Virgin births… in snakes!

Species that reproduce sexually usually need two partners to reproduce, right? Right. What I didn’t know was, females of some species (that usually reproduce sexually) have apparently been observed to be able to reproduce without a mate—rarely, and when they’re in captivity and away from potential mates.

But now, virgin births have been observed in snakes–in the wild, with males present nearby!

They captured pregnant copperhead and cottonmouth female pit-vipers from the field, where males were present.

The snakes gave birth, allowing the scientists to study the physical and genetic characteristics of the litters. […]

“That’s between 2.5 and 5% of litters produced in these populations may be resulting from parthenogenesis.

“That’s quite remarkable for something that has been considered an evolutionary novelty,” he said.

No insights yet on how and why this happens, though, or what implications it may have.

But this is fascinating, nonetheless.


☛ Rethinking Dinosaurs

The latest in paleontology:

[…] “a filamentous body covering obviously represents the plesiomorphic state for dinosaurs in general,” wrote Rauhut’s team.

Plesiomorphic is another way of saying “ancestrally typical.” In short, it was feathers all the way down.

What?! All two legged dinosaurs had feathers? What were we thinking all these years? Has this been verified?

Now they’ll have to make Jurassic Park all over again.


Of Space Worms

Found this article recently, where they wanted to check how microscopic worms would do in space. Turns out, they do fine—in fact, they actually live longer in space! Additionally:

“We identified seven genes, which were down-regulated in space and whose inactivation extended lifespan under laboratory conditions,” Szewczyk said in a press release. This basically means that seven C. elegans genes usually associated with muscle aging were suppressed when the worms were exposed to a microgravity environment. Also, it appears spaceflight suppresses the accumulation of toxic proteins that normally gets stored inside aging muscle.

They’re not sure what the biological mechanisms might be behind this phenomenon.

I wonder, though—how much of it can be simple chemistry and fluid dynamics? We know that at small enough length scales (such as those of microscopic organisms) viscosity is a much stronger agent than inertia (governed by mass, and to an extent, gravity). Often, gravitational effects are ignored when doing small scale analyses. How do things change in the actual biology when gravity is really zero, not just as an approximation?

Also from the article:

“Most of us know that muscle tends to shrink in space. These latest results suggest that this is almost certainly an adaptive response rather than a pathological one. Counter-intuitively, muscle in space may age better than on Earth. It may also be that spaceflight slows the process of aging.”

I’m not sure why this seems novel. My thought has always been that muscle atrophy in space is due to lack of use, i.e. adaptation. This is why astronauts take special care to exercise their leg muscles while at the International Space Station. The legs no longer need to support the considerable weight of the human body, and the body efficiently starts optimizing its resources!

But perhaps (and most likely) my lack of knowledge allows me to simplify a phenomenon that a physiologist would find many angles to! I’d love to know those angles though—anyone reading this who can help?


Confusing correlation with causation

One of my pet peeves with scientific journalism is the propensity to confuse correlation with causation. The idea is that just because two things are observed to happen at the same time (or before, or after, one another), does not imply that one causes the other.

In the latest example of this, the link between chocolate and good health is revisited.

The article opens with:

People who eat chocolate regularly tend to be thinner, new research suggests.

… which implies that a causation has been observed. The article goes on to make the following points:

[…] those who ate chocolate a few times a week were, on average, slimmer than those who ate it occasionally.

The link remained even when other factors, like how much exercise individuals did, were taken into account.

[…] it is how often you eat chocolate that is important, rather than how much of it you eat. The study found no link with quantity consumed.

So… I’d still lose weight if I ate a tonne of chocolate very frequently? Really?!

The most important statement, however, comes a little later:

But the findings only suggest a link - not proof that one factor causes the other.

… and,

And if you are looking to change your diet, you are likely to benefit most from eating more fresh fruits and vegetables.

Now guess what the headline of this article, which itself says that it’s only a link, and talks about maintaining an overall good diet, reads.

Chocolate ‘may help keep people slim’

Perfect, isn’t it?


Tapeworms inside the human brain

Most of us have heard of tapeworms, the parasitic creatures that find their way into the human digestive system, and can grow very long indeed. They can cause quite a bit of trouble, but I had no idea how extreme the trouble can sometimes be.

Theodore Nash sees only a few dozen patients a year in his clinic at the National Institutes of Health in Bethesda, Maryland. That’s pretty small as medical practices go, but what his patients lack in number they make up for in the intensity of their symptoms. Some fall into comas. Some are paralyzed down one side of their body. Others can’t walk a straight line. Still others come to Nash partially blind, or with so much fluid in their brain that they need shunts implanted to relieve the pressure. Some lose the ability to speak; many fall into violent seizures.

Underneath this panoply of symptoms is the same cause, captured in the MRI scans that Nash takes of his patients’ brains. Each brain contains one or more whitish blobs. You might guess that these are tumors. But Nash knows the blobs are not made of the patient’s own cells. They are tapeworms. Aliens.

This is scary—they can find their way into the bloodstream, and in the human brain, where they happily live and grow as cysts.

Well, let’s back up a bit. I didn’t know that the tape worm life cycle involves humans and pigs, and that the normal life cycle can only be completed via undercooked pig meat. There you go, I thought, that’s why you should avoid undercooked meat.

But—no. That’s not the half of it.

The more serious trouble (of the brain cyst kind) happens when the normal tapeworm cycle is disrupted. Instead of finding their way inside a pig, tapeworm eggs sometimes find their way straight back inside humans, and the confused eggs behave as they would in a pig—reach for the blood stream. And that’s the recipe for disaster. You could be having tapeworm cysts in your brain, without ever having had raw or undercooked meat.

I won’t give everything away; go read the whole article. It’s excellent, informative, and as I said, a little scary.