Here’s a cool idea: pick a color palette for your website by sampling photomicrographs. There are some nice color samples there; I think I’d go with something along the lines of a DIC image of a zebrafish embryo, which would have lots of blues, a few weakly saturated yellows, and an occasional flare of gold from the birefringence. Time for a site redesign! If I had any time, that is.
Perhaps you haven’t noticed, but we’ve got a serial spammer in the comments. This twit, calling himself Peter Moore (also known as Ken DeMyer, or Kdbuffalo, as he was known on Wikipedia before being banned there), is repeating himself over and over again, asking the same stupid question, never satisfied with any answer anyone gives him. Forty nine insipid comments in three days is enough.
I will answer him one last time. Any further attempt to spam multiple comment threads with his demands (and this alone makes him an ass: an incompetent, unqualified hack like Moore is in no position to make demands) will result in his immediate banning.
The scienceblogs team seems to be forming a united front on at least one specific issue: in support of research in the face of animal rights extremists. This is prompted by the case of a researcher in drug addiction whose home was vandalized by domestic terrorists, and who has written an op-ed defending the use of animals in research.
I said at length what I think about animal research several years ago, in our biology discipline’s policy statement on dissection. It’s pretty darned simple: we can’t figure out how something we don’t understand works without studying the subject. We can’t learn more about cells without studying cells; we can’t learn more about animals without studying animals; software simulations and thought experiments do not substitute.
My latest column for Seed is now available online. It’s an abbreviated summary of how vertebrates make segments (so it’s illustrated with a fly…), with special emphasis on the global and clocklike mechanism we use.
We’ve got a question going around: it’s been a good year for Europe in the Nobel Prizes, so what does it mean for American science? Are we slipping? Is there a European bias?
This is a nicely done periodic table on the web — I particularly liked the little slider that would let me change the temperature and see which ones would melt and boil.
Early Cambrian shrimp! I just had to share this pretty little fellow, a newly described eucrustacean from the lower Cambrian, about 525 million years ago. It’s small — the larva here is about 1.8mm long, and the adults are thought to have been 3mm long — but it was probably numerous, and I like to imagine clouds of these small arthropods swarming in ancient seas.
I have some thoughts on the topic of male and female dominance brought up by Blue_Expo.
In fact, it was the topic of a paper for my Evolution of Human Aggression class…
Females are under some different sexual selection pressures than males stemming from the fact that they are the limited sex. They can only produce a finite number of offspring and are heavily invested in their progeny. Perhaps this is the basis for the female dominance social hierarchies observed in bonobos (Parish et al., 1994) and hyenas (Jenks, 1995). In both these systems, offspring inherit their mother’s rank and a mother is willing to engage in physical combat or establish social coalitions designed to elevate their offspring in rank. Because rank determined ability to procure resources, survive and reproduce, and females had high parental investment, there was sufficient evolutionary pressure for females to evolve the capacity to establish dominance even over males on their offsprings’ behalf.
I’ve written a long introduction to the work I’m about to describe, but here’s the short summary: the parts of organisms are interlinked by what has historically been called laws of correlation, which are basically sets of rules that define the relationship between different characters. An individual attribute is not independent of all others: vary one feature, and as Darwin said, “other modifications, often of the most unexpected nature, will ensue”.
Now here’s a beautiful example: the regulation of the growth of mammalian molars. Teeth have long been a useful tool in systematics—especially in mammals, they are diverse, they have important functional roles, and they preserve well. They also show distinct morphological patterns, with incisors, canines, premolars, and molars arranged along the jaw, and species-specific variations within each of those tooth types. Here, for example, is the lower jaw of a fox. Look at the different kinds of teeth, and in particular, look at the differences within just the molars.
Note that in this animal, there are three molars (the usual number for most mammals, although there are exceptions), and that the frontmost molar, M1, is the largest, M2 is the second largest, and M3, the backmost molar, is the smallest. This won’t always be the case! Some mammals have a larger M3, and others may have three molars of roughly equal size. What rules regulate the relative size of the various molars, and are there any consistent rules that operate across different species?
To answer those questions, we need to look at how the molars develop, which is exactly what Kavanagh et al. have done.
Cuvier, and his British counterpart, Richard Owen, had an argument against evolution that you don’t hear very often anymore. Cuvier called it the laws of correlation, and it was the idea that organisms were fixed and integrated wholes in which every character had a predetermined value set by all the other characters present.
In a word, the form of the tooth involves that of the condyle; that of the shoulder-blade; that of the claws: just as the equation of a curve involves all its properties. And just as by taking each property separately, and making it the base of a separate equation, we should obtain both the ordinary equation and all other properties whatsoever which it possesses; so, in the same way, the claw, the scapula, the condyle, the femur, and all the other bones taken separately, will give the tooth, or one another; and by commencing with any one, he who had a rational conception of the laws of the organic economy, could reconstruct the whole animal.
Cuvier famously (and incorrectly) argued that he could derive the whole of the form of an animal from a single part, and that this unity of form meant that species were necessarily fixed. An organism was like a complex, multi-part equation that used only a single variable: you plugged a parameter like ‘ocelot’ into the Great Formula, and all the parts and pieces emerged without fail; plug in a different parameter, say ‘elephant’, and all the attributes of an elephant would be expressed. By looking at one element, such as the foot, you could determine whether you were looking at an elephant or an ocelot, and thereby derive the rest of the animal.
