Load-bearing adaptation of women’s spines

i-edcb755a5dfe1a6f437f3fbe7e3df312-vert_tease.gif

Blogging on Peer-Reviewed Research

Those of you who have been pregnant, or have been a partner to someone who has been pregnant, are familiar with one among many common consequences: lower back pain. It’s not surprising—pregnant women are carrying this low-slung 7kg (15lb) weight, and the closest we males can come to the experience would be pressing a bowling ball to our bellybutton and hauling it around with us everywhere we go. This is the kind of load that can put someone seriously out of balance, and one way we compensate for a forward-projecting load is to increase the curvature of our spines (especially the lumbar spine, or lower back), and throw our shoulders back to move our center of mass (COM) back.

Here’s the interesting part: women have changed the shape of individual vertebrae to better enable maintenance of this increased curvature, called lordosis, and fossil australopithecines show a similar variation.

[Read more…]

Bisexual flies and the neurochemistry of behavior

Blogging on Peer-Reviewed Research

On the one hand, this is a strange tale of mutant, bisexual, necrophiliac flies, and you’ve got to love it for the titillating nature of the experiments. But on the other, much more interesting hand, it’s a story about drilling down deeply into the causes of a complex behavior, and tracing it to a single gene product — and it also reveals much about the way the chemicals sloshing about in the brain can modulate responses to stimuli. Work by Grosjean and others on a simple Drosophila mutant, genderblind, which causes flies to be indiscriminate about gender in their courtship, opens up a window into how sexual responses are shaped and specified.

Think about human sexual responses. Some of us, when we see an attractive woman, are at least mildly aroused; others are have their sexual interest picqued when they see an attractive man; still others might feel sexual urges when they see a shoe, or a plush animal, or a pot of baked beans. No matter what the stimulus, these are all biological responses, with something in the environment matching some trigger in our brains and initiating a cascade of neural, neurochemical, and hormonal activity that leads to sexual behaviors. The question we want to address is what every step in the biology is doing; unfortunately, human behaviors are both too complex and not amenable to ethical experimentation, so we turn instead to simpler organisms that allow us to find simpler causes and carry out thorough experiments to probe the behavior.

[Read more…]

Great glowing spiders

Blogging on Peer-Reviewed Research

I’ve known that scorpions have fluorescent cuticles — if you go out into the desert with a black light and shine it on the ground, the scorpions will often glow green and blue and be easy to spot. I had no idea that many spiders exhibit the same phenomenon, but there they are, glowing away. I may have to visit my local head shop (in Morris? Hah!) and get some black light bulbs to see what the fauna in my living room is up to.

Fluorescence is actually a fairly common property: all it requires is a molecule called a fluorophore that can absorb and capture transiently photons of a particular wavelength, or energy, and release them at a lower energy. What this means is that a fluorescent substance absorbs light at one range of wavelengths, and then re-emits those photons at a longer wavelength; there is a color shift. In the case of black light posters and spiders and scorpions, they are absorbing light at wavelengths our eyes can’t detect (wavelengths below about 400nm, or ultraviolet light) and shifting it to a wavelength we can see, for instance to a nice blue at 450nm, cyan at around 500nm, or green at about 550nm. So to test this, all you need is a dark room, a spider, and a light source that glows at the wavelength that is absorbed by the fluorophore, and a detector (like, say, your eyes) that can collect light at the emission wavelength.

[Read more…]

Say hello to Charlie

I have to second Steve — this is an amazing blog, The Daily Coyote. A woman and a cat living in remote Wyoming have a friend, a young coyote.

This has got to be a frightening relationship. That’s a place where coyotes are shot on sight, with no remorse … maybe if a few more people read about Charlie, though, they won’t be so quick to kill.

Tasmanian devils need your help

i-baf7b18f15e7e3eaeb70e809e9383495-tas_devil.jpg

We had a seminar from Marco Restani of St Cloud State University yesterday — he’s a wildlife biologist who talked about Tasmanian Devils. Just a little tip: don’t ever invite wildlife biologists or conservation ecologists to give talks. They are the most depressing people in the world, and they really make it hard to hide away from the ugly realities. This talk was no exception: the Tasmanian Devil is in big trouble, and is facing at least two major threats, each of which may be sufficient to wipe them out. And just looke at that guy! He’s adorable! How can you let them go extinct?

[Read more…]

Nigersaurus, a Cretaceous hedge-trimmer

Blogging on Peer-Reviewed Research

Last August, when I was at the Sci Foo camp, Paul Sereno brought along the skull of one of his latest discoveries…and whoa, is it ever a weird one. This is Nigersaurus taqueti, an herbivorous dinosaur with specializations for ground-level grazing. Look at this picture; in reality, it’s even more striking.

i-f4ef9d4d5fa37f0f9e2b1f2b0c6e53f2-nigersaurus.jpg

Those jaws and teeth—they are so neatly squared off and flat-edged. In addition, the skull itself on the spinal column is turned habitually downward. This is a creature that kept its face pressed to the ground as it nibbled its way across the landscape.

Another feature that was apparent is that the skull is awesomely light — it’s mostly empty spaces with a delicate webwork of bony struts holding it together. It’s so specialized it’s almost comical, and you can imagine something like this appearing on the Flintstones as a lawn mower or hedge trimmer.

Bora has more, and you can read the original on PLoS.

Sereno PC, Wilson JA, Witmer LM, Whitlock JA, Maga A, et al. (2007) Structural Extremes in a Cretaceous Dinosaur. PLoS ONE 2(11): e1230. doi:10.1371/journal.pone.0001230