Friday Cephalopod: Force of arms

octopusarmimage

Who among you has taught or studied vertebrate anatomy? I have. It’s cool. Skeletal and muscular anatomy are weird, though, because we so take the principles for granted that we’re often not aware of it. We can move because we have a jointed framework, a collection of levers that are moved by the contractions of muscle fibers, which have distinctive attachments and insertions via tendons on those bones (or, in some cases, the muscles attach to sheets of connective tissue called fascia). The musculoskeletal part of anatomy classes consists of a lot of memorization of muscles, their origins and insertions, and the effect of the action of contracting the muscle. In some ways, vertebrate limbs are actually rather crude, made up of bony rods with joints that are prone to failure (I am very aware of that as I get older), with a collection of long muscles cobbled together to carry out specific movements.

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Parks have rules for a reason

Jebus, people. Lately it’s nothing but bad news about people doing stupid things in our national parks: ignoring signs and strolling out to fragile ponds, picking up abandoned bison calves, getting up close to adult bison and getting trampled for their trouble, and now the most horrible story of them all: a young man left the boardwalk and fell into a boiling hot spring.

The grisly death of a tourist who left a boardwalk and fell into a high-temperature, acidic spring in Yellowstone National Park offers a sobering reminder that visitors need to follow park rules, park officials and observers said.

Efforts to recover the body of Colin Nathaniel Scott, 23, of Portland, Oregon, were suspended on Wednesday after rangers determined there were no remains left in the hot spring.

There’s just a thin mineral crust over the seething water, which is highly acidic, so boiling a body in that for a day leaves nothing. Stay on the designated trails. Wild animals are wild and active volcanic springs are deadly dangerous.

Also to keep in mind, besides personal danger: it’s a good thing the body dissolved, because park rangers were risking their lives trying to recover the remains, until it became pointless.

What’s in these things?

gummibears

Haribo Gummi Bears sound fun. They’re sugar free and a harmless sweet snack, right? Until you read the reviews. It seems to have a dramatic effect on people, which I’ve filed away in my memory, next to my Enemies List.

But what’s in them to cause this effect? That’s where it gets interesting. It says on the bag that they’re “Sugar Free”, but it’s a lie. They’re free of glucose and lactose, two specific sugars, but read the list of ingredients, and you discover that they’re full of other sugars.

Corn Syrup, Sugar, Gelatin, Dextrose, Citric Acid, Corn Starch, Artificial and Natural Flavors, Fractionated Coconut Oil, Carnauba Wax, Beeswax Coating, Artificial Colors Yellow 5, Red 40, Blue 1

Corn syrup is nothing but oligosaccharides. Sugar: more oligosaccharides, specifically disaccharides like sucrose (and how can they advertise that they’re sugar free when the second ingredient is “sugar”?). Gelatin, at least, is not a sugar, but a protein, collagen. Dextrose is a simple sugar, a monosaccharide, but it’s true, it’s not glucose. Still, consuming dextrose is a great way to get a rapid blood sugar spike.

So what these things are are pure, concentrated sugar bombs that pass straight into your colon as a potent syrup that drive your gut flora into a frenzy. Watch out for them.

Also, never trust that “sugar free” label.

But if you do have enemies, you can buy them in five pound bags on Amazon. Makes me wonder if they also sell pocket nukes and bulk neurotoxins.

MRAs don’t understand evolution or development

Since form is a consequence of differential growth of tissues, and since different tissues grow at different rates, one of the ways evolution can shape morphology is through changes in growth rate, so changes in timing can produce very different forms. There are genes that affect specific tissues discretely; for instance, the gene ASPM regulates mitotic activity in regions of the brain, so mutations in it can produce smaller brains, or microcephaly. There are also global regulators of growth, and just changing the rate of maturation of the organism can produce changes in the proportion of different tissues, because of allometric variation in different regions.

So, for instance, if developmental maturation of the somatic tissues is slowed, while sexual maturation is maintained at the standard rate, individuals retain juvenile characters at reproductive age, a process called neoteny (similarly, you can get a similar effect by maintaining a standard rate of somatic growth, but accelerating the rate of sexual maturation, a process called progenesis.) Note that what’s key here is that different tissues are regulated differently; if you just slow the rate of development of both somatic and reproductive organs, you get individuals with the standard morphology, it just takes longer for them to get there. Everyone who knows anything about development and evolution understands that neoteny/progenesis requires independent regulation of different tissues.

One of the factors thought to play a role in human evolution is neoteny. Compared to other primates, adult humans retain a juvenile morphology: heads large in proportion to our bodies, larger eyes, smaller jaws, etc. This is not particularly controversial, although I’d really like to see more specific identification of the genes involved. Our shape could, after all, alternatively be explained by character by character changes in gene expression. The neoteny hypothesis implies that a large cranium and small jaw are correlated, that is, by changing one regulator of growth you get both effects. It would also be possible that they’re uncorrelated, that (as a simplified example) one gene that generates larger brains evolved, and that a second gene for reduced jaws evolved completely independently.

Neoteny can also be a mosaic process. Big head and small jaws are a retention of a juvenile character, but other features, like our bigger noses and ears as adults compared to babies (creepy visualization: imagine a baby with a nose as big in proportion to its head as an adult’s; all cuteness disappears). Even if the neoteny hypothesis is generally valid, it can’t explain all the features of an adult human, and does not imply that humans are all big babies in every respect. Donald Trump excepted.

That’s the background. Now for the pseudoscientific appropriation of a concept from development and evolution.

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Agriculture was a mistake…except to the 7 billion people who wouldn’t exist without it

Jared Diamond’s 1987 article, The Worst Mistake in the History of the Human Race, got me wondering. How do you define “mistake”? He doesn’t. What would a successful species look like? He doesn’t say. While it’s thought-provoking, it’s very hard to pin down his meaning without some explanation for those concepts.

The biggest mistake, he claims, was agriculture. He argues against a progressivist view of history, which argues that agriculture couldn’t possibly be a mistake, because it must have improved human lives or we wouldn’t have adopted it, and on those grounds, I think he’s right in principle — we adopt stupid ideas all the time. But then he tries to take an extreme opposite tack, that agriculture was bad for human beings, and there I think he’s going wrong. Agriculture produced a different environment for our species, and it had a mix of consequences.

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I am not fooled: the zombie apocalypse is nigh

Yesterday was awful. All the aches and pains of being confined to a tiny space for more than a day jumped up and bit me in the butt, and I’m also struggling with a bad case of jet lag and the crankies. So I spent yesterday in an achey, woozy fog, and today looks only slightly better.

Then to top it all off, the internet connection at my house died. I could not communicate with the rest of the world from my comfy chair, and I was too messed up to stagger someplace with a live connection. I dropped off the internet for most of yesterday, which, considering my mood, might have been a good thing.

Also, this morning I read this story about resurrecting Renaissance technologies. Internet down, and people are building wooden printing presses and trying to bring back bookmaking? Definitely signs that we’re in the End Times.

The way I feel right now, though, I’m just going to bow to the zombies, presenting them my head, and tell them to eat and get it all over with.