Re-grown lizard tails are cheap knock-offs of the original —

A new study suggests that the "miracle" of re-growing a lost tail is less awesome than it might first appear. Sure, growing a new tail is cool and all. But the new tails have completely different anatomy — a tube of cartilage in place of vertebra, for instance — and are likely less flexible than the original model. (Via Brian Switek) — Maggie •

Justine Larbalestier provides some context for Republican MO senate nominee Todd Akin statement that, "from what I understand from doctors [pregnancy from rape] is really rare. If it’s a legitimate rape, the female body has ways to try to shut that whole thing down."

It turns out that this belief in magic sperm-rejecting vaginas was the kind of thing that was believed in 1785, when Samuel Farr argued in his groundbreaking treatise on law and medicine that:

Samuel Farr, in the first legal-medicine text to be written in English (1785), argued that “without an excitation of lust, or enjoyment in the venereal act, no conception can probably take place.” Whatever a woman might claim to have felt or whatever resistance she might have put up, conception in itself betrayed desire or at least a sufficient measure of acquiescence for her to enjoy the venereal act. This is a very old argument. Soranus had said in second-century Rome that “if some women who were forced to have intercourse conceived . . . the emotion of sexual appetite existed in them too, but was obscured by mental resolve,” and no one before the second half of the eighteenth century or early nineteenth century question the physiological basis of this judgement. The 1756 edition of Burn’s Justice of the Peace, the standard guide for English magistrates, cites authorities back to the Institutes of Justinian to the effect that “a woman can not conceive unless she doth consent.” It does, however, go on to point out that as matter of law, if not of biology, this doctrine is dubious. Another writer argued that pregnancy ought to be taken as proof of acquiescence since the fear, terror, and aversion that accompany a true rape would prevent an orgasm from occurring and thus make conception unlikely.

(Quote from Thomas Laqueur’s Making Sex).

Justine notes that Farr's work was written in the same century in which Mary Toft was widely believed to have given birth to rabbits.

So yeah, that the kind of "science" that Todd Akin will bring to the Senate.

“Legitimate Rape” and Other Craptastic Beliefs From the Olden Days

Given the trend lately to look backwards, historically, in search of the ideal human diet, I found this article by Rob Dunn really interesting. Dunn discusses some new research that gives us a better idea of what our closest relatives—chimpanzees and bonobos—are eating out in the wild.

Some of the takeaways fit neatly into the current human food zeitgeist—chimpanzees eat a diverse and varied diet, only consume small amounts of meat, and (for obvious reasons) focus on what happens to be in season and available. But some of the information is less apparently applicable to us. For instance, chimpanzees fracking love figs. In fact, different species of figs make up nearly half of all the food the chimpanzees in the study were eating. Figs, people. Can't get enough of 'em.

But the larger point, Dunn writes, is that we can't really apply any of the facts about chimpanzee diets directly to ourselves in a "Just So Story" sort of way. Geography, resource availability, and culture don't work like that. Neither does biology.

You are unlikely to eat like a chimpanzee eats. If you are the average American, you eat more meat and more simple sugar. You eat differently because of choices you make and choices our societies have made (e.g., to produce huge quantities of the foods that most simply satisfy our ancient urges). You also eat differently because the species around you are different, unless you happen to own a greenhouse specializing in tropical African trees.

But even if you were to abandon agricultural food and move into a forest in Tanzania you would still not eat exactly like a chimpanzee. By most reports the food chimpanzees eat tastes bad, at least to humans, (though, one hopes, not to chimpanzees). By some accounting the food chimpanzees eat is also insufficient to keep a human alive and fertile.

Read the rest of the story at Scientific American blogs

Via Mariette DiChristina

Image: Female chimpanzee eating banana, a Creative Commons Attribution Share-Alike (2.0) image from dkeats's photostream

Spider molting from Karli Larson on Vimeo.

Spiders don't have an internal skeleton like we do. Instead, their muscles are anchored to an exoskeleton—a sort of hard, semi-flexible shell that encases a spider's whole body. In order to grow bigger, spiders have to grow new exoskeletons and shed old ones.

Karli Larson found a spider on her window frame in the process of shedding its exoskeleton. Naturally, she filmed it and set the whole thing to music. She says:

The entire molting process took about 30 minutes to fully complete. This is the interesting part, sped up.

The camera is a little shakey, so if that bothers you, well, sorry. But I think this is still way fascinating.

Read more about spiders, their exoskeletons, and the molting process at HowStuffWorks

Thanks, Maggie Ryan Sandford!

IUDs are the weird form of birth control. We don't really know exactly how they work, for instance. And they've been largely unpopular my entire lifetime—really, ever since a couple of poorly designed IUDs set off a mini-panic in the late 1970s and early 1980s. But IUDs are effective birth control. The ones that you can buy today are safe. And, more importantly, they represent birth control that you don't have to think about, and birth control that is really hard to get wrong.

If you've ever done research on the effectiveness of various methods of birth control, you'll notice that the statistics usually come with a little asterisk. That * represents a concept that few of the people who rely on birth control ever think about—perfect use. Let's use condoms as an example. With perfect use, 2 out of 100 women will get pregnant over the course of a year's worth of condom-protected sex. Without perfect use—maybe you don't use a condom every time, maybe you don't put it on right when you both get naked—the number of accidental pregnancies jumps to 18 out of 100. The same basic problem affects birth control pills, as well. Ladies, did you know you're supposed to take those things at the same time of day every day? That's the kind of use error that can make a difference between 1 out of 100 women getting pregnant in a year, and 9 out of 100 getting pregnant.

In contrast, IUDs represent a fit-it-and-forget-it method of birth control. Which is a big part about why they're up there with outright sterilization as the most effective means of birth control available. Bonus: Depending on which kind you use, you can avoid hormonal side effects. This, experts say, is why IUDs are experiencing something of a resurgence in popularity. In an article at Wired, Jennifer Couzin-Frankel writes that 5.5 percent of American women who use birth control use IUDs. That's up from only 1.3 percent in 1995.

Somewhat unbelievably, no one is quite sure how they work, but the theory goes like this: The human uterus has one overriding purpose, which is to protect and sustain a fetus for nine months. If you stick a poker-chip-sized bit of plastic in there, the body reacts the way it does to any foreign object, releasing white blood cells to chase after the invader. Once those white blood cells are set free in the uterus, they start killing foreign cells with efficient zeal. And sperm, it turns out, are very, very foreign. White blood cells scavenge them mercilessly, preventing pregnancy. In copper- containing IUDs, metal ions dissolving from the device add another layer of spermicidal action.

... Most modern IUDs incorporate copper, which has an assortment of benefits, including increased durability and effectiveness. They’re also free of hormones and can be made cheaply, a boon for women in developing countries. But copper IUDs can cause heavy menstrual bleeding and cramping. The Mirena solves that problem by forgoing the metal for a synthetic version of the hormone progesterone. Here again, the mode of action isn’t completely understood, but researchers suspect that the hormone thickens cervical mucus, which makes it nearly impossible for sperm to swim upstream. It may also thin the uterine lining, rendering it inhospitable to an embryo should fertilization occur. The hormone-based IUD has the opposite side effect of the copper ones: It sometimes leaves women with little uterine lining to shed, so they hardly get any period at all.

... Even though many more doctors are comfortable with the IUD, a generation of doctors didn’t get practice inserting it. And if they don’t know how to put one in, they’re less likely to recommend it as an option. Also, the devices are expensive—the ParaGard costs $500, the Mirena $850. “It’s absolute highway robbery that these companies charge so much,” Espey says. “If you went to Home Depot and got the raw materials for a copper IUD, it would cost less than 5 cents.” And the hormones don’t contribute much more to the cost, she adds. In fact, amortized over years of use—10 for the ParaGard and five for the Mirena—an IUD is far cheaper than birth control pills, which can cost $30 or more a month. But the initial outlay is difficult for some women to manage, and it’s not always covered by insurance.

Read the rest of the story at Wired

Read more about different kinds of birth control, their effectiveness, and how to use them correctly at Planned Parenthood

Via Scicurious

Image: X-Ray showing an IUD in place. Photo taken by Wikipedia user Nevit Dilmen, used via CC license.

Many's the time I've rolled around on the ground, grimacing and making animal keening noises and wondering why the hell humans evolved to experience such dramatic pain from toe-stubbing. Here is a plausible-sounding threefold answer from Chris Geiser, director of Marquette College's College of Health Sciences athletic training program. Part one is that we've just got a lot of nerves in our extremities because they're our interface to the world. But more interestingly:

Secondly and related to the first point, there is very little tissue in our toes to absorb this type of impact. Much like hitting our shin, there is no fatty tissue or muscle tissue overlying the bones in the toe to cushion the impact. Every bit of the kinetic energy created in moving our legs forward is absorbed by the skin and bone of the toe, resulting in very high compressive forces on the many nerve endings that reside there. Because the foot is at the end of the longest lever system in the body — the leg — feet tend to be moving much faster than any other part of the body when they come into contact with an unknown object. For these same reasons a pitcher can throw a baseball 90-plus miles per hour and a soccer player can strike the ball at roughly the same speed; the further away from the axis of rotation, in this case our hip, the faster the end of that segment is moving. Add the mass of our entire leg to this equation, and there's a large mass applying force to the toe at a great velocity in a small area not capable of adequately dissipating that impact. OUCH!

"The last part of this explanation comes from an evolutionary perspective. In the not so distant past, infections killed many people. Stubbing a toe can open wounds on the feet, which are constantly in contact with the bacteria-laden environment. It has been suggested that individuals who received lots of sensory information from their toes were less likely to strike them, creating an evolutionary advantage for people blessed with this type of sensory information. So there are many components to this amazingly painful question."

Big Question: Why does it hurt so much when I stub my toe? (via MeFi)

(Image: Toes, a Creative Commons Attribution (2.0) image from wonderferret's photostream)

Retinal neuroscientist and photographer Bryan Jones sends in this gorgeous shot of an archaeopteryx fossil displayed in the Museum für Naturkunde in Berlin, Germany.

"As a biologist, seeing this fossil represents something of a pilgrimage," says Bryan, "[Visiting this museum is] a journey that all biologists would benefit from making."

Snip from his blog post:

This particular sample was found in the Solnhofen limestone formation in Bavaria and is the basis for the link between the dinosaurs and the feathered birds. Archaeopteryx itself is a feathered theropod, but is though of as the oldest documented bird dating back approximately 150 million years ago.

The fossil was found in 1874 by Jakob Niemeyer who traded it to Johann Dorr for a cow. Johann then sold the fossil to Ernst Haberlein for 2,000 German Marks. This sale was then turned around to the founder of Siemens, Werner von Siemens for 20,000 German Marks for the University of Berlin which has provided this specimen to scientists around the world as the best preserved specimen found with elegant feathers and an exquisitely preserved skull.

From a public perspective, biology in the oceans, like biology on the land, tends to favor the charismatic megafauna. Stop by your local aquarium and you'll find masses huddled around the seal pool or the shark tank. People will even attempt to interact with the octopodes. Meanwhile, smaller creatures sit on the sidelines. Crabs, starfish, and ray-like skates have some admirers at the touch tanks. But in the world of small things, they're actually quite large. The ocean is full of even tinier organisms—worms and snails, small shelled animals and even stationary colonies of life that look like rocks or lumps of sand.

The ocean is an amazing place, and Bill Grossman can tell you about the things that live there—large, small, or tiny. Grossman is specimen collector for the Marine Biological Laboratory. Essentially, he's part of a system of support staff for scientists. When researchers at MBL need sea creatures to study, it's people like Grossman who go out on the water and find them.

Back in May, I got to take a short trip aboard the R/V Gemma, MBL's specimen collection boat. The videos I brought back can teach you some amazing things about animals you thought you knew well, and introduce you to creatures you probably never noticed before.

Read the rest

Last January, at the Science Online conference, I noticed that there was a research group collecting swabs taken from the bellybuttons of scientists, science bloggers, and science journalists. That culture above? It's made from the bellybutton of Anton Zuiker, one of the organizers of that conference.

Beyond personalized petri dishes, what is the point of all this? Turns out, the goal is to learn more about the bacteria that lives on us. Some of the data from analyzing all those bellybutton samples is starting to come back, and it's turning up some interesting facts about the tiny ecological niches on our tummys.

About 18 months ago, researcher in the laboratory of Dr. Dunn, a North Carolina State University professor, came up with an idea to explore the ecology and evolution of daily life and wanted to find a spot on the body that could provide an understanding of the natural skin microbiome. They needed a place that was infrequently disturbed, avoided the scrubbing of daily wash and was common to all humans. There was no better choice than the bellybutton. Dunn and his clan of navel gazers then invited people from two conferences, 60 in total, to swab their bellybuttons and provide him with the samples, which he took back to his lab and cultured. The next several months were spent not only growing the bacteria, but also typing them to identify the species.

The first set of data is in review, but the results suggest that the bellybutton offers far more to our understanding of life and our journey through it. From these 60 people, Dr. Dunn identified close to 1,400 species of bacteria. From these, a number were predictable, such as the ever-prominent Staphylococcus epidermidis and the corynebacteria, both of which give off that "eau de germs" scent when we don't wash frequently. But others, such as those found on volunteer Carl Zimmer, were completely unexpected, such as species that are found only in the ocean or the soil or in faraway lands.

...The navel bacteria were related to where the person has lived over the course of their lifetime. The tiny anatomical vestibule was actually a museum of lifetime experiences.

Read the rest of this story by microbiologist Jason Tetro at Huffington Post.

Learn more about the Bellybutton Biodiversity Project

Slate has a nice explainer covering heat wave health problems. The central question: If my body temperature is 98.6 degrees Fahrenheit, why am I uncomfortable when it's 98.6 degrees Fahrenheit outdoors?

The answer is both basic and interesting. Sure, 98.6 degrees F is the healthy temperature for a human body, but that's only because we are pretty good at transferring heat away from ourselves. Your metabolism and your muscles generate more heat than that, but you get rid of it using tricks like breathing out hot air and sweating. Basically, your body works like a heat exchanger. It's the same sort of system that keeps your refrigerator cool—take the heat from inside a closed space and dump it into the surrounding environment.

Unfortunately, this system works best when the surrounding environment is cooler than the closed space. Your body is happiest when the air temperature is around 70 degrees F. That's when it's most efficient at getting rid of your excess heat. When the weather gets to warm, it's a lot hard to make the heat exchange. With nowhere else to put the heat, your body temperature starts rising.

Because exercise causes the body to generate so much extra heat, optimal temperatures for intense physical activity are lower than those for daily life. Athletes can raise their core temperatures six degrees just by working out. Add an environment that makes heat dispersal more difficult—not to mention possible dehydration from sweat losses that sometimes exceed six liters (for marathoners) or two liters per hour (team game players)—and performance can take a nosedive.

... For example, researchers in Darwin, Australia, observing a long-distance runner taking a 30-minute jog through the humid air, noted that his body temperature increased from 98.96 degrees to 105.8 degrees. When he’d gone on a similar jaunt under cooler conditions, his temperature had risen by just two degrees. Such a spike spells trouble for maintaining an optimal heart rate: The man’s soared to 200 beats per minute during the last 15 minutes of his run, where, previously, it was a more sustainable 154 beats per minute.

Read the rest of Slate's Explainer on body temperature.

Image: Suck It Heat Wave!, a Creative Commons Attribution Share-Alike (2.0) image from instantvantage's photostream