Senses - a Baker's Dozen

 kw: book reviews, nonfiction, natural history, science, senses, physiology

I discovered something shocking about Chinese soup. At a church potluck dinner we all enjoyed a bowl of soup from a big pot one Chinese sister brought. It had an intriguing taste, similar to soups made with Star Anise, but subtly different. In my bowl I found a black pod. I was told it was the seed pod of water chestnut. I bit into it, and had quite a surprise! Suddenly the soup tasted awful. Water tasted like battery acid. Every taste was distorted, in quite unfortunate ways, for about a day. When I told this to the cook, she laughed and said, "You aren't supposed to eat Chinese spices!" I couldn't stand to eat or drink anything until the next day.

I found out that this seed pod goes by many names, including Devil's Pod. You can get them from two sources: Chinese food stores, and Etsy, where they are sold for use in crafts (not as a food item).

The words "taste" and "flavor" have different meanings. For a physiologist, "flavor" includes both taste and smell. That is but one tidbit I find in Sentient: How Animals Illuminate the Wonder of Our Human Senses by Jackie Higgins. Another is that the five kinds of taste we know may actually number seven. In addition to sweet, sour, salty, bitter, and savory ("umami", triggered by glutamine from protein), some researchers have found hints that our tongues have sensors for calcium (a different kind of salty) and fat.

We all learned that the "five senses" are sight, hearing, taste, smell, and touch. These are the senses that have visible organs. However, we also have senses of balance, hunger, and a host of others that may number more than 20. Indeed, our eyes sense two different regimes of light. When the only light in a room is a candle, but we can still see colors in all except the gloomiest corners, our sight is near the threshold of photopic vision. Light bright enough for us to distinguish colors is sensed by the color-selective cones in our retina. Moonlight, particularly when the moon is a few days past full, or a few days shy of full, is sensed by the color-blind (actually blue-green sensitive) rods in our retina, and we can see rather well by scotopic vision.

There is actually another network of light-sensing cells in our retina that connect to our body clock, so that day/night cycles reset it daily. Long-term experiments with people in caves and bunkers have shown that without this daily resetting, our body clock tends to run on a 25-hour cycle. Thus, in addition to color vision and night vision, our eyes have a third function related to our sense of time. Body temperature, blood pressure, and alertness run in daily cycles; the "afternoon sleepies" aren't just because of that big lunch you ate.

The 12 chapters in Sentient each focus on a different sense. Eleven of these are known in humans: 

• color vision
• night vision
• hearing
• touch (but this is a multi-modal group of senses with different receptors for each)
• pleasure and pain (two levels of stimulation of one set of receptors)
• taste
• smell (by itself, or as bundled into "flavor" with taste)
• desire (pheromones)
• balance
• time
• proprioception (required to touch your nose with eyes closed)

The twelfth (Chapter 11) is direction, which we'll get to shortly. There is a bonus chapter on a 13th sense, the electric sense in the bill of a platypus. Sharks and other aquatic predators also have it. Humans don't; getting an electric shock stimulates nerves directly, but there is no sensor that allows us to know the subtle electric fields around moving animals. That's probably a good thing. If we had an electric sense it would be overloaded by the pervasive 60- (or 50-) cycle hum found everywhere except unpopulated areas and Amish homes, and by the multitude of electromagnetic signals that bring our favorite programs to AM and FM radios and TV antennas.

The iconic animal in each chapter is renowned for excellence, or exceedance, in the chosen sense. For example, the Mantis Shrimp of Chapter 1 has, not just the three color sensors that we (and most primates) have, but a total of TWELVE, including one or two that see ultraviolet. Apparently, in the extremely colorful environment of a coral reef, it is thus better able to discriminate specific prey by their colors. Chapter 6 on Taste tells of a large catfish. Catfish are known to have numerous taste receptors all over their bodies; one researcher calls a catfish a "swimming tongue". The Goliath Catfish is the largest; think of a ten-foot tongue swimming around.

I was quite interested in the directional sense that some people exhibit (Chapter 11). Many animals including migrating birds are found to have pieces or chains of magnetite crystals that let them sense, and perhaps even see, the magnetic field of the earth. When migrating, they follow the direction of the force, or go at an angle to it; at the end of the trip, they may sense the steepening angle as they approach the magnetic pole, and finish their journey when the angle reaches a certain degree. Do humans have a magnetic sense? Many experiments include quite a number that seem to say "Yes", but some seem to say "No" and others are equivocal. If humans do not have a magnetic sense, that'll be odd, because so many mammals do have one, and members of nearly every other group of animals have it. We do have something, or some of us at least, for there are those who always know which way is north, or home, or another chosen direction, even after being taken somewhere blindfold.

This is so far my favorite book this year: Fascinating, packed with very interesting information, and easy to read.

I'd like to end with speculation about a fourth sense that may be located in our eyes. It is something I've noticed after I turn out the lights in my bedroom. In the dark, with my eyes closed, I seem to be able to see my hand and arm move, and also the blanket, when I rearrange the covers. This is not scotopic vision somehow seeing through my eyelids. The rods are sensitive to blue-green light peaking at 500 nm (normal green-sensitive cones peak about 540 nm). Rods cut off on the longwave side at about 600 nm, but hardly any light shorter than 600 nm gets through our red-colored eyelids, because of the blood in them.

By my bedside is a clock radio with bluish LED numerals. I have a pink filter over it so it doesn't light up the whole room (the radio is poorly designed). It is plenty bright enough for me to see the blue color. I can't see it at all through my eyelids, even when fully dark adapted. But there is a little reddish light in the room from a couple of pilot lights on equipment, and a pinkish light that comes through the windows from skyglow. When there is still enough light in the room to see faint colors it looks like this (picture edited to look like what I remember):

On moonless nights, after my eyes have become dark-adapted, it looks more like this:

The slight bluish hue is typical of scotopic vision. A scene by moonlight looks bluish, even though the moon's actual color is brown. Although rods outnumber cones 20-to-1 (120 million rods and 6 million cones), they are ganged together for greater sensitivity, which greatly reduces the sharpness of the scene.

Now, here is what I noticed about a year ago. I typically turn out the light around 11 or a little later. Even before I am fully dark-adapted, when my eyes are closed and I readjust the covers or move my hand, I can see the movement of my hand and the covers, and if—still with closed eyes—I look around the room, I can see the outlines of what is in the room, a little more faintly than if I open my eyes, but distinctly. The windows seem the brightest. Further editing of the photo from above yields this, which matches what I see:

It is perhaps twice as blurry as scotopic vision, and the light and dark areas are a little different. If I hold up my hand and wave it about it seems black. If I raise my head and look at the clock radio, with its dim blue numerals, I don't see them at all.

Is it possible that I am seeing right through my eyelids? If so, it must be by sensors that see by the pink light from the windows, and/or the faint red light of the pilot lights. It could be something else entirely.

I have considered that my brain may be conjuring a dim memory of the room, as part of a normal vision function that anticipates what is "normal", priming the visual system to detect any differences. My brain knows where my hand is; it knows how the bedcovers move when I shift them; it knows where the windows and furniture are. It could know enough to meld proprioception (knowing where my head is pointed and where my hands are) with this calculated scene so that the scene "stays put" when I turn my head.

I cannot decide at present whether I am actually seeing, or constructing, what I sense.

Learn all about fat. Get depressed.

kw: book reviews, nonfiction, physiology, fat, weight loss

I have known for a long time that for many of us in affluent countries, weight management is a fierce challenge. We can see this from the very existence of Weight Watchers, Nutrisystem, Jenny Craig and literally hundreds of other clinics, systems, and plans, and the $60 to $150 billion that Americans spend on weight loss proves it. If weight management were easy it would be cheap, and we wouldn't need all those clinics and "life coaches" and the rest.

Now we can learn in great detail just what we are up against…if we really want to know. I suspect many folks don't want to! I am not sure if I am happy about knowing, either. Like it or not, I just finished reading The Secret Life of Fat: The Science Behind the Body's Least Understood Organ and What it Means For You, by Sylvia Tara, PhD.

You read right: Dr. Tara calls our fat system an organ. It is the largest and most complex endocrine organ in our body, except perhaps for a very few people who cannot deposit fat and as a consequence must eat tiny meals two to four times hourly to stay alive and comparatively pain-free. Do you think you'd like to be truly fat free? Without a system of depositing fat, which our liver and other organs produce continually, the blood gets milky with circulating lipids that just go 'round and 'round until they are used up by metabolic processes. Heart attack at a young age is the typical fate. People with this affliction who try to eat "more normally" wind up with painful lipid deposits in the skin, rather than normal layers of healthy fat, and in either case they look like walking skeletons, like it or not.

Fat does a lot more than regulate our energy stores. As an endocrine organ, it communicates with the rest of the endocrine system, regulates appetite and metabolism, determines our fertility (or its lack), and stands ready to help us stave off a famine. In babies, the "brown" and "beige" varieties of fat produce extra energy to keep the little body warm. When you have the weight-to-skin area ratio of a house cat, but no fur, you need to produce a lot more energy per pound to keep from freezing to death at "normal" temperatures in the 70's (or the low 20's in Celsius). A strange therapy that turns some "white" fat to "beige" fat is being tested to shift people's energy balance for weight loss. It promises to be even more costly than staying at a Mayo Clinic Weight Loss residence.

You may have heard of ghrelin, leptin and adiponectin. These are just three of the signaling molecules that make us hungry, or not. Leptin turns down our "appestat", the others raise it. Several other signals shift our cravings here and there. Others "tell" fat to deposit itself in our subcutaneous layer ("safe" fat) or viscerally ("dangerous" fat). Guess what can shift all of these in a healthy direction? Exercise. Lots of it. Nothing else is as effective.

Also, as we are only recently learning (partly because of a genuine conspiracy carried out 50 years ago), sugar is much more of a culprit in making us fatter and making that fat less healthy than we used to think, as compared to dietary fat. To be clear, trans fat is truly evil (and all of us who grew up eating Margarine rather than butter must shed a tear here), and also, while saturated fat is a little better and some is actually necessary, saturated fat has to be balanced with the mono- and poly-unsaturated varieties or it does cause problems. But excess sugar is the worst, and sugar substitutes, oddly enough, are almost as bad, because the insulin system kicks in when we taste sweetness, regardless of source. An insulin spike causes fat to be deposited.

During my last ten years working, I got in the habit of drinking about a liter of sugar-free cola daily (Pepsi Max had the best taste). Upon retirement I stopped drinking soda almost entirely, and lost 15 pounds. At first I thought the weight loss was because I was under much less stress; chronic stress also causes weight gain. But now I think it is probably at least half due to stopping my soda pop habit.

After nine chapters of the science of fat—and fascinating science it is—the last four chapters are the "how to" section. The author is a woman, she is descended from an ethnic group in India that endured repeated famines for millennia, and both of these work to make her metabolically fitted to gain weight and hold it, waiting for the next famine. She has also done a certain amount of yo-yo dieting. Guess what? If you have never been overweight, you have a metabolism that matches the calculations at sites such as the Basal Metabolic Rate Calculator. There I find that my basal metabolism is about 1,750 Cal/day, with a dietary intake need of between 2,400 and 3,000, depending on how active I am. Were I female, these numbers would be 1,550, 2,050 and 2,650 (Note: I rounded the numbers from the overly-exact calculations. Also, when I write Calorie, I refer to kilocalories. The calorie of physics is 1/1000 of a Calorie).

What if you have dieted, and regained your weight? Your fat system changes, permanently, so that maintaining the weight now requires fewer Calories, a lot fewer (20-30%). So, you struggled with a 1,200 Calorie per day diet and lost 25 pounds. You used to eat 2,400 Calories daily. If you go back to a 2,400 Cal/day diet, you'll gain it all back, and then some. You'll even gain it back, more slowly, at 2,000 Cal/day! If the BMR Calculator says your dietary need at the weight you want to maintain is 2,250 Calories, you'll actually now barely be able to hold the new weight at 1,700 Cal/day. That is a cruel fact of weight loss-and-regain.

Chapter 12 is titled "Fat Control II: How I Do It". Dr. Tara eats no dinner. Ever (hardly ever!). She chronicled, almost pound-by-pound, how she lost a certain amount of weight over about a year, and how she did it using a "partial fast" of no food intake for 18 of the 24 hours a day, and small high-fiber meals in that 6-hour "eating window". She also boosted her activity level, mightily. She recommends 5 workouts per week of 45 minutes' duration, sufficiently vigorous to make us sweat and have a hard time talking (none of this treadmill-walking while holding a conversation on the phone!).

I decided to check something. I used the short-form Longevity Calculator at Wharton twice, making one change between. The first time, I put "1-2 workouts per week", the second "5+ workouts per week". My life expectancy in the first instance is 91, and in the second 92. In either case, the tool reports that I have a 75% chance to live beyond age 84. Going back and changing activity to "rarely", returned a life expectancy of 90. Hmm. I am 70 now. If I hold up, and am able to do those vigorous workouts 5x/week, I'd spend an extra three hours weekly working out. That is 156 hours yearly or, in 15 years (until age 85, when I'd probably have to slow down!), 2,340 hours. My waking hours in one year are 6,570 (I sleep 6 hours on average, in spite of trying to stay abed longer).

So I can gain another year of life if I spend about a third of it working out. Would I be healthier? Certainly, as long as I don't tear up my body doing all those workouts. I'd have to get into it gradually. So it is likely that those 15 years would be pretty good ones. On the other hand, it would have to go hand-in-hand with less eating, meaning I'd be living with being chronically hungrier. That is not an easy choice, but this is the kind of cost/benefit analysis we need to do. Unless the FDA approves an economical form of Leptin treatment to help us manage appetite, it's the best hope I have of being svelte again. That's mildly depressing.

We are all just tubes wrapped in muscle and bone

kw: book reviews, nonfiction, alimentary canal, physiology, lore

The squeamish may wish to avoid eating while reading Gulp: Adventures on the Alimentary Canal by Mary Roach. But that goes for many of her books, particularly Stiff (about cadavers) and Bonk (about sex science). I do intend to hunt down a copy of Packing for Mars.

A large part of Gulp is debunking myths. Such as that the human bite is the most dangerous, in terms of causing infection. That's only likely to be true for the bite of someone accustomed to eating food so rotten it endangers his health. Otherwise the Komodo Dragon holds gets the prize for the riskiest bite. And how about the other end? A gastroenterologist of our acquaintance once said he can do all kinds of cutting inside someone's colon, and it'll heal without infection or even a scar. He said he seldom needs to prescribe antibiotics. I've seen the followup colonoscopies after having part of my colon removed, and the trimmed end fitted to re-attach to the ileum, which is something like one-third its diameter. The "fitting" section, called an anastomosis, is a smooth taper from big tube to small tube. My intestinal flora didn't cause any trouble during healing.

OK, that paragraph is about 20% upper GI, and 80% lower GI, just like the book. The mouth gets a couple of chapters, saliva one by itself, the stomach two, the ileum (small intestine) just one, and about 8 chapters dwell on the colon, rectum and anus, plus "gas". This is particularly because of the many uses to which our lower GI is put. You'll just love learning how cell phones get smuggled into prisons… or the recreational uses of the rectum and nearby parts.

Recreation aside, the book is very well researched. The author traveled and interviewed and studied. For the macabre end of things, she discusses some of the exhibits of the Mütter Museum in Philadelphia, including a "megacolon" 29 inches in circumference (over 9" diameter; a normal colon maxes out at about 3" diam at the cecum). This is caused by a nerve problem that prevents peristalsis, so the colon won't empty without extreme measures: lots of enemas. Most sufferers die young, Elvis included. She also visited the Restaurant of the Future at the University of Utrecht, the Netherlands. They study chewing. You know that business about chewing 32 times, to do a thorough job, or "Fletcherizing" (chewing each bite for several minutes; you spend all day chewing), to do a thoroughly obsessive job? Neither is needed for proper digestion. Chewing mixes sufficient saliva with the food so it'll go down. Experiments with barely moistened, swallowed chunks found they digested just fine. However, chewing is pleasurable for most of us, such that people who have esophagus damage and must eat by putting macerated food into a tube that enters the stomach through a fistula never feel they've eaten, and are continually famished, regardless how much they stuff through the tube!

Just as studies of "abnormal psychology" help us understand "normal psychology" (I prefer the terms less-usual and more-usual psychology), studies of pathology all along our bodily canal tend to focus on the unusual so as to illuminate the usual. The very few people who have literally eaten themselves to death had to overcome a series of bodily mechanisms that make it harder and harder to keep eating, long before we are in physical danger of bursting our innards. But it has been done, usually by first consuming barbiturates to numb the inner nerves. A clue to the unwary: don't go to a buffet line just after taking medicine that might numb your stomach's defense mechanisms! A paragraph or two on those performers who eat things like broken glass or a chopped-up piano would have been right at home in this chapter, but no go.

Among the major animal groups, we vertebrates are deuterostomes, a term meaning "two mouths". Ms Roach reminds us to be thankful we are not monostomatic like sea anemones, which must defecate back through their mouth, as their body cavity has only one opening. The same goes for all corals and jellyfish and similar critters. Our body plan is essentially a tube wrapped in muscle, enclosed in bone, with skin over all. Insects and relatives such as lobsters differ from vertebrates primarily in having no skin over their bones (it is just inside), and in being "upside down", with the main nerve chord (equal to our spinal chord) along their front side, and the alimentary canal more to the back.

Seeing as how I typically read if I am eating alone, I scheduled reading time away from the table, and read other things (such as Wired or Scientific American) at mealtimes. Much of the book is actually not icky at all, but you never know when turning the page might unleash a surprise. But Ms Roach's surprises are laced with gentle humor. Like a good meal, it left me wanting more.

Our marvelous kluge

kw: book reviews, nonfiction, physiology, brain, evolution

For the handful of people who actually follow this blog, the past nine days without a post indicate the difficulty I had finishing the latest book. While I enjoyed it and learned much, it was rough sledding, which I'll get into. I also find that, having retired, I am busier than when I was working, so for these few months at least, I have only written to review a book.

This common illustration of the Ascent of Man represents what most people think of as Evolution. As described in The Brain: Big Bangs, Behaviors and Beliefs by Rob DeSalle and Ian Tattersall, evolution works more like one of those massive multiplayer quest games. Imagine the players being all species of animals, from flatworms and beetles and clams and fish to birds and frogs and squids and primates and cattle. As the "players" move through the game, this one will encounter some new charm or tool or whatever, and that one will encounter something else. "Picking up" the new gewgaw may increase the survival of that kind of animal. After some time passes (lots of it!) some players will have gathered a number of such items, more might have gained one or two, even more have nothing new, and many have in one way or another "lost" and vanished from the game.

But what, exactly, is winning? Attaining the greatest percent of the biosphere? Certain species of termite seem to have won that hands down. Of course, in the context of The Brain, the biggest brain is thought of as the "winner", and many folks confidently expect humans to get brainier in the future.

The authors emphasize repeatedly that there was no preordained big brained "winner" of the "smarts lottery". Looking further back than the ape in the picture above, many of us learned that there is a "lizard brain" deep in our skulls, covered over with a "mammal brain", and finally covered over with the famed "gray matter" that makes us human, but with certain lizardly and "primitive mammal" mental quirks. Not really.

True, we are the current expression of 3.5 billion years or more of biological evolution. However, so is every other species on Earth! Your pet dog or cat, the robin in the yard, the worms in the dirt, the ants invading your kitchen, and the bacteria that help all of them digest their food, all have the same 3.5 billion-year evolutionary descent. Every leaf on a tree can be traced back to the same root. Humans are, as regards brains, the "lucky ones". If we succeed in bombing ourselves to smithereens, though, "lucky" isn't really the right word for it.

Well, the above is my take on it. The authors' take is detailed and comprehensive, showing (as well as we may know) how many features of the brain were developed and appended to what came before. The jargon gets a bit dense at times, but it seems the authors' attitude must be, "The readers are adults. They'll catch on, or look up what they must." We even find an occasional long chemical name, for no good reason I can determine. Lazy readers won't get far.

So, starting with the lowliest animals—and even with plants, which have some rudiments of cell-to-cell communication—we are led through the development of nerve nets, nervous systems, clusters of ganglia, brains, and the higglety-pigglety addition of features and structures to brains of all types, insofar as they tended to improve the lot of the animals possessing them. Along the way, we learn certain principles of evolutionary study, such as the importance of an out-group to clarify how to structure a portion of an evolutionary tree.

Natural selection is strict. Every feature of every creature has to be adaptive or it (the feature) will vanish. It can take many generations, but just as the human race is evolving toward having 28 teeth instead of 32, and losing our appendix, stuff we don't need is being done away with. That goes for the many parts of our brains. We have 'em because they are useful. At the end, the singular new feature that is, so far as we know, not present in any other Earthly animal, is our capacity to create and manipulate symbols.

Yes, I know that certain great apes have been taught to communicate using Yerkish or ASL, but the level of discourse possible with any of them is very, very limited. None of them created something like Yerkish; human experimenters did so. And transcripts of "conversations" that go for more than two or three exchanges make it clear that apes' intellect stops well before the level of a human 2-year-old. Abstract reasoning is beyond young human children, and much further beyond apes. Not only so, the behavioral clues gathered by anthropologists indicate that symbol manipulation, that is, language skills that we take for granted, were probably not present in our cousins the Neandertals or the earlier Homo heidelbergensis. The Neandertals (the book uses the word Neanderthals), though their average brain size was slightly larger than ours, apparently had a qualitatively different brain. They were very, very bright and capable, but there were no Neandertal Spinozas or Mozarts or Picassos or Feynmans. Hey, I just thought of a title for a great book for someone competent to research and write it: Did Neandertals Dance? I am betting they didn't.


At this point, I am going to chase another rabbit. I like the book and recommend it, but it does show marks of overspecialization on the part of the authors. They needed some more broadly-based scientists to check it. I hope this doesn't sound like sour grapes or piling on, but here goes:

• In the second half of the book, where the authors are wholly comfortable with the material, there is only one deficiency. They do not mention the Mirror Test. Humans over the age of 18 months, the great apes, one or two species of monkey, bottlenose dolphins, orcas, elephants, and at least one species of bird, the European Magpie, can all recognize themselves in a mirror. This indicates a level of self-awareness that might be called consciousness, though many bridle at that notion for nonhuman animals.
• Working back to front: on p. 174 in an illustration of the limbic system in 3 animals, the Olfactory Bulb in the 3 labels is called the Optic Bulb in the main caption. Proofreading needed.
• On p. 142, we find the sentence, "Many bacteria have light-sensing cells that help them orient…" Bacteria are single-celled. They don't have cells, they are cells. They have light-sensing chemicals, perhaps even localized within the cell.
• On p. 135, they state that magnetotactic bacteria sense up and down magnetically, because the natural magnetic field is horizontal. The key sentence is "The magnetosomes allow the bacteria to orient North-South, so theat they are parallel to the earth's surface." Not so. Earth's magnetic field is horizontal only at the magnetic equator. Everywhere else it dips. Throughout most of the U.S., and at similar latitudes in Europe and Siberia, and in South America and southern Africa, the dip is in the 40°-60° range. The dip is vertical at the geomagnetic poles. The bacteria can follow the dipping field either toward or away from light. Bacteria from very near the geomagnetic equator would find the field useless for guiding vertical motion.
• On p. 105, an unusual typo appears: "A micrometer is one billionth of a meter…'. No, it is a millionth of a meter. I don't know if this was an author error, but since most folks do their own typesetting these days, I think it was.
• I find two problems on p. 85. Firstly, the reason creatures that molt are called Ecdysozoa is stated "…because a hormone called ecdysone is involved in the molting". The two "ecdy" words are related, but in this way: εκδύομαι, or ecdyomai, is the Greek word for "undress". Secondly, it is stated that Barnacles are Bryozoans. Whoo, boy! These are in different phyla. Barnacles are arthropods, essentially like crayfish hiding in a cone-shaped shell, without claws. Bryozoa are "moss animals", more similar to sponges.
• Now for something truly extraordinary. On p. 58 it is stated that the number of connections in a human brain is about 100 trillion (10¹⁴). That's right. Then we find, "Using the area of axons as a guide, the number of potential connections in a human brain has been estimated to be more than 10 to the 76th power. That is a 1 with 76 zeroes after it, a number in the same range as the number of particles in the known universe." I must conclude that the authors are entirely ignorant of both astronomy and physics! Whoever did this "estimate" is worse. Brain connections are made via synapses, and a synapse has a volume of about one cubic micron. That means a cubic millimeter could contain a billion synapses. So far so good. A small, 1,000 cc brain contains one million cubic millimeters, so if that brain were nothing but synapses (no room left for axons, dendrites and so forth), there would be a million billion of them, or 10¹⁵. The largest human brains are about 2,000 cc in size, so at most, the number of connections must be quite a bit less than 2x10¹⁵. This error, a factor of about 10⁵¹, is in magnitude the largest error I have ever encountered in print!

Enough of that. I have a chemist friend who is pretty unaware of anything except chemistry. Chemical IQ: 180; all other kinds of IQ: about 80. A little more thoughtful proofreading would have helped The Brain a great deal. It makes me wonder if the 5 people who wrote the blurbs on the back book jacket actually read the book. Maybe they're equally over-specialized and just didn't notice.

Human personal ecology

kw: book reviews, nonfiction, biology, physiology, parasites, predators, symbiosis

Let's see, to be optimally healthy we need worms in our guts, germs on our skin (and inside also), and a better variety of foods to eat. In addition, our abilities including 3-color vision and startle reflexes, and our adrenaline flight-or-fight system, were honed by millions of years of being chased and eaten by predators large and small, and bitten by snakes.

The worm thing gets me. As Rob Dunn writes in The Wild Life of Our Bodies: Predators, Parasites, and Partners That Shape Who We Are Today, ingesting a dose of whipworm eggs, or contracting hookworm, three or four times yearly, can eliminate many "allergic" and "autoimmune" diseases such as Crohn's Disease. Humans and our ancestral primates, prior to the Twentieth Century, were universally infested with worms. Such diseases were unknown. In much of the world, most people are still full of parasitic worms, and don't get Crohn's Disease or a host of similar afflictions.

It seems to work like this: millions of years of byplay between worms and our immune system have resulted in a sort of draw. The worms trigger immune responses, but reply with "peacekeeper" molecules that calm down the immune response, thus allowing them to live in our bodies. The immune system is now used to having these peacekeeper molecules around, and overreacts when they are not, leading to allergic syndromes. I suppose if I had some really debilitating disease like Crohn's, I'd be willing to drink a worm cocktail, but the thought gives me the willies.

Then there are the germs. We are getting used to probiotics, which are germ cocktails, and yogurt with "active cultures", so we are just getting our feet wet, learning to manage our internal ecology. A chapter in the book addresses the appendix, which turns out to be a functioning organ. Millions of people have it removed every year, and seem to do well. But if you ever get Cholera, your appendix might save your life.

Cholera flushes nearly all the bacteria out of your intestines. If you can drink enough clean water while it is doing so, you'll live and come out the other side without the bacteria that produce about half the vitamins you need to survive. How will you repopulate your gut? Enter the appendix. It is filled with lymph tissue and a thick biofilm of essential symbiotic bacteria. After a bout of cholera or any other kind of heavy diarrhea, these stored bacteria repopulate the bowels and restore your internal ecology.

There are chapters about our fears and the predators that shaped them, and our color vision with its peculiar ability to detect a snake, and make you jump back, before your conscious mind notices it. The author asked his colleagues for stories about people they might know who'd been bitten by a venomous snake. To his surprise, about half of those colleagues had stories of their own. Among practicing biologists, with their worldwide travels (and tendency to pick up anything interesting), snakebite is a frequent occurrence! The reaction we have to snakes was determined when our ancestors were the size of housecats, or smaller. It takes learning to perceive a serpent as attractive.

And there is a long section about agriculture, with quite a different take on it than you'll find in most textbooks of ancient history. Rather than some triumph of ingenuity, agricultural practices, which arose many, many times and places (not just in Mesopotamia), were responses to food crises such as drought, famine or the exhausting of game reserves in an area. One group managed to subsist by drinking the milk of the Aurochs, the proto-cow; or, at least those who could tolerate the lactose in the milk survived and subsisted thereby. Others took advantage of one or another cereal grain and learned, from scratch, how to make some kind of bread, to replace whatever "gather" crop(s) had failed. Others sought out new root crops.

Imagine you live by fruits and a cold year comes along and freezes off the fruit before they are edible. You can roughly winnow barley by hand and eat it as is (I've done so). If you are an inefficient eater, and most are, some grains will scatter further from the stand of barley you found. The next year, the extra barley growing may not matter, but if several spring freezes in a row clobber the fruiting bushes, your little band of gatherers is likely to find barley is more reliable, and settle down to cultivate it. In addition to the "big four" (maize, wheat, rice and soy), there are dozens of sustenance crops worldwide, and each was probably first cultivated to stave off a food crisis. The foods that feed us well, and those that don't, will depend on which group out of several dozen or maybe several hundred, from which we are descended.

There is much more to the book. It is a fascinating read. Some of the things that might make our lives better may repel you, as the worms did me. But there is much to learn here. The kind of future we live in could well depend on those species that we welcome back into our lives.

Men gotta stand

kw: observations, physiology

This is for men who are getting to "a certain age".

I had a bit of an unpleasant experience late last year, and it took some thinking to reason it out. My regular physician, after a "digital exam", was worried about my prostate—it has always been oversize—and sent me for an ultrasound and an exam by a urologist. The urologist repeated the ultrasound exam, while adding a dynamic voiding test (catching the urine in a beaker on a recording scale). Both ultrasound exams showed that I was not completely voiding. Thus a half-year saga began.

First he wanted to do a cystoscopy, to see if my bladder showed signs that it was suffering overpressure. This happens when the prostate gets tight and the muscular bladder has to squeeze harder to drive urine out. As any muscle, exercise makes it stronger, and this is visible. The cystoscopy showed no such signs. Then he thought that perhaps my bladder was too weak. With some arm-twisting, he persuaded me to undergo a "urodynamics" test. He gave me a date a few months in the future, for no reason I could fathom.

I used the time well. I decided that if I indeed had a weak bladder, perhaps I could strengthen it. (Feel free to stop reading whenever you've had enough) I remembered that I had, for both ultrasound tests, sat to urinate. I had been sitting to void ever since I'd had cancer surgery in 2000, initially because of fatigue due to chemotherapy, later because I'd become slow to empty, and didn't like standing at a urinal for long periods. But I read that the bladder is tipped in an unfavorable way when a man sits "on the throne". I decided to re-learn to "stand and deliver".

Surprisingly, it wasn't much of a problem. My changed attitude soon removed my anxiety about how much time I might be standing there, and that actually sped things up. Then, by waiting longer before "going", I had the chance to consciously push and void as fast as possible, hoping this would strengthen the bladder walls.

It seems to have worked. The Urodynamics test required two catheters, one to the bladder, and one in the rectum to measure muscular pressures and myoelectrical signals. The attendant recorded my verbal reports of various feelings of fullness and urgency as a machine slowly forced water into the bladder. Once we reached the point of "Enough, already!", I was allowed to stand, push out the catheter and void into a recording beaker.

Afterward, the doctor was puzzled. He said I'd emptied my bladder completely. He could not at that point justify further testing or other interventions. That's good, because he had earlier been speaking of some rather drastic-sounding procedures. He set up an appointment for a year later, to "check on things." I plan to break that one. I'll decide when I think I have a problem. Maybe I'll check back with him in five or ten years.

This is one more case of having to be my own diagnostician. While I'd thought for a long time that I was doing right by sitting to void, I found by experience that the geometry of the bladder makes it harder to get that last couple of ounces out that way. Once again, I stand and deliver, as I had not done for a decade.