Science Literature

It is well known that Darwin speculated on what might happen in "some warm little pond" (previously discussed here). But it was not until 1929 that J.B.S. Haldane developed a testable hypothesis involving a "prebiotic broth, or primordial soup". He proposed that organic compounds were made when methane, ammonia and water reacted as a result of energy supplied by ultraviolet radiation. The reaction products were suggested to have accumulated in a "hot dilute soup" in the primeval earth. In this scenario, further reactions led to macromolecules, protocells and then life.

"Backed up by Stanley Miller's (1953) inorganic synthesis of organic molecules in the laboratory, it seemed to generations of scientists that Haldane's narrative was basically right, and all that was left was to sort out the details."

It is time to move on from this unproductive research (source here)

Miller's experiments became an icon of naturalistic evolution and entered the textbooks with very little critical analysis of the findings. Even recently, Miller's work was acclaimed in the journal Science. Happily, there are opportunities to get beyond the hype but, as Jonathan Wells showed in his Icons of Evolution, these contributions rarely get beyond the technical literature. William Martin and colleagues have presented a strong case for retiring the primordial soup concept from active service. It has reached the grand old age of 81 and, as a hypothesis, it has not been confirmed. Normally, when hypotheses are tested and found wanting, they are discarded - but we are now overdue for this to happen with the primordial soup. It is "well past its sell-by date".

Two reasons are provided in the paper. The first is that a soup of organic chemicals will be in thermodynamic equilibrium. The reaction products are already present and there is no obvious source of energy to drive polymerisation or any other significant change. "Ionizing UV radiation inherently destroys as much as it creates."

"[T]he homogeneous soup has no internal free energy that would allow them to react further. Life is not just about replication; it is also a coupling of chemical reactions - exergonic ones that release energy and endergonic ones that utilise it, preventing the dissipation of energy as heat. It is commonplace to say that life requires energy, but the conception of a primordial soup fails to recognise or incorporate the importance of energy flux. On the congruence principle, what life needed was not some harsh and problematic source of energy like UV radiation (or lightning), but a continuous and replenishing source of chemical energy."

The second reason concerns fermentation as the primordial mechanism of energy generation in a world without oxygen. Haldane promoted this idea, and De Duve supported it as the mechanism for sustaining anaerobic life. "If there can be said to be a textbook view, this is it."

"But there are profound difficulties - both chemical and biological - in viewing fermentation as primitive rather than derived. Fermentation is chemically a disproportionation - not a simple redox reaction, in which electrons are stripped from a donor and passed onto an acceptor, driven by strong thermodynamics. In contrast with respiration, the amount of energy released by fermentation is tiny, reflecting its lack of thermodynamic driving force. To tap such an insignificant source of energy requires more rather than less sophistication, and indeed about 12 enzymes are needed to catalyse a complex succession of steps in glycolytic-type fermentations based around the Embden-Meyerhoff pathway. These enzymes are proteins encoded by genes, which would have had to evolve as a functional unit without any other source of energy in the primordial oceans - close to an impossibility in an RNA world, let alone the only way to evolve one."

The authors go on to defend their view that fermentation is a sophisticated, rather than a primordial, derivation. This brings them to the crunch question:

"But if there was no soup, and no energy from UV radiation or fermentation, then where was the energy that powered the emergence of life?"

They go on to propose alkaline hydrothermal vents as the primordial source of energy for life. They develop their idea that the origin of life can be considered distintly from the origin of replication. They support Russell et al's (1993) proposal that chemiosmosis is "an inherent property of life, one inherited from the very place and space where it arose". Their paper is exploratory, not plotting out any details of what the Last Universal Common Ancestor (LUCA) looked like, but considering how chemiosmosis might have worked in the setting of alkaline hydrothermal vents. Further discussion of this is needed, of course, but this blog is to draw attention to the challenge these authors present to OOL researchers generally and to textbook authors/educators.

"It is time to cast off the shackles of fermentation in some primordial soup as 'life without oxygen' - an idea that dates back to a time before anybody had any understanding of how ATP is made - and to embrace the most revolutionary idea in biology since Darwin as the key not only to the bioenergetics of all life on Earth today, but to its very origin.(80) Thus it seems to us likely that LUCA grew on the H2/CO2 couple, and that she was naturally chemiosmotic."

How did LUCA make a living? Chemiosmosis in the origin of life
Nick Lane, John F. Allen, William Martin
Bioessays, Published Online: Jan 27 2010 | DOI: 10.1002/bies.200900131

Despite thermodynamic, bioenergetic and phylogenetic failings, the 81-year-old concept of primordial soup remains central to mainstream thinking on the origin of life. But soup is homogeneous in pH and redox potential, and so has no capacity for energy coupling by chemiosmosis. Thermodynamic constraints make chemiosmosis strictly necessary for carbon and energy metabolism in all free-living chemotrophs, and presumably the first free-living cells too. Proton gradients form naturally at alkaline hydrothermal vents and are viewed as central to the origin of life. Here we consider how the earliest cells might have harnessed a geochemically created proton-motive force and then learned to make their own, a transition that was necessary for their escape from the vents. Synthesis of ATP by chemiosmosis today involves generation of an ion gradient by means of vectorial electron transfer from a donor to an acceptor. We argue that the first donor was hydrogen and the first acceptor CO2.

See also:

New Research Rejects 80-Year Theory of 'Primordial Soup' as the Origin of Life, ScienceDaily (3 February 2010)

Warren, D. Back to the beginning, The Ottawa Citizen (6 February 2010)

Two years ago, "the most primitive bat known" was reported in Nature. It was not primitive in its wings and body, but "the morphology of the ear region suggests that it could not echolocate, making it a possible intermediate link between bats and their non-flying, non-echolocating mammalian ancestors". At the time, the find was suggested to settle the question as to which came first: flight or echolocation? The answer was a definite flight first.

"The problem of understanding bat evolution dates back at least to Charles Darwin, who in The Origin of Species enumerated a list of difficulties he saw with the theory of evolution by natural selection. The example often discussed is the origin of the eye. But Darwin also mentioned the vexed issue of how bats had arisen from terrestrial ancestors." Speakman 2008).

Onychonycteris finneyi was featured on the cover of Nature in February 2008 (Source here)

This assessment of the fossil must now be reappraised. New work on modern-day bats has revealed another mechanism of echolocation. One of the authors described the work thus:

"We borrowed 35 specimens from the Royal Ontario Museum in Toronto and performed micro-computed tomography on them. This imaging technique allowed us to see the fine details of the bats' ear and throat regions: the larynges, stylohyals and tympanic bones. Previous work had relied on dissecting these bones, a challenge in animals as small as bats. We found that the fusion or connection of two bone structures - the stylohyal bone in a bat's throat and the tympanic bone in the ear region of its skull - was a feature of all laryngeally echolocating bat species we studied."

This finding is new and unexpected. It means that previous conclusions need to be reappraised. This is exactly what is happening with the "most primitive fossil bat".

"The relatively small cochleae and lack of paddle-like expansions on the cranial tips of the stylohyal bones have been interpreted as evidence that O. finneyi lacked laryngeal echolocation, which supports the hypothesis that flight evolved before echolocation. However, we find that articulation between the stylohyal and tympanic bones is a better predictor of laryngeal echolocation ability than the shape of the stylohyal bone, at least among extant bats. If the stylohyal bones articulated with the tympanic bones in O. finneyi, then we propose that this species had the capacity for laryngeal echolocation. Our results thus reopen basic questions about the timing of the appearance of echolocation and flight in the evolution of bats."

There are several lessons to be learned here - and one of these is to always be prepared to hold judgment on the word "primitive" - even if it is said to be the "most primitive"!

A bony connection signals laryngeal echolocation in bats
Nina Veselka, David D. McErlain, David W. Holdsworth, Judith L. Eger, Rethy K. Chhem, Matthew J. Mason, Kirsty L. Brain, Paul A. Faure & M. Brock Fenton
Nature 463, 939-942 (18 February 2010) | doi:10.1038/nature08737

Echolocation is usually associated with bats. Many echolocating bats produce signals in the larynx, but a few species produce tongue clicks. Here, studies show that in all bats that use larynx-generated clicks, the stylohyal bone is connected to the tympanic bone. Study of the stylohyal and tympanic bones of a primitive fossil bat indicates that this species may have been able to echolocate, despite previous evidence to the contrary, raising the question of when and how echolocation evolved in bats.

Last year, a workshop was hosted by the International Society of Protistologists at their North American Section Meeting. The workshop was given the title "Horizontal Gene Transfer and Phylogenetic Evolution Debunk Intelligent Design". Some of the presentations have recently been published, and one of these is the focus of attention here. One does not get beyond the first paragraph before finding that the authors regard Neodarwinism as robust and that all challengers have abandoned science:

"Despite the overwhelming body of evidence that supports the basic tenets of evolution (i.e. common descent of organisms with different forms being the result of natural selection acting upon naturally occurring variation), there is a large proportion of the American population that does not accept the validity of what is perhaps the most rigorously tested scientific hypothesis in history."

The "six" kingdom taxonomic scheme (Image from Purves et al., source here)

The second paragraph points the finger at Dr Michael Behe and his influential books Darwin's Black Box and The Edge of Evolution. Although the paper covers much ground, it is one of Behe's arguments that engage their attention.

"In his book "The Edge of Evolution: The Search for the Limits of Darwinism" Behe (2007) draws heavily upon the example of drug resistance in the malarial parasite Plasmodium falciparum as one biochemical pathway that is supposedly too complex to have arisen through natural evolutionary processes. According to Behe (2007), the odds that mutations required to impart chloroquine resistance in Plasmodium could arise naturally are so impossibly long that they lie beyond what he considers "The Edge of Evolution".

Anyone who has read Behe's book and understands his analysis would be alerted at this point to a wearying straw man argument. If you are going to critique someone, you ought to, at least, be able to paraphrase their arguments correctly. One wonders why the workshop participants did not put the authors right. In addition, one wonders why the referees did not point out the need for correction. But further, one wonders why the journal editor did not invite peer review from an ID microbiologist. Certainly, the peer review system failed on this occasion. Happily, the internet does allow misinformation to be corrected, and Behe has posted comments which show that the authors, instead of "dispelling the myths of Intelligent Design" are actually promoting myths about Intelligent Design. Here are Behe's concluding words:

"To recap, several years after The Edge of Evolution was published a scientific society held a workshop to demonstrate the book's errors. Yet they couldn't even get the book's argument straight, and the experimental work they cited against my argument is not even pertinent to it. Apparently the design argument drives some scientists so much to distraction that they lose their normally robust powers of reasoning."

Clearly, there is more to be said about the underlying issues. In the abstract of the paper, ID advocates are said to have the goal of "challenging the philosophy of scientific materialism". This is a good place to start an analysis of the issues: because scientific materialism needs to be challenged. Science has no basis for concluding that matter is all there is and that all causation is natural. Those who claim this are importing an ideology that was absent in the early days of science (when the pioneers were theistic scientists, who were quite comfortable with the thought that the natural world is designed). People with different ideologies look at the same data in different ways, and protagonists who do not recognise this are spreading more heat than light. My fear is that instead of discarding this paper as based on false premises, blind crusaders for philosophical materialism will hail it as "excellent article" and will add it to their list of peer reviewed publications showing that the ID approach is bankrupt.

Using Protistan Examples to Dispel the Myths of Intelligent Design
Mark A. Farmer and Andrea Habura
Journal of Eukaryotic Microbiology, 57(1), 2010, 3-10 | doi 10.1111/j.1550-7408.2009.00460.x

ABSTRACT: In recent years the teaching of the religiously based philosophy of intelligent design (ID) has been proposed as an alternative to modern evolutionary theory. Advocates of ID are largely motivated by their opposition to naturalistic explanations of biological diversity, in accordance with their goal of challenging the philosophy of scientific materialism. Intelligent design has been embraced by a wide variety of creationists who promote highly questionable claims that purport to show the inadequacy of evolutionary theory, which they consider to be a threat to a theistic worldview. We find that examples from protistan biology are well suited for providing evidence of many key evolutionary concepts, and have often been misrepresented or roundly ignored by ID advocates. These include examples of adaptations and radiations that are said to be statistically impossible, as well as examples of speciation both in the laboratory and as documented in the fossil record. Because many biologists may not be familiar with the richness of the protist evolution dataset or with ID-based criticisms of evolution, we provide examples of current ID arguments and specific protistan counter-examples.

Misusing Protistan Examples to Propagate Myths about Intelligent Design
Michael J. Behe
Uncommon Descent, 15 February 2010

Introductory sentences: The Journal of Eukaryotic Microbiology recently published several papers from a workshop sponsored by the International Society of Protistologists entitled "Horizontal Gene Transfer and Phylogenetic Evolution Debunk Intelligent Design." So here we have a respected scientific society, presumably planning a workshop months in advance, and finally laying out their considered case for why intelligent design fails. As you might imagine, I was most anxious to read about it. Unfortunately, rather than scholarly papers, the manuscripts read like press releases from the National Center for (Darwinian) Science Education.

Much to the dismay of the BADs (Birds Are Dinosaurs), there is a group of scientists who are in denial of the thesis that theropod dinosaurs evolved into birds. Furthermore, this BAND of scholars (Birds Are Not Dinosaurs) have published in the esteemed PNAS and not in some obscure low-ranked journal. The research was concerned with the dromaeosaurid Microraptor gui, which was first described in 2002 and has flight feathers on all four limbs. The research team modelled M. gui flight and concluded that gliding was its forte.

"We suggest that Microraptor was an adept glider and would have had little difficulty gliding from tree trunk to tree trunk or climbing trees, but would have been very awkward and vulnerable on the ground. The primary feathers on the tarsometatarsus (foot) of the hindwing of M. gui were too long in relation to the limb bones to have allowed the hindwing to fold compactly as does the modern bird wing. Just as colugos and sloths have their limbs encumbered by patagia, the hindwing feathers on Microraptor would severely hamper any terrestrial locomotion."

John Ruben draws attention to an image drawn in 1915 by naturalist William Beebe. It suggests a hypothetical view of what early birds may have looked like, gliding down from trees - and it bears a striking similarity to a fossil discovered in 2003 that is raising new doubts about whether birds descended from ground-dwelling theropod dinosaurs (Source here)

In an accompanying commentary, John Ruben reviewed the history of the controversy over the origins of bird flight. Much to the disapproval of the BADs, Ruben presents those skeptical of the cursorial, ground-upwards hypothesis as scholars who have championed reasoning from evidence. The new research, Ruben suggests, favours gliding, arboreal proto-birds. But he also suggests that some more radical thinking may be warranted:

"So, is the answer, after all, a hybrid of the two old theories, i.e., avian origins from an arboreal, gliding theropod dinosaur? Perhaps, but then this is paleobiology - very recent data suggest that many clearly cursorial theropods previously thought to have been feathered may not have been so and that dromaeosaurs, the group that birds are assumed to have been derived from, may not even have been dinosaurs. What pops up next is anyone's guess."

The Science Daily report points to these more fundamental divergences of view:

The weight of the evidence is now suggesting that not only did birds not descend from dinosaurs, Ruben said, but that some species now believed to be dinosaurs may have descended from birds.
"We're finally breaking out of the conventional wisdom of the last 20 years, which insisted that birds evolved from dinosaurs and that the debate is all over and done with," Ruben said. "This issue isn't resolved at all. There are just too many inconsistencies with the idea that birds had dinosaur ancestors, and this newest study adds to that."

Breaking out of the conventional wisdom? Yes - we need some more of that!

Paleobiology and the origins of avian flight
John Ruben
Proceedings of the National Academy of Sciences, published online before print February 9, 2010 | doi:10.1073/pnas.0915099107

First sentence: Interpreting the paleobiology of long extinct taxa, pesky new fossils, and reinterpretations of well-known fossils, sharply at odds with conventional wisdom never seem to cease popping up.

Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui
David E. Alexander, Enpu Gong, Larry D. Martin, David A. Burnham, and Amanda R. Falk
Proceedings of the National Academy of Sciences, Published online before print January 25, 2010 | doi: 10.1073/pnas.0911852107

Abstract: Fossils of the remarkable dromaeosaurid Microraptor gui and relatives clearly show well-developed flight feathers on the hind limbs as well as the front limbs. No modern vertebrate has hind limbs functioning as independent, fully developed wings; so, lacking a living example, little agreement exists on the functional morphology or likely flight configuration of the hindwing. Using a detailed reconstruction based on the actual skeleton of one individual, cast in the round, we developed light-weight, three-dimensional physical models and performed glide tests with anatomically reasonable hindwing configurations. Models were tested with hindwings abducted and extended laterally, as well as with a previously described biplane configuration. [. . .] Although the biplane model glided almost as well as the other models, it was structurally deficient and required an unlikely weight distribution (very heavy head) for stable gliding. Our model with laterally abducted hindwings represents a biologically and aerodynamically reasonable configuration for this four-winged gliding animal. M. gui's feathered hindwings, although effective for gliding, would have seriously hampered terrestrial locomotion.

See also:

Bird-from-Dinosaur Theory of Evolution Challenged: Was It the Other Way Around?, ScienceDaily (Feb. 10, 2010)

Deyes, R. B.A.R.B: Birds Are Really.....Birds!, ARN Literature Blog (25 June 2009)

Tyler, D. Did birds fly in the Late Triassic? ARN Literature Blog (16 June 2009)

Professor Steve Fuller is known as a prolific author whose analysis of the scientific enterprise is iconoclastic. He was famously involved as a defense witness in the Kitzmiller v. Dover Area School District (2005) trial, for which he has received a great deal of flak. The essay cited below provides an explanation of his involvement and a challenge for other qualified people to ensure that their voices are heard.

"I believe that tenured historians, philosophers, and sociologists of science - when presented with the opportunity - have a professional obligation to get involved in public controversies over what should count as science. I stress 'tenured' because the involved academics need to be materially protected from the consequences of their involvement, given the amount of misrepresentation and abuse that is likely to follow, whatever position they take."

Why are so few willing to follow this advice? (Source here)

Those who want to read specific comments on the trial should read the essay. My interest here is in the broader issue of what science studies brings to the discussion of origins. Fuller is dissatisfied with the limited scope of the discourse to date because the dominant voices have functioned as "underlaborer[s] to science". He points out "two types of public exemplars" that have been associated with science studies:

"On the one hand, there is the Michael Ruse figure who supplies a historical and philosophical hinterland to the dominant scientific paradigm so as to complement its purely empirical success with a broader cultural and conceptual grounding that will appeal to those unfamiliar with the technical science. On the other hand, there is the Robert Pennock figure, more typical of the younger generation, who outright collaborates with established scientists in their research, providing a running legitimizing narrative in co-authored articles published in technical and popular forums. In both cases, the science studies scholar functions as an underlaborer to science, as opposed to a true metascientist."

Science studies need to rise above partisanship and develop robust contributions to knowledge that do not need the endorsement of the 'scientific consensus' to justify their validity.

"A metascientist evaluates science from a standpoint that does not presuppose the legitimacy of the dominant paradigm. He or she starts by asking why we pursue science in the first place - the question of ends - and then turns to consider the extent to which the normal pursuit of science satisfies those ends. This is the role I have tried to exemplify. [. . .] The approach is 'constructivist' without being 'relativist' in the way these two terms are normally understood in epistemology."

These social epistemological principles are then applied to the origins controversy. Fuller is interested in this debate because it presents so many important and interesting issues needing rational discussion. However, Fuller finds that far too much bigotry has been expressed and has concluded that something needs to be done to raise the level of debate.

"In terms of the evolution-creation controversy, the bottom line for me, then, is not to satisfy the wishes of particular communities by allowing creationism to be taught, but to avoid the opportunity costs to everyone if creationism is not allowed to be taught."

These opportunity costs are worthy of elaboration. Fuller identifies several of these. The first draws attention to the history of science and the fact that many scientists have done good work motivated by the presupposition that the natural world is the handiwork of an Intelligent Designer. Those who say that toleration of ID will be the death of science and the beginning of a new dark age are in denial of history.

"Here I have in mind the overwhelmingly positive role that belief in an intelligent designer has played in motivating religious people to enter and stick with scientific careers, which have resulted in findings that command the assent of even those who lack faith."

The second opportunity cost is academic freedom. Fuller has already made it clear that he thinks tenured academics should be taking the lead in challenging the dominant paradigm. It is simply too risky for others to stick their heads above the parapet - they are easy targets and they get hurt. They are treated as guilty by association and their ideas are deemed unworthy of any further consideration.

"When we start to judge ideas rather than texts, intentions rather than practices, we become complicit in the erosion of academic freedom. Perhaps the most widely publicized recent case to cross that line was the forced resignation of Michael Reiss as director of science education for the Royal Society. Reiss had the temerity to suggest that science teachers should take seriously - albeit critically - creationist queries raised by their students. Reiss, who also holds a chair at the University of London's Institute of Education, based this judgment on his own research on science pedagogy. It is worth noting that he did not propose that teachers should themselves introduce the creationist ideas - yet the Royal Society deemed he still had to go."

The third opportunity cost is concerned with the quality of debate. Academics are supposed to use their minds when defending a position or critiquing others. However, the origins issue reveals people ruled by emotions, prejudices and ideologies.

"The pervasive anti-Christian bigotry surrounding the evolution-creation debate has had other knock-on effects on the conduct of intellectual discourse. It becomes an excuse to lower the tone in both academic and public discussions. Anyone prepared to defend any form of creationism should expect enormous negative attention in the blogosphere, ranging from occasional derision to outright invitations to trash the defender. At first I believed that my own intervention would clarify misunderstandings but it only seemed to intensify them, not least because I addressed my opponents in the spirit they addressed me. They were not prepared to entertain the idea that it was they and not I who misunderstood."

These three opportunity costs deserve the serious attention of all who are engaged in the controversy. However, the dominant response has been to ignore these points and persist in old patterns of thinking and tired polemics. Some have expressed their frustration with Fuller for his bad judgment. One of these is Michael Lynch, Professor of Science & Technology Studies at Cornell University, who has published several articles condemning Fuller's role as an expert witness in the Dover trial. One of these was in the same journal Spontaneous Generations that carried the essay under consideration here, to which Fuller has recently responded. He pointed out that his "game" is not for short-term gain but for long-term success.

"In that context, I undertake a risky performance in the spirit of a living experiment, the results of which should prove instructive not only to myself but also to others who in the future are similarly well-positioned to bring science studies to bear on public policy. The only mistake would be for others not to repeat the experiment."

Fuller is prepared to criticize Ruse and Pennock for being "traitors to their training" and guilty of "intellectual treason". He is prepared to say that Barbara Forrest's tactic has been to shift the argument from evaluation of ideas to the "intentions of those promoting them", thereby following in the footsteps of John Dewey who used this approach to earn a reputation as "one of the foremost Red-baiters in the US philosophical establishment in the 1940s and '50s". These charges are not ad hominems but are based on analysis of their arguments. The issues are far too important to allow room for complacency - academic freedoms are being eroded, young scientists are fearful of expressing any positive views on design, parental responsibilities for the education of their children are being eroded (with charges of "child abuse" being thrown around), and much more. But Fuller is also prepared to press upon tenured academics the obligation he thinks they have to use their positions of relative security to contribute to public controversies about the nature of science. There is an urgency about the situation. The least that can be said is that Fuller is a trail blazer. No one can criticize him for not acting out what he is encouraging others to do.

Science Studies Goes Public: A Report on an Ongoing Performance
Steve Fuller
Spontaneous Generations, 2(1), (2008), 11-21

First para: I believe that tenured historians, philosophers, and sociologists of science - when presented with the opportunity - have a professional obligation to get involved in public controversies over what should count as science. I stress 'tenured' because the involved academics need to be materially protected from the consequences of their involvement, given the amount of misrepresentation and abuse that is likely to follow, whatever position they take. Indeed, the institution of academic tenure justifies itself most clearly in such heat-seeking situations, where one may appear to offer a reasoned defense for views that many consider indefensible. To be sure, the opportunities for involvement will vary in kind and number, but I believe that we are obliged to embrace them. In the specific case of 'demarcation' questions of what counts as science, the people who possess the sort of general and comparative knowledge most relevant for adducing this matter are historians, philosophers, and sociologists of science - not professional scientists unschooled in these areas.

Response to Lynch
Steve Fuller
Spontaneous Generations, 3(1), (2009), 220-222.

See also:

Lynch, M. Going Public: A Cautionary Tale, Spontaneous Generations, 3(1), (2009), 212-219.

Tyler, D. A "teachable moment" regarding the departure of Michael Reiss, ARN Literature blog (25 September 2008)

Tyler, D. Michael Reiss and the science-religion issue, ARN Literature blog (17 September 2008)

Over the years, there has been much interest in the design of running shoes, with product designers building in protection against impacts and other perceived hazards. However, continuing reports of repetitive strain injuries warrant further research and product re-design. The topic has come to the surface recently with a comparison of the forces experienced by feet of habitually shod versus habitually barefoot runners. It emerges that barefoot runners make contact with the ground in a way that avoids impact-related discomfort and injury.

On the left, a habitually shod Kenyan who is heel-striking; on the right, a Kenyan who has never worn shoes and who is forefoot striking in the way most barefoot runners land. Below are representative force traces (in units of body weight) showing how the two styles of running differ in the force generated when the foot collides with the ground. The barefoot runner lands with no collisional force. (Image: Daniel E. Lieberman, Source here)

As a matter of observation, most habitually shod runners first contact the ground with their heel. This is referred to as heel-striking or rear-foot strike. Modern running shoes have been designed to reduce the impact forces with the help of additional cushioning at the heel. Barefoot runners first contact the ground with the front part of their feet and bend their ankles more as they run. This is referred to as fore-foot or mid-foot strike. This mode of running results in reduced collision forces and enhanced comfort.

"People who don't wear shoes when they run have an astonishingly different strike," says Daniel E. Lieberman, professor of human evolutionary biology at Harvard University and co-author of a paper appearing this week in the journal Nature. "By landing on the middle or front of the foot, barefoot runners have almost no impact collision, much less than most shod runners generate when they heel-strike. Most people today think barefoot running is dangerous and hurts, but actually you can run barefoot on the world's hardest surfaces without the slightest discomfort and pain. All you need is a few calluses to avoid roughing up the skin of the foot. Further, it might be less injurious than the way some people run in shoes."

Since this is a topic where there are numerous agents with commercial interests, the authors of the research paper have felt the need to issue a disclaimer that their reported work is essentially empirical in nature.

"Please note that we present no data on how people should run, whether shoes cause some injuries, or whether barefoot running causes other kinds of injuries. We believe there is a strong need for controlled, prospective studies on these problems." (Source here)

However, the authors go well beyond the empirical data in their analysis when they ground their work in a framework of evolutionary biology. This is also the starting point for Jungers' commentary on the research: "A commitment to walking and running on two legs distinguishes humans from apes, and has long been the defining adaptation of the hominins - the lineages that include both humans and our extinct relatives. This form of locomotion (bipedalism) has been around for millions of years, and we have been unshod for more than 99% of that time." The view, therefore, is that the context for understanding running is that it has evolved as an adaptation under the influence of natural selection.

"Our feet were made in part for running," Lieberman says. But as he and his co-authors write in Nature: "Humans have engaged in endurance running for millions of years, but the modern running shoe was not invented until the 1970s. For most of human evolutionary history, runners were either barefoot or wore minimal footwear such as sandals or moccasins with smaller heels and little cushioning."

There is another perspective on this, which is that of design. Design advocates will affirm: 'Our feet were designed in part for running'. Humans live in many different environments, and the design issues are affected by the need to walk, jump, climb, carry and run in these different environments. A sensitivity to design means that we need to understand how our feet work best in different conditions, so it follows that runners should adopt a biomechanical and physiological approach to developing good running habits. Runners should train to develop the full potential of the design features of their bodies. An evolutionary story of how ape-like animals developed bipedalism is simply a veneer overlying the empirical data.

Foot strike patterns and collision forces in habitually barefoot versus shod runners
Daniel E. Lieberman, Madhusudhan Venkadesan, William A. Werbel, Adam I. Daoud, Susan D'Andrea, Irene S. Davis, Robert Ojiambo Mang'Eni & Yannis Pitsiladis
Nature 463, 531-535 (28 January 2010) | doi:10.1038/nature08723

First para: Humans have engaged in endurance running for millions of years, but the modern running shoe was not invented until the 1970s. For most of human evolutionary history, runners were either barefoot or wore minimal footwear such as sandals or moccasins with smaller heels and little cushioning relative to modern running shoes. We wondered how runners coped with the impact caused by the foot colliding with the ground before the invention of the modern shoe. Here we show that habitually barefoot endurance runners often land on the fore-foot (fore-foot strike) before bringing down the heel, but they sometimes land with a flat foot (mid-foot strike) or, less often, on the heel (rear-foot strike). In contrast, habitually shod runners mostly rear-foot strike, facilitated by the elevated and cushioned heel of the modern running shoe. Kinematic and kinetic analyses show that even on hard surfaces, barefoot runners who fore-foot strike generate smaller collision forces than shod rear-foot strikers. This difference results primarily from a more plantarflexed foot at landing and more ankle compliance during impact, decreasing the effective mass of the body that collides with the ground. Fore-foot- and mid-foot-strike gaits were probably more common when humans ran barefoot or in minimal shoes, and may protect the feet and lower limbs from some of the impact-related injuries now experienced by a high percentage of runners.

See also:

The Barefoot Professor: by Nature Video

Jungers, W.L., Barefoot running strikes back, Nature 463, 433-434 (28 January 2010) | doi:10.1038/463433a

Tyler, D. The human body is built for running, ARN Literature blog (29 October 2009)