evolution
pharyngula | August 24, 2007
Some of you may have never seen an arthropod embryo (or any embryo, for that matter). You're missing something: embryos are gorgeous and dynamic and just all around wonderful, so let's correct that lack. Here are two photographs of an insect and a spider embryo. The one on the left is a grasshopper, Schistocerca nitens at about a third of the way through development; the one on the right is Achaearanea tepidariorum. Both are lying on their backs, or dorsal side, with their legs wiggling up towards you.
There are differences in the photographic technique — one is an SEM, the other is a DAPI-…
evolvingthoughts | August 24, 2007
I'm very late to this, but one of the significant figures in the synthesis, Verne Grant, died in May. Grant's book The Origin of Adaptations (1963) was one that influenced a lot of theorising about evolution. His essay on species concepts in 1957 pointed out that botanical notions of species had to be very different to the reigning Mayrian biospecies concept.
Grant, Verne. 1957. The Plant Species in Theory and Practice. In The Species Problem, edited by E. Mayr. Washington DC: American Association for the Advancement of Science.
———. 1963. The origin of adaptations. New York: Columbia…
evolvingthoughts | August 23, 2007
You'll remember, because you have all memorised my blog going back two years, that I blogged on what microbial species are before, and have a paper on that subject coming out in History and Philosophy of the Life Sciences. In it I argue that microbial species, particularly bacterial species, are maintained as phenomenal clusters by two mechanisms. One is the exchangeability of genetic material, which is akin to interfertility in sexual organisms, a hypothesis proposed by Dykhuizen and Green called the "core genome" hypothesis. The other is adaptive niche tracking.
Now a paper has come out…
pharyngula | August 23, 2007Aaargh. When will the media learn? National Geographic is running this ridiculous headline right now: New Fossil Ape May Shatter Human Evolution Theory, in which the reporter claims a discovery of some teeth could "demolish a working theory of human evolution." It's not true. Where is this nonsense coming from?
I read the article. It's titled "A new species of great ape from the late Miocene epoch in Ethiopia." The exciting news is that the "combined evidence suggests that Chororapithecus may be a basal member of the gorilla clade, and that the latter exhibited some amount of adaptive and…
voltagegate | August 23, 2007
When we think of communication, foremost on our mind is our own sophisticated means of language - writing and speaking mainly - communicating ideas or concepts through our manipulation of sound and symbology.
Evolutionarily speaking, this is a recent development; there are certainly no written documents from the time of the Australpithocenes or Homo erectus, and scientists can only guess at their ability to use a complex language.
Scent marking, then, is a much more ancient, much more prevalent form of communication between animals. Even humans use scents for communicative purposes - we use…
oracknows | August 23, 2007You know, even though I know he's been a Republican talker for a long time, that he worked for the Nixon administration as a speechwriter and lawyer, I've always kind of liked Ben Stein. My wife and I used to like to watch Win Ben Stein's Money, and he was quite amusing as the principal in Ferris Bueller's Day Off. He's always come across as a pleasant doofus, even though I know that image appears to be carefully calculated one.
Now I learn that he's the narrator and a driving force behind a pro-"intelligent design" movie called Expelled: No Intelligence Allowed, which is due to be released…
grrlscientist | August 22, 2007tags: researchblogging.org, evolution, social behavior, cooperative breeding, environment, global warming, climate change, African starlings, birds
Superb starling, Lamprotornis superbus, a cooperative breeding savanna dweller that is abundant throughout northeast Africa.
Image: Dustin R. Rubenstein [larger]
Postponing one's own reproductive efforts to help other individuals raise their offspring might seem like a bad choice, evolutionarily speaking. But cooperative breeding, as this behavior is known, is fairly common in the animal kingdom, although the reasons underlying the evolution…
evolvingthoughts | August 22, 2007
The National Geographic and the news services are touting a new ape fossil found in Ethiopia as "forcing a rethink on human evolution". As usual, the headlines are hyperbolic. This ape is fragmentary, and so far only teeth and a jaw bone have been found, and the teeth are similar to gorilla teeth. Gorillas are thought on molecular grounds to have split off from the chimp-human clade about 7 million years ago, but this specimen is 10 million years old. What gives?
I can think of a couple of options. One is that, as I have reported previously, teeth are not great diagnostic material for…
evolvingthoughts | August 22, 2007
Historian Mary P. Winsor published recently (2006b, in the December 2006 edition, but it just came out) a paper discussing how the Essentialism Story was constructed by Arthur Cain, Ernst Mayr, and David Hull.
The Essentialism Story is the claim that before Darwin systematists and biologists in general treated natural kinds such as species as being defined by necessary and sufficient conditions. That is, to be a member of a species, an organism has to have all the right properties. After Darwin, goes the story, "population thinking", which denies that there are such necessary properties…
grrlscientist | August 21, 2007tags: researchblogging.org, evolution, squirrels, rattlesnakes, tail-flagging, behavior, biology
A mother squirrel rapidly waves her tail to warn off a rattlesnake in a confrontation staged by researchers in May 1987. Adult squirrels are immune to rattlesnake venom, but their offspring are vulnerable. New infrared research found that heat from the mother's tail sends an alarming signal to the slithery predators.
Image: Donald H. Owings, UC Davis.
Researchers have long been mystified by the defensive behaviors exhibited by California ground squirrels, Spermophilus beecheyi, when they are…
zooillogix | August 20, 2007Although most humans probably do not lament the disappearance of dog-sized insects, a handful of scientists do. These scientists obviously don't watch the same movies we do. Recently, a group of researchers from Argonne National Laboratory's Advanced Photon Source along with some other researchers from less badass sounding institutions used advanced x-ray equipment to try to determine why giant insects don't roam the earth devouring amorous teenage couples today.
X-ray imaging of beetles helps confirm that tracheal system design may limit size in insects.
The answer lies in their primitive…
pharyngula | August 20, 2007Here's some exciting news: Artificial life likely in 3 to 10 years. It is exciting but not surprising at all — but of course we're going to be able to assemble entirely artificial life forms soon. It's just a particularly complicated kind of chemistry, and it's more of a deep technical problem than anything else. I wouldn't be quite so specific about the date — there are also all kinds of surprises that could pop up — but I'm optimistic, and I think the overall assertion is supported by the increasing rate of accomplishment in the field.
But of course, in addition to the usual suggestions…
grrlscientist | August 20, 2007tags: walking with monsters, life before dinosaurs, evolution, streaming video
This streaming video gives you a snapshot of evolution prior to the rise of the dinosaurs. Even though it's kinda long, it's definitely worth watching .. although that giant spider gave me the heebie-jeebies! [9:17]
loom | August 19, 2007My wife and I were following our children across Appledore Island, reaching a crest where we could see the mainland coast--Massachusetts, New Hampshire, and Maine all stretched out in a single sweep--when a woman in bloody surgical gear stepped out into our path. She warned us that behind the old radar tower next to us some pathologists were cutting open a seal. It would be a good idea if we steered the children away.
Naturally, I let my wife head on with the kids and snuck around the tower to check out the necropsy for myself...
There, on an open porch, a dozen people huddled around a table…
oracknows | August 18, 2007For those of you who missed it, Steve Colbert explains what DNA is with Twisty the DNA Helix:
DNA: It's what makes you you.
I do have to admit, though, that it irritated me when Colbert referred to DNA as a "wonder protein" even though I'm sure it was part of the joke...
pharyngula | August 17, 2007
I just finished Sean B. Carroll's Endless Forms Most Beautiful: The New Science of Evo-Devo the other day, and I must confess: I was initially a bit disappointed. It has a few weaknesses. For one, I didn't learn anything new from it; I had already read just about everything mentioned in the book in the original papers. It also takes a very conservative view of evolutionary theory, and doesn't mention any of the more radical ideas that you find bubbling up on just about every page of Mary Jane West-Eberhard's big book. One chapter, the tenth, really didn't fit in well with the rest—the whole…
evolgen | August 17, 2007
I'd be remiss to not mention this paper from Hopi Hoekstra's group after I previously discussed the anti-evo-devo paper she wrote with Jerry Coyne. The premise of the paper from Hoekstra and Coyne is that Sean Carroll overplays the importance of cis-regulatory changes in the evolution of form. Well, Hoekstra and colleagues mapped the genes responsible for natural coat color variation in subspecies of a beach mouse. They isolated two QTLs, and they identified one candidate gene for each. One candidate gene contains a substitution in a protein coding region, while the other gene has no change…
sporte | August 16, 2007Thanks to Steven Colbert you can hear about DNA directly from Dr. Spencer Wells from the National Genographic Project.
I read about this video in the GenomeWeb Daily Scan and had to check it out.
Who would have thought scientists could be so funny?
Watch it quick! There was a note at the Comedy Central site saying the video expires on Sept. 15th 2007.
or you can go here and find out whether DNA could happen to you, too!
oracknows | August 16, 2007Yes!
As intelligent and powerful as he is, Orac has always lacked something, and that's mobility. He's always been more or less at the mercy of the humans with whom he travels when it comes to locomotion. In short, being a clear box of blinking lights, he has to be carried everywhere, sometimes in a rather undignified fashion:
In this week's edition of the Skeptics' Circle, Bronze Dog gives Orac exactly what he needs:
Yes, a giant robot! Controlling such awesome machinery directly, finally, Orac is unshackled from his dependence on irrational humans to take him where he wants to go!…