It's A Yawn, It's A Sneer

No, it's the Flehmen Response.


Have you ever wondered why your horse or your cat gives that "gurning" face after smelling something intensely? I did; I thought it was something in the smell that made my cat react that way, as if she didn't like it -- except she kept going back to it again. It seemed like she was a glutton for punishment.


Now I find it wasn't that at all: she was exhibiting the Flehmen Response, a way of smelling that does not involve the nose.


What it does involve is an organ inside the roof of the mouth called the vomeronasal organ, otherwise known as the Jacobson's organ. The "gurning" face (or, in the case of goats and horses, the weird lip-lifting) is actually a way of getting air to circulate inside the mouth so that the vomeronasal organ can pick up molecules of the scent in question. It helps the animal see what kind of scent it is, really, and gives them more information about the source of the scent.

Generally, the scents that cause this kind of interest are things that contain pheremones or other compounds that tell the animal about other animals, either of their own species or, in the case of cats, those of prey. Curiously, it is believed to be the basis of the Cheshire Cat from Alice in Wonderland.


"Flehming allows the animals to determine several factors, including the presence or absence of estrus, the physiological state of the animal, and how long ago the animal passed by. This particular response is recognizable, for example, in stallions when smelling the urine of a mare in heat." [wiki]

This is a small fact, something you can bring out in odd moments to impress your friends; but as an activity it rarely fails in comic charm. Here is a video of a pony with the Flehmen Response in action:



Lastly, I'm not certain the video below is a flehmen response (if so it's a very lively one), but it is pretty funny.



You can also type "Flehmen Response" into Google Images and see what you get: a veritable rogue's gallery of weird facial tics.

Very Small Post About Tomato Blossoms

So I'm just not getting many tomatoes this year.

The bees come and hang out with the squash blossoms and the sunflowers, and pretty much ignore the tomatoes. The bumblebees like them, though the two poor bumblebees I see in there are working hard trying to cover all those blossoms.

So I went to look up tomato pollination, and I find there is a whole mythos about tomatoes being self-pollinating. Apparently, according to this site, "The wild progenitor of our domestic tomato, in its native Peru, was pollinated by a solitary bee that was specifically adapted to it. As tomatoes were carried to other areas, its pollinator did not go with it, and pollination was often lacking."

Looking around, I came across a wonderful Instructables which explained things further:

"Tomatoes, as well as other members of the Solanaceae require a special kind of pollination to achieve proper fruit set. This form of pollination is known as "buzz pollination". Buzz pollination is accomplished by Bumblebees (Bombus), by gripping the flower with their legs and vibrating their flight muscles; honeybees (Apis) are incapable of doing this. In small gardens, bumblebee populations can be insufficient to properly pollinate tomatoes and related plants. Here's how to buzz pollinate your plants to produce larger fruits."

The 10-second video and the one-step Instructable then goes on to demonstrate a perfect (and hilarious) way to pollinate your tomatoes, which I will allow you the pleasure of discovering. It made me laugh.

Back at the first site, they tell us "Greenhouse growers for many years employed humans with electric vibrators (one brand name: Electric Bee!) to accomplish pollination. Today these have been mostly replaced with cultured bumblebees who do it more efficiently and cheaply."

All of which explains why I saw the single bumblebee in my garden, going from flower to flower and making a strange "bzazz" noise as it climbed onto each one. Yay, bumblebees! Still, I think I'll follow the Instructables and see if it helps.

Hubble: Deep Field

My friend Gwyan just sent me this and I actually can't find many words to describe the effect it had on me. There was a moment, and I will let you find that moment, when I caught my breath and actually became too emotional to speak. I hope you enjoy it as much as I did. It is, quite literally, awesome.

Ze Widow, She Is Black

One of the not-so-great joys of my new trailer is that it came with an infestation of black widow spiders. We would open the galley, and there one would be: black, and shiny, with horribly pointy legs and a big, fat abdomen. And a few days ago, for the first time, I saw the Hourglass. Red and very clear, it shone on her chitinous tummy. She quivered in her web, horrified that we had opened the lid on her lovely darkness.


We don't see a lot of black widows here; they tend to like it warm and dry, like in the central valley, and they don't like being disturbed. They like the dark. They like it still and they like hard, close places like the spaces between woodpiles or behind cabinets.

Latrodectus hesperus, the Western black widow, is, like all widow spiders of the Latrodectus genus, very shy. If you intrude on her life she will flee first and ask questions later. Though her bite is incredibly venomous, she prefers not to bite unless grabbed, pinched or squeezed. I have seen black widows (in my precious trailer, no less) with abdomens more than a quarter inch across, and leg-spans close to one and a half inches (the males look very different, smaller and differently-colored and -patterned, so when I say "she" I know for sure that it's the female I'm talking about).

The male black widow isn't even black, most of the time

Unlike brown recluse spiders, whose venom is cytotoxic, meaning it is meant to slow down the prey, partially digesting the tissues and making for failure of the prey's systems, the black widow spider's venom is based on a neurotoxin, which I would much prefer. In mammals, when they are bitten by a spider with cytotoxic venom, it means the tissue surrounding the bite turns necrotic (dies) and is often unable to heal afterwards. There are some truly horrific pictures on the Internet of brown recluse spider bites several months on, which I would rather not contemplate.

"Spider venom falls into two categories: neurotoxic and cytotoxic. Neurotoxic venoms interfere with the transmission of nerve impulses to the muscles, frequently causing spasm and paralysis. Neurotoxins act rapidly, important to spiders confronted with large or dangerous prey intent on escape or retaliation. Cytotoxins, on the other hand, act more slowly. They principally act to slow down the prey, and actually begin the process of digestion by liquefying the tissues of the prey. Such venom can cause tissue necrosis in mammals, wherein the flesh surrounding an injection site dies, and heals very slowly or not at all."

The venom of a black widow, being a neurotoxin, has a more widespread effect, entering the bloodstream and being deposited at the nerve endings where the endings insert into the muscles. This causes intense, painful cramping and muscle spasms, and is very painful. It lasts a few days and then disperses, leaving only a few minor symptoms - spasms, tingling, nervousness and weakness - to remember her by. For me - though I would not want to encounter a black widow bite - the biggest fear has been for my children, because the smaller the body mass, the more likely the venom is to cause shock to the system and death.


Ultimately, though, I think black widows have gotten a bad rap. They really, really do not want to bite you. And only one kind of widow has been sighted as actually devouring the male of its own species after sex, in the wild. And although they are not artistic - building sticky, tangled and irregular webs from which they hang upside down to catch their prey - their silk is, like many spiders, stronger than its own weight in steel. If you built a bridge of spider silk, I remember hearing, it could be a hundred times thinner than the steel cables used in modern suspension bridges, and still just as strong. Less brittle, too. In fact, the strands are so fine and strong that for many years they were used in the crosshairs in the reticles for rifles and navigational instruments.

The chitin of the black widow, her exoskeleton, is so shiny and tough that simply spraying her living quarters with Raid will not kill her; you must spray it directly on her body for the insecticide to take effect. Even then, you have to use some pretty strong stuff for it to work. And it means you can't kill her without a little personal, face to face combat. Some people say that any strong essential oil will drive the spider away, as they prefer unlively quarters with little or no smell. Personally, I'm a big believer in a tightly-constructed house and a live and let live mentality; usually, I catch them in a glass (or get someone braver than me to do so) and release them far from where my children are likely to be. Sometimes, when I'm enraged (usually because I've been taken by surprise), I squash one - and then immediately regret it, because it always feels like I am killing someone, not something, when I kill a spider - they are so very much smarter than flies and their ilk. Plus, those widows are big, and it just isn't pleasant.


I remember once, in a shop in southern San Francisco where I went to buy a lizard when I was younger and had more time to be interested in the impression I made on others, I saw a large tank full of black widow babies. The shop was either displaying them (presumably under the same youthful impulse to be cool that made me buy a tegu, one of the world's most hostile lizards - sorry, another story) or they were selling them. I remember being in awe that the store owners, or the future pet owners, could be that hardcore. Despite the heavily-tattooed and pierced person behind the counter (very much less prevalent then than now), and the array of odd pets on display, I hadn't considered that anyone would be into selling poisonous spiders. Now, when I look back, I can't help seeing it as a little irresponsible, spreading poisonous beings who are pretty good escape artists via people who probably have no idea how venomous their new pets really are.

In any case, we tend to live side by side, the spiders and I, and I try to keep to the busy light and let them live in their quiet darkness. And if I or my children enter or move those dark places, we check carefully to see who we're disturbing before we go there. We demand the same awareness of the denizens of the dark, and if they cross that line, we do not forgive them. But all in all, we leave each other alone, living our lives and raising our children as if the other side did not exist.

Links:

Stringybark graphics has a fabulous redback spider pattern which they will put on t-shirts, linen dress shirts or any clothes they produce (click on the "prices" link). Guaranteed to stop conversations when you walk in. My friend Gwyan has had one for years and loves it.

A gruesome article, in the vein of the tegu store people, from the oh-so-reliable Sun tabloid where, of all the poisonous species in a man's home, the Widow takes the rap.

The Black Widow Hearse Club is a group of people who love funeral coaches.

Arachnids poster from the Big Zoo

Spider web ear wrap, covers your ear with a silver spider web

Drunk On Color

"Imagine, if you will," he said, "that we are not in a dank and mossy crypt, but in a room of gold... that warm rays make the air softer and yellower than butter; that you breathe not this base, black, wet mist, but a sparkling bronze infusion that has been mellowed by its constant reverberation within walls of pure gold." He sucked in his breath. "The light of this room would be just that shade that we are told arises sometmes against the clouds beyond the bay, making the world gold the way it is said happens once in a... every... well... sometimes. My plan, you see," he said in pain, writhing internally, "is to build a golden room in a high place, and post watchmen to watch the clouds. When they turn gold, and the light sprays upon the city, the room will be open. The light will stuff the chamber. Then the doors will seal shut. And the goldenness will be trapped forever...

"You can bathe in the light, drink in the air, run your hands along the smooth walls. Even in the pit and trough of night, the golden room will be brightly boiling. And it will be ours."
- Mark Helprin, Winter's Tale

My writing group has a term for that period every writer goes through in phases: the "I Suck" phase, where you can't imagine anyone would ever want to read what you've written. It's difficult to get anything done during this phase because you are so self-critical; it's hard to edit things when you can't see the merit in it.

During these phases I retreat into making things. I find that a certain amount of physical creativity keeps me alive, keeps me full of interest in the world around me, and makes me more able to write. I come back to the keyboard refreshed, with new stimulus to inspire my descriptions. And my favorite kind of making things pretty much always involves the mixing, blending, and juxtaposition of color.


Knitting, for example. I must stay away from yarn stores, because the intensity of all that color makes me lose some portion of my reason, and I find myself buying hundreds of dollars worth of yarn. And, though I love knitting - capturing all that color into something I or my loved ones can wear, it's never quite as beautiful as the raw yarn. The transformation removes some random quality of the way the colors overlap and interact, and I'm left with some nice item which is merely an echo of that original glowing dream.


Similarly, the pastels section in the art store grabs me. I want to have it, to dive in it and swim through it the way Scrooge McDuck swims through his money. Color, to me, is riches. I want to surround myself with it, lay it next to itself, play in it. It is a gastronomic experience of the eyes, like eating. It has flavor and timbre; each color is a note in a riotous and elegant orchestra of beauty.


So when I make something, color is a big part of the making. But, similarly, I am caught by it in the everyday world. In the grocery store, for example, I buy tangerines when they are in season not only because I love their flavor, but because they are presented in big, shining orange heaps, sometimes with wonderfully crackly dark green leaves mixed in. And the heritage tomato booth at the Farmer's Market draws me like an addict to her dealer. Somehow, the color and the flavor become mixed in my perception so that the depth of the fragrance mingles with the richness of color and incites me to salivation, both physically and mentally.


Another place I absorb color's juicy goodness is fabric stores, especially really good stores with imported fabrics. Tweeds, especially, get me, with their subtle flecks of color; or the deep intensity of the velvets. Iridescent fabrics and deep, changing furs and the liquid brilliance of good satin. And the trim: thin strips of fluttering color to edge your sewing, bobbling tassels and piping and the thin, gauzy brilliance of translucent ribbon.


Color has always been symbolic, and very culturally driven: from the Victorian construct of the meaning of roses, to the colors people have been allowed to wear (as in the Sumptuary Laws of Elizabethan England and earlier), to the colors worn traditionally for rituals such as marriage and mourning. In Western culture, for example, black symbolizes darkness and the unknown, and death is nowadays associated with the extinguishing of light. In Asia, on the other hand, white is the color for mourning, either to symbolize enlightenment, winding-sheets, bones, the leaching of joy, or perhaps some other point of view I'm not familiar with: but interestingly, there is evidence that until recently, white was a mourning color in Western society, as well.

The sumptuary laws of Rome defined exactly who could wear the Tyrian purple dye, and how much. The Victorians believed that yellow roses symbolized jealousy (though my father gave my mother yellow roses when I was born. I doubt that was the understood symbolism between them). In America, a bride wearing a red dress would traditionally be frowned upon as a hussy; but in China, Japan, and Korea it is a traditional bridal color, symbolizing good luck and auspiciousness. And with this influence entering Western society (along with the decrease in popularity of virginal brides), the red wedding dress has become all the rage.

So the cultural definitions of the meaning of color are constantly changing. Until quite recently, men's clothing was much more on the model of male birds: the more colorful ones were more successfully showing their desirability. And less than eighty years ago, pink was considered a masculine color.


One of the greatest contributions the early Modernist painters made to art was to break with tradition, painting not in the accepted colors of nature but in the colors of feelings, of nuance, and of mood. Who, for example, has a green line down the middle of their face? Or the idea that you can sprinkle together wildly varying colors which have nothing to do with the subject at hand - and still end up with an image that is recognizable, even full of light and beauty. So perhaps my knitter's obsession with flecked yarns is not simply an addiction, but is rooted in a deeper artistic vision: that of the greater beauty of delicately trembling variety.


Everywhere I look, there is something to drink in. The seasons themselves aid me in my color addiction, changing ordinary things subtlely each month so that I cannot stop looking. The oak trees around my house, for example, are covered with a type of fast-acting moss, which interacts with water over the course of minutes to transform from dull, dry-looking brown stuff into glowing green fairy-carpet. When it rains hard, I go outside to look: I can't help it.


Big Sur, one of my favorite places to visit, is largely attractive to me because of the varied carpet of plants which grow on the roadside: sage brush, Indian paintbrush, yellow lupine, yarrow, iceplant reddened by salt, and any number of others which I can't name but which add to the mixture in rich but imperceptible ways.


Similarly, there is an ever-changing panoply of plants along the road where I live - sage, sticky monkey flower, yarrow, succulents and ferns - which has a completely different flavor, a milder, more delicate spice. And both change, depending on when you visit. Right now we are drenched in orange and blue, the color simply licking at your eyeballs, as the pastures explode with purple lupine and California poppies. When this happens, which is not quite as often as I would like - certainly not every year - I try to go and sit, at least once in the season, in the middle of one of these seas of color and just keep my eyes open until I'm full. There are so many things to see around us: the electrical fizz of the California sky against the edges of things; the phosphorescence of the right kinds of geraniums (the Mediterranean kind, not the English kind). And every country has a different light, making the colors wash over you all over again.


Cities, with their muted greys and sombre, sooty brick, hold a peculiar fascination in the romance of the grit, but after living in some very industrial cities I can truly say I don't miss the oppressive lack of color. Although in the east end of London, sometimes, the brilliant green glow of London Fields against the sooty backdrop of the rest of Hackney used to make my mood rise and my eyes dazzle.


Interestingly, the science of color tends to look the same no matter if you are coming at it from biology, computers, or painting; the structures are similar, if the specific results are different. For example, mixing colored light is what's known as additive color: you start with blackness, and add light to get a color. Mixing pigments is subtractive color - you start with a white reflective surface and add things which absorb some of the light (subtract it), changing what is reflected, in order to make color. When you mix all additive colors together (mix light together), you will end up with white; when you mix all subtractive colors together, you get... well, a dull grey - but in theory, you'll end up with black.

Computers use additive color, mixing red, green and blue to create, if not every color in the universe, then at least millions of them (which for our eyes is close enough, most of the time; the human eye can distinguish about 10 million separate colors). By adding no colors, you can get black; by adding red, green, and blue (RGB) in equal amounts, you can begin to approach white. The more of all three colors you add, the more pastel the colors.


Pigment, on the other hand, works quite differently. The traditional color wheel shows red, yellow, and blue as primaries, which, by mixing any two equally, creates the secondary colors orange, green, and violet. But as anyone who has tried mixing fire-engine red with blue can tell you, these colors in actuality don't work that well. So for color printers, the inks are actually cyan (turquoise), Magenta (pinky red), and Yellow (and black, to make things get dark, because the pigments for printers tend to be somewhat transparent and let the light through).


Our nervous system, on the other hand, "derives color by comparing the responses to light from the [three] types of cone photoreceptors in the eye [as opposed to rods, which distinguish only dark and light]. These cone photoreceptors are sensitive to different portions of the visible spectrum. For humans, the visible spectrum ranges approximately from 380 to 740 nm, and there are normally three types of cones. The visible range and number of cone types differ between species." [wiki]

Long ago, before the dinosaurs, our early fish-like ancestors had trichromatic vision (three cone receptors). For some reason, this was lost it in the time of the dinosaurs, and then later, regained by a few primates, in an act of complete Darwinian fluke. This explains why primates are the only mammals who have trichromatic vision - it is a trait mostly found in birds and reptiles (dinosaur descendents). Even then, it's mostly old-world primates who are trichromatic; for new-world monkeys, only some females (depending on individual inheritance rather than species) are trichromatic. All the males of most species, and many of the females, are dichromatic, meaning they only have two kinds of cone cells. This is because two kinds of cone designation are passed down on the X chromosome, so the males can only ever have those two, while females who have a double helping, so to speak, of cone types actually end up able to inherit all three.

Eggs: Green or Red?
For the monkeys, this has been shown to make for an evolutionary advantage, since the color-blind monkeys can't see fruit so well, and so therefore, not being distracted, tend to concentrate on other foods (such as certain kinds of leaves) which are noticeable by their shape; these foods, combined with the fruit found by the color-sighted monkeys, ensure that the group as a whole has a much broader diet than it would otherwise.

There seems to be a very interesting possibility that more cone types actually exist, because most genetic color-blindness is based on a mutation of the X chromosome's color receptor genes. In other words, they shift to a type of cone that doesn't perceive color the way it is supposed to. Theoretically, this could mean that both the monkeys and color-blind people, then, could have a type of cone which perceives something else - something which hasn't been measured.


Perhaps there is, then, some higher purpose, some evolutionary advantage, to those of us who get drunk on color. My children have a book by Leo Lionni called Frederick, about a mouse who doesn't help with the work all summer, harvesting and storing and preparing for winter. When the other mice complain, he says he is storing up all the color, the sounds and smells of the warm weather. When winter comes and all the food they have gathered is running low, he then begins to recite to them his poems, which warm the mice and fill them with the poems' evocation of flowers, sunshine, the color of fresh berries, and so on. So, in a very real sense, he was doing his work as well.

On this basis, I would like to think that my attraction to color is not merely some form of magpie consumerism, but a hoarding of beauty which I can then play back in my writing - bit by bit, during the dark times, the moments of I Suck-ness: those periods when things have gone dull and flavorless. All hail those piled-up tangerines!

Lions and Tigers and Bears, Oh My!

Note: 5 out of 7 of the pictures in this post were taken by me, with my daughter's cheap instant camera. The quality of the photos isn't very good, but it doesn't seem to matter, which says much about the quality of their subject matter...

This spring break I took two days to go to New York City with my elder daughter, aged ten. This is not a simple thing when you live in California. I sent her on ahead alone to stay with her uncle for a few days, then met her there. And one of the things she wanted to do was go to the American Museum of Natural History..

I've heard about this place (and even walked past it) for many years, and I always thought it was another one of those "New York things you're supposed to see," like Times Square (which really isn't much more than a touristy place with a lot of neon, like Piccadilly Circus or the Umeda district in Osaka - or, of course, Yasukuni-dori in Shinjuku, and the Akihabara area, both in Tokyo). But when we got inside, I understood why this museum is famous.

We came in via the subway station, so at first it simply seemed to be floor after floor of echoing halls, with little sense of how to get from here to there. Then I saw a gaping doorway which said above it "African Mammals," and I dragged my daughter inside, though she wanted to find the North American Mammals. As we walked into the darkness we were greeted by a huge herd of stampeding elephants, coming right at us, their size more stunning than I had thought possible; and then we began to walk around.


Much to my surprise, the dioramas were breathtaking, complete works of art which stunned both of us.

The taxidermy was beautiful and incredibly lifelike, thanks to the efforts of Carl Akeley, who developed a technique for insanely detailed and perfectly shaped taxidermy techniques. Mr. Akeley, who grew up on a farm and only had three years of school as a child, learned taxidermy and created the world's first complete museum habitat diorama in 1890. His Wikipedia page is absolutely fascinating - he changed not only how museums display things but affected publice thinking on the collection of specimens and farming and other encroachment on natural habitats.


Akeley's method was to insist his artists visit the field and take careful measurements of each individual specimen, along with plaster casts of each animal's body. They then brought casts, measurements, skeletons, and skins of the animals back to the museum. They then set up the skeletons and built perfect replicas of the musculature of the individual animals out of clay on the animal's own skeleton. Every muscle that should be flexed for the pose, was flexed, and every muscle that should be relaxed was relaxed. They then took multipart plaster casts of this, pulled out the clay and the skeletal remains, and used the mold to make a hollow papier mache form, on which the skins were then laid. It was the first time anyone had tried to replicate individuals rather than going with a generalized model of a typical specimen.


William R. Leigh, master painter in charge of the backgrounds in the African Hall, was hired by Akeley himself, and accompanied Akeley to Africa to do field sketches. He and eighteen other painters painted all the backgrounds in the dioramas in the African Hall, the North American Hall, and most of the other dioramas. They started in the 1920's and worked on through WPA times, crafting dazzling scenes with startling detail and accuracy; many of the North American scenes were taken from national parks, which were, at that point, in their heyday.


The interesting thing about Akeley and most of the other people who participated in the creation of the dioramas is that they saw, as they traveled, the habitats of the animals and the incredible variety and beauty of the places they were trying to represent; and all of them were touched by it. It became the goal of the museum to show the public this beauty, and to represent to them the delicacy and individuality of the habitats, so that the general public would understand the need to preserve these places. They predated nature photography and film, and were, as Stephen Quinn, the Senior Project Manager in the Department of Exhibitions, says, "an early form of virtual reality. Curators, who were concerned about vanishing wilderness and wildlife, were looking for a medium to nurture environmental awareness and raise concerns about wildlife species. The intent was to recreate nature within the artifice of the museum, to recreate that close incounter with wildlife that would move a person to care."


I can hardly see how a person could help but be moved: the care and detail evident in these loving recreations are so evident that we find ourselves caring, just because the creators cared so much themselves. I can't recommend it enough; next time you are in New York for whatever reason, take a couple of hours and check them out. Personally, I want to go back and spend a whole day there.



Links:

The AMNH website's very cool section on the dioramas, how they were made, and who made them, complete with interesting little videos of Stephen Quinn speaking about the exhibits (He is also the author of Windows on Nature, a book on the history and influence of the dioramas).

How the American Museum of Natural History's model of a giant flea was made - Scientific American, 1914

How Twins Go Bad

or: The Thing Inside


Caution: may meander into the squeamish zone in both words and pictures... be warned.

I don't exactly know why I am fascinated by cojoined twins. Sometimes I guiltily cruise YouTube, watching videos about successful and unsuccessful separations. Very often the way the twins are joined is terribly difficult: at the top of the head, sharing organs, or with one twin unable to function because of their relationship to the other child. One of the most famous examples of a successful pair is Abigail and Brittany Hensel, a pair of "highly symmetric dicephalic parapagus" (ie, joined at the bottom, with two heads). It is difficult to tell but it looks as though they only have two arms, as well. They are both conscious, functioning girls with very separate personalities and interests, and are growing up apparently without problems, a very unusual case.


In fact, when you look at how their body is arranged, it's nearly miraculous: they have two heads and two stomachs but their small intesting has a "Y" intersection which, with a few minor problems, works fairly well. They have separate spines but one ribcage, two hearts and four lungs, but a shared diaphram. They can only feel their own half of the body, but they can do things such as type, ride a bike, and drive a car without mishap or misunderstanding. It's rather amazing.


More often, cojoined twins do not do well. Their mortality rate is about 75%. There are just too many complications, and all the things which seem to have gone right for the Hensel girls could just as easily fail through lack of alignment or poor formation of organs, which leads to their failure. Twins that are cojoined at the head often cannot function together, but separation can lead to the death of one or both of them, as the brains are involved.

What causes twins to be cojoined? There seem to be two separate theories on that. The older theory, the one I'm more familiar with and which leads to cases like the Hensel girls, is that during development the fetus separates as it does in the case of identical twins, who are two children made by one fertilized egg splitting completely in half. Except that in the case of cojoined twins, the split is incomplete. So you get children who share pelvises, skulls, etc.

Another theory is that in some cases, "a fertilized egg completely separates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuse the twins together." [wiki] Which implies that in the kinds of cases for whom this theory would apply, the joint is less extreme: some fleshy part of the (mostly separate) twins is joined. In the case of Chang and Eng Bunker, a pair of Thai cojoined twins who traveled with P.T. Barnum's circus for many years and from whom the term "siamese twins" comes, they were joined by "a band of flesh, cartilage, and their fused livers at the torso." This type of cojoining is very easy nowadays to separate.


Then there is the scenario where one twin is described as "parasitic," because it does not have a heart and/or a head of its own, and therefore lives off the circulatory system and resources of its twin. Parasitic twins can be attached in many different places, and are often much smaller than their fully-formed twin. A well-known example of this was the recent case of Lakshmi Tatma, found in a remote area of India at age two, who was joined to her twin pelvis-to-pelvis (with the twin between her legs). Thirty-six doctors took turns separating her spine and moving her bladder, then moving her pelvis together so her legs could point downward instead of off to the side. She had one non-functioning kidney, so the doctors replaced it with one of her twin's; she was then put in a cast designed to keep her legs together. A year later, it seems she was doing fine, beginning to learn to walk, and so on.





Parasitic twins generally do not improve the life of the main twin, not just because it is uncomfortable or embarrassing, but because it is a drain on their health and resources. One form of parasitic twin, called fetus in fetu is another, more rare and often devastating case of poor twinning, where the fetus of one twin, it seems, actually forms around the other, in effect born with another body inside it. One man, in India, lived for thirty-six years with his twin inside him, growing as he grew. I can only imagine how much weight it was to carry around, and how much he must have eaten to keep them both healthy.

Another boy in India went to the doctor because of his abdominal swelling, which was seen to move. A nearly-fully-formed twin was found inside him, with hair, toes, arms, legs, and even a vague face. This kind of completeness is rare in parasitic twins, especially among fetus in fetu, which tend not to be "alive" in the sense we think of, but rather a sort of growth in human form.


There seems to be a grey area between a fetus in fetu and what is called a teratoma: a kind of encapsulated tumor which contains "tissue or organ components resembling normal derivatives of all three germ layers. There are rare occasions when not all three germ layers are identifiable. The tissues of a teratoma, although normal in themselves, may be quite different from surrounding tissues, and may be highly disparate; teratomas have been reported to contain hair, teeth, bone and very rarely more complex organs such as(...) hands, feet, or other limbs." [wiki] ...or tissues from various organs. Teratomas are more common, and more benign, in women and girls, because they often form on the ovaries, where undifferentiated cells can be found; in men, they are more often malignant, for no reason that I've been able to find. Teratomas are considered to be congenital, in other words, they are present at birth, but not found until later on.


You can get teratomas in your brain or other organs, on the outside of your body (such as on the skull sutures or on the back of the pelvis), around your tongue and in your throat. I find them incredibly creepy, because they can contain pieces and parts of a person, encapsulated in a little pod in the body, as if someone had been trying to form, and failed miserably.

Curiously, I don't always find the parasitic twin phenomenon creepy; as the wonderful Human Marvels website describes, in the case of Ernie Defort, who was born with his "brother" Lem attached to his sternum, some people, if left to themselves, will become quite emotionally attached (hur, hur) to their extra parts.


It strikes me that this is not so different from the imperfections we all experience: if left to ourselves, we can become used to them and even like them, as being an integral part of ourselves. It is only when we listen to the media, or other external voices, that we begin to doubt who we should be.


Some interesting books on freaks/human marvels (which is what many cojoined twins and people with parasitic twins did to make a living in the old days):

Monsters: Human Freaks in America's Gilded Age: The Photographs of Chas Eisenmann, a book of really quite wonderful photos taken in the late 1800s by Mr. Eisenmann in his studio in New York.

American Sideshow, a lovingly-detailed and warmly described history of sideshow performers in America from the 1830s to the present. With recommendations on Amazon by some of the participants.

links:

Colorado Doctor Finds Foot in Baby's Brain [link]

More info on parasitic twins, thanks to The Human Marvels

Gecko's Feet, Redux

John Stevens sent me this fabulous video he took of a gecko moving its foot, after reading my old post on gecko feet. Please note the backwards arrangement of its joints, so that the gecko can change the angle that the setae (the tiny hairs on their foot) touch the surface with, helping to shift the way the Van der Waal's force holds them there, and thus peel their foot away. John actually posted it on YouTube at my request -- many thanks!

A Rule of Thumb

"Fingerprints have been found on ancient Babylonian clay tablets, seals, and pottery. They have also been found on the walls of Egyptian tombs and on Minoan, Greek, and Chinese pottery — as well as on bricks and tiles in Babylon and Rome. ...on some pottery, fingerprints were impressed so deeply that they were likely intended to serve as the equivalent of a brand label." [wiki]

There is something eternally fascinating about the ridges and whorls on our hands and feet, those unrepeatable patterns which cover most of what is termed our "volar skin", that is, skin of the palms of the hands or the soles of the feet. When I was a kid I spent hours staring at the swirls and lines, looking at where they ended - and wondering why they were there. "Designs" I called them, when I was young.

I even went through a period, when I learned about fingerprinting and the idea that everyone has completely different fingerprints, where I made everyone around me (mostly adults) squash their fingers onto my ink-pad and leave their mark on the paper which I carried around for the purpose. Of course, it wasn't washable ink, so there seemed to be an inordinate number of long-suffering, black-fingered folks around my household.

The other night I got to talking with friends about fingerprints. How do they work? Why do we have them? The conversation didn't go very far, but it did make me decide to go look it up. Forty websites later, I am still no expert, but I continue to be fascinated.


(Koala fingerprint, above, versus human, below)

For example, did you know that koalas are one of the few mammals besides primates who have fingerprints, and in fact even with an electron microscope, it is difficult to tell koala prints apart from human prints? There's a mystery story in there somewhere, like The Murders in the Rue Morgue only (hopefully) more believable (anyone met a murderous orangutan lately?). Fishers are also said to have fingerprints, which seems to me very strange: if fishers do, why not stoats? Weasels? And so on?


Spider monkeys, whose prehensile tail-tips are so sensitive and flexible that they can pick a dime up off a floor, also have prints on the bare spot at the end of their tails. Since the tails are used not only as a sort of third arm when swinging in the trees (as a safeguard from falling), but often supports the entire weight of their bodies while they feed, this would make sense: fingerprints, and other places with "friction ridges" - the volar regions - generally tend to occur where one needs to grip something. This can mean gripping an object to keep from dropping it, or (as in the case of trees) to keep it from dropping you, or simply to keep your feet steady on the rocks so you don't fall off a cliff.

But how does it work? One source I was perusing posited that there could be a Van der Waals force element, like gecko's feet. The person cited the fact that our fingertips can feel the grittiness of a powder down to about 150 microns, and then it just didn't feel gritty anymore; since Van der Waals' forces tend to show up more when something is 150 microns or smaller, he conjectured a connection.


Other sources, however, didn't support this idea, even if it appealed to me. The general belief among my local pundits was that friction ridges weren't deep enough, enclosing enough or wet enough for either suction or for cohesion; and their structure wasn't complex enough for Van der Waals. The consensus was almost entirely on friction. Given that the flesh in these dermal ridges (to use another term) are notoriously squashy (thus making crime scene fingerprints - known as "latent prints" seriously difficult to decipher), the friction thing holds up as an answer. Just as tires made of squishy gel are more likely to stick to the road than ones made of hard plastic, so do the flexible, moist areas on our hands and feet provide an excellent surface to grip with. Thus does the fingerprint contribute to our development as tool-users.


Dermal ridges develop in the womb, and are pretty much developed by seventeen weeks. The patterns on our fingers are influenced by our time in the womb: subtle stresses and tensions affect how they grow, creating uniqueness through a combination of genetics and in utero experience (as can be seen by genetically identical twins, who don't have identical fingerprints). Once the fingerprints are set, they cannot be altered easily:

"Should the top layer of skin suffer any injury, the ridges grow back after healing in the exact pattern they had before. Therefore, superficial cuts or abrasions alter fingerprint characteristics only temporarily. If the injury reaches deep into the dermis and destroys the dermal papillae, then growth of new epidermal cells is impaired and a permanent scar is created."
[New South Wales Police Department]


The way the ridges develop, oddly, depends on the arrangement of the sweat glands, rising to pores which, in the volar regions, protrude in papillae (nipple-like structures) above the baseline of the skin surface. As these grow, they also grow connections to each other in rows - and this is how the lines and whorls of the fingerprint are created.

It also explains why fingerprints - the kind the police use for identification - are often made up of what appear to be rows of dots, rather than nice smooth lines:

"Such pore holes are critical to the production of latent prints since sweat reaches the surface of the hand and efficiently coats the tops of the fingerprint ridges with sweat. Sweat glands serve as small chemical reservoirs and contain a variety of water-soluble chemical compounds, produced or stored by the body."


In other words, we leave a chemical trace when we touch things, as rows of little oily mineral sweat-dots.

For those of you who have ever worried about the old hair-on-the-palm story, you can relax: both sebaceous glands and hair follicles appear in the dermal layer of other skin surfaces but don't in friction skin. Probably for good reason. How useful would it be to have painful pimples on the palms of your hands if your best escape from predators was to swing up into a tree?

Johann Christoph Andreas Mayer recognized in 1788 that although friction ridge patterns could appear similar, they never seemed to repeat themselves. Using fingerprints' unique patterns as an identification system, however came in much later, starting with the movement to the cities in the Industrial Revolution, when people began leaving their ancestral homes, where every face was familiar, and moving into more populous environments, where they were more difficult to identify and it was harder to find out their history.

"...felons quickly learned to lie about their names, and the soaring rate of urban crime forced police to search for a more exacting way to determine and keep track of identities. The first such system was devised in 1883 by a Parisian police clerk named Alphonse Bertillon. His method, called anthropometry, relied on an elaborate set of anatomical measurements -- such as head size, length of the left middle finger, face height -- and features like scars and hair and eye color to distinguish one person from another. Anthropometry proved useful, but fingerprinting, which was then coming into use in Britain, held more promise...


Francis Galton

"In 1880, Dr. Henry Faulds published the first comments, in the scientific journal Nature, on the use of fingerprints to solve crimes. Soon afterward, Charles Darwin's misanthropic cousin, Sir Francis Galton, an anthropologist and the founder of eugenics, designed a system of numbering the ridges on the tips of fingers -- now known as Galton points -- which is still in use throughout the world. (Ultimately, though, he saw fingerprints as a way to classify people by race.)"
-- [Michael Specter, from a fascinating article on the fallibility of fingerprints in the New Yorker]


Bertillon's method was actually quite popular in France long after fingerprints had become popular everywhere else (a member of the Bonnot Gang actually sent his fingerprints to the French police because he knew they only had his physical measurements on record). This popularity after his long struggle for the legitimization of his system meant that Bertillon was able to go on to implement such innovations as mug shots, systematized crime scene photography, ways to preserve footprints and ballistics, and the dynamometer, used to determine the degree of force used in breaking and entering.

Now, after a nearly hundred and fifty years of fingerprint analysis being considered unquestionably right, despite any evidence against it in trials across the world, a few cases have brought the practice into the limelight. Much of fingerprint analysis hasn't changed since it was first created, and its status as a "science" is coming into question, since scientific method, not to mention actual studies of the practice to see how accurate it is, seem to be missing from the process.


Some people are, actually, born without fingerprints. A genetic disorder due to defects in the protein Keratin 14 lead to two different diseases causing embryos not to form friction ridges. It makes it difficult to do certain things, like turn pages or deal cards. Most of all, it makes it difficult to get certain kinds of jobs - such as school teacher, nurse, and so on. Not to mention working for the government in either law enforcement or classified work.


In the old days, safecrackers used to sand the ends of their fingers to make them more sensitive and to make their fingerprints less identifiable; but that seems to be going out of fashion in contemporary times. Nowadays, you are more likely to affect your whorls by picking up a tiny virus-based skin tumor called a plantar wart (veruca), which deforms the skin striae as it grows, making the ridges go around it. When the wart finally goes away, your striae never look quite the same...

So, the next time you are lying on the couch with a loved one's feet in your lap, have a look, and marvel at the fanciful shapes and swirling minutae of their toes. Think about how long they have been on our feet, probably millions of years, and how even though we wear shoes, our bodies still create these wonderful artworks. They really are amazing.




Links:

A simple timeline on the history of fingerprints

Michele Triplett's Fingerprint Dictionary: Every term you could possibly want to know about fingerprint analysis and police procedure.

A little YouTube of the beginning of my favorite story about safecrackers, Butch Minds The Baby

Website about Sir Francis Galton, above

Photoshop brushes which give you fingerprint effects over at DeviantArt