help people get medical care," conservative columnist Jonah Goldberg said. "No other Republican in the field has that type of baggage. And in the end, in order to defeat President Obama, the GOP needs someone who has a track record of never wanting to help sick people."

Thus far, Romney is polling strongly in early primary states like New Hampshire and Iowa, but Republican strategists and voters agree that even in a general election, his sordid past would continue to dog him.

"I don't think I can vote for someone like that," Pennsylvania Republican Eric Tolbert said. "He says he's sorry, but how do I know that's the real Mitt Romney? What happens if he gets elected and tries to help sick people again?"

"I like Michele Bachmann now," Tolbert added. "Because what this country needs is a president who doesn't give a fuck about helping people."

Tuesday, April 19, 2011

Astro (and planetary) biology

Caleb Scharf is the director of Columbia University's multidisciplinary Astrobiology Center. He also writes an ongoing blog. He is a wonderful writer. His posts are full of intelligent wonder at the nature of life and the universe in which it finds itself. Here's today's post in full—although I don't get the image he included.
The Earth is still forming. Every year our planet accumulates another 40 million kilograms of material, mostly in the form of microscopic interplanetary dust. More sporadically the planet is also hit by larger bodies. Hundred meter diameter asteroids or cometary lumps arrive on average every thousand years, kilometer-sized civilization manglers arrive roughly every million years. This had been going on since the Earth coagulated from the material of the proto-planetary disk around a baby Sun 4.54 billion years ago.

As we turn back the cosmic clock the rate of accumulation of material increases. The pockmarked lunar surface has served as a proxy for reconstructing the history of asteroidal and cometary impact on the Earth. Without an atmosphere or significant geophysical activity the Moon has an excellent memory of impacts, while the Earth had eroded and resurfaced itself in continual reinvention. This record has indicated that during a period between about 4.1 and 3.8 billion years ago the Earth must have been subject to a particularly brutal pummeling. A substantial fraction of the outer shell of our planet could have been laid down during what has become known as the Late Heavy Bombardment.
It's a fascinating time in the history of our world. The first indications that microbial life might have been at work come not so very long after this quite cataclysmic episode ended.

The reason for this infall of material seems likely to be connected to a period of dynamical evolution in the outer planets. Models suggest that both Neptune and Uranus could have migrated outwards and dug into a rich belt of outer, Kuiper or trans-Neptunian objects. Many of those distant small bodies would have been pushed into orbital paths that would eventually lead to passage through the inner solar system and collision with the Earth. At the same time, Jupiter and Saturn would have migrated inwards and could have scattered material from the asteroid belt onto inbound trajectories. Once the dynamical reorganization of the giant planets was finished the Late Heavy Bombardment would have tailed off. A settling planet Earth then gave rise to the tentative steps of biochemistry and single-celled organisms.

Or so we thought. New evidence is emerging from the terrestrial rock record that the Earth actually continued to be pounded by very significant impacts from 3.8 billion years ago all the way up to around 2.5 billion years ago. "Life Killer" type asteroid impacts seem to have happened roughly every 40 million years during this timespan, rather than every 500 million years as had previously been thought.

So what gives? Where did these chunks of material come from? W. Bottke and colleagues have studied the gravitational dynamics of the teenage solar system and suggest that a now-depleted inner belt of material between Mars and Jupiter could have been scattered onto an inclined set of orbits - out of the plane of the planets. This population would then slowly "leak" into Earth-crossing paths, thereby greatly extending the tail of the Late Heavy Bombardment over another billion years or so. The leftovers of these bodies are still there, known as the Hungaria asteroids.

It all looks to fit rather well. The dynamics are believable, and provide a mechanism for the impacts that littered the planet with the molten globs of rock that geologists find in layers of ancient strata. There's just one teensy question. What are the implications for the evolution of life on Earth? While evidence of microbe-built structures like stromatolites from 3.5 to 3.8 billion years ago remain a little controversial, the presence of a diverse planet-wide biosphere is pretty incontrovertible in the 3 to 2.5 billion year ago span. Apparently microbial life not only dealt with continual destructive asteroid impacts but really did rather well for itself.

This raises another intriguing issue. As W. Bottke and colleagues point out, this prolonged period of heavy impacts does effectively stop around 2.5 billion years ago. That is suspiciously coincident with the first signs of a rising oxygen content in the Earth's atmosphere (the "Great Oxidation Event"), and the eventual emergence of multi-cellular life somewhere around 1.6 to 2 billion years ago. Is there a connection? Could the continual accumulation of planetary material have held back the full-on evolutionary party of early life? It's highly speculative, but one is tempted to think that this might be further evidence for the incredible resilience of life and its near-relentless nature once it becomes entrenched on a planet.
As Brad DeLong says
Republicans. They lie all the time. About everything. We as a country would be much better off if they simply vanished today, and we had a different opposition party to the Democrats.
See these too.

From cow to steak

I couldn't bring myself to watch this. Do you want to? It starts with a live cow, and ends like this.

Sunday, April 17, 2011

Taxes as the cost of living here


Republicans love to complain about taxes. But they also worship the free market.

What do you suppose the market price of US citizenship is. Let's put it on the market. What could we get for it?

The price would be expressed in terms of the amount of yearly income one would be willing to pay for being a US citizen. Do you suppose the price would be less than we now pay in taxes? I doubt it. If it were, a lot of people would be trying to move somewhere else.

But I don't see that happening. On the contrary, even with all our problems and all our taxes, there are far more people who want to live here than who want to leave.

If the Republicans think they can create a better society with lower taxes, I challenge them to point to one that they prefer.

Toys “R” Us sells the iPad2

Seems about right.

Friday, April 15, 2011

"Insincerely yours"

Krugman on how serious the Republicans are about the deficit.
Republicans are deeply, sincerely concerned about the budget deficit. That’s why, in unveiling their plan last week, they declared themselves willing to give ground on their traditional priorities, signaling a willingness to accept higher taxes on the wealthy and reduced defense spending as part of a deficit-reduction deal.

Oh, wait. You mean they didn’t do anything like that? You mean that even while warning about an imminent fiscal crisis, they actually tried to cut taxes on the rich to their lowest level since 1931?

Why, you might actually think that they’re not sincerely concerned about the deficit. But that can’t be true, since they keep saying that they are.
Clearly, we need to cut taxes even further so as to balance the budget.
More charts from the CBPP.

Thursday, April 14, 2011


From Obama's speech about the deficit yesterday.
Our leaders came together three times during the 1990s to reduce our nation's deficit. They forged historic agreements that required tough decisions made by the first President Bush and President Clinton; by Democratic Congresses and a Republican Congress. All three agreements asked for shared responsibility and shared sacrifice, but they largely protected the middle class, our commitments to seniors, and key investments in our future.

As a result of these bipartisan efforts, America's finances were in great shape by the year 2000. We went from deficit to surplus. America was actually on track to becoming completely debt-free, and we were prepared for the retirement of the Baby Boomers.

But after Democrats and Republicans committed to fiscal discipline during the 1990s, we lost our way in the decade that followed. We increased spending dramatically for two wars and an expensive prescription drug program but we didn't pay for any of this new spending. Instead, we made the problem worse with trillions of dollars in unpaid-for tax cuts tax cuts that went to every millionaire and billionaire in the country; tax cuts that will force us to borrow an average of $500 billion every year over the next decade.

To give you an idea of how much damage this caused to our national checkbook, consider this: in the last decade, if we had simply found a way to pay for the tax cuts and the prescription drug benefit, our deficit would currently be at low historical levels in the coming years.

Monday, April 11, 2011

The budget is already balanced!

From The Incidental Economist.

See Ezra Klein's comment.

Actually it's not really balanced. The graph excludes interest on the national debt. But it's close!

Sunday, April 10, 2011

Restoring American Democracy

From Jeffrey Sachs
In poll after poll, the actual views of the public about the budget are clear: cut military spending, raise taxes on the rich, and cut health care costs by taking on private health insurers. These are the policies put forward last week in the "People's Budget" (which I recently wrote about) proposed by the leaders of the Congressional Progressive Caucus.

Even though we don't know the still secret details of the $38.5 billion in the cuts, we can be sure that not one of these sensible mainstream ideas is even remotely represented in the new "historic" agreement. The President and the Congressional leadership of both parties are pursuing the opposite strategy: cut taxes for the rich; sustain record-high military spending and indeed a growing number of wars; turn over even more of health care to price-gouging private health insurers; and cut urgently needed help for the poor, the public schools, higher education, and the unemployed.

In the end, we have gotten from President Obama what we feared from Senator McCain: an expanded war in Afghanistan, an extension of the Bush-era tax cuts, sharp cuts in spending for communities and programs for the poor, a continuation of Guantanamo and military tribunals, unchecked bankers' pay and bonuses, and enough loopholes to reduce corporate taxes to less than 2 percent of GDP this year, despite a boom in corporate profits.

Wednesday, April 06, 2011

Bertrand Russell says

The time you enjoy wasting is not wasted time.
From BrainyQuotes.

Why haven't existing medical plans held down the cost of insurance?

Paul Ryan's proposed plan to have individuals buy their own medical insurance claims to take advantage of the ability of buyers to drive better bargains when they have an interest in the negotiation. When individuals buy their own insurance, the claim goes, they will force providers to offer better medical coverage for less money.

If that's so why hasn't it already happened? Most medical plans contract with providers for the actual medical coverage. Why haven't insurance companies been able to force providers to provide more medicine for less money? Surely insurance companies have more leverage over providers than individual policy holders. If giant insurance companies can't keep the cost of medical insurance down, how can we expect individuals to do so?

The impossible assumption at the heart of Ryan’s budget

From Ezra Klein - The Washington Post.
There’s difference between cutting costs and shifting them. As the Congressional Budget Office noted, a lot of what Ryan’s budget does is shift costs from the federal budget to someone else’s budget: Medicaid’s costs moves to the states, and then when the states cut it, to the people who need it, or to their families. Medicare’s costs move to seniors, or to the families of seniors. The budget doesn’t have a clear theory for how to spend less on health care. It has a clear theory for how the federal budget can spend less, and other people can spend more. But that’s not good enough.

Fair Elections Now

Support the Fair Elections Now Act.

The Fair Elections Now Act (S. 752 and H.R. 1826) was introduced in the Senate by Sens. Dick Durbin (D-Ill.) and Arlen Specter (D-Pa.) and in the House of Representatives by Reps. John Larson (D-Conn.), Walter Jones, Jr. (R-N.C.), and Chellie Pingree (D-Maine). The bill would allow federal candidates to choose to run for office without relying on large contributions, big money bundlers, or donations from lobbyists, and would be freed from the constant fundraising in order to focus on what people in their communities want.

Participating candidates seek support from their communities, not Washington, D.C.
  • Candidates would raise a large number of small contributions from their communities in order to qualify for Fair Elections funding. Contributions are limited to $100.
  • To qualify, a candidate for the U.S. House of Representatives would have to collect 1,500 contributions from people in their state and raise a total of $50,000.
  • Since states vary widely in population, a U.S. Senate candidate would have to raise a set amount of small contributions amounting a total of 10% of the primary Fair Elections funding. The number of qualifying contributions is equal to 2,000 plus 500 times the number of congressional districts in their state.
See the Fair Elections Now website for more details.

Monday, April 04, 2011

Got to give Christopher Hitchens credit for writing well

I'm normally not a Christopher Hitchens fan, but here's a paragraph from a piece about the reaction in Afghanistan to the burning of a Quran in Florida.
How dispiriting to see, once again, the footage of theocratic rage in Kandahar and Mazar-i-Sharif. The same old dreary formula: self-righteous frenzy married to a neurotic need to take offense; the easy resort to indiscriminate violence and cruelty; the promulgation of makeshift fatwas by mullahs on the make; those writhing mustaches framing crude slogans of piety and hatred, and yelling for death as if on first-name terms with the Almighty. The spilling of blood and the spoliation of property—all for nothing, and ostensibly 'provoked' by the corny, brainless antics of a devout American nonentity, notice of whose mere existence is beneath the dignity of any thinking person.
Very nicely put.

The Dependence Economy: whatever can't go on forever won't

Catherine Rampell has a post on the trends in where our personal income is coming from. The long term trend is that more of it is coming from transfer payments and less from earnings. The steep blue rise and red decline at the end reflect the recent great recessions, but the trend has been established for far longer. As she notes,
These underlying trends are partly because of demographic changes; an aging populace means that an ever-smaller share of Americans are working, and so a larger share are receiving Social Security benefits. Policy changes, more Americans’ going on disability and growing inequality, which in some cases may be leaving more Americans on the dole, are also likely contributing to the growing Dependence Economy.

Whatever the causes, these trends are not infinitely sustainable. The money for transfer payments has to be transferred from somewhere, after all — and if not from other people’s wages, then from China and other foreign creditors. But foreign creditors won’t foot the bill forever without an exit strategy.

The Transmission Mechanism for Quantitative Easing

Paul Krugman wonders why (through what mechanism) has quantitative easing (QE2) worked—to the extent that hit has. Previously the Fed affected the economy through its effect on housing. But that can't be the case this time. So what is it? He suspects that QE2 has had its effect through encouraging high-end consumption. That is, people with money in the stock market, primarily people who have money, have made lots of money recently and have therefore been more willing to spend it. So instead of encouraging housing the Fed has encouraged consumption by giving people with money more money.

The other major contributor to the economy has been an increase in the balance of exports over imports. That's been the result—at least in part—of a weaker dollar, possibly also a consequence of QE2. Krugman's two supporting charts are to the right.

The bottom chart tracks ETFs over the past 6 months for consumer discretionary spending (XLY), consumer staples spending (XLP), and the S&P 500 (SPY).

Speaking of complex systems

Caleb Scharf discusses possibilities for earth's climate 4 billion years ago.
Understanding the climate and overall environment of the very young Earth continues to be an extremely tricky business. Previous posts on several issues (I, II) surrounding the so-called Faint Young Sun paradox have discussed some of the sticking points. In a nutshell; 4 billion years ago the Sun was about 30% fainter than it is today, a direct consequence of the fundamentals of stellar evolution. So the puzzle is that as far as we can tell the surface environment harbored liquid water, yet today's atmospheric composition would have resulted in a vastly colder climate. Boosts to greenhouse gases might solve the problem, but it remains at the hairy edge of plausibility.

Now a new study by Court and Sephton casts an even murkier pall over the problem, literally. We have high confidence (from the record of lunar cratering, as well as the orbital evolution of the outer planets) that some 4.1 to 3.8 billion years ago the Earth was subjected to period of sustained impact over about 100 million years by asteroidal-type material. The so-called Late Heavy Bombardment (LHB) was quite a pounding. It likely provided the major constituents of the juvenile Earth's outer layers. Court and Sephton have studied the effect of the sand-grain sized components of material that may have poured into the Earth's atmosphere as micrometeorites during this era. Atmospheric friction as these tiny particles raced into the upper atmosphere produces high temperatures and the grains ablate, releasing sulfur dioxide - among other gases.

Sulfur dioxide is great for making particulates in a planetary atmosphere. This increases reflectivity, and can dramatically lower the solar radiation reaching the surface. Net result; planet cools. During the LHB roughly 20 million tonnes of sulfur dioxide a year may have been dumped into the atmosphere by this flux of tiny meteorites. That's equivalent to having a massive volcano erupt into the stratosphere every year for a hundred million years. The problem of keeping the Earth warm is greatly exacerbated. Court and Sephton also point out that Mars would have received a significant flux of these sulfur-bearing micrometeorites, seemingly creating an even bigger problem for an early temperate martian climate.

There are still a lot of questions. Was the sulfur content of these particles really as high as claimed? Do we really know the rate at which such tiny grains hit the Earth? Could the atmospheric chemistry of the young Earth have mitigated the production of sulfate aerosols?

Understanding what happened on the young Earth is a major issue. It seems for every solution to keeping the planetary surface warm there is an opposing mechanism that will plunge it into deep freeze. Yet the evidence remains for the presence of substantial liquid surface water during at least the tail end of the LHB and likely much earlier. Clearly somewhere we're missing a piece of the equation, or perhaps several pieces. Being able to study the deep geological history of Mars could help enormously, since it would allow us to separate out some of the planet-specific mechanisms at play. It may also be time to think a little more radically. Putting aside the mineralogical evidence for an early aqueous environment then perhaps a deep-frozen young Earth offers some advantage for the subsequently rapid emergence of life?

Sunday, April 03, 2011

Why Your Taste Cells Love Sugar So Much

From the Monell Chemical Senses Center.
PHILADELPHIA (March 7, 2011) – A new research study dramatically increases knowledge of how taste cells detect sugars, a key step in developing strategies to limit overconsumption. Scientists from the Monell Center and collaborators have discovered that taste cells have several additional sugar detectors other than the previously known sweet receptor.

“Detecting the sweetness of nutritive sugars is one of the most important tasks of our taste cells,” said senior author Robert F. Margolskee, M.D., Ph.D., a molecular neurobiologist at Monell. “Many of us eat too much sugar and to help limit overconsumption, we need to better understand how a sweet taste cell ‘knows’ something is sweet.”

Scientists have known for some time that the T1r2+T1r3 receptor is the primary mechanism that allows taste cells to detect many sweet compounds, including sugars such as glucose and sucrose and also artificial sweeteners, including saccharin and aspartame.

However, some aspects of sweet taste could not be explained by the T1r2+T1r3 receptor. For example, although the receptor contains two subunits that must join together for it to work properly, Margolskee’s team had previously found that mice engineered to be missing the T1r3 subunit were still able to taste glucose and other sugars normally.

Knowing that sugar sensors in the intestine are important to how dietary sugars are detected and absorbed, and that metabolic sensors in the pancreas are key to regulating blood levels of glucose, the Monell scientists used advanced molecular and cellular techniques to see if these same sensors are also found in taste cells.

The results, published in the Proceedings of the National Academy of Sciences USA, indicate that several sugar sensors from intestine and pancreas also are present in exactly those same sweet-sensing taste cells that have the T1r2+T1r3 sweet receptor.

“The taste system continues to amaze me at how smart it is and how it serves to integrate taste sensation with digestive processes,” said Margolskee.
This story was also featured on NPR's Science Friday. In the Science Friday interview with Margolskee, Joe Palca asked
Okay, and so this chemical interaction or biochemical interaction between the protein that makes the receptor on the surface of the taste bud, that's a chemical event. But something happens in the brain that makes this turn into a perception of an event or a sweetness event.
But he never got an answer.
Correct. So you can think of the sweet receptor protein and the sugar or sweetener as kind of a lock and key, and when they encounter each other, it opens the lock. The door opens up. It excites the sweet taste cell, and that sends a signal to the brain, to particular centers of the central nervous system that respond to sweet.
That's as far as it went. Palca raised the question of the mystery of consciousness, and Markolskee ignored it.

Tasting sweetness is a very good example of what we mean by qualia. And our lack of knowledge about how it works is evident. We know a great deal about the chemical interactions that occur when sugar meets the body. But if you look at those interactions, you won't find anything there that tastes sweet. One would never know just by looking at chemicals that the result is the experience of sweetness. The gap between the chemistry and the experience is enormous, and we have no idea how to bridge it. It seems that no amount of chemistry will do the job.

Suppose we knew every last chemical reaction that occurs when we taste sweet. Would anyone know by looking at the chemistry that the result is sweet? No. How could they. The experience of sweet is not part of the language of chemistry. Worse, we don't know where that language does originate. How does the experience of sweetness appear in the world? We don't know. I wish I could say more, but that's the state of our knowledge about consciousness.