David Tyler

Genome sequencing has allowed families of genes to be mapped across the phyla, and it is presumed that the presence of a specific gene in different animal groups signifies a shared common ancestor. Over the years, it has become apparent that many significant genes are widely shared in the animal kingdom, and this blog is concerned with two more cases recently published. Pax genes are typically linked to eye development, although they have a variety of other functions. Pax-6 is regarded as a master control gene known to turn on eye development in the arthropoda, the mollusca, and the vertebrata. The new work extends the analysis to a jellyfish. “Here we have isolated three Pax genes (Pax-A, Pax-B, and Pax-E) Read More ›

Over the years, samples of amber recovered from numerous sites around the world have been found to contain petrified insects, plants and a variety of other exotic inclusions. Invariably, we get an insight into a past world where the flora and fauna look very modern. A recent discovery has identified mammalian hair in amber, whose original owner was a contemporary of dinosaurs. The dimensions and topography of the two fossilised hairs were analysed carefully, because the find provides the first opportunity to look at Mesozoic mammal hairs preserved in 3D. The result: “With such features, the cuticular surface of the Archingeay-Les Nouillers hairs shows a modern aspect, implying that the morphology of hair cuticula has remained unchanged throughout most of Read More ›

Most of the time, scientific research seeks to build on theoretical foundations that have been carefully constructed by the wider research community, often over many years. If a theoretical framework is found to be robust, it gains widespread assent, with few interested in challenging it. Those who are attracted to the idea that science develops progressively are the least likely to talk about challenges. For them, any change is a minor modification of the theoretical edifice. Thomas Kuhn referred to these theoretical frameworks as ‘paradigms’, and the progressive refinement of that framework as ‘normal science’. Kuhn pointed out that anomalies do not trigger the practitioners of ‘normal science’ to question the paradigm, but they either treat them as problems waiting Read More ›

It is well known that orb-weaving spiders put droplets of adhesive all over their webs to catch prey. Although there have been many attempts to study the nature of these adhesives, it is only recently that experiment designs have allowed the mechanism of adhesion to be analysed properly. Single adhesive droplets have been probed at varying extension rates. “Here, by directly probing single adhesive droplets used by spiders, we demonstrate the importance of the mechanics of adhesive in dramatically enhancing adhesion. We show that glue drops function as a viscoelastic material instead of as a viscous material and that the elasticity of the principle adhesive in this system, the glycoproteins, increases adhesion by two orders of magnitude in comparison with Read More ›

Conspiracies to suppress, manipulate and distort information undoubtedly occur. Society needs to be vigilant to guard against deception. An increasing number of alleged conspiracies are being covered by the media, all reflecting in some way on the integrity of politicians, or business leaders or the scientific enterprise. Conspiracy theorists are skilled in appealing to emotion, phrasing allegations in a provocative way, and promoting their own reconstructions of events so as to capture the imagination of the public. Ted Goertzel’s essay on this theme sounded some alarm bells when it provided four recent examples: “Conspiracy theorists – some of them scientifically trained – have claimed that the HIV virus is not the cause of AIDS, that global warming is a manipulative Read More ›

Our knowledge of the fossil record has changed immensely since 1859, when Darwin felt obliged to explain why his hypothesis of gradualism was not confirmed by the study of fossil successions. His argument was, as is well known, that the fossil record exhibits extreme imperfection. The abrupt appearance of macrofossils at the base of the Cambrian was recognized and Darwin deduced that the evolutionary origins of those animals must have extended well back into the Precambrian. “One-and-a-half centuries of subsequent research have revealed a vast microscopic fossil record of unicellular protists and bacteria extending, some would argue, as far back as there are sedimentary rocks from which they could be recovered. But although fossils of millimetre- to metre-scale multicellular organisms Read More ›

Although geographically widespread, the genus Pelecanus has only 7 or 8 species extant (depending on the classification system used). A similar number of fossil species have been identified, although the morphological differences are quite small. Until recently, the earliest fossil form was dated as Early Miocene. Newly published work pushed the first appearance back to the Early Oligocene, considered to be about 30 million years old. The point of interest for us is that the fossil, and specifically the beak, is said to be “morphologically identical to modern pelicans”. “All these characteristics of the fossil are identical to those of the species in Pelecanus, the single extant genus in the family. [. . .] Therefore, [the specimen] can be considered Read More ›

Today, there seem to be many vested interests in scientific consensus. Universities and science associations often make use of the concept when explaining the importance of science in society and in making pronouncements on issues of public significance. Consensus is relevant to funding agencies, who focus their awards on science that appears to be building on an existing knowledge base. It is a factor in peer review, for it is much harder to get unorthodox ideas past the journal review processes. It influences the media: who is regarded as an ‘expert’ and who should not get exposure because of their unorthodox ideas. How refreshing, then, to find the Royal Institute of Philosophy offering some cautionary words in an editorial: “One Read More ›

It took 20 skilled people working for a decade, and an estimated $40 million of funding, but the outcome is spectacular. It is described as “a defining moment in the history of biology and biotechnology” by Mark Bedau, editor of the journal Artificial Life. The BBC News headline was succinct: ‘Artificial life’ breakthrough announced by scientists. The Economist declared: “Artificial life, the stuff of dreams and nightmares, has arrived“. The research paper claims to have made a synthetic cell, and uses the word “creation” in the title. “We refer to such a cell controlled by a genome assembled from chemically synthesized pieces of DNA as a “synthetic cell”, even though the cytoplasm of the recipient cell is not synthetic. Phenotypic Read More ›

The polar bear (Ursus maritimus) exhibits numerous adaptations to cold environments, fur, foot pads, head shape, exclusively carnivorous diet, heightened sense of smell, etc. Their close relationship to the brown bear (Ursus arctos) has long been recognised. Fertile hybrids are well-documented in captivity and there are rare examples of hybrids in the wild – the most recent being in 2006. Interbreeding, however, has not outweighed other taxonomic criteria, although it has been a factor in moving the polar bear from the genus Thalarctos back to the genus Ursus. “With their distinctly different morphology, metabolism, and social and feeding behaviors, the polar and brown bears are classified as separate species.” Interestingly, a cluster of brown bears (known as ABC bears) have Read More ›

It was 15 months ago that Science carried a story about the completion of a rough draft of the Neandertal genome. Palaeogeneticist Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig was reported as saying “he can’t wait to finish crunching the sequence through their computers”. It has been quite a long time coming, as it is more than a decade since Paabo first demonstrated it was possible to analyse Neandertal DNA sequences. Earlier reports suggested that Neandertals were sufficiently distinct from humans for them to be classified as a separate species of Homo. The draft genome has more than 3 billion nucleotides collected from three female Neandertals. “By comparing this composite Neandertal genome with the complete Read More ›

A previous blog drew attention to Glial (or Muller) cells that conduct light from the surface of the eye’s retina to the photoreceptor cells. These cells provide a low-scattering passage for light from the retinal surface to the photoreceptor cells, thus acting as optical fibres. Their function was reported to “mediate the image transfer through the vertebrate retina with minimal distortion and low loss”. New research in this area has increased knowledge of their functionality after constructing a light-guiding model of the retina outside the fovea. As a result, the “retina is revealed as an optimal structure designed for improving the sharpness of images”. For more, go here.

John Avise commences his paper with a quotation from Michael Behe affirming that research into the molecular workings of the cell leads unambiguously to the conclusion: “design!” To counter this, Avise presents the human genome as clear evidence for non-sentient design. He thinks that conventional evolutionary mechanisms are perfectly capable of explaining complexity, declaring: “it is not my intent here to repeat the voluminous evidence for how natural selection in conjunction with other nonsentient evolutionary forces can yield complex adaptations”. Instead, he suggests that the decision as to whether the design is intelligent or non-sentient can be made by looking at the imperfections and flaws evident in the cell’s molecular systems. “Both a Creator God and natural selection are powerful Read More ›

There has been a complexity explosion in biology – the fuse was lit in 1953 when the structure of DNA was discovered, but during the past two decades we have witnessed a dramatic expansion of data pointing to unanticipated levels of complexity. The hype surrounding the Human Genome Project suggested it would give us the blueprint of human biology and, as a consequence, would provide answers to our most probing questions. “Mina Bissell, a cancer researcher at the Lawrence Berkeley National Laboratory in California, says that during the Human Genome Project, she was driven to despair by predictions that all the mysteries would be solved. “Famous people would get up and say, ‘We will understand everything after this’,” she says. Read More ›

The Laetoli trackways from Tanzania were first reported in 1979 and immediately attracted attention because they provided evidence of bipedalism. The tracks were preserved in volcanic ash dated at 3.6 million years. Many at the time thought they looked exactly like human footprints, but few of the researchers were willing to adopt this interpretation. The debate has been extensive and inconclusive, but some positive leads have recently been published. Evidence is now available to answer the question: did the makers of the trackways walk like humans or like apes? “In particular, debates over the origins and evolution of bipedalism revolve around whether early bipeds walked with energetically economical human-like extended limb biomechanics, or with more costly ape-like bent-knee, bent-hip (BKBH) Read More ›