Tag: Biology

Coevolution and Artificial Selection

“The ancient relationship between bees and flowers is a classic example of coevolution. In a coevolutionary bargain like the one struck by the bee and the apple tree, the two parties acton each other to advance their individual interests but wind up trading favors: food for the bee, transportation for the apple genes. Consciousness needn’t enter into it on either side …”

***

In The Botany of Desire: A Plant’s-Eye View of the World Michael Pollan tells the story of four domesticated species—the apple, the tulip, cannabis, and the potato—and the human desires that link their destinies to our own.

“Its broader subject,” he writes, “is the complex reciprocal relationship between the human and natural world.”

It’s a simple question really: Did I choose to plant these tulips or did they make me do it? Pollan concludes that, in fact, both statements are true.

Did the plant make him do it? Only in the sense that the flower “makes” the bee pay it a visit.

Evolution doesn’t depend on will or intention to work; it is almost by definition, and unconscious, unwilled process. All it requires are beings compelled, as all plants and animals are, to make more of themselves by whatever means trial and error present. Sometimes an adaptive trait is so clever it appears purposeful: the ant that “cultivates” its own gardens of edible fungus, for instance, or the pitcher plant that “convinces” a fly it’s a piece of rotting meat. But such traits are clever only in retrospect. Design in nature is but a concatenation of accidents, culled by natural selection until the result is so beautiful or effective as to seem a miracle of purpose.

The book is as much about the human desires that connect us to plants as it is about the plants themselves.

“Our grammar,” Pollan writes, “might teach us to divide the world into active subjects and passive objects, but in a coevolutionary relationship every subject is also an object, every object a subject.”

Charles Darwin didn’t start out The Origin of Species with an account of his new theory, rather, he began with a foundation he felt would be easier for people to get their heads around. The first chapter was a special case of natural selection called artificial selection.

Artificial wasn’t used in the sense of fake but as in things that reflect human will. He wrote about a wealth of variation of species from which humans selected the traits that will be passed down to future generations. In this sense, human desire plays the role of nature, determining what constitutes “fitness.” If people could understand that, they would understand nature’s evolution.

Pollan argues that the crisp conceptual lie “that divided artificial from natural selection has blurred.”

Whereas once humankind exerted its will in the relatively small arena of artificial selection (the arena I think of, metaphorically, as a garden) and nature held sway everywhere else, today the force of our presence is felt everywhere. It has become much harder, in the past century, to tell where the garden leaves off an pure nature begins.

We are shaping things in ways that Darwin could never have imagined.

For a great many species today, “fitness” means the ability to get along in a world in which humankind has become the most powerful evolutionary force.

Artificial selection, it appears, has become at least as powerful as natural selection.

Nature’s success stories from now on are probably going to look a lot more like the apple’s than the panda’s or white leopard’s. If those last two species have a future, it will be because of human desire; strangely enough, their survival now depends on what amounts to a form of artificial selection.

The main characters of the book—the apple, the tulip, cannabis, and the potato—are four of the world’s success stories. “The dogs, cats, and horses of the plant world, these domesticated species are familiar to everyone,” Pollan writes.

Apples

In the wild a plant and its pests are continually coevolving, in a dance of resistance and conquest that can have no ultimate victor. But coevolution ceases in an orchard of grafted trees, since they are genetically identical from generation to generation. The problem very simply is that the apple trees no longer reproduce sexually, as they do when they’re grown from seed, and sex is nature’s way of creating fresh genetic combinations. At the same time the viruses, bacteria, fungi, and insects keep very much at it, reproducing sexually and continuing to evolve until eventually they hit on the precise genetic combination that allows them to overcome whatever resistance the apples may have once possessed. Suddenly total victory is in the pests’ sight — unless, that is, people come to the tree’s rescue, wielding the tools of modern chemistry.

Put another way, the domestication of the apple has gone too far, to the point where the species’ fitness for life in nature (where it still has to live, after all) has been dangerously compromised. Reduced to the handful of genetically identical clones that suit our taste and agricultural practice, the apple has lost the crucial variability — the wildness — that sexual reproduction confers.

The Tulip

The tulip’s genetic variability has in fact given nature–or, more precisely, natural selection–a great deal to play with. From among the chance mutations thrown out by a flower, nature preserves the rare ones that confer some advantage–brighter color, more perfect symmetry, whatever. For millions of years such features were selected, in effect, by the tulip’s pollinators–that is, insects–until the Turks came along and began to cast their own votes. (The Turks did not learn to make deliberate crosses till the 1600s; the novel tulips they prized were said simply to have “occurred.”) Darwin called such a process artificial, as opposed to natural, selection, but from the flower’s point of view, this is a distinction without a difference: individual plants in which a trait desired by either bees or Turks occurred wound up with more offspring. Though we self-importantly regard domestication as something people have done to plants, it is at the same time a strategy by which the plants have exploited us and our desires–even our most idiosyncratic notions of beauty–to advance their own interests. Depending on the environment in which a species finds itself, different adaptations will avail. Mutations that nature would have rejected out of hand in the wild sometimes prove to be brilliant adaptations in an environment that’s been shaped by human desire.

In the environment of the Ottoman Empire the best way for a tulip to get ahead was to have absurdly long petals drawn to a point fine as a needle. In drawings, paintings, and ceramics (the only place the Turks’ ideal of tulip beauty survives; the human environment is an unstable one), these elongated blooms look as though they’d been stretched to the limit by a glassblower. The metaphor of choice for this form of tulip petal was the dagger. … Though these … traits are not uncommon in species tulips, attenuated petals are virtually unknown in the wild, which suggests that the Ottoman ideal of tulip beauty—elegant, sharp, and masculine—was freakish and hard-won and conferred no advantage in nature.

All in all The Botany of Desire is one of the best books I’ve read on how our Apollonian desire for control and order increasingly butts up against the natural Dionysian wildness.

The Honeybee Conjecture: What Is It About Bees And Hexagons?

honeycomb

Why is every cell in this honeycomb a hexagon?

More than 2,000 years ago, Marcus Terentius Varro, a roman citizen, proposed an answer, which ever since has been called “The Honeybee Conjecture.” He thought that if we better understood, there would be an elegant reason for what we see.

“The Honeybee Conjecture” is an example of mathematics unlocking a mystery of nature. And luckily, NPR, with the help of physicist/writer Alan Lightman, (who wrote The Accidental Universe: The World You Thought You Knew) helps explains Varro’s hunch.

Why the preference for hexagons? Is there something special about a six-sided shape?

“It is a mathematical truth,” Lightman writes, “that there are only three geometrical figures with equal sides that can fit together on a flat surface without leaving gaps: equilateral triangles, squares and hexagons.”

So which to choose? The triangle? The square? Or the hexagon? Which one is best? Here’s where our Roman, Marcus Terentius Varro made his great contribution. His “conjecture” — and that’s what it was, a mathematical guess — proposed that a structure built from hexagons is probably a wee bit more compact than a structure built from squares or triangles. A hexagonal honeycomb, he thought, would have “the smallest total perimeter.” He couldn’t prove it mathematically, but that’s what he thought.

Compactness matters. The more compact your structure, the less wax you need to construct the honeycomb. Wax is expensive. A bee must consume about eight ounces of honey to produce a single ounce of wax. So if you are watching your wax bill, you want the most compact building plan you can find.

In 1999 Thomas Hales produced a mathematical proof, confirming that Varro was right.

Why are they all the same size?

For bees to assemble a honeycomb the way bees actually do it, it’s simpler for each cell to be exactly the same. If the sides are all equal — “perfectly” hexagonal — every cell fits tight with every other cell. Everybody can pitch in. That way, a honeycomb is basically an easy jigsaw puzzle. All the parts fit.

Update: I ran across this interesting paper, which argues the honeybee comb have a circular shape at first and then transform into the hexagon.

We report that the cells in a natural honeybee comb have a circular shape at ‘birth’ but quickly transform into the familiar rounded hexagonal shape, while the comb is being built. The mechanism for this transformation is the flow of molten visco-elastic wax near the triple junction between the neighbouring circular cells. The flow may be unconstrained or constrained by the unmolten wax away from the junction. The heat for melting the wax is provided by the ‘hot’ worker bees.

Still Curious? Learn more about The Honeycomb Conjecture.

Benoit Mandelbrot — The Fractalist: Memoir of a Scientific Maverick

“I have never done anything like others,” Benoit Mandelbrot (1924-2010) once said.

That statement is proven time and time again in his autobiography: The Fractalist.

Mandelbrot is independent almost to a fault, his book an interesting memoir from the man who revitalized visual geometry, and whose ideas about fractals have changed how we look at physics, engineering, arts, medicine, finance, and biology.

The Fractalist: Memoir of a Scientific Maverick

Nearly all common patterns in nature are rough. They have aspects that are exquisitely irregular and fragmented—not merely more elaborate than the marvelous ancient geometry of Euclid but of massively greater complexity. For centuries, the very idea of measuring roughness was an idle dream. This is one of the dreams to which I have devoted my entire scientific life.

Let me introduce myself. A scientific warrior of sorts, and an old man now, I have written a great deal but never acquired a predictable audience. So, in this memoir, please allow me to tell you who I think I am and how I came to labor for so many years on the first-ever theory of roughness and was rewarded by watching it transform itself into an aspect of a theory of beauty.

Mandelbrot was full of insight.

What shape is a mountain, a coastline, a river or a dividing line between two river watersheds? … Clouds are not spheres, mountains are not cones, coastlines are not circles, and bark is not smooth, nor does lightning travel in a straight line.

While that sounds obvious it wasn’t at the time. In showing that triangles, squares, and circles are more prevalent in textbooks than reality, he brought to life the discipline now known as fractal geometry, a general theory of “roughness.”

Mandelbrot was fascinating, in part, because he never stayed in one place very long.

An acquaintance of mine was a forceful dean at a major university. One day, as our paths crossed in a busy corridor, he stopped to make a comment I never forgot: “You are doing very well, yet you are taking a lonely and hard path. You keep running from field to field, leading an unpredictable life, never settling down to enjoy what you have accomplished. A rolling stone gathers no moss, and—behind your back—people call you completely crazy. But I don’t think you are crazy at all, and you must continue what you are doing. For a thinking person, the most serious mental illness is not being sure of who you are. This is a problem you do not suffer from. You never need to reinvent yourself to fit changes in circumstances; you just move on. In that respect, you are the sanest person among us.”

Quietly, I responded that I was not running from field to field, but rather working on a theory of roughness. I was not a man with a big hammer to whom every problem looked like a nail. Were his words meant to compliment or merely to reassure? I soon found out: he was promoting me for a major award.

Is mental health compatible with being possessed by barely contained restlessness? In Dante’s Divine Comedy, the deceased sentenced to eternal searching are pushed to the deepest level of the Inferno. But for me, an eternal search across countless scientific fields beyond obvious connection managed to add up to a happy life. A rolling stone perhaps, but not an unresponsive one. Overactive and self-motivated, I loved to roll along, stopping to listen and preach in lay monasteries of all kinds—some splendid and proud, others forsaken and out of the way.

He had a different way of looking at things. For example, he saw math problems as geometry.

I would raise my hand and describe my findings: “Monsieur, I see an obvious geometric solution.” I quickly grasped the most abstract problem that the teacher could contrive. And then — with no effort, conscious search, or delay — I continued along a path that somehow avoided every difficulty…. I managed to be examined on the basis of speed and good taste in, first, translating algebra back into geometry, and then thinking in terms of geometric shapes. My analytic skills remained so-so, but that did not matter — the hard work was done by geometry, and it sufficed to fill in short calculations that even I could manage.

Ultimately, The Fractalist is proof that “force of character and independence” can take some to great heights.

What Animals Teach Us About Health and the Science of Healing

“Obesity is a disease of the environment.”

— Richard Jackson

Barbara Natterson-Horowitz, a cardiologist at the University of California Los Angeles, believes that her fellow human physicians have much to learn from their veterinary counterparts. These are not separate fields, she argues in her book, coauthored with science writer Kathryn Bowers, Zoobiquity: What Animals Can Teach Us About Health and the Science of Healing.

Did you know that animals get cancer? heart disease? They also faint. Even diseases we think of as uniquely human, like depression, sexual performance, and addiction are found in the animal world. A lot of animals even self-injure when faced with stress or boredom.

When asked, “why should doctors listen to veterinarians,” in a recent interview she responded:

I can speak from my own personal experience. I had spent almost a couple decades being a human doctor, a cardiologist, and I had very little awareness about veterinary medicine. I, like most physicians, only interacted with veterinarians when my own animals got sick….I had this wonderful opportunity to help out at the Los Angeles Zoo, and through that experience I began seeing, both through the patients I was helping with and listening to the veterinarians on their rounds, that they were dealing with heart failure, and cancer, and behavioral disturbances, and infectious diseases, and really essentially the same diseases that I was taking care of in human patients.

Only a century or two ago, many humans and animals were treated by the same practitioner.

However, animal and human medicine began a decisive split around the turn of the twentieth century. Increasing urbanization meant fewer people relied on animals to make a living. Motorized vehicles began pushing work animals out of our daily life. With them went a primary revenue stream for many veterinarians. And in the United States, federal legislation called the Morrill Land-Grant Acts of the late 1800s relegated veterinary schools to rural communities while academic medical centers rapidly rose to prominence in wealthier cities.

Most physicians would never dream of consulting a veterinarian about human diseases.

Most physicians see animals and their illnesses as somehow “different.” We humans have our diseases. Animals have theirs.

Well that and the undeniable, and unspoken, medical establishments bias against veterinary medicine. Like all humans, doctors can be snobs. The unwritten hierarchy is based on a combination of factors but it’s pretty safe to bet that a veterinarian is below general practitioner.

Zoobiquity: What Animals Can Teach Us About Health and the Science of Healing

“We do not like to consider [animals] our equals,” Charles Darwin once remarked. And yet we are animals. In fact, we share most of our genetic makeup with other creatures. Of course, we do learn from animals. Mice are commonly used to better understand human conditions.

Zoobiquity isn’t about animal testing. It’s about the fact that “animals in jungles, oceans, forests, and our homes sometimes get sick—just as we do. Veterinarians see and treat these illnesses among a wide variety of species. And yet physicians largely ignore this. That’s a major blind spot, because we could improve the health of all species by learning how animals live, die, get sick, and heal in their animal settings.”

One example of where we can learn from is why animals get fat and how they get thin.

Fattening in the animal world has enormous potential lessons for humans—including dieters looking to shed a few pounds and doctors grappling with obesity, one of the most serious and devastating health challenges of our time.

Millions cope with this life-threatening epidemic. Millions of domestic animals that is. These pets are “fatter than ever before, and steadily gaining more weight.” While hard to determine, studies put the number of overweight and obese dogs and cats somewhere between 25 and 40 percent. In case you’re wondering, that’s still, at least for now, well below the proportion of U.S. human adults who are now either overweight or obese, which is closer to 70 percent.

What sets domestic animals apart from their wild cousins? We feed them.

They are mostly or completely dependent on humans for every meal, and we regulate both the quality and the quantity of everything that passes their lips and beaks. Consequently, we can’t really blame them for their weight problems. … And so we’re left with one conclusion: we, the species that both manipulates food to make it more unhealthful and has the intelligence to understand that we shouldn’t eat so much of it, are to blame. We’re responsible not only for our own expanding waistlines but for those of our animal charges as well.

It’s easy and pleasing to assume that animals in their native environments effortlessly stay lean and healthy. That’s not the case.

Abundance plus access—the twin downfalls of many a human dieter—can challenge wild animals, too.

Although we may think of food in the wild as hard to come by, at certain times of the year and under certain conditions, the supply may be unlimited.

So wild animals get fat the same way we humans do: access to abundant food.

Of course, animals also fatten normally—and healthily—in response to seasonal and life cycles. But what’s key is that an animal’s weight can fluctuate depending on the landscape around it.

Learning from animals, call it the zoobiquitous approach, we learn that “weight is not just a static number on a chart. Rather, it’s a dynamic, ever-changing reaction to a huge variety of external and internal processes ranging from the cosmic to the microscopic.”

Richard Jackson says “Obesity is a disease of the environment.” In 2010 he explained what he meant:

One of the problems with the obesity epidemic is we too often blame the victim. And yes, every one of us ought to have more self-control and ought to exert more willpower. But when everyone begins to develop the same set of symptoms, it’s not something in their mind, it’s something in our environment that is changing our health. And what’s changing in our environment is that we have made dangerous food, sugar-laden food, high-fat food, high-salt food … and we’ve made it absolutely the easiest thing to buy, the cheapest thing to buy, and yes, it tastes good, but it’s not what we should be eating.

In a 2009 book, The End of Overeating, David Kessler made a similar point: excess sugar, fat, and salt “hijack our brains and bodies and drive cycles of appetite and desire that make it nearly impossible to resist certain fattening foods.” In a new book I’ve just started reading, Salt Sugar Fat: How the Food Giants Hooked Us, Michael Moss makes the same point. (In case you’re wondering, the calories in calories out argument is bunk.)

One of the lessons we can take away

If you want to lose weight the wild animal way, decrease the abundance of food around yourself and interrupt your access to it. And expend lots of energy in the daily hunt for food. In other words: change your environment.

Nassim Taleb makes a similar point in his book Anti-Fragile:

Perhaps what we mostly need to remove is a few meals at random, or at least avoid steadiness in food consumption. The error of missing nonlinearities is found in two places, in the mixture and the frequency of food intake.

The problem with the mixture is as follows. We humans are said to be omnivorous, compared to more specialized mammals, such as cows and elephants and lions. But such ability to be omnivorous had to come in response to more variegated environments with unplanned, haphazard, and, what is key, serial availability of sources—specialization is the response to a very stable habitat free of abrupt changes, redundancy of pathways the response to a more variegated one. Diversification of function had to come in response to variety. And a variety of certain structure.

Note a subtly in the way we are built: the cow and the other herbivores are subjected to much less randomness than the lion in their food intake; they eat steadily but need to work extremely hard in order to metabolize all these nutrients, spending several hours a day just eating. … The lion, on the other hand, needs to rely on more luck; it succeeds in a small percentage of the kills, less than 20 percent, but when it eats, it gets in a quick and easy way all these nutrients produced thanks to very hard and boring work by the prey. So take the following principles derived from the random structure of the environment: when we are herbivores, we eat steadily; but when we are predators we eat more randomly. Hence our proteins need to be consumed randomly for statistical reasons.

So if you agree that we need “balanced” nutrition of a certain combination, it is wrong to immediately assume that we need such balance at every meal rather than serially so. … There is a big difference between getting them together at every meal … or having them separately, serially.

Why? Because deprivation is a stressor—and we know what stressors do when allowed adequate recovery. Convexity effects at work here again: getting three times the daily dose of protein in one day and nothing the next two is certainly not biologically equivalent to “steady” moderate consumption if our metabolic reactions are nonlinear.

… I am convinced that we are antifragile to randomness in food delivery and composition—at least over a certain range or number of days.

We’ve all known that antibiotics are used to stop the spread of certain diseases. But, Zoobiquity, offers another explanation:

Antibiotics don’t kill just the bugs that make animals sick. They also decimate beneficial gut flora. And these drugs are routinely administrated even when infection is not a concern. The reason may surprise you. Simply by giving antibiotics, farmers can fatten their animals using less feed. The scientific jury is still out on exactly why these antibiotics promote fattening, but a plausible hypothesis is that by changing the animals’ gut microflora, antibiotics create an intestine dominated by colonies of microbes that are calorie-extraction experts. This may be why antibiotics act to fatten not just cattle, with their multistomached digestive systems, but also pigs and chicken, whose GI tracts are more similar to ours.

This is really a key point: antibiotic use can change the weight of farm animals. It’s possible that something similar occurs in other animals—namely, us. Anything that alters gut flora, including but not limited to antibiotics, has implications not only for body weight but for other elements of our metabolism, such as glucose intolerance, insulin resistance and abnormal cholesterol.

The diet and exercise dogma:

Even without an assist from 32-ounce sodas, the yellow-bellied marmots in the Rockies, blue whales off the coast of California and country rats in Maryland have gotten steadily chubbier in recent years. The explanation might lie in the disruption of circadian rhythms. Of the global dynamics controlling our biological clocks — including temperature, eating, sleeping and even socializing — no “zeitgeber” is more influential than light.

The cycle

Modern, affluent humans have created a continuous eating cycle, a kind of “uniseason.” … Sugar is abundant, whether in our processed foods or in beautiful whole fruits that have had their inconvenient seeds bread out of them and that “unzip” from easy-to-peel skins and pop open into ready to eat segments. Protein and fat are everywhere available—in eternal harvest the prey never grows up and learns to run away or fight us off. Our food is stripped of microbes, and we remove more while scrubbing off dirt and pesticides. Because we control it, the temperature is always a perfect 74 degrees. Because we’re in charge, we can safely dine at tables aglow in light long after the sun goes down. All year round, our days are lovely and long; our nights are short.

As animals, we find this single season an extremely comfortable place to be. But unless we want to remain in a state of continual fattening, with accompanying metabolic diseases, we will have to pry ourselves out of this delicious ease.

Check out the book

Richard Feynman — Take the World From Another Point of View

In this clip from a documentary film shot in Yorkshire in 1973, physicist and philosopher Richard Feynman (1918-1988) talks with Fred Hoyle, an accomplished astronomer from the United Kingdom.

Feynman poses the question: “What, today, do we not consider part of physics, which may ultimately be part of physics?”

His answer (which should be cued up here at the 7:10 mark) is the initial conditions of the universe, as well as the possibility that the physical laws themselves, evolve with time.

As he explains, there was a time when we considered the properties of substances to be chemistry, but as the quantum mechanical understanding of the atom evolved, we came to discover that this was actually all a part of physics.

In physics, our acceptance of the way things are (i.e. given conditions) without wondering why they’re like that is akin to playing chess without asking where the pieces should be placed before the game even starts.

It’s as though we’re doing a chess game and we’re working on the rules but we’re not worrying about how the pieces are supposed to be set up on the board in the first place. We tell ourselves, that’s not our business, that’s the business of cosmology and how the universe came to be. It’s interesting that in many other sciences, there’s a historical question. Like geology, we ask “How did the earth evolve into its present condition?” In biology, it’s “How did the various species evolve to get to be the way they are?” But the one field that has not admitted any evolutionary question is physics. “Here are the laws!” we say. We don’t even think about how they got that way. We think, well it’s been that way forever, it’s always been that way. It’s always been the same laws. And we try to explain the universe that way. So it might turn out that they’re not the same all the time, and that there is a historical, evolutionary question.

 

This fascinating conversation between two great minds continues in the follow-up video. Listen on to hear Feynman explain why he’s afraid to speculate about things.