evolution
evolvingthoughts | October 2, 2006Repost from the old blog:
One of the problems in having a philosophy related blog is that ideas are hard things to generate on demand, so often you need someone to raise the problems for you to think about. Being naturally (and preternaturally!) lazy, I don't go out looking for problems (of a philosophical nature; the ordinary kind seem to find me like flies find rotting garbage). Hence, this blog is sporadic.
Well, I just tripped over an interesting question raised by Certain Doubts: can we reconcile the Platonic value of truth with an evolutionary view of epistemology? That is, if we think…
loom | October 2, 2006This morning it was announced that two American scientists won the Nobel Prize in Physiology and or Medicine, for their 1998 discovery of a hidden network of genes. It may seem odd that a network of genes could lurk undiscovered for so long. But the cell is very much a mysterious place. In the 1950s, scientists established the basic model for how genes work. A gene is made of DNA, the cell makes a single-stranded copy of a gene in a molecule called RNA, and it then uses the RNA as a template for building a protein. This so-called Central Dogma proved to be correct for many thousands of genes…
evolvingthoughts | October 1, 2006
Here is a working list of species concepts presently in play. I quote "Concepts" above because, for philosophical reasons, I think there is only one concept - "species", and all the rest are conceptions, or definitions, of that concept. I have christened this the Synapormorphic Concept of Species in (Wilkins 2003). More under the fold:
A Summary of 26 species concepts
There are numerous species "concepts" (i.e., conceptions of "species") at the research and practical level in the scientific literature. (Mayden 1997) has listed 22 distinct species concepts along with synonyms, which…
pharyngula | September 30, 2006Nick Matzke has
compiled all the data on hominin cranial capacities into a single chart:
I think I can see a pattern there, can you? He also has data on body size and brain size over there, take a gander at it. It looks like a simple and obvious example of evolutionary change in our lineage, I think.
Alas, it only shows specimens older than 10,000 years. I'm sure that right around 6,000 years ago, there was a sudden, dramatic change as the deity injected a soul into those crania.
mikethemadbiologist | September 30, 2006Since I'm going away for a long weekend, I'll leave you with this post about phage therapy from the archives.
So Aetiology, in her new digs, wants a post. Well, here's one, inspired by a comment: phage therapy. "Phage therapy" is short for bacteriophage therapy. Bacteriophage are viruses that kill bacteria (literally, "bacteria devourers"). The basic concept of phage therapy is to introduce the phage into an infected patient. The phage infect the bacterium-an infection of an infection! Then the phage multiply within the bacterium, lyse (explode from the inside) the host bacterium and…
pharyngula | September 30, 2006Here's a prediction for you: the image below is going to appear in a lot of textbooks in the near future.
(click for larger image)Confocal image of septuple in situ hybridization exhibiting the spatial expression of Hox gene transcripts in a developing Drosophila embryo. Stage 11 germband extended embryo (anterior to the left) is stained for labial (lab), Deformed (Dfd), Sex combs reduced (Scr), Antennapedia (Antp), Ultrabithorax (Ubx), abdominal-A (abd-A), Abdominal-B (Abd-B). Their orthologous relationships to vertebrate Hox homology groups are indicated below each gene.
That's a technical…
razib | September 29, 2006Dienekes reports on a paper which chronicles the change height of "Europeans" over the last 20,000 years ago. Anthropologist Henry Harpending once told me that when the first modern humans arrived in European 40-30 thousand years ago they were as slim and towering as modern Nilotic peoples, in other words, they were evolutionary reflections of the African environment. But soon enough the nouveau Europeans shape shifted and developed a more robust physiognomy, with a reduction in median height. As you can see from the graph which I generated the Neolithic Revolution and the introduction of…
pharyngula | September 28, 2006Carl Zimmer brings up another essential point about the HAR1F study: it was work that was guided by evolutionary theory. The sequence would not have been recognized in the billions of nucleotides in the genome if it hadn't been for an analysis directed by the principles of evolution.
Wells' diatribe was amazingly wrong. I looked at it again and there could be another half-dozen essays in just picking up apart the stupidity in it.
loom | September 28, 2006PZ Myers did an excellent job yesterday of dismantling the latest from intelligent-design advocate Jonathan Wells. Wells wrote a piece on WorldNetDaily called "Why Darwinism is Doomed." It is based some new research identifying an important gene involved in the human brain--which I blogged about last month. Wells claims that this discovery is a serious threat to evolution. Why? Because scientists have only just found the gene, because many genes are involved in building the human brain, and because finding a gene that's different in humans than in other animals doesn't actually reveal what…
clock | September 28, 2006Beauty And The Brain:
Experiments led by Piotr Winkielman, of the University of California, San Diego, and published in the current issue of Psychological Science, suggest that judgments of attractiveness depend on mental processing ease, or being "easy on the mind."
"What you like is a function of what your mind has been trained on," Winkielman said. "A stimulus becomes attractive if it falls into the average of what you've seen and is therefore simple for your brain to process. In our experiments, we show that we can make an arbitrary pattern likeable just by preparing the mind to recognize…
clock | September 28, 2006First posted on December 12, 2005 on Science And Politics, then re-posted on January 16, 2006 on The Magic School Bus and most definitely worth reposting again here...
The new article on PLoS, Evolution for Everyone: How to Increase Acceptance of, Interest in, and Knowledge about Evolution by David Sloan Wilson, describes a successful experiment of teaching evolution to a broad segment of the student population at Bighampton College (the paper looks nicer in PDF format).
Here are just a couple of snippets:
The main problem with accepting evolution involves implications, not facts.…
evolvingthoughts | September 27, 2006
Tarantulas produce silk from their feet:
"Researchers have found for the first time that tarantulas can produce silk from their feet as well as their spinnerets, a discovery with profound implications for why spiders began to spin silk in the first place."
I love these sorts of discoveries. Now we have an interesting project - what evolved first and why? Silk for climbing or silk for spinning and prey capture? Some previous work suggested that orb web spinning evolved twice, with one group spinning dry silk webs that use electrostatic forces to capture prey, while another group evolved glue-…
clock | September 27, 2006Mother Birds Give A Nutritional Leg Up To Chicks With Unattractive Fathers:
Mother birds deposit variable amounts of antioxidants into egg yolks, and it has long been theorized that females invest more in offspring sired by better quality males. However, a study from the November/December 2006 issue of Physiological and Biochemical Zoology shows that even ugly birds get their day. Providing new insight into the strategic basis behind resource allocation in eggs, the researchers found that female house finches deposit significantly more antioxidants, which protect the embryo during the…
clock | September 27, 2006A really cool new study:
DailyScience: How Butterflies Got Their Spots: A 'Supergene' Controls Wing Pattern Diversity:
To explore the genetic backgrounds of each of these species, the authors crossed different races of each species and genotyped the offspring in order to identify genes responsible for the color patterns. Thus, they were able to map the color pattern controlling loci in each species: N, Yb, and Sb for H. melpomene; Cr for H. erato; and P for H. numata. Using molecular markers within the pattern encoding genic regions, the authors then found that the loci controlling color…
clock | September 27, 2006I saw this ScienceDaily report earlier today and thought: "What's new?" I recall a study with similar conclusions from just a couple of months ago, and even that was not that new - I used the example in teaching about 5-6 years ago (then dropped the example as the literature got more and more contentious).
But a few minutes ago, Afarensis posted about this and cleared it up for me - the previous study was from zoos and this one is from the wild. Also, the new study incorporates ontogenetic data - the effects of age.
So, the size and color of the lion's mane is not driven by sexual selection…
pharyngula | September 27, 2006There are days when I simply cannot believe how dishonest the scoundrels at the Discovery Institute can be. This is one of them. I just read an essay by Jonathan Wells that is an appalling piece of anti-scientific propaganda, an extremely squirrely twisting of some science news. It's called "Why Darwinism is doomed", and trust me, if you read it, your opinion of Wells will drop another notch. And here you thought it was already in the gutter!
First, here's the science news that was published in Nature back in August, and which has set Wells off. The research is the result of the ability to…
pharyngula | September 26, 2006
It’s April (not anymore—it's September as I repost this), it’s Minnesota, and it’s snowing here (not yet, but soon enough). On days like this (who am I fooling? Every day!), my thoughts turn to spicy, garlicky delicacies and warm, sunny days on a lovely tropical reef—it’s a squiddy day, in other words, and I’ve got a double-dose of squidblogging on this Friday afternoon, with one article on the vampire squid, Vampyroteuthis infernalis, and this one, on squid evolution and cephalopod Hox genes.
Hox genes are members of a family of genes with a number of common attributes:
They all contain a…
pharyngula | September 26, 2006Archy goes looking for mastodons, finds fanged hippos with massive organs instead.
sporte | September 26, 2006Razib inspired me to share some of the story behind why white people are considered derivatives.
Reposted from the Classic Digital Bio.
No red herrings, here! Lamason et. al. found a single gene that controls human skin color while studying pigmentation in zebra fish (1).
These zebra fish had an unusual golden color that turned out to be an important clue. Lamason and collaborators found that the golden zebra fish lost their normal color because of a mutation in the slc24a5 gene. When the zebra fish have the mutant form, they produce fewer melanosomes.
A short language lesson
Fewer…
pharyngula | September 26, 2006
We need to appreciate beer more. Alcohol has a long history in human affairs, and has been important in purifying and preserving food and drink, and in making our parties livelier. We owe it all to a tiny little microorganism, Saccharomyces cerevisiae, which converts complex plant sugars into smaller, simpler, more socially potent molecules of ethanol. This is a remarkable process that seems to be entirely to our benefit (it has even been argued that beer is proof of the existence of God*), but recent research has shown that the little buggers do it all entirely for their own selfish reasons…