The results of the Cambrian explosion are well documented in the fossil record, but its cause -- why and when it happened, and perhaps why nothing similar has happened since -- has been a mystery. Now a recent paper in Nature (abstract) suggests that the answer may lie in a second geological curiosity -- a dramatic boundary, known as the Great Unconformity, between ancient igneous and metamorphic rocks and younger sediments.
"For nearly two centuries, biologists have been struck by a mystery of geography and biodiversity peculiar to Europe. As Edward Forbes pointed out as far back as 1846, there are a number of life forms (including the Kerry slug, a particular species of strawberry tree and the Pyrenean glass snail) that are found in two specific distant places—Ireland and the Iberian Peninsula—but few areas in between." -- How did a specific snail species from the Pyrenees end up in Ireland but nowhere else?
The evolution of Daft Punk's "Get Lucky" is an excellent interpretation of their latest single through different decades.
Cocks (almost) don't have a penis, a trait common to 97% of bird species, but they can grow one when the expression of the Bmp4 gene is prevented. The expression of this gene causes the percursor of the phallus in the chick embryo to undergo apoptosis (cell death) and Bmp genes are also involved in 3 other bird traits: feather development, toothlessness and beak shape. In penis-less bird species, copulation requires a sex maneuver nicknamed the cloacal kiss (in French) which requires a full cooperation of the female (3 min of tender parrot sex). In species where males have a penis, like ducks, females are less lucky: the coevolution of the rather convoluted morphology of male and female genitalia has been hypothezised to occur through sexual conflict [many previouslies]. The evolutionary mechanisms that drove phallus reduction in most birds species are still unknown.
In the past few days, the Internet has been filled with commentary on whether the National Science Foundation should have paid for my study on duck genitalia, and 88.7 percent of respondents to a Fox news online poll agreed that studying duck genitalia is wasteful government spending. The commentary supporting and decrying the study continues to grow. As the lead investigator in this research, I would like to weigh in on the controversy and offer some insights into the process of research funding by the NSF.
Come for the passionate defense of basic science, stay for the explosive eversion of a duck penis.[more inside]
With incisor-like claws that can tunnel beneath your skin in seconds, ticks are rapidly establishing themselves as the Swiss Army knife of disease vectors. Carl Zimmer walks into the woods to find out why these tiny beasts appear to be skyrocketing in number – and outsmarting environmental scientists trying to control them with every bite.
Social Evolution - The Ritual Animal "Praying, fighting, dancing, chanting — human rituals could illuminate the growth of community and the origins of civilization." [more inside]
Researchers have found that size does matter as it relates to overall proportions of the male body (PNAS link, PDF)
"What happens if you repeatedly run Kafka's Metamorphosis through YouTube's auto-transcription? Structure emerges!" via Sean Roberts
Is it time to put natural selection in its place? Jello Biafra once famously wrote that "If evolution is outlawed, only outlaws will evolve." But while it likely comes as no surprise to specialists working in the field or to those who've been following developments in evolutionary biology closely, there's an emerging view among experts that Darwin's view of natural selection as the primary driver of speciation and evolutionary change may be incorrect or at least drastically overstated. It's long been understood that non-adaptive evolutionary mechanisms like "genetic drift" and random mutation also play non-trivial roles in evolutionary processes, but a recent study (link to abstract with full-text PDF available) casts new doubts on the primary role of natural selection, finding that "Neutral models, in which genetic change arises through random variation without fitness differences have proven remarkably successful in describing observed patterns of biodiversity." [more inside]
Andrew Ferguson explains and defends eminent philosopher Thomas Nagel, who has been stirring up outraged refutations (e.g. here or here) with his new book Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False. Also in the defense column is philosopher Edward Feser's extensive series on Nagel's book.
seaQuest: what if we could learn to live on/underneath the oceans (or in orbit)? [previously(er)] [more inside]
To put a human face on our ancestors, scientists from the Senckenberg Research Institute used sophisticated methods to form 27 model heads based on tiny bone fragments, teeth and skulls collected from across the globe. Here is a video showing those different models morphing into one another. Original article here. [via] [more inside]
Evolution of Mom Dancing [SLYT] In honor of the First Lady's "Let's Move" campaign, and to encourage parents everywhere to get up and get moving with their kids, Jimmy Fallon and Michelle Obama present the "Evolution of Mom Dancing."
"Hundreds (maybe thousands) of spiders congregate between poles in the town of Santo Antonio de Plantina / PR." [more inside]
Dougal Dixon is a scientist, author, and illustrator. While he is most famous for his work on dinosaurs, his books After Man: A Zoology of the Future and Man After Man: An Anthropology Of The Future attempt to explore what might happen in the far future. The Posthuman Art Of Dougal Dixon. [more inside]
Even though you've heard of Darwin, it's quite possible that you're not familiar with Alfred Russel Wallace (previously), co-discoverer of the theory of evolution (a shame; in many respects he's the more interesting of the two!). Fortunately you can now learn more about the man through transcripts and scans of his letters with family and colleagues, which the UK Natural History Museum have just published online. [more inside]
Go home, evolution, you're drunk. A photo of a pelican that looks like a urinal. Brought to you by WTF, Evolution?
Group selection, which was once widely rejected as a significant evolutionary force, is now accepted by all who seriously study the subject. There is still widespread confusion about group selection, however, not only among students and the general public, but among professional evolutionists who do not directly study the subject. We list eight criticisms that are frequently invoked against group selection, which can be permanently laid to rest based upon current knowledge. Experts will always find something to critique about group selection, as for any important subject, but these eight criticisms are not among them. Laying them to rest will enable authors to openly use the term group selection without being handicapped during the review process. [HTML], [PDF]
"it's quite clear that there's tons of cultural transmission that's just strictly by observational learning."
The Norovirus: A Study in Puked Perfection, "Each norovirus carries just nine protein-coding genes (you have about 20,000). Even with that skimpy genetic toolkit, noroviruses can break the locks on our cells, slip in, and hack our own DNA to make new noroviruses. The details of this invasion are sketchy, alas, because scientists haven’t figured out a good way to rear noroviruses in human cells in their labs. It’s not even clear exactly which type of cell they invade once they reach the gut. Regardless of the type, they clearly know how to exploit their hosts. Noroviruses come roaring out of the infected cells in vast numbers. And then they come roaring out of the body. Within a day of infection, noroviruses have rewired our digestive system so that stuff comes flying out from both ends." [more inside]
Woese once said of himself and his work that when a wise man points out the moon, only a fool looks at the finger. Let us all be fools if just for a moment .
Microbiology's Scarred Revolutionary(PDF), Carl Woese (pron.: /ˈwoʊz/), a biophysicist and evolutionary microbiologist whose discovery 35 years ago of a “third domain” of life in the vast realm of micro-organisms altered scientific understanding of evolution, died on Sunday at his home in Urbana, Ill. He was 84. [more inside]
“When I spoke at the two Ron Paul events in Tampa, a young man kind enough to pick me up at the airport told me a fascinating story. The vast majority of young Ron volunteers in offices he visited all over the country were paleo. If a kid ordered pizza — which was always the primary or perhaps only campaign food — he was practically booed,” Atossa Araxia Abrahamian writes in The New Inquiry about the paleo diet, libertarianism, and the appealing idea of a healthy, undistorted state of nature to which we can return if we are only pure enough. [more inside]
What's Going On In Japan? "Really Japan is quite a remarkable case, since neither fiscal nor monetary policy seems to be working to achieve the anticipated results. This year Japan will have a fiscal deficit of around 10% of GDP and gross government debt will hit 235% of GDP, yet the country is still struggling to find growth. Instead of reiterating old dogmas (whether they come from Keynes or from Hayek) more people should be asking themselves what is happening here. This is not a simple repetition of something which was first time tragedy and is now second time tragedy, it is something new, and could well be a harbinger for more that is to come, elsewhere. Oh, why oh why are economists not more curious?" [more inside]
'If you’re like me, you’ll have asked yourself many times, “Why do toucans have such ridiculously big bills?”' [more inside]
It is common behavior for humans to develop an avatar to present a larger-than-life version of themselves on the web, often as a defense mechanism. For the first time, this activity has been observed in another species.
The Translucent Jewel Caterpillar, the Nudibranch of the Forest. Gorgeous caterpillar covered in break-off gumdrops that may help it escape predators. Turns into a bright orange furry moth.
Deciphering the Tools of Nature’s Zombies: The ability of parasites to alter the behaviour of their hosts fascinates both scientists and non-scientists alike. One reason that this topic resonates with so many is that it touches on core philosophical issues such as the existence of free will. If the mind is merely a machine, then it can be controlled by any entity that understands the code and has access to the machinery. This special issue of The Journal of Experimental Biology highlights some of the best-understood examples of parasite-induced changes in host brain and behaviour, encompassing both invertebrate and vertebrate hosts and micro- and macro-parasites. Full issue annotated inside: [more inside]
In just a few weeks single-celled yeast have evolved into a multicellular organism, complete with division of labour between cells. This suggests that the evolutionary leap to multicellularity may be a surprisingly small hurdle. More from Scientific American blogs. [Full Text PDF of the Publication of Note] [more inside]
The cosmos is also within us, we're made of star-stuff. We are a way for the cosmos, to know itself.
Cosmos: A Personal Voyage is a thirteen-part television series of one hour shows written by Carl Sagan, Ann Druyan, and Steven Soter, that was aired at the tail end of 1980 and was - at the time - the most widely watched series in the history of American public television. It is best introduced by an audio excerpt of one of his books, The Pale Blue Dot. Inside is a complete annotated collection of the series. [more inside]
"Pretty much everyone interested in dinosaurs, in the history of life, or in such matters as the evolution of intelligence and/or brain size, will be familiar with the various speculations on ‘humanoid dinosaurs’ that have made their way into the literature." - Tetrapod Zoology on Dinosauroids [more inside]
Secrets of T-Rex sex! An interview with John Long, author of The Dawn of the Deed: The Prehistoric Origins of Sex. Long's four-part series on Evolution: This View of Life - 1) Down and Dirty in the Devonian; 2) Palaeozoic Paternity Problems; 3) From Bones to Behavior; 4) From Clasper to Penis. Also a Scientific American video ("Long discusses a fossil central to this new view of the origin of copulation and live birth: a 375-million-year-old expectant mother fish dubbed Materpiscis attenboroughi").
State of the Species: Will the unprecedented success of Homo sapiens lead to an unavoidable downfall? [Via]
One of the many problems farmers of various kinds of legumes need to deal with is the pea aphid. They reproduce incredibly fast and live by sucking the sap out of the plants, an electron micrograph of one in action. However, while they are terrifying parasites of legumes, they have their own yet more horrific parasites, a parasitoid wasp. Here is a really nice close up picture of one doing its thing, a video of the act, and here is a brain meltingly horrific video of a dissection of the mummified aftermath 8 days later. Essentially, these wasps deposit their eggs in a pea aphid and the growing larva feeds on it, developing there for about a week, and then consuming the host from the inside out like a Xenomorph. When it’s done, the wasp larva dries the aphid’s cuticle into a papery brittle shell and an adult wasp emerges from the aphid mummy. Legume farmers love them, and you can even order their mummies online these days. However, farmers noticed that the wasps didn't work as effectively on all of the aphids, and so researchers went to work figuring out why. It turns out that all aphids have a primary bacterial endosymbiont living inside their cells, in addition to and just like a mitochondria, and that many have some combination of five other secondary endosymbionts. Interestingly, two of those other five, Hamiltonella defensa and Serratia symbiotica have been shown to confer varying levels of resistance to the parasitoid wasp, allowing the aphid to survive infection. However, it turns out that there is yet one more layer to this story, [more inside]
Maurice Sendak's (probable) inspiration. Campbell's blog is the antidote for anyone bored with religion: Barbarella and Xenu, evolution from the simple to... the simple, how God evolved (possibly backwards), and more. [more inside]
"Why do parasites harm their hosts? Conventional wisdom holds that because parasites depend on their hosts for survival and transmission, they should evolve to become benign, yet many parasites cause harm. Theory predicts that parasites could evolve virulence (i.e., parasite-induced reductions in host fitness) by balancing the transmission benefits of parasite replication with the costs of host death. This idea has led researchers to predict how human interventions—such as vaccines—may alter virulence evolution, yet empirical support is critically lacking." Two papers demonstrate empirical evidence for related models predicting the origin of virulence: [more inside]
In this sprightly talk (transcript and video) Daniel Lieberman describes why our bodies are so good at running long distances, how our social intelligence developed and how modernity and capitalism require us to learn (or relearn) how to use our bodies. (May inspire tolerance for people who wear five-fingered shoes.) Prof. Lieberman studies human evolution at Harvard where he focuses on heads and feet. (via Tyler Cowen)
The Puzzle of Plastid Evolution: A comprehensive understanding of the origin and spread of plastids remains an important yet elusive goal in the field of eukaryotic evolution. Combined with the discovery of new photosynthetic and non-photosynthetic protist lineages, the results of recent taxonomically broad phylogenomic studies suggest that a re-shuffling of higher-level eukaryote systematics is in order. Consequently, new models of plastid evolution involving ancient secondary and tertiary endosymbioses are needed to explain the full spectrum of photosynthetic eukaryotes. [Full Text HTML] [Full Text PDF] [more inside]
Mitigating Mutational Meltdown in Mammalian Mitochondria PLoS Biol 6(2): e35. [The PDF, where you can read the paper in its much prettier intended format.]
Mitochondria are remarkable microorganisms. About two billion years ago, their distant free-living ancestors hooked up with a truly foreign lineage of archaebacteria and started a genomic merger that led to the most successful coevolved mutualism on the planet: the eukaryotic cell. Along the way, evolving mitochondria lost a lot of genomic baggage, entrusted their emerging hosts with their own replication, sorted out genomic conflicts by following maternal inheritance, and have mostly abstained from sex and recombination. What mitochondria did retain was a subset of genes that encode critical components of the electron transport chain and ATP synthesis enzymes that carry out oxidative phosphorylation. Because mitochondria house the biochemical machinery that requires us to breathe oxygen, it was first assumed that mitochondrial genes would show very slow rates of molecular evolution. So it was big news almost 30 years ago when mitochondrial DNA (mtDNA) evolution was observed to be quite rapid . How could the genes for a highly conserved and critical function sustain the consequences of high mutation pressure and permit rapid rates of nucleotide substitution between species? Without the benefits of recombination, where offspring can carry fewer mutations than either parent, mutations should accumulate in mitochondrial genomes through the random loss of less-mutated genomes, a process referred to as Muller's ratchet [2,3]. How have mitochondria avoided a mutational meltdown, or at least significant declines in fitness?Here is a jaw droppingly beautiful 3D animation of what Mitochindria look like in action. [more inside]
Constitutive formation of caveolae in a bacterium. [Full Text]
Caveolin plays an essential role in the formation of characteristic surface pits, caveolae, which cover the surface of many animal cells. The fundamental principles of caveola formation are only slowly emerging. Here we show that caveolin expression in a prokaryotic host lacking any intracellular membrane system drives the formation of cytoplasmic vesicles containing polymeric caveolin. Vesicle formation is induced by expression of wild-type caveolins, but not caveolin mutants defective in caveola formation in mammalian systems. In addition, cryoelectron tomography shows that the induced membrane domains are equivalent in size and caveolin density to native caveolae and reveals a possible polyhedral arrangement of caveolin oligomers. The caveolin-induced vesicles or heterologous caveolae (h-caveolae) form by budding in from the cytoplasmic membrane, generating a membrane domain with distinct lipid composition. Periplasmic solutes are encapsulated in the budding h-caveola, and purified h-caveolae can be tailored to be targeted to specific cells of interest.Elio Schaechter writes in plain English about how fantastically amazing and unexpected the researchers actually pulling this off is, and he also talks about it in more detail in his podcast.
Provirophages and transpovirons as the diverse mobilome of giant viruses
Abstract: A distinct class of infectious agents, the virophages1 that infect giant viruses of the Mimiviridae family, has been recently described. Here we report the simultaneous discovery of a giant virus of Acanthamoeba polyphaga (Lentille virus) that contains an integrated genome2 of a virophage (Sputnik 2), and a member of a previously unknown class of mobile genetic elements3, the transpovirons4. The transpovirons are linear DNA elements of ∼7 kb [kilobases]5 that encompass six to eight protein-coding genes, two of which are homologous6 to virophage genes. Fluorescence7 in situ hybridization8 showed that the free form of the transpoviron replicates within the giant virus factory and accumulates in high copy numbers inside giant virus particles, Sputnik 2 particles, and amoeba cytoplasm. Analysis of deep-sequencing data showed that the virophage and the transpoviron can integrate9 in nearly any place in the chromosome of the giant virus host and that, although less frequently, the transpoviron can also be linked to the virophage chromosome. In addition, integrated fragments of transpoviron DNA were detected in several giant virus and Sputnik genomes. Analysis of 19 Mimivirus strains revealed three distinct transpovirons associated with three subgroups of Mimiviruses. The virophage, the transpoviron, and the previously identified self-splicing introns10 and inteins11 constitute the complex, interconnected mobilome12 of the giant viruses and are likely to substantially contribute to interviral gene transfer.[Full Text PDF] and two explanations in English [more inside]
"In an effort to outwit raccoons, are we pushing their brain development and perhaps even sending them down a new evolutionary path? Using high-definition, infrared cameras that turn pitch dark into daylight ... Raccoon Nation [alt link] achieves something that has never been done before: it intimately follows a family of urban raccoons over the course of six months as the young – under the watchful eye of their mother – grow, develop, and begin to find their way in the complex world of a big city." "Raccoon populations have grown twenty-fold in North American cities over the last seventy years. And as this documentary will show, city life is changing raccoons in remarkable ways." (45:08 min. video)
"I attempted to repeat the experiment, however once my assistant discovered that I didn’t really have any tuna, she declined to participate in any further tests."
The Pliocene Pussy Cat Theory (which originally appeared in The Annals of Improbable Research) argues that the human ancestor Australopithecus domesticated cats for hunting, defense and harvesting static electricity to make it easier to climb trees. The theory, which was proposed by Lorenzo Love, is a parody of the Aquatic Ape Hypothesis (which is critiqued here and in shorter form here). Whether you know about the Aquatic Ape Hypothesis or not, the Pliocene Pussy Cat Theory, and Love's follow-up, the Subterranean Ape Theory, will completely alter your understanding of human evolution.
With the possible exception of the Nobel awards, physicists seem to get all the press these days, whether they're doing quantum level work at the LHC, or cosmology via the latest satellite data. Biologists, not so much. It's too bad, because Richard Lenski is running one of the great evolutionary experiments of our time, and it's producing interesting results. [more inside]
The Man Who Wasn't Darwin. 2009 was Darwin's Year. 2013 will be the Year of Alfred Russel Wallace. The title and last link lead to a recent, excellent website, Wallace Online. Read the biography and proceed from there.
Since mid-2011, a substantial rise in pertussis [Whooping Cough] cases has been reported in the state of Washington. In response to this increase, the Washington State Secretary of Health declared a pertussis epidemic on April 3, 2012. By June 16, the reported number of cases in Washington in 2012 had reached 2,520 (37.5 cases per 100,000 residents), a 1,300% increase compared with the same period in 2011 and the highest number of cases reported in any year since 1942 [Make sure you don't miss Figure 1]. Commentators are already drawing corellations with the fact that Washington State leads the nation in vaccine non-compliance, Washington State's recent cutbacks in public health funding, and increases in the number of uninsured (PDF). [more inside]
Nature constantly engineers new and creative solutions to all sorts of problems—turning our stereotypes about sex upside-down along the way.
Bill Nye recently described in a Youtube video why he thinks that Creationism is inappropriate for children. Representatives of the Creation Museum have a response.