Science Literature

Entomologists interested in the Coleoptera (beetles) may find themselves struggling with an information overload because there are said to be about 350,000 species alive today. A previous blog drew attention to Darwinian approaches to explaining these large numbers, and to an evidence-based explanation that is not Darwinian. The presumption seems to have been that speciation has occurred so readily that the life-time of an individual species is short. This has affected studies of Pleistocene sub-fossil specimens, in that the finds were assumed to represent extinct species:

"Originally, the remains from the Pleistocene peat-bog or asphalt deposits were assigned to extinct species by historical authors, supporting the idea of a high evolutionary rate induced by the climate changes during the Pleistocene."

General view of the modern Helophorus sibiricus and its newly discovered Early Miocene fossil counterpart. The close-ups show the species-specific granulation of the pronotum in both the recent specimen (top) and the fossil (bottom), one of the characteristics that allowed a reliable identification of the fossil. (Source here. Credit: Martin Fikacek)

With further research, similarities with modern species were recognised and the previous "finding" was completely overturned!

"Later, more detailed studies of sub-fossil specimens sometimes based even on the study of their well-preserved genitalia revealed that the majority of Pleistocene sub-fossil beetles belong to recent species and resulted in the Pleistocene evolutionary stasis paradigm."

The stasis paradigm has not been applied to pre-Pleistocene specimens. This is largely because the information needed to assign a fossil to a modern species is largely lacking in these fossils - so it is assumed (again) that the finds represent extinct species.

"A large missing piece for the acceptance of long-living insects as a general phenomenon and for understanding the reasons for survival of the particular species is the scarcity of the fossils of such species. The reasons seem to be rather straightforward - the majority of the fossils bear too few details to allow a detailed comparison with living species, whose taxonomy is often based on the shape of male genitalia and other details."

Consequently, the recent find of an early Miocene beetle that can be assigned to an extant species was unexpected. The ScienceDaily report notes: "A study of an Early Miocene fossil from southern Siberia [. . .] led to the surprising find that the fossil belongs to a species of aquatic beetles which is still alive today and widely distributed in Eurasia." We should note that the age assigned to this fossil is 16-23 million years, but the average duration of an insect species (let alone a beetle species) is considered to be much shorter.

"The Siberian fossil provides new data for the long-lasting debate among scientists about the average duration of an insect species. It was originally estimated to be ca. 2-3 million years based on the available fossil record, but slowly accumulating data begin to show that such an estimate is an oversimplification of the problem."

Oversimplification is a problem, but it is not solved by the token concession that acknowledges there are a few long-lived species. The root problems are the assumptions that scholars bring to the study of fossil beetles. Just as reconsideration of the Pleistocene beetles led to the recognition of stasis, coleopterists need to be open to stasis being a pervasive feature of the fossil record. Although diversification has occurred readily in the past, in general speciation is followed by stasis. This is not the Darwinian paradigm! Sad to say, this is point in the argument where we struggle to get a meaningful response from Darwinists. There is plenty of scope for discussion of these issues - for more on this and the relevance to intelligent design, go here.

A long-living species of the hydrophiloid beetles: Helophorus sibiricus from the early Miocene deposits of Kartashevo (Siberia, Russia)
Martin Fikacek, Alexander Prokin, Robert Angus.
ZooKeys, 2011; 130 (0): 239 | DOI: 10.3897/zookeys.130.1378

Abstract: The recent hydrophiloid species Helophorus (Gephelophorus) sibiricus (Motschulsky, 1860) is recorded from the early Miocene deposits of Kartashevo assigned to the Ombinsk Formation. A detailed comparison with recent specimens allowed a confident identification of the fossil specimen, which is therefore the oldest record of a recent species for the Hydrophiloidea. The paleodistribution as well as recent distribution of the species is summarized, and the relevance of the fossil is discussed. In addition, the complex geological settings of the Kartashevo area are briefly summarized.

See also:

Living Species of Aquatic Beetle Found in 20-Million-Year-Old Sediments, ScienceDaily (Oct. 6, 2011)

Steven Pinker wants to challenge the claim that "The twentieth century was the bloodiest in history". Those who advance this idea are said to be numbered among "the romantic, the religious, the nostalgic and the cynical". The reason why they make the claim is "to impugn a range of ideas that flourished in that century, including science, reason, secularism, Darwinism and the ideal of progress". However, according to Pinker, there is no substance to this "historical factoid" because historical records are better as we come closer to the present time, because it is a human trait to overestimate the frequency of wars ("vivid, memorable events") and because we care more about violence today. Against all this, Pinker asserts that there has been a historical decline in violence that deserves our attention.

Pinker in a nutshell: "Our dark side is driven by a evolution-based propensity toward predation and dominance. On the angelic side, we have, or at least can learn, some degree of self-control, which allows us to inhibit dark tendencies." (Quote from Robert Epstein, image credit Viking Adult)

As might be anticipated from the list of impugned ideas, Pinker puts himself on the side of "science, reason, secularism, Darwinism and the ideal of progress". He sees himself as an advocate of Enlightenment Humanism. The article stimulating this blog appears in the Comment section of Nature, signifying that the science community in general is willing to promote such views. It is something of a challenge to scientists and historians who take a different approach to these issues, because their scholarship is already undermined by Pinker's labels for them: "the romantic, the religious, the nostalgic and the cynical".

Those who are accustomed to saying that science deals with "How?" questions and religion deals with "Why?" questions have a real problem with Pinker's article, because it appears in a leading science journal and is all about why humans behave the way they do. The philosophical stance of much modern science treats morality, ethics, social behaviour and much else as a sub-set of phenomena in the natural world.

The essay in Nature is remarkably light on evidence, although references are provided on the web version and Pinker's new book on this theme makes reference to much relevant data. Undoubtedly, we are not short of data, but the challenge is in selecting relevant data and constructing a robust interpretation of these data. History provides a warning. Before the First World War, there were numerous voices making optimistic noises about the world being bathed in peace. The 1911 issue edition of the Encyclopaedia Britannica carried a prediction by Sir Thomas Barclay that "in no distant future, life among nations" would be characterized by "law, order and peace among men". We look back on that and see it as a cultural relic of the Victorian age, when the idea of progress for civilised society seemed compelling. Such idealism appeared to be swept away by the military ambitions of a highly civilised nation. But in more recent years, the same vision is being promoted. Mueller (2009) is cited by Pinker as a source, and this paper sets out to make the case again for the decline of armed conflict:

"It may be time to revisit the visions and optimism of a century ago and to assess the massive intervening literature on war because we may be reaching a point where war - in both its international and civil varieties - ceases, or nearly ceases, to exist, a remarkable development that has attracted little notice."

It is not my purpose in this blog to appraise the evidence used to support Pinker's thesis. However, Some reviewers of Pinker's book have expressed strong disagreements. One of these is John Gray in Prospect Magazine:

"The Korean war, the Chinese invasion of Tibet, British counter-insurgency warfare in Malaya and Kenya, the abortive Franco-British invasion of Suez, the Angolan civil war, decades of civil war in the Congo and Guatemala, the Six Day War, the Soviet invasion of Hungary in 1956 and of Czechoslovakia in 1968, the Iran-Iraq war and the Soviet-Afghan war - these are only some of the armed conflicts through which the great powers pursued their rivalries while avoiding direct war with each other. When the end of the Cold War removed the Soviet Union from the scene, war did not end. It continued in the first Gulf war, the Balkan wars, Chechnya, the Iraq war and in Afghanistan and Kashmir, among other conflicts. Taken together these conflicts add up to a formidable sum of violence. For Pinker they are minor, peripheral and hardly worth mentioning. The real story, for him, is the outbreak of peace in advanced societies, a shift that augurs an unprecedented transformation in human affairs."

My interest is the subtle equating of the "decline of war" with the "decline of violence". Even allowing some substance to the argument for reducing military conflict, is war a good measure of "violence"? For a start, some of us consider that some conflicts have resulted from a sense of justice - to overpower the aggressor. We do not accuse members of the police of violence when they restrain those who have committed crimes; nor should we consider all military conflicts as though both sides are in the wrong. A country's military strength may have been a factor in reaching a settled peace. Violence has its roots in anger and other strong passions within, and we should ask if there are other forms of violence that have flourished in otherwise peaceful societies. It is worth noting that Pinker does not do this.

Consider these two ways of identifying violence on a global scale. The first concerns economic exploitation: using the poor to work long hours to make consumer products that can be transported to developed countries. The exploiters of these vulnerable people are usually of the same nationality and their passion is one of making money for themselves. They find all sorts of ways of concealing exploitation (which extends sometimes to economic slavery) and their customers are assured that the business is ethical. Auditors find they can tick all the boxes. Meanwhile, statistics of average earnings usually show figures far below the minimums determined by organisations concerned about people receiving a living wage. The workers often have to experience hazardous working conditions linked to producing products at the lowest possible cost. Consumers in developed countries have learned to ask no questions about ethical sourcing and enjoy acquiring low-priced products. The second window on violence concerns the practice of abortion. The global total number of abortions is currently estimated to be 1,237,000 per month. The estimated cumulative total is nearly 1 billion. The vast majority of these abortions are of healthy babies, and their deaths always involve some violence to both child and mother. This is a practice that stirs strong passions in people, but most developed societies have learned to live with it and not to ask too many questions. They do not think much about the numbers, but if they did, they might be surprised to learn that in the past 100 years, far more humans have been killed by abortion than the estimated 175 million deaths resulting from armed conflict.

The most sensible sentence in Pinker's essay is the following:

"Reason, by itself, can lay out a road map to peace or to war, to tolerance or to persecution, depending on what the reasoner wants."

A similar sentence can be constructed around science. Reasoning and science are both human activities, and humans can use them in many different ways. However, Pinker does not say this to undermine his stance; he goes on to argue that there are two conditions tending to align reasons with non-violence. The first is "that reasoners care about their own well-being". He sees this not so much as a matter of logic but more as an example of what natural selection will do: "any product of natural selection [. . .] is likely to have [those prejudices]". The second condition is "that a reasoner be part of a community of reasoners who can impinge on their well-being and who can comprehend each other's reasoning". This is how he develops a "morality" of non-violence:

"Self-interest and sociality combine with reason to lay out a morality in which non-violence is a goal. If one agent says, "It's bad for you to hurt me", he has also committed to "It's bad for me to hurt you", because logic cannot tell the difference between 'me' and 'you'. Therefore as soon as you try to persuade someone to avoid harming you by appealing to reasons why he shouldn't, you're sucked into a commitment to the avoidance of harm as a general goal."

This argument is one that has eluded me. I can tell the difference between 'me' and 'you' because we are two distinct individuals and not clones of each other. I can envisage a situation where I could gain an advantage from hurting my benefactor, and logic would not be able to prevent me taking that advantage. I am not the only one who thinks Pinker is out of his depth on the grounds for morality - John Gray can also see gaping holes in the arguments:

"Shaped by imperatives of survival, the human mind will not normally function as an organ for seeking out the truth. If science is the pursuit of truth - an assumption that begs some tricky questions - it doesn't follow that anything similar is possible in other areas of human life. The idea that humans can shape their lives by the use of reason is an inheritance from rationalist philosophy that does not fit easily with what we know of the evolution of our mammalian brain. The end result of scientific inquiry may well be that irrational beliefs are humanly indispensable."

My greatest objection to Pinker's essay is not with the arguments he presents, but with the way he has airbrushed out so many of my heroes from history. It is as though the words "Blessed are the peacemakers" were never spoken! He refers to slavery several times, even asking the question: "Why did human rationality need thousands of years to conclude that something might be a wee bit wrong with slavery?" This is not a matter of reason, but it points to something being wrong with the human condition. This is where William Wilberforce and the converted slave-trader John Newton provide a landmark in history, taking seriously biblical texts like Exodus 21:16 and 1 Timothy 1:10 because they were Christians. Regarding reason, Pinker keeps returning to the Enlightenment scholars - but the consistent champions of reason and logic through history have been Christians. Consider the early colleges of Oxford and Cambridge university; consider the founding of the Royal Society, consider the early setting up of schools for common people - history provides ample testimony to the way Christians have promoted reason and logic. Liberty is to be prized, but it was not always deemed a human right. Kings and leaders have always sought to control people under them - their minds as well as their behaviour. The torch of liberty was carried by Christians who were prepared to suffer for their obedience to God - and we need to honour these men and women, not forget them. Pinker's view of history is entirely secularised. There is no acknowledgement that people of faith have changed the course of history.

I think Gray's concluding paragraph is profound. He realises that the secular humanists are showing all the signs of sectarian religion. They rewrite history, they selectively sift data, they do not critique their own arguments, and they turn science into scientism. They look to their version of science to be the saviour of humanity. But in all this, they are living in denial of the most fundamental principle in science: to follow the evidence wherever it leads.

"Pinker's attempt to ground the hope of peace in science is profoundly instructive, for it testifies to our enduring need for faith. We don't need science to tell us that humans are violent animals. History and contemporary experience provide more than sufficient evidence. For liberal humanists, the role of science is, in effect, to explain away this evidence. They look to science to show that, over the long run, violence will decline - hence the panoply of statistics and graphs and the resolute avoidance of inconvenient facts. The result is no more credible than the efforts of Marxists to show the scientific necessity of socialism, or free-market economists to demonstrate the permanence of what was until quite recently hailed as the Long Boom. The Long Peace is another such delusion, and just as ephemeral."

Decline of violence: Taming the devil within us
Steven Pinker
Nature, 478, 309-311 (20 October 2011) | doi:10.1038/478309a (pdf here)

First paragraph: "The twentieth century was the bloodiest in history." This frequently asserted claim is popular among the romantic, the religious, the nostalgic and the cynical. They use it to impugn a range of ideas that flourished in that century, including science, reason, secularism, Darwinism and the ideal of progress. But this historical factoid is rarely backed up by numbers, and it is almost certainly an illusion. We are prone to think that modern life is more violent because historical records from recent eras are more complete, and because the human mind overestimates the frequency of vivid, memorable events. We also care more about violence today. Ancient histories are filled with glorious conquests that today would be classified as genocide, and the leaders known to history as So-and-So the Great would today be prosecuted as war criminals.

See also:

Gray, J. Delusions of peace, Prospect Magazine (21 September 2011, Issue 187)

Tyler, D. On science as the saviour of humanity, ARN Literature blog (27 June 2011)

It looks like a carnivore, has a digestive tract like a carnivore - but its staple diet is bamboo. Any other member of the ursidae would starve on this cellulose-rich fare. How does the Giant Panda get enough energy to keep itself alive? In January 2010, a study of the panda's genome revealed that it has maintained the genetic requirements for being purely carnivorous, despite being a herbivore. Further, no evidence of genes that encode enzymes for digesting cellulose was found. The hypothesis proposed at that time was that the bamboo diet "may instead be more dependent on its gut microbiome". Now this hypothesis has been tested and validated. This is from a report in Nature News:

"Fuwen Wei, an ecologist at the Institute of Zoology at the Chinese Academy of Sciences in Beijing, and his colleagues took a closer look at the microbes that live in the guts of giant pandas. The team collected stool samples from seven wild pandas in the Qinling and Xiangling mountains in central and western China, as well as from eight captive pandas. By sequencing stool DNA, the researchers determined the different kinds of bacteria present, as well as the identity of thousands of microbial genes. Although wild and captive pandas have different diets and lifestyles - the captive pandas eat a more diverse diet that includes fruit and milk - they tended to harbour similar microbe species in their guts. Wei's team found that samples from both groups contained previously unknown genes produced by Clostridium bacteria, which resembled known genes for enzymes that break cellulose into simpler sugars. The microbial enzymes may help giant pandas to extract extra energy from the small amount of bamboo that they manage to process, says Wei."

How can an animal that has the characteristics of a carnivore eat bamboo? (Source here)

Interestingly enough, most of the gut flora was similar to other carnivores. This is from the Nature News report:

"Most herbivores have developed ways to break down cellulose into sugars; for example, cows and other ruminants have complicated digestive systems - involving multiple stomachs filled with microbes - that process plants many times to extract the maximum nutrition. But pandas are bears, a generally carnivorous family, and neither produce the enzymes necessary to digest cellulose nor harbour the same microbes as ruminants. A broad survey of animal gut microbes found that pandas' microorganisms resembled those of black bears, polar bears and other meat-eaters."

So, although the Panda gut appears to be appropriate for a carnivore, it does not eat meat. As the genome paper (2010) revealed, "The giant panda has lost the capability of sensing umami, which means that meat has become unappetizing." Now, a Chinese team has found evidence for cellulose matabolising microbes that are unique to mammals. This is from their research paper:

"Our metagenomic analysis and 16S rRNA gene data confirm the presence of putative cellulose-metabolizing symbionts in this little-studied microbial environment and clarifies how giant pandas are able to partially digest bamboo fibers despite a genome lacking enzymes that can degrade cellulose."

The mystery is revealed! But what should we make of it all? The Chinese researchers explain it in terms of evolutionary adaptation:

"It is becoming increasingly clear that giant pandas possess a suite of evolutionary adaptations for the highly specialized herbivory. Our findings offer a more in-depth look at the microbiome of a species that occupies an interesting place in the evolutionary tree and has an unusually narrow diet. Thus, the putative harboring of cellulose and hemicellulose-digesting microbes in the gut of the giant panda, along with a suite of other traits, including pseudo-thumbs; well-developed teeth, mandible and skull morphology, and chewing muscles; high-volume food ingestion (12.5 kg/day); brief digestion time; and high mucous levels in the digestive tract, likely have arisen as a result of adapting to a highly fibrous bamboo diet within the constraints imposed by the panda's innate carnivore-like digestive system."

It is this conclusion that prompts some cautionary words in this blog. Adaptions they likely are, but the context for these adaptations is degeneration rather than any increase in biological information. These adaptations fit the pattern of "evolutionary tinkering" so beloved by evolutionists. They do not reveal the "exquisite design" that is so often found when we look in detail at living things. Darwinian mechanisms have not equipped the Panda with the genetic information to digest cellulose. They have not led to changes in the gut to make the process of digesting cellulose more efficient. One report put it this way:

"Wei and his team believe that some of the bacteria they've found in the panda stools help the bears break down that cellulose, if only a little bit. A very little bit. In a study conducted at the Washington National zoo several years ago, it was found that pandas only process something like eight percent of the cellulose in the bamboo they eat. Thus, they have to eat not just a lot, but constantly to get enough nutrition from the bamboo to survive."

So the Giant Panda is not an example of a species that is more fit because of adaptation. Rather, it looks more like a species that has suffered some major degenerative mutations in the past, but has (by a process of "tinkering" with what's still working) managed to survive. The design perspective gives us a story of how a superbly designed carnivore has managed to survive the effects of genetic degradation. Design perspectives are needed, also, if we are to secure a future for the Giant Panda - if we leave it to experience the effects imposed by blind Darwinian mechanisms, it will not be long before the species becomes extinct.

Evidence of cellulose metabolism by the giant panda gut microbiome
Lifeng Zhu, Qi Wu, Jiayin Dai, Shanning Zhang, and Fuwen Wei
Proceedings of the National Academy of Sciences, Published online before print October 17, 2011, doi: 10.1073/pnas.1017956108

Abstract: The giant panda genome codes for all necessary enzymes associated with a carnivorous digestive system but lacks genes for enzymes needed to digest cellulose, the principal component of their bamboo diet. It has been posited that this iconic species must therefore possess microbial symbionts capable of metabolizing cellulose, but these symbionts have remained undetected. Here we examined 5,522 prokaryotic ribosomal RNA gene sequences in wild and captive giant panda fecal samples. We found lower species richness of the panda microbiome than of mammalian microbiomes for herbivores and nonherbivorous carnivores. We detected 13 operational taxonomic units closely related to Clostridium groups I and XIVa, both of which contain taxa known to digest cellulose. Seven of these 13 operational taxonomic units were unique to pandas compared with other mammals. Metagenomic analysis using ~37-Mbp contig sequences from gut microbes recovered putative genes coding two cellulose-digesting enzymes and one hemicellulose-digesting enzyme, cellulase, beta-glucosidase, and xylan 1,4-beta-xylosidase, in Clostridium group I. Comparing glycoside hydrolase profiles of pandas with those of herbivores and omnivores, we found a moderate abundance of oligosaccharide-degrading enzymes for pandas (36%), close to that for humans (37%), and the lowest abundance of cellulases and endohemicellulases (2%), which may reflect low digestibility of cellulose and hemicellulose in the panda's unique bamboo diet. The presence of putative cellulose-digesting microbes, in combination with adaptations related to feeding, physiology, and morphology, show that giant pandas have evolved a number of traits to overcome the anatomical and physiological challenge of digesting a diet high in fibrous matter.

See also:

Callaway, E. Microbes help giant pandas overcome meat-eating heritage, Nature News (17 October 2011) | doi:10.1038/news.2011.596

Tyler, D. Jingjing decoded in part, ARN Literature Blog (28 January 2010)

With headlines like "Caveman from 2m years ago may be missing link", the world's media made a field day of some recent work on Australopithecus sediba. For those with a memory, it has all happened previously in 2010. The announcement was made in the journal Science, that the evolutionary path "From Australopithecus to Homo" had been found. Consequently, the media trumpeted the significance of the bones to their readers (see here). You had to read carefully to realize that hype and science were being confused. Move on to the present and the newly reported research: the journal Science carried three News Focus stories and five scientific papers on the fossils. This was picked up by the popular science journals (New Scientist: South African fossils halfway between ape and human) and the press (as in the Telegraph "caveman" headline quoted above). Just like last year, the hype was the message (see here). After this flurry of excitement, we are starting to get a more nuanced assessment - this blog is based on a News & Views piece in Nature by Fred Spoor. He summarises the data reported as follows:

"Overall, the authors find that A. sediba is australopith-like, with a small brain and long arms, and is most similar to its likely ancestor Australopithecus africanus, remains of which have been found at several South African sites. However, some aspects of the A. sediba skeletons seem to show a closer resemblance to the morphology found in species of the genus Homo. These include aspects of the shape of the pelvis and ankle joint, as well as the long thumb and short fingers that are characteristic of hands capable of precise manipulation. The authors suggest that these features are phylogenetically shared with Homo species, rather than being examples of homoplasy (similar traits that evolved independently in separate lineages), and conclude that A. sediba is a plausible candidate ancestor of Homo."

The cover of Science - announcing the new finds (source here)

Basically, the A. sediba fossils are australopith-like, but with some morphological similarities to the genus Homo. There is talk of it having a mosaic form, with a mixture of "primitive" and "advanced" characters. The question being discussed is whether this justifies placing A. sediba on the lineage leading to Homo. There are many problems with taxonomy, not the least of which is that organisms do not always fit the nice neat boxes we create for them. Probably the best known mosaic forms are Archaeopteryx and the duck-billed platypus. The animals have been classified, of course, but taxonomists have to give emphasis to characters that they think are diagnostic. Then, there is the phenomenon of convergent evolution (which leads to homoplasy, as in the quote from Spoor above). Similar characters do not mean that two organisms have a common ancestor, nor does it mean that the presence of a character set in one organism makes it an ancestor of another with the same set. So why should homo-like characters found in one or more of the australopithecenes be regarded as a proof of ancestry?

Spoor points out that this reasoning creates a methodological conflict with Homo-like fossils that predate A. Sediba.

"The fossil most secure in its affinities and provenance is the approximately 2.35-Myr-old upper jawbone from Hadar, Ethiopia, which is more Homo-like than that of A. sediba and pre-dates the Malapa finds by some 370,000 years. This evidence seems at odds with the idea that A. sediba was involved in the first appearance of Homo."

There is a way of resolving the conundrum. A. sediba could be ancestral to the putative Homo fossils. This scenario was suggested in the 2010 paper and developed in the recent report. This is why the authors are prepared to contest the Homo affinities of all the fossil material older than 2.0 Myr. However, Spoor finds this a speculation that pushes past the limit of credibility:

"It will, however, be difficult to uphold the suggestion that the extensive evolutionary change required could have occurred in the time available (a maximum of 80,000 years) if A. sediba at Malapa gave rise to Homo species. Moreover, the idea that no fossil older than 2.0 Myr is legitimately attributable to Homo is highly debatable - the arguments provided in the paper are insufficiently specific to be conclusive, particularly with respect to the Hadar jawbone."

After discussing several of the morphological analyses made by the research team, Spoor gives his conclusion:

"Taken together, the published evidence indicates that A. sediba is a late australopith that has several intriguing Homo-like features. If these features do indeed associate A. sediba with the emergence of Homo, rather than reflecting homoplasy, then it seems that the scenario in which the Malapa specimens represent a late surviving population is the most plausible explanation for Berger and colleagues' findings."

Thus, the evidence is by no means conclusive. It is perfectly legitimate to advance homoplasy as the explanation of the similarities - and more and more evidence can be advanced to support this interpretation (see here). If (and this is a big if) A. sediba has a place in human ancestry, then it must have been around significantly earlier so as to predate all Homo-like fossils and to have time to experience the "extensive evolutionary change" that was necessary. This scenario requires the Malapa specimens to be a relict population of this species - which can be regarded as a hypothesis needing to be tested before getting too excited.

Before we conclude, it is worth revisiting the headline that introduced this story. The problem with the term "missing link" is not that we get two gaps in the fossil record to replace one. This is not a serious problem for palaeontologists - because if a trajectory exists, it is more clearly displayed when more links are identified. The real problem with the term is that it presupposes Darwinism and small incremental changes. This mindset colours the way people perceive the fossil record - and it hides the fact that most morphological change is punctuated and the main trend is one of stasis. It is Darwinism that is responsible for the term, and until Darwinism is dropped as the conceptual framework for evolutionary theory, we will continue to have the "missing link" issue.

However, the alternative phrase "transitional fossil" is not much better. The danger here is that any morphological character can be interpreted in terms of being transitional. As we have seen above, there are other explanations for similarities because the phenomenon known as "convergent evolution" is ubiquitous. Consequently, claims for transitional status can be devoid of substance. A study by DeWitt has looked closely at these similarities and reached exactly this conclusion:

"In spite of certain human-like characteristics - many of which are consistent with tree dwelling - the overwhelming evidence is that Au. sediba was a type of Australopithecine and thus an extinct ape rather than a human ancestor."

Malapa and the genus Homo
Fred Spoor
Nature, 478, 44-45 (06 October 2011) | doi:10.1038/478044a

Abstract: Two remarkably well-preserved skeletons of the hominin species Australopithecus sediba, found at Malapa, South Africa, show an intriguing combination of features, and open up a debate about the origins of the genus Homo.

See also:

Tyler, D. Learning from the history of human evolution research, ARN Literature Blog (4 March 2011)

The thumbnail portrait of science that most children get in schools is that science is objective and "value-free" knowledge. Science is supposed to reach the same outcomes in whatever culture it is practised and whoever does the research. The simplest response to this is to say that the thumbnail is misleading: science is an activity practised by creative but fallible human beings who bring cultural values into their work, sometimes consciously but mostly unconsciously. A well-written contribution on these issues is by Henry Gee in Nature, reviewing a book by palaeoanthropologist Dean Falk. Her subject is human evolution and the controversies about Australopithecus africanus in 1924 and Homo floresiensis in 2003. Gee begins his review with this iconoclastic paragraph:

"We have all seen the canonical parade of apes, each one becoming more human. We know that, as a depiction of evolution, this line-up is tosh. Yet we cling to it. Ideas of what human evolution ought to have been like still colour our debates."

"This line-up is tosh" - Henry Gee (source here)

The 1924 paper, authored by Raymond Dart, was received with scepticism. Whilst the fossil became known as the "Ape-Man of South Africa", the skull was that of a juvenile. Everyone knows (or should know) that juvenile apes have more human-like characteristics than adult apes. But resistance to Dart's hypothesis came mainly because his peers considered that brain expansion preceded bipedalism and these people defended their thinking by reference to Piltdown Man. Gee sees this as evidence of prejudice affecting the course of science.

"Dart's original paper on A. africanus was, it is true, long on waffle and short on substance. But the reason that this small-brained, possibly erect-walking creature took two decades to be accepted as a hominin was that researchers were in thrall to the idea that the expansion of the human brain came first, before the adoption of a fully erect gait. This preconception was supported by the discovery of the large-brained, ape-jawed Piltdown Man in 1912. The fact that it took 40 years to expose Piltdown as a fraud is a mark of how deeply rooted such prejudices can be."

Falk has unearthed a new angle on this story. It is known that Dart "was critically mauled by the London establishment - notably the 'Piltdown Committee' who believed in the fake fossil" and that "he almost deserted palaeoanthropology". Nevertheless, he did continue to develop his hypothesis and submitted a paper to the Royal Society in 1929. This paper suggested that the cognitive capacity of Australopithecus was belied by its small brain. However, the paper was rejected (as Gee suggests: "presumably on the basis of reports by the Piltdown Committee").

Falk has, of course, a similar story to tell about Homo floresiensis, alias the Hobbit. Her role was to scan the cranium of the LB1 fossil and show its affinities are closest to Homo erectus. Papers are still being published suggesting that the Hobbit is not a separate species but the bones are from deformed humans.

"Almost every time someone claims to have found a new species of hominin, someone else refutes it. The species is said to be either a member of Homo sapiens, but pathological, or an ape. Brickbats of the first kind were levelled recently at H. floresiensis - that it wasn't a genuine species, but a modern human suffering from one of several kinds of microcephaly or from cretinism. But they had also been aimed at Neanderthal Man, discovered back in 1856, and thought by some to be the remains of a Mongolian Cossack from the Napoleonic wars."

Thus, to grasp the meaning of fossils, particularly human fossils, we need not just to have an appreciation of technical issues, but also an understanding of the cultural, social and ideological contexts for the reporting.

Craniums with clout
Henry Gee
Nature, 478, 34 (06 October 2011) | doi:10.1038/478034a

Abstract: A look at two early human fossils reveals the prejudices in ideas about human evolution, finds Henry Gee.

Book reviewed:
The Fossil Chronicles: How Two Controversial Discoveries Changed Our View of Human Evolution, Dean Falk, University of California Press: 2011. 280 pp. ISBN: 9780520266704