Science Literature

2011 got off to an exciting start with the announcement of Kepler-10b, the first rocky planet ever discovered outside our solar system. The announcement was widely expected. Last August, a NASA scientist referred to 140 candidates for rocky planet status and now, it appears, they have a confirmed result. The discovery was announced at the a meeting of the American Astronomical Society by Nasa's Kepler team, accompanied by a press release. Richard Kerr, writing in Science, pointed to the significance of the find:

"Astronomers have announced the discovery of an extrasolar planet not much larger than Earth - the smallest exoplanet yet found. Although the world orbits too close to its sun to sustain life, the finding is a milestone in the quest to find out how common Earth-sized, habitable planets really are. It also shows that, with some luck and some innovative new technology, astronomers could be announcing the discovery of a habitable Earth-like exoplanet within a few years."

Artist concept of Kepler-10b (Credit NASA, source here)

According to NASA, the planet has a diameter 1.4 times that of Earth, a mass 4.6 times that of Earth, and an average density of 8.8 grams per cubic centimetre. In the words of Dimitar Sasselov, one of the scientists leading the project, "This planet is unequivocally rocky, with a surface you could stand on". However, according to Nasa, Kepler-10b orbits once every 0.84 days, and is more than 20 times closer to its star than Mercury is to our sun. The daytime surface temperature is about 1500 degrees C, making it likely that if anyone tried to stand on the irradiated surface, there would be a danger of sinking into molten lava. Furthermore, at these temperatures, there is no prospect of the planet retaining an atmosphere.

What then is the significance of this discovery? Several reasons have been adduced. First, it is a rocky planet. All the previous planets discovered (about 500 of them) are giant - Jupiter-like bodies. Astronomers have always expected rocky planets to be discovered when the instruments became sufficiently sensitive - but this only became possible with the Kepler instrument. Second, it demonstrates that Kepler can sense planets of comparable magnitude to the Earth. This gives encouragement that other finds will be forthcoming. "All of our very best capabilities have converged on this one result and they all converge to form a picture of this planet," said Natalie Batalha, an astrophysicist who helped lead the Kepler mission.

The other reasons offered go beyond the science and reveal the aspirations of researchers and the significance of this find for them. For these, we must look at the reports carried by the popular media. BBC News carried some informative comments:

"[. . .] as Professor Batalha explained, it is a significant step in Kepler's mission. "We want to know if we're alone in the galaxy, simply put - and this is one link in the chain toward getting to that objective. First we need to know if planets that could potentially harbour life are common, and we don't know if that's true - that's what Kepler is aiming to do."
A pioneer of the hunt for exoplanets, Geoffrey Marcy, from the University of California Berkeley, said that Kepler 10b represented "a planetary missing link, a bridge between the gas giant planets we've been finding and the Earth itself, a transition... between what we've been finding and what we're hoping to find". "This report... will be marked as among the most profound scientific discoveries in human history," he said.

These comments show that a major driver for these scientists is the quest to find planets in the habitable zone that could potentially harbour life. They are excited because here is the first rocky planet. It does not matter to them that it is not in the habitable zone, that its day side is a furnace, nor that it has lost all atmosphere and water. Finding this hostile rocky planet is nevertheless a milestone for these researchers that they are determined to celebrate. It is perhaps significant that in September 2010 another object was claimed as the first rocky planet: Gliese 581g. This was said to lie in the habitable zone of its star and have a 37-day orbit. Its mass was said to be between 3.1 and 4.3 times that of Earth. One astronomer commented: "That's the most exciting exoplanet I've seen yet". Significantly, Prof Steven Vogt, who led the team that discovered this planet, said that he was 100% convinced it would contain life:

"Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent," he said during a press briefing. "I have almost no doubt about it." [. . .] Prof Vogt estimates that as many as one in five to 10 stars in the universe have planets that are Earth-sized and in the habitable zone. With an estimated 200 billion stars in the galaxy, that means that around 40 billion planets could have the potential for life, he said.

However, excitement about this find was short-lived, as another research team reported their failure to find the signal diagnostic of Gliese 581g. This provides the context for Nasa reporting the "first solid evidence of a rocky planet". They did not have a habitable zone planet, but they are convinced that will come in the not too distant future. However, the evidence on which this hope is based is actually rather tenuous. All the extrasolar planets discovered before this first rocky Earth-like planet are either gas giants, hot-super-Earths in short period orbits, or ice giants. The presumption that there are millions of Earth-like planets in habitable zones is based on theory that is not supported by evidence. This point has recently been made by Howard Smith, a senior astrophysicist at Harvard. He has made the claim that "we are alone in the universe" after an analysis of the 500 planets discovered so far showed all were hostile to life.

"Dr Smith said the extreme conditions found so far on planets discovered outside out Solar System are likely to be the norm, and that the hospitable conditions on Earth could be unique.
"We have found that most other planets and solar systems are wildly different from our own. They are very hostile to life as we know it," he said."

This argument for extrasolar planets is essentially the same as it is for planets in our solar system. The Earth is unique in the mix of characteristics it has: size, distance from the sun, oxygenated atmosphere, substantial coverage by oceans, and so on. Based on evidence, some argue that the Earth is a Privileged Planet. The basic approach of that book is being vindicated as research discovers just how extraordinary the Earth is.

"Gonzalez and Richards counter the prevailing notion among scientists that Earth is merely an average rocky planet revolving around an ordinary star on the outskirts of an undistinguished galaxy. The authors present evidence that suggests life in the cosmos is a rarity due to a variety of prerequisite conditions, such as the unique properties of water, the peculiarities of the Earth-moon system, the sheltering effects of Jupiter and Saturn, and the fine-tuned nature of the universe. The authors maintain that these same conditions allow mankind's significant discovery of the structure of physical laws and the universe. The appendices examine a revised Drake Equation and tackle the idea of "panspermia" - the seeding of life on Earth." (Source here)

Kepler's First Rocky Planet: Kepler-10b
Natalie M. Batalha et al.
Astrophysical Journal, 2011, 729(1), 27 | doi: 10.1088/0004-637X/729/1/27

NASA's Kepler Mission uses transit photometry to determine the frequency of Earth-size planets in or near the habitable zone of Sun-like stars. The mission reached a milestone towards meeting that goal: the discovery of its first rocky planet, Kepler-10b. Two distinct sets of transit events were detected: 1) a 152 +/- 4 ppm dimming lasting 1.811 +/- 0.024 hours [. . .] and 2) a 376+/-9 ppm dimming lasting 6.86+/-0.07 hours [. . .] Statistical tests on the photometric and pixel flux time series established the viability of the planet candidates triggering ground-based follow-up observations. Forty precision Doppler measurements were used to confirm that the short-period transit event is due to a planetary companion. The parent star is bright enough for asteroseismic analysis. Photometry was collected at 1-minute cadence for > 4 months from which we detected 19 distinct pulsation frequencies. Modeling the frequencies resulted in precise knowledge of the fundamental stellar properties. Kepler-10 is a relatively old (11.9+/-4.5 Gyr) but otherwise Sun-like Main Sequence star [. . .] Physical models simultaneously fit to the transit light curves and the precision Doppler measurements yielded tight constraints on the properties of Kepler-10b that speak to its rocky composition: [. . .] Kepler-10b is the smallest transiting exoplanet discovered to date.

See also:

Kerr, R.A. First Earth-Sized Exoplanet Discovered, ScienceNow, 10 January 2011

Mann, A. Space scope finds scorched super-Earth, Nature, 469, 143-144 (10 January 2011) | doi:10.1038/469143a

Inclusive Fitness Theory (IFT) is of considerable importance to Darwinian evolutionists. The theory is concerned with the phenomena of altruistic behaviour and eusocial societies, both of which involve the willingness of some animals to sacrifice themselves for the benefit of the group. Darwin struggled to provide a rationale, and so did those who followed him. It was Bill Hamilton who put together a coherent theory and Richard Dawkins who popularised it in The Selfish Gene. For many, IFT has achieved the status of orthodoxy. It was an intellectual and an emotional shock, therefore, when a paper appeared in Nature (August 2010) from three prominent evolutionary biologists saying that the IFT paradigm is unproductive. Responses were immediate and much of it was hostile. Science journalist Roger Highfield provided an overview of the controversy:

"The mainstream media often like to portray the scientific community as regularly riven by blazing rows. Scientists, understandably, complain: after all, if you go to any mainstream academic conference, you won't find any hint of controversy about the MMR jab or the reality of climate change, let alone argy-bargy over the basic facts of evolution. But in the past few weeks, I have witnessed a bare-knuckle brouhaha that would make an uninformed outsider gasp at how bloody a battle over a seemingly arcane issue can be. The row was triggered by a paper in Nature by Martin Nowak, Edward Wilson and Corina Tarnita of Harvard University. While some hailed it as "revolutionary" and a "return to rigour", others condemned it as "sad", "baffling", "irritating" and "unscholarly"."

Honeybees and ants are eusocial insects. In the colonies, individuals cooperate and share tasks to increase productivity. (Source here)

Readers of this blog might be interested in the reactions of Jerry Coyne, who was mystified by Ed Wilson's participation in the paper.

"I don't know what's gotten into E. O. Wilson. He's certainly the world's most famous evolutionary biologist, and has gone from strength to strength over the years, winning two Pulitzer Prizes, writing great general books on not only ants but conservation and social behavior. [. . .] But now Wilson, along with some collaborators like David Sloan Wilson and Martin Nowak, is definitely heading off on the wrong track. They're attacking kin selection, maintaining not only that it has nothing to do with the evolution of social insects, but that's it's also a bad way to look at evolution in general. And they're wrong - dead wrong."

Coyne is also outraged by the publication of this paper in a prestigious journal: "Finally, a big raspberry to the folks at Nature who decided to publish such a strange paper in the interest of stirring up controversy. If they'd gotten decent reviewers, and followed their advice, it never would have seen print." Richard Dawkins was also quick to repudiate the paper and say that the authors display numerous misunderstandings:

"This is no surprise. Edward Wilson was misunderstanding kin selection as far back as Sociobiology, where he treated it as a subset of group selection [. . .] Inclusive fitness theory is not some kind of supernumerary excrescence, to be 'resorted to' only if 'standard natural selection theory' is found wanting (Misunderstanding One). On the contrary, inclusive fitness theory is one way of expressing what was logically inherent in the synthesis ever since Fisher and Haldane, but had been largely overlooked because people (with the exception of those two geniuses) didn't think about collateral kin. [. . .]"

A welcome, reflective, commentary on the controversy is provided by David Hughes in Trends in Ecology and Evolution. As a young researcher, Hughes had Hamilton as a supervisor; then became a member of the socio-biology research community; then worked at Harvard University where he "engaged extensively with all three of the authors" as they developed their ideas on IFT. He made a point of talking to both sides of the controversy. His short essay does not grapple with the technical issues, but presents some analysis of "the manner in which we carry out evolutionary biology today" and offers some reflective guidelines for constructive debate.

The first problem identified is that "we currently give far too much weight to celebrity status, impact factors and instant commentary". It would appear that far too many have not had the time to engage with the arguments, but are swayed by which experts they trust. In response to this, Hughes first advocates thorough preparation by reading the relevant literature, followed by a ruthless quest for precise language on the part of active participants in the debate. Only then can hard, but relevant, questions be asked.

"Having publically (at conferences) and privately questioned both the authors and opponents, I know that these celebrities on both sides are willing to patiently explain their position. However, because it is difficult to raise hard questions with high profile celebrities we are typically left to discuss the validity and significance of the suggested new approach amongst ourselves. Earnest discussions on difficult topics in biology departments and on conference circuits are oftentimes less than ideal."

Secondly, the science community has imbibed the zeitgest of our age that "lacks a culture of respectful debate". This means that close questioning is often perceived as aggression.

"It seems gladiatorial to ask a difficult question, whether at a conference, seminar or a journal club, but how else can we resolve important issues? Leaving it to comment boxes on blogs is not the way forward. Respectful debating is especially needed now that biology is so large and diverse: we are all ignorant, only on different topics. Eroding this ignorance requires the respectful exchange of information."

Thirdly, there is a confusion of evidence-based science and expert opinion. Hughes finds that much of the debate actually boils down to the expression of opinion, and this cannot be a good thing. The response should be to build arguments on data.

"Because science is evidentiary we do ourselves a disservice by not pushing the data forward. I know that it has become difficult to grasp the meaning of certain data as the standard of both data collection and analysis has risen very sharply. That is why thoughtful and earnest discussions are required. The goal of both parties should be to clearly explain the facts and the ways in which those facts have been collected, however torturous that may be."

Fourthly, Hughes refers to the problem of publishing. As well as the cult of the expert, we have to realise that there is a cult of the high impact journal. These two cults feed off each other. The science community needs to "recognise the playing field we are on". But judgments have to be made.

"However, to decide this you, dear colleague, need to read the paper and question, question, question. We as a community need to experiment, experiment, experiment so as to make available the data that a forward-moving, integrative biology needs. (This of course requires that we increase the rate at which we publish negative results as well). The decisions on such great issues of the day cannot be derived from sound bites in on-line magazines manipulated by sensationalist journalists whose industry thrives on polarization. Nor should our view be the recycled opinion of a celebrity. As idealistic as it sounds, do please be part of a movement to build a society where what is important is the content of the research, the quality of the evidence and the originality and validity of the ideas and not the venue of publication or the celebrity status of the researchers."

All this is good advice and it is also transferable advice. Shift the focus to the issue of intelligent design in nature and all is relevant. Darwinians often play the card of "celebrity status, impact factors and instant commentary". There is typically a lack of respectful debate, with ad hominem arguments and the dark shadow of being expelled hanging over those who step out of line. The point about confusion between evidence-based science and expert opinion is directly relevant: it comes up again and again. The cult of the high impact journal affects the ID debate, as one often comes across examples of people appealing to a journal critique of ID as though it has said the last word and debate is over. There is no acknowledgement that ID scholars have responded to the challenge and demonstrated that the debate is far from over.

A point not made by Hughes but nevertheless relevant is that evolutionary biology is, for many, more than a science. It forms part of their world view. Their opinions take on an identity of their own, because they have persuaded themselves that they have reached the position where they can deliver truth. This explains something of the passion and the polarisation of debates.

"Theologians worry away at the 'problem of evil' and a related 'problem of suffering.' ... On the contrary, if the universe were just electrons and selfish genes, meaningless tragedies like the crashing of this bus are exactly what we should expect, along with equally meaningless good fortune. Such a universe would be neither evil nor good in intention. It would manifest no intentions of any kind. In a universe of blind physical forces and genetic replication, some people are going to get hurt, other people are going to get lucky, and you won't find any rhyme or reason in it, nor any justice. The universe we observe has precisely the properties we should expect if there is, at bottom, no design, no purpose, no evil and no good, nothing but blind, pitiless indifference. As that unhappy poet A.E. Housman put it: 'For Nature, heartless, witless Nature Will neither care nor know.' DNA neither cares nor knows. DNA just is. And we dance to its music."
(Dawkins R., River out of Eden: A Darwinian View of Life, Phoenix: London, 1996, p.155.)

Recent developments in sociobiology and the scientific method
David P. Hughes
Trends in Ecology and Evolution, Volume 26, Issue 2, February 2011, Pages 57-58 | doi:10.1016/j.tree.2010.12.002

You might have noticed that a recent high profile paper on Inclusive Fitness Theory (IFT), presented in the journal Nature, has lead to an enormous and emotional response in sociobiology. The authors, Martin Nowak, Corina Tarnita and Ed Wilson, state that Bill Hamilton's (and the majority of subsequent researchers') paradigm of how altruistic behaviors and eusocial societies evolve is unproductive. The reaction to the publication has been vocal and polarizing, leading to camps of opinions. [snip]

The evolution of eusociality
Martin A. Nowak, Corina E. Tarnita and Edward O. Wilson
Nature, 466, 1057-1062 (26 August 2010) | doi:10.1038/nature09205

Eusociality, in which some individuals reduce their own lifetime reproductive potential to raise the offspring of others, underlies the most advanced forms of social organization and the ecologically dominant role of social insects and humans. For the past four decades kin selection theory, based on the concept of inclusive fitness, has been the major theoretical attempt to explain the evolution of eusociality. Here we show the limitations of this approach. We argue that standard natural selection theory in the context of precise models of population structure represents a simpler and superior approach, allows the evaluation of multiple competing hypotheses, and provides an exact framework for interpreting empirical observations.

See also:

Gilbert, N., Altruism can be explained by natural selection. Evolutionary biologists overturn long-held kin-selection theory. Nature News, (25 August 2010) | doi:10.1038/news.2010.427

Highfield, R. The evolution of altruism: selflessness in ants? That's fighting talk (The Daily Telegraph, 12 October 2010).

The remarkable abilities of flies and other insects to walk with ease on vertical smooth surfaces, and even upside down, has aroused human curiosity for hundreds of years. How do they do it? Furthermore, are there ways for us to do it? If we can master the technology, is there money to be made via innovation? In a helpful review article, Jan-Henning Dirks looks at the history of research into his phenomenon, and draws some fascinating conclusions.

"Even back [in the 17th Century], scientists knew that there is more to insects than meets the eye. While the most basic system of mechanical interlocking found in arthropods is the claw, insects do not merely have a miniature version of this. Many surfaces in the natural world are simply not soft enough to allow claws to be inserted, or are too smooth to provide a safe grip. The question of how insects stick, crawl and run on vertical surfaces and even upside down remains as hotly debated between scientists now as it was in the 17th century."

In 1665 Robert Hooke was one of the first to publish hand-drawn images of a fly's foot in his well-known book Micrographia (left). He speculated that flies adhere by using small hairs that interlock with the roughness of the substrate. Today, we can use more elaborate methods to study the adhesive pads of insects. This electron-microscope image shows a close-up of the smooth pad of a living weaver ant depositing adhesive fluid on a substrate (right). (Image courtesy: Walter Federle, source here)

These insects have tarsal attachment pads that can secrete a nanometre-thin film of a special fluid. The fluid has to provide an adhesive bond that can (at least) support the weight of the insect, but the bond must also be easily broken so that the insect can detach its legs easily for walking or taking flight. On smooth vertical surfaces, the secretion must provide not only adhesion, but also friction, so that the insect does not slide down, out of control. A first milestone in research has been to determine the chemistry of the fluids. The findings reveal several layers of complexity.

"Chemical analyses of this fluid in beetles showed that it contains saturated and unsaturated linear hydrocarbons of C20-C28 chain length, fatty acids and alcohols, as well as true waxes. A recent study on locusts detected not only shorter chain fatty acids (C16-C20) but also significant amounts of polar and amphiphilic components such as saccharides, amino acids and cholesterol. From the low contact angles of footprints on glass, it was concluded that the secretion consists of lipid nano-droplets in an aqueous fluid. However, in vivo observations using interference reflection microscopy (IRM) in ants and stick insects showed that the emulsion's continuous phase is oily and contains volatile, hydrophilic droplets."

The discovery that the adhesive is an emulsion stimulated hypotheses about the breaking of the bond when walking and also the generation of static friction to avoid sliding. It is known that many emulsions have a higher viscosity than their components and some display marked non-Newtonian properties. In a research paper, Dirks et al. report on experimental work designed to test these hypotheses.

"In this study, we test the effect of the pad secretion's two-phasic nature on friction forces by selectively reducing the hydrophilic phase of a stick insect's emulsion in vivo, using a polymeric, water-absorbing substrate."

The authors confirmed that the adhesive secretion is a water-in-oil emulsion and that the two phases were essential to avoid sliding. They found that, on the nano-scale of operation, non-Newtonian effects were even more marked than anticipated.

"When confined to thin films, emulsions can show even more complex non-Newtonian behaviour, which may no longer be dominated by bulk-continuum properties but by processes at the interface. Many emulsions are shear-thinning and exhibit Bingham flow, where shear stress is linearly dependent on shear rate, with a positive intercept. Thus, Bingham fluids require an initial minimum 'yield stress' before they start to flow. The stick insects' relationship between shear stress and sliding velocity is consistent with Bingham flow. A yield point of the two-phasic pad secretion provides an explanation for the significant static friction observed in insects."

Although emulsions are widely used in cosmetics and food technology, each emulsion should be regarded as an engineered fluid - fine-tuned for purpose. This principle is even more relevant to the adhesive secretions of insects.

"The insects' use of an emulsion as an adhesive fluid conveys the benefits of 'wet' adhesion (better adhesion to rough surfaces, wear resistance) without sacrificing the essential ability to withstand shear forces. Our results suggest that insect adhesive organs take advantage of non-Newtonian properties of emulsions and these properties may have been optimized by natural selection. Thus far, engineers have concentrated on biomimetic adhesives inspired by the dry, fibrillar system of geckos. However, the insects' secretion-aided attachment systems also provide an as yet unexplored source of inspiration for novel biomimetic adhesives. Moreover, understanding the detailed function of the insect adhesive system may lead to the development of a new type of non-toxic, wear-resistant insect-repellent coating."

The more we understand these adhesive fluids, the more sophisticated they appear to be. There are still many unexplored aspects - for example, we do not know how the fluids are produced, nor do we understand the self-cleaning mechanisms. Attributing the fine-tuning of the fluid compositions to natural selection is not because the authors have gathered evidence to show that natural selection is responsible. What they have done is show that fine-tuning characterises the materials. Their working theory is one that drives a specific deduction about the cause of this fine-tuning. This is not evidence against design, but the promotion of an alternative theoretical model. The evidence for design lies in the "insect pad secretion" system being characterised as 'exquisitely assembled' rather than 'cobbled together'. It is the Darwinists who have championed evolutionary transformation as a blind, cobbling together, process - then let them demonstrate the cobbled-together features before they appeal to the system being "optimized by natural selection".

Insect tricks: two-phasic foot pad secretion prevents slipping
Jan-Henning Dirks, Christofer J. Clemente and Walter Federle
Journal of the Royal Society Interface, 6 April 2010, Vol. 7, no. 45, 587-593 | doi: 10.1098/rsif.2009.0308

Abstract: Many insects cling to vertical and inverted surfaces with pads that adhere by nanometre-thin films of liquid secretion. This fluid is an emulsion, consisting of watery droplets in an oily continuous phase. The detailed function of its two-phasic nature has remained unclear. Here we show that the pad emulsion provides a mechanism that prevents insects from slipping on smooth substrates. We discovered that it is possible to manipulate the adhesive secretion in vivo using smooth polyimide substrates that selectively absorb its watery component. While thick layers of polyimide spin-coated onto glass removed all visible hydrophilic droplets, thin coatings left the emulsion in its typical form. Force measurements of stick insect pads sliding on these substrates demonstrated that the reduction of the watery phase resulted in a significant decrease in friction forces. Artificial control pads made of polydimethylsiloxane showed no difference when tested on the same substrates, confirming that the effect is caused by the insects' fluid-based adhesive system. Our findings suggest that insect adhesive pads use emulsions with non-Newtonian properties, which may have been optimized by natural selection. Emulsions as adhesive secretions combine the benefits of 'wet' adhesion and resistance against shear forces.

See also:

Dirks, J-H., Not slippery when wet, (physicsworld.com, Dec 1, 2010)