David Tyler

Sinosauropteryx holds a special place in evolutionary studies, partly because of exquisite preservation and partly because it displays integumental structures (described as proto-feathers by many). Alternative hypotheses about these structures were considered in a previous blog, showing that there is compelling evidence contrary to the protofeather hypothesis. However, it remains to be established what the integumental structures of Sinosauropteryx actually are and how they became fossilised. This is the theme of this blog. The relevant research is again that of Professor Lingham-Soliar from South Africa. He has presented new data allowing two alternative hypotheses to be tested. “A sound understanding of the externally preserved fossilized tissue of Sinosauropteryx is crucial to resolving the differences in interpretation. If the tissue represents Read More ›

It is fundamental to the methodology of science that hypotheses are proposed and tested. The human face of science surfaces when researchers enthusiastically endorse false positives, when hypothesis testing is less than rigorous, and when false dichotomies are proposed (i.e. if hypothesis B is falsified, hypothesis A is declared to be verified). The science of origins is well-supplied with examples of hypotheses that were once widely accepted as valid, but which are now discredited. A significant example has recently become apparent and is the theme of this blog. In 2009, Zhang et al. considered integumentary filaments of the theropod dinosaur Sinosauropteryx, knowing that Lingham-Soliar and colleagues had proposed that dino-fuzz filaments are structural collagen fibres released by processes of decay. Read More ›

Nearly a decade ago, Darwin’s thinking on sexual selection was considered by numerous scientists to be overdue for revision. At the 169th annual meeting of the American Association for the Advancement of Science, researchers took “dead aim at one of Charles Darwin’s pet evolutionary theories – the theory of sexual selection, which says that males should compete among themselves for access to mates, or compete for the favours of choosy females.” Two leading voices were those of Joan Roughgarden (“There are too many exceptions for the theory to hold”) and Patricia Adair Gowaty, who said that the theory may still hold, but researchers have been accepting it without good evidence (“What’s wrong is our failure to test the theory adequately”). Read More ›

How should schools and universities teach their students? Pedagogy occupies the minds of all educators, although there are many different applications of this aspect of educational theory. For example, some answer the question above by advocating learning-by-doing. Students are given projects which involve a structured activity such as experimentation. This is enquiry-based learning. Others favour a process of information gathering to reach answers. This is resource-based learning. Although not recommended by educationalists, some students learn by rote or memorise the way to solve problems but this typically means the student has little understanding of what they are doing. Earlier this year, in an editorial in the journal Science, Bruce Alberts wrote about the trivialisation of science education. He commented: “Tragically, Read More ›

Bipedalism, walking and running are characteristics that we tend to take for granted because they are so much a part of human experience. Yet, each of these traits requires a set of inter-related components and information processing machinery. To appreciate this, all we need to do is to reflect on the challenges faced by robot engineers attempting to mimic human behaviour (see also Walking with arthropods). New insights into the physiology of walking are provided in a recent analysis of the heel-sole-toe stance of the human foot. The authors recognise that the morphology and action they are studying is unusual among cursors, and this leads them to make a design inference. The hypothesis is that there are physiological reasons for Read More ›

The phenomenon of convergence has been recognised in external morphology (e.g. the streamlined shape of sharks and porpoises), structural detail (e.g. the camera-like construction of the vertebrate eye and the octopus eye), and in many other functional aspects of organisms (e.g. the echolocation systems used by bats and whales). In textbooks and popular science writing, convergence is often explained in a Darwinian way, invoking the amazing powers of natural selection. However, far from being a curiosity that pops up from time to time, convergence appears to be a pervasive feature of the living world. Championing this perspective is Professor Simon Conway Morris, an evolutionary palaeontologist from Cambridge University, who is actively contributing to debate and constructing an online database of Read More ›

Richard Owen is best known for naming the Dinosauria and for opposing Darwin’s “On the origin of species“. For the former, he is (usually) celebrated, as the name is in common usage around the world. For the latter, he is reviled as a bigot and his stance allowed subsequent generations of evolutionists to tar him as an obscurantist (although conveniently overlooking his scientific arguments). Owen’s statue used to have pride of place in London’s Natural History Museum (he oversaw the transfer of the natural history collections to the new South Kensington museum in 1881 and he was knighted in 1884). However, in the lead up to the bicentennial celebrations for Charles Darwin, Owen was moved and a marble statue of Read More ›

Visitors to the Grand Canyon, and especially those who hike to Plateau Point at the end of Bright Angel Trail, will see a major change in rock type when looking into the inner canyon. The steep walls reveal metamorphosed basement rocks, but resting on these are the horizontally-bedded fresher looking Tapeats Sandstones. The linear boundary between them is known as the “Great Unconformity”. There are many other unconformities to be found in the Grand Canyon, but this one is by far the most dramatic. It can be traced as far as the eye can see – and beyond. It is found on most continents: “The Great Unconformity is well exposed in the Grand Canyon, but this geomorphic surface, which records Read More ›

It is 50 years since The Structure of Scientific Revolutions presented a radically different perspective on the way scientists carry out their work. Most readers of this book would have been familiar with the scientific method, which sets out the way science is supposed to work. But the textbook “scientific method” underplays the creative contributions provided by scientists, and Thomas Kuhn knew that the history of science provides abundant evidence showing that human factors deserve a much higher profile in our thinking. Yet he knew his book was iconoclastic: “Kuhn was not at all confident about how Structure would be received. He had been denied tenure at Harvard University in Cambridge, Massachusetts, a few years before, and he wrote to Read More ›

The quest for the Higgs boson has been headline news in the world’s media, perhaps owing more to its nickname (the “God particle”) than to public understanding of why it is so significant. What is not in doubt is that this attention is good for physics and good for science. With so much attention given to technology exploitation, it is important to remind ourselves that fundamental science provides the foundations for advances in technology – and we still need blue-sky research. The excitement surrounding the Higgs boson stimulated a reflective essay in Nature from science writer Heidi Ledford. The question she addresses is: “What fundamental discoveries in biology might inspire the same thrill?” “We put the question to experts in Read More ›

The DNA code is made up of codons (3-letter words) derived from 64 different arrangements of bases linking the two DNA strands. Yet these 64 combinations code for only 20 amino acids and a stop signal. Thus, different codons are able to produce the same amino acid. The phenomenon is described as the genetic code having “redundancy”. In the early years of molecular biology, this redundancy was perceived as an evolutionary accident, unworthy of detailed research but fortunate because it meant that any damaging effects of point mutations were cushioned. However, the evidence has been accumulating that “redundancy” is a misleading word. “Scientists have known about this redundancy for 50 years, but in recent years, as more and more genomes Read More ›

A previous blog on Devonian tetrapods remarked on their aquatic lifestyles and noted their suite of mosaic characters that make discussion of evolutionary trajectories highly speculative. Few fossils from the lower Carboniferous were known, but the diversified forms from the middle and upper Carboniferous were clearly components of terrestrial faunas. So, we find a group of aquatic amphibians in the Upper Devonian and a diversified group of terrestrial amphibians in the middle-upper Carboniferous. The puzzle is the lack of any terrestrial fossil material in the lower Carboniferous, leaving evolutionary palaeontologists little or no data to work with. The absence of evidence has been so noticeable that this part of the record has been labelled Romer’s Gap (after the distinguished American Read More ›

Although fossil plants are well documented from the Silurian Period of Earth history, spores from land plants are known from the preceding Ordovician and Cambrian Periods. However, it is not until the Mid-Devonian that fossil forests appear in the fossil record. The Gilboa Forest from New York State was first described in the 1920s and it became known as the earliest fossil forest. It has the same status today. Only one plant was known from this forest – the Eospermatopteris, or “ancient seed fern” – thought to grow up to 10 metres above the ground. They were not woody, but they had characters that that suggest affinities with tree ferns. The original analysis reinforced the evolutionary assumption that the earliest Read More ›

The abrupt appearance of Cambrian life forms in the Cambrian Period of Earth history continues to provide us with spectacular evidence of sophistication. New research on fossils recovered from petroleum exploration drill cores assigned to the Deadwood Formation of western Canada documents “a cryptic but significant diversity of Cambrian crustaceans”. Previously, palaeontologists have had hints of these animals from the nonmineralised remains of minute organisms (<2mm). The new finds are of disarticulated body parts that are unambiguously crustacean, representing branchiopods, copepods and ostracods. They are part of an assemblage known as SCFs (small carbonaceous fossils). They show many signs of modernity. “The fresh taphonomic perspective of SCFs provides the only direct evidence for sophisticated particle-handling in larger-bodied Cambrian arthropods. This Read More ›

In the year 2000, an international conference considered the question “What is life?” Every participant was asked to draft a definition, and every speaker was required to address the central question. According to David Abel, who was one of the speakers, no two definitions of life were the same. This finding replicated that obtained by Rizotti who, in 1996, published a book with the title Defining Life. Abel considers that definitions can be grouped into two subsets: one of which perceives life as an essentially physicochemical phenomenon, and the other has an emphasis on coded information superimposed on material systems (developing Hubert Yockey’s seminal ideas). “Yockey was among the first to realize the linear digital nature of genetic control. Many Read More ›