Life Sciences

Talk about a perfect combination of topics that are of interest to Science Blogs readers. I just came across this starred review in Publisher's Weekly: January 30, 2006 Pilgrim on the Great Bird Continent: The Importance of Everything and Other Lessons from Darwin's Lost Notebooks Lyanda Lynn Haupt. Little, Brown, $24.95 (288p) ISBN 0-316-83664-8 When Charles Darwin set out on his voyage of discovery aboard the Beagle in 1831, he was a naive naturalist. Upon his return to England five years later, as nature writer Haupt (Rare Encounters with Ordinary Birds ) capably demonstrates, he was a…
This image came out a couple months ago in Nature, but I just came across it today. I quite like the way it sums up the history of life--something that's maddening hard to do, since the time scales are so vast. It shows how life's diversity has been accumulating for billions of years. This chart shows the timing of the earliest paeolontological evidence for different kinds of life, ranging from fossils to chemical markers. A few definitions may help. Phototrophic bacteria can harness sunlight to grow. Cyanobacteria are also known as blue-green algae (aka pond scum). Eukaryotes are species…
This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic. Objection: The Earth has had much warmer climates in the past, what is so special about the current climate? It seems like a generally warmer world will be better. Answer: I don't know if there is a meaningful way to define an "optimum" average temperature for planet Earth. Surely it is better now for all of us than it was 20,000 years ago when so much land was trapped beneath ice sheets. But anywhere between the recent climate and the most extreme…
The "standard model" of intellectual history presents the Presocratics as the pioneers of naturalistic explanations of the universe around us. This narrative explains how the messy natural philosophy of the Presocratics gave way to the more metaphysical and ethical schools of the late Classical and Hellenistic and Roman eras. In any case, Socialist Swine asks below: I know that prior to Darwin people had some notion of evolution though they didn't have a notion of the mechanism involved. Do you have any idea, who might have first suggested that species change over time? Well, 10 minutes…
Go back far enough in our history--maybe about 650 million years--and you come to a time when our ancestors were still invertebrates. That is, they had no skulls, teeth, or other bones. They didn't even have a brain. How invertebrates became vertebrates is a fascinating question, made all the more fascinating because the answer tells us something about how we got to be the way we are. In order to reconstruct what happened, scientists can study several different kinds of evidence. They can look at the bodies of invertebrates to find the ones that share traits with vertebrates not found in…
Janet Stemwedel has a long post which elucidates various angles of the Cohen & algebra story. I agree with many of Janet's points, and I tend to believe that knowing algebra is an important necessary precondition for being a well rounded modern intellect. But I want to emphasize modern, I've mentioned before that John Derbyshire is writing a history of algebra, Unknown Quantity. Derb mentioned to me that though the Greek mathematician Diophantus lurched toward symbolic algebra 2,000 years ago, his work did not lay the seeds for any further developments because a scientific culture did…
Bald eagle, Haliaeetus leucocephalus. Click image for larger view in its own window. Birds in Science A fossil of one adult Psittacosaurus dinosaur surrounded by 34 juveniles (pictured), has provided the most compelling evidence to date that dinosaurs raised their young after hatching. But what makes this 125-million-year old fossil find from Liaoning province more convincing is that the skeletons are complete, and crowded together in life-like positions with their legs tucked under and heads raised, indicating that they were buried alive rather than swept together after death. âIt looks…
A few disclaimers: I do get kickbacks from affiliate programs when you purchase books after clicking through those links. If you'd rather not fund a perfidious atheist's book addiction, just look up the titles at your preferred source—I don't mind. This list is not a thinly-veiled attempt to get readers to buy me presents, either; I've read all these, so please don't try to order them for me. Get them for a creationist instead, they need them more. A while back, I presented a book list for evolutionists. Now I've updated it, adding a few recommendations and adding links so you can choose your…
I meant to post yesterday on Darwin Day, but I was swept up in doing tasks around the house that some have posited women are better at and/or care about more for reasons that lie deep in our evolutionary past. I don't buy it (nor do others, who you are encouraged to read), and the Free-Ride household seems to me a good example that tidiness is not a sex-linked trait (or, if it is, it's riding on the Y chromosome). Anyway, first I wanted to link a fine appreciation of Darwin written by Michael Weisberg and Richard M. Leventhal, both of the University of Pennsylvania. The closing paragraphs…
Mountain Owlet-Nightjar, Aegotheles albertisi . Photo by Bruce Beehler. Click image for larger version in its own window. Birds in Science A team of 25 American, Australian and Indonesian scientists flew by helicopter last December into the midst of a large tract of uninhabited tropical forest in New Guinea where they discovered a "lost world" brimming with new wildlife. Permit me to brag just this once, but I wrote a story about this that you might enjoy. Congratulations to a colleague of mine from grad school, Brian Walker, because he made the front page of the NY Times Science section…
Here's some very cool news: scientists have directly observed the evolution of a complex, polygenic, polyphenic trait by genetic assimilation and accommodation in the laboratory. This is important, because it is simultaneously yet another demonstration of the fact of evolution, and an exploration of mechanisms of evolution—showing that evolution is more sophisticated than changes in the coding sequences of individual genes spreading through a population, but is also a consequence of the accumulation of masked variation, synergistic interactions between different alleles and the environment,…
Male Berlepsch's Six-wired Bird of Paradise, Parotia berlepschi. Photo by Bruce Beehler. Click image for larger version in its own window. I would give anything -- in fact, I'd give absolutely everything I ever had, currently have and could ever hope to have -- to be part of the recent Conservation International (CI) expedition to Indonesia. This month-long expedition was the brain child of scientist and CI vice president, Bruce Beehler. His goal? To explore the mysterious Foja Mountains in western New Guinea, formerly known as Irian Jaya. Beehler gathered a team of 25 international…
Next month: Science & Politics
I saw on Muton, and several readers have mentioned it to me, this article about the world's smallest vertebrate, fish of the genus Paedocypris. It's a gorgeous translucent cyprinid, so is somewhat related to my favorite fish, Danio rerio. They live in cool, slow moving water in peat swamp forests of Southeast Asia. One female, only 7.9mm long, contained about 50 eggs, so they know it was sexually mature. Living Paedocypris progenetica, CMK 18496, (a, b) male, ca 9 mm; (c) female, ca 8.8 mm. That size isn't at all shocking—my zebrafish larvae at about that size are active hunters with…
First, a tiny bit of quantitative morphological data you can find in just about any comparative anatomy text: mammal number of vertebrae cervical thoracic lumbar sacral caudal horse 7 18 6 5 15-21 cow 7 13 6 5 18-20 sheep 7 13 6-7 4 16-18 pig 7 14-15 6-7 4 20-23 dog 7 13 7 3 20-23 human 7 12 5 5 3-4 The number of thoracic vertebrae varies quite a bit, from 9 in a species of whale to 25 in sloths. The numbers of lumbar, sacral, and more caudal vertebrae also show considerable variation. At the same time, there is a surprising amount of invariance in the number of cervical vertebrae in…
Since I mentioned yesterday that penis size mattered, upon stumbling on this article about the horrific effects of a trematode infestation, I thought everyone might enjoy a grim and vivid picture of what trematodes can do to a poor, innocent mollusc. This is a photo of a trematode, or fluke. Trematodes are parasitic flatworms with very complex life cycles; this particular one is a cercaria, or tailed larva. They swim about and infest various hosts at various stages, proliferating and spreading through tissues, before moving on to infect the next host in their cycle. This particular trematode…
Brown Pelican, Pelecanus occidentalis. Photo by permission. Arthur Morris, Birds as Art. Birds in Science Two University of Canterbury biologists are part of a team whose evolutionarily-informed approach to conservation is aiding the recovery of New Zealand's critically endangered parrot, the kakapo, Strigops habroptilus (pictured). Bruce Robertson and Neil Gemmell, Associate Professor of Biological Sciences, are members of a research team that has just had a paper published in the Royal Society of London's prestigious journal Biology Letters. The manuscript outlines how the team, led by…
The Endangered Species Act (ESA) has provided protection to our most threatened and endangered plants and animals for over 30 years. As new legislation makes its way through Congress that would weaken the ESA, undermine its scientific foundation, and cripple federal efforts to protect and preserve wildlife and their habitats, scientists' voices are critical. A strong, unified statement will help ensure that the science in the ESA remains strong. Several organizations have written a letter and are seeking signatures from scientists. To sign this letter, go to the electronic form provided by…
Western Grebe, Aechmophorus occidentalis copyright by Ted Steinke. Birds in Science; Researchers at Rutgers, The State University of New Jersey, believe they have located a place in the brain where songbirds store the memories of their parents' songs. The discovery has implications for humans, because humans and songbirds are among the few animals that learn to vocalize by imitating their caregivers. In a paper published this week in the top scientific journal, Proceedings of the National Academy of Sciences, David Vicario and Mimi Phan of Rutgers, and Carolyn Pytte of Wesleyan University…
I have to confess to being tired of answering William Gibbons' occasional replies. It's to be expected that someone with a "PhD in creation science apologetics" (which is roughly the same as having a PhD in defending astrology) would have mastered the "Gish Gallop", but Mr. Gibbons, it appears, simply has not a shred of intellectual honesty or concern for accuracy. Rather than offering a line by line response, let me point ouf the evidence on which I rest that conclusion. To begin with, let's look at his disturbing habit of appropriating the work of others and pretending they are his own. In…