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The importance of loneliness

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In Quanta Emily Singer writes about a theory proposed by John Cacioppo, the director of the Center for Cognitive and Social Neuroscience at the University of Chicago, on why loneliness is important:

social animals, we depend on others for survival. Our communities provide mutual aid and protection, helping humanity to endure and thrive. “We have survived as a species not because we’re fast or strong or have natural weapons in our fingertips, but because of social protection,” saidJohn Cacioppo, the director of the Center for Cognitive and Social Neuroscience at the University of Chicago. Early humans, for example, could take down large mammals only by hunting in groups. “Our strength is our ability to communicate and work together,” he said.

But how did these powerful communities come to exist in the first place? Cacioppo proposes that the root of social ties lies in their opposite — loneliness. According to his theory, the pain of being alone motivates us to seek the safety of companionship, which in turn benefits the species by encouraging group cooperation and protection. Loneliness persists because it provides an essential evolutionary benefit for social animals. Like thirst, hunger or pain, loneliness is an aversive state that animals seek to resolve, improving their long-term survival.

If Cacioppo’s theory is correct, then there must be an intrinsic biological mechanism that compels isolated animals to seek out companionship. Something in our brains must make it feel bad to be alone and bring relief when we’re with others. Researchers at the Massachusetts Institute of Technology think they’ve found the source of that motivation in a group of little-studied neurons in part of the brain called the dorsal raphe nucleus. Stimulating these neurons drives isolated mice to find friends, according to research published earlier this year in the journal Cell. The finding provides critical support to Cacioppo’s theory and illuminates a deep connection that links specific structures in the brain to social behavior.

The new study — the first to link specific neurons to loneliness — is part of a growing effort to map out the genetics of social behavior and its underpinnings in the brain. “Over the last roughly 15 years, there has been a tremendous increase in the desire to understand the basis of social behavior, including caring for others, social rejection, bullying, deceit and so forth,” said Patricia Churchland, a philosopher at the University of California, San Diego, who studies the brain and social behavior. “I think we have a good idea for the evolutionary basis for caring and sharing and mutual defense, but the brain mechanisms are bound to be very complex.”

Together, Cacioppo’s work and the new findings from MIT are helping to move loneliness from the realm of psychology and literature to biology. “I think the bigger picture is not to understand why loneliness is painful but rather how our brain is set up to move us out of that lonely state,” said Steve Cole, a genomics researcher at the University of California, Los Angeles. “Instead of thinking about loneliness, we could think about social affinity.”

Social Creatures

Gillian Matthews stumbled across the loneliness neurons by accident. In 2012 she was a graduate student at Imperial College London who had been studying how cocaine changes the brain in mice. She would give the animals a dose of the drug, place each one alone in a cage, and then examine a specific set of its neurons the next day. She did the same for a control group of mice, injecting them with saline instead of cocaine.

When Matthews returned to her mice 24 hours after dosing them, she expected to see changes in their brain cells, a strengthening of neuronal connections that might help explain why cocaine is so addictive. To her surprise, both the drug-treated mice and the control mice showed the same changes in neuronal wiring. Overnight, the neural connections onto a certain set of cells had grown stronger, regardless of whether the animals were given drugs or not. “We first thought there was something wrong, that we had mixed up our procedure,” said Matthews, who is now a postdoctoral researcher at MIT.

The brain cells she was interested in produce dopamine, a brain chemical typically associated with pleasurable things. Dopamine surges when we eat, have sex or use drugs. But it does more than simply signal pleasure. The brain’s dopamine systems may be set up to drive the search for what we desire. “It’s not what happens after you get what you want, it’s what keeps you searching for something,” Cole said.

The researchers focused on dopamine neurons in a brain region called the dorsal raphe nucleus, best known for its link to depression. (This may not be a coincidence — loneliness is a strong risk factor for depression.) Most of the neurons that reside there produce serotonin, the chemical messenger that drugs such as Prozac act on. Dopamine-producing cells make up roughly 25 percent of the region and have historically been difficult to study on their own, so scientists know little about what they do.

Matthews speculated that other environmental factors during the experiment might have triggered the changes. She tested to see if simply moving mice to new cages altered the dopamine neurons, but that couldn’t explain the effect. Ultimately, Matthews and her colleague Kay Tye realized that these brain cells were responding not to the drug but to the 24 hours of isolation. “Maybe these neurons are relaying the experience of loneliness,” Matthews said.

Mice, like humans, are social creatures that generally prefer to live in groups. Isolate a mouse from its cage mates, and once confinement ends it will spend more time interacting with other mice, to a much greater extent than if it had been with its mates all along.

To better understand the role the dorsal raphe neurons play in loneliness, the researchers genetically engineered the dopamine cells to respond to certain wavelengths of light, a technique known as optogenetics. They could then artificially stimulate or silence the cells by exposing them to light.

Stimulating the dopamine neurons seemed to make the mice feel bad. Mice actively avoided stimulation if given the choice, just as they might avoid physical pain. Moreover, the animals appeared to enter a state of loneliness — they acted like they had been alone, spending more time with other mice.

“I think this reveals something about how our brains may be wired to make us innately social creatures and protect us from the detrimental effects of loneliness,” Matthews said.

Spectrum of Loneliness

Cacioppo first formally proposed his evolutionary theory of loneliness a decade ago. Strong support comes from the fact that . . .

Continue reading.

An interesting sidebar to the article:

The Danger of Solitude

Loneliness not only feels bad, it can have profound health consequences. Animals raised in isolation, from flies to mice to chimps, have shorter life-spans. Solitary confinement — considered one of our harshest criminal punishments — boosts stress in humans and other animals, weakening the immune system and increasing the risk of death. Indeed, some estimates suggest that loneliness raises risk of mortality by nearly 30 percent — as much as obesity — even when controlling for confounding factors like age and depression.

Scientists hope that better understanding the neural circuits underlying loneliness will not only help explain why it exists but also ultimately point to new treatments. “Is there a way,” Hawkley asked, “of moderating activity in the brain like we do for depression?”

Written by LeisureGuy

11 May 2016 at 9:50 am

The Evolutionary Argument Against Reality

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Amanda Gefter has an interesting interview with Donald Hoffman in Quanta:

As we go about our daily lives, we tend to assume that our perceptions — sights, sounds, textures, tastes — are an accurate portrayal of the real world. Sure, when we stop and think about it — or when we find ourselves fooled by a perceptual illusion — we realize with a jolt that what we perceive is never the world directly, but rather our brain’s best guess at what that world is like, a kind of internal simulation of an external reality. Still, we bank on the fact that our simulation is a reasonably decent one. If it wasn’t, wouldn’t evolution have weeded us out by now? The true reality might be forever beyond our reach, but surely our senses give us at least an inkling of what it’s really like.

Not so, says Donald D. Hoffman, a professor of cognitive science at the University of California, Irvine. Hoffman has spent the past three decades studying perception, artificial intelligence, evolutionary game theory and the brain, and his conclusion is a dramatic one: The world presented to us by our perceptions is nothing like reality. What’s more, he says, we have evolution itself to thank for this magnificent illusion, as it maximizes evolutionary fitness by driving truth to extinction.

Getting at questions about the nature of reality, and disentangling the observer from the observed, is an endeavor that straddles the boundaries of neuroscience and fundamental physics. On one side you’ll find researchers scratching their chins raw trying to understand how a three-pound lump of gray matter obeying nothing more than the ordinary laws of physics can give rise to first-person conscious experience. This is the aptly named “hard problem.”

On the other side are quantum physicists, marveling at the strange fact that quantum systems don’t seem to be definite objects localized in space until we come along to observe them — whether we are conscious humans or inanimate measuring devices. Experiment after experiment has shown — defying common sense — that if we assume that the particles that make up ordinary objects have an objective, observer-independent existence, we get the wrong answers. The central lesson of quantum physics is clear: There are no public objects sitting out there in some preexisting space. As the physicist John Wheeler put it, “Useful as it is under ordinary circumstances to say that the world exists ‘out there’ independent of us, that view can no longer be upheld.”

So while neuroscientists struggle to understand how there can be such a thing as a first-person reality, quantum physicists have to grapple with the mystery of how there can be anything but a first-person reality. In short, all roads lead back to the observer. And that’s where you can find Hoffman — straddling the boundaries, attempting a mathematical model of the observer, trying to get at the reality behind the illusion. Quanta Magazine caught up with him to find out more. An edited and condensed version of the conversation follows.

QUANTA MAGAZINE: People often use Darwinian evolution as an argument that our perceptions accurately reflect reality. They say, “Obviously we must be latching onto reality in some way because otherwise we would have been wiped out a long time ago. If I think I’m seeing a palm tree but it’s really a tiger, I’m in trouble.”

DONALD HOFFMAN: Right. The classic argument is that those of our ancestors who saw more accurately had a competitive advantage over those who saw less accurately and thus were more likely to pass on their genes that coded for those more accurate perceptions, so after thousands of generations we can be quite confident that we’re the offspring of those who saw accurately, and so we see accurately. That sounds very plausible. But I think it is utterly false. It misunderstands the fundamental fact about evolution, which is that it’s about fitness functions — mathematical functions that describe how well a given strategy achieves the goals of survival and reproduction. The mathematical physicist Chetan Prakash proved a theorem that I devised that says: According to evolution by natural selection, an organism that sees reality as it is will never be more fit than an organism of equal complexity that sees none of reality but is just tuned to fitness. Never.

You’ve done computer simulations to show this. Can you give an example?

Suppose in reality there’s a resource, like water, and you can quantify how much of it there is in an objective order — very little water, medium amount of water, a lot of water. Now suppose your fitness function is linear, so a little water gives you a little fitness, medium water gives you medium fitness, and lots of water gives you lots of fitness — in that case, the organism that sees the truth about the water in the world can win, but only because the fitness function happens to align with the true structure in reality. Generically, in the real world, that will never be the case. Something much more natural is a bell curve  — say, too little water you die of thirst, but too much water you drown, and only somewhere in between is good for survival. Now the fitness function doesn’t match the structure in the real world. And that’s enough to send truth to extinction. For example, an organism tuned to fitness might see small and large quantities of some resource as, say, red, to indicate low fitness, whereas they might see intermediate quantities as green, to indicate high fitness. Its perceptions will be tuned to fitness, but not to truth. It won’t see any distinction between small and large — it only sees red — even though such a distinction exists in reality.

But how can seeing a false reality be beneficial to an organism’s survival?

There’s a metaphor that’s only been available to us in the past 30 or 40 years, and that’s the desktop interface. Suppose there’s a blue rectangular icon on the lower right corner of your computer’s desktop — does that mean that the file itself is blue and rectangular and lives in the lower right corner of your computer? Of course not. But those are the only things that can be asserted about anything on the desktop — it has color, position and shape. Those are the only categories available to you, and yet none of them are true about the file itself or anything in the computer. They couldn’t possibly be true. That’s an interesting thing. You could not form a true description of the innards of the computer if your entire view of reality was confined to the desktop. And yet the desktop is useful. That blue rectangular icon guides my behavior, and it hides a complex reality that I don’t need to know. That’s the key idea. Evolution has shaped us with perceptions that allow us to survive. They guide adaptive behaviors. But part of that involves hiding from us the stuff we don’t need to know. And that’s pretty much all of reality, whatever reality might be. If you had to spend all that time figuring it out, the tiger would eat you.

So everything we see is one big illusion?

We’ve been shaped to have perceptions that keep us alive, so we have to take them seriously. If I see something that I think of as a snake, I don’t pick it up. If I see a train, I don’t step in front of it. I’ve evolved these symbols to keep me alive, so I have to take them seriously. But it’s a logical flaw to think that if we have to take it seriously, we also have to take it literally.

If snakes aren’t snakes and trains aren’t trains, what are they?

Snakes and trains, like the particles of physics, have no objective, observer-independent features. The snake I see is a description created by my sensory system to inform me of the fitness consequences of my actions. Evolution shapes acceptable solutions, not optimal ones. A snake is an acceptable solution to the problem of telling me how to act in a situation. My snakes and trains are my mental representations; your snakes and trains are your mental representations.

How did you first become interested in these ideas?

As a teenager, I was very interested in the question “Are we machines?” My reading of the science suggested that we are. But my dad was a minister, and at church they were saying we’re not. So I decided I needed to figure it out for myself. It’s sort of an important personal question — if I’m a machine, I would like to find that out! And if I’m not, I’d like to know, what is that special magic beyond the machine? So eventually in the 1980s I went to the artificial intelligence lab at MIT and worked on machine perception. The field of vision research was enjoying a newfound success in developing mathematical models for specific visual abilities. I noticed that they seemed to share a common mathematical structure, so I thought it might be possible to write down a formal structure for observation that encompassed all of them, perhaps all possible modes of observation. I was inspired in part by Alan Turing. When he invented the Turing machine, he was trying to come up with a notion of computation, and instead of putting bells and whistles on it, he said, Let’s get the simplest, most pared down mathematical description that could possibly work. And that simple formalism is the foundation for the science of computation. So I wondered, could I provide a similarly simple formal foundation for the science of observation?

A mathematical model of consciousness.

That’s right. My intuition was, there are conscious experiences. I have pains, tastes, smells, all my sensory experiences, moods, emotions and so forth. So I’m just going to say: One part of this consciousness structure is a set of all possible experiences. When I’m having an experience, based on that experience I may want to change what I’m doing. So I need to have a collection of possible actions I can take and a decision strategy that, given my experiences, allows me to change how I’m acting. That’s the basic idea of the whole thing. I have a space X of experiences, a space G of actions, and an algorithm D that lets me choose a new action given my experiences. Then I posited a W for a world, which is also a probability space. Somehow the world affects my perceptions, so there’s a perception map P from the world to my experiences, and when I act, I change the world, so there’s a map A from the space of actions to the world. That’s the entire structure. Six elements. The claim is: This is the structure of consciousness. I put that out there so people have something to shoot at.

But if there’s a W, are you saying there is an external world?

Here’s the striking thing about that. I can pull the W out of the model and stick a conscious agent in its place and get a circuit of conscious agents. In fact, you can have whole networks of arbitrary complexity. And that’s the world.

The world is just other conscious agents?

I call it conscious realism: Objective reality is just conscious agents, just points of view. Interestingly, I can take two conscious agents and have them interact, and the mathematical structure of that interaction also satisfies the definition of a conscious agent. This mathematics is telling me something. I can take two minds, and they can generate a new, unified single mind. Here’s a concrete example. We have two hemispheres in our brain. But when you do a split-brain operation, a complete transection of the corpus callosum, you get clear evidence of two separate consciousnesses. Before that slicing happened, it seemed there was a single unified consciousness. So it’s not implausible that there is a single conscious agent. And yet it’s also the case that there are two conscious agents there, and you can see that when they’re split. I didn’t expect that, the mathematics forced me to recognize this. It suggests that I can take separate observers, put them together and create new observers, and keep doing this ad infinitum. It’s conscious agents all the way down.

If it’s conscious agents all the way down, all first-person points of view, what happens to science? Science has always been a third-person description of the world. . .

Continue reading.

Written by LeisureGuy

1 May 2016 at 12:45 pm

Posted in Evolution, Science

Why don’t they just feed us kibble? It’s going in that direction. — Jaw-dropping story of a Silicon Valley juice-box startup

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Yes, really. Read this NY Times article by David Gelles: what sure seems like a crackpot money-sinkhole of an idea is sold on the basis of machine feeding, more or less. From the article:

By some measures, Juicero is very much on trend. Soylent, a liquefied meal replacement, is already popular among single-minded coders too busy to eat. Chime, a device meant to brew Indian chai, will soon be on the market. A company called Tovala is raising money on Kickstarter, hoping to build a hybrid microwave and toaster, and also sell specialized meal packs.

You have to read the article to believe it.

BTW, note also in the article this very clear depiction of meme competition and evolution (and dead-ends).

To succeed, Juicero will have to buck these trends, and also clear a more pedestrian hurdle — persuading people to pay a premium for another kitchen doodad. “Seven hundred dollars for a small cooking appliance is extremely high,” said Virginia Lee, beverage analyst for Euromonitor. “There are a lot of appliances competing for counter space, never mind the wallet.”

And I personally, as a type-2 diabetic (and I’ve heard that there are more than a few of us around), juice is contraindicated: a type-2 diabetic needs the fiber that the Juicero discard and definitely doesn’t need the quickly-digestible high-carb product. So I think the reception might be substantially underwhelming. But I’m sure he’s made his bundle, which is what the whole exercise seems to be about, unless it actually is to move us all closer to a piped-in diet of kibble and sludge.

Written by LeisureGuy

31 March 2016 at 8:45 pm

Evolution and diet

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One thing about evolution: it may be blindly responding to the current environment, but it never ever stops—and over (long periods of) time, it does produce amazing results.

Take food. I recently blogged how some humans have genetically adapted to vegetarian diets. That makes sense if for many generations a regional group of humans subsist on a vegetarian diet: those who can get more nutrients from non-meat foods will then have a survival advantage, so that tiny mutations and changes in that direction tend to accumulate. At one extreme of this in the animal kingdom, you have animals that can detrive nutrients from bamboo (like the giant panda), a food with not much nutritional density.

And natural selection also favored those among the Inuit who could best tolerate the high-meat, high-fat diet on which they subsist, so they evolved to do some tricks with the available foods.

And then another obvious example occurred to me: how a mutation for lactose tolerance conveyed a survival advantage to some groups and enabled some humans to digest milk as adults. (More (and better) information here.)

I continue to be unable to understand how so many in the US can deny the truth of evolution when the evidence is so overwhelming and the idea makes so much sense. But I suppose I could say the same about global warming.

Written by LeisureGuy

31 March 2016 at 11:41 am

Posted in Evolution, Food, Science

Did humans evolve to believe in God?

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Certainly humans (and other predators) find hope a survival advantage. I’ve watched my cats check certain spots for prey, day after day, despite prey never being present. But predators that lose hope—that give up looking—would not survive so well as those that always continue looking, despite many failures. So hope certainly would seem to convey a survival advantage and thus be favored by natural selection.

As this article points out, attributing events to a conscious agent that has a purpose also offers a survival advantage, even though the result is many false positives (since most events are random and lacking in purpose—e.g., the tree that topples onto your car in a windstorm: it’s not doing that for a purpose, it just happened. It’s not because (for example) you overdrew your account at the bank or were mean to your kids, but it might feel that way—particularly if you already harbor beliefs in a conscious controlling superpower.

Sarah Emerson writes at Motherboard:

More than eight in ten people worldwide have some sort of religious belief, according to a Pew Research Center study. Approximately one third of those people are Christian.

Even though the percentage of people who identify as atheist is on the rise, the world is an overwhelmingly devout place.

And while science versus religion has been debated since classical antiquity, we’re still a long ways off from definitively knowing how and why the human species came to attribute its existence—and the creation of everything in the universe—to spiritual entities we cannot see, and cannot prove to be real.

One theory, as illustrated in this short video from New Scientist’s Explanimator series,presents the possibility that religion emerged a long time ago as an evolutionary adaptation. According to this argument, early forms of organized religion were necessary for the building of clans that helped to ensure the long-term survival of large groups of people. Religion encouraged clans to unite around a shared belief or ritual, and allowed for the cultivation of community practices like foraging for food, hunting, and sharing childcare duties. These things would have given religious groups a key advantage over their competitors.

So as these clans continued to thrive and survive, their genes were passed on, and religion was selected for by evolution, according to the video. Clans, over time, grew into large communities that supposedly benefited from the stability that a shared faith provided, until religion eventually appeared in some form throughout every human society.

No matter how we ended up like this, our brains do seem biologically wired for religion, the video adds. “Many think our brains evolved to assume that things that happen in the world have a purpose, and if that purpose is mysterious, perhaps an unseen supernatural agent is at work.”

The argument here is that humans are “strongly attracted to explanations of events in terms of agent action—particularly events that are not readily explained in terms of ordinary causation.” Existential threats scare us, and we desire tools that help us reason with them.

Religion is therefore much like language. Humans aren’t born with an innate knowledge of French, English, Chinese, or whatever. But we are born with the ability to learn those languages based on the societies into which we are born or raised, the video adds. They help us to make sense of the world around us. Likewise, none of us are born believers, but we can pick up our faiths depending on whether or not we’re raised to believe.

It’s pointed out that religion came to be so diverse because of the different needs of different types of societies. Agrarian tribes, for example, believed in gods that represented the things they found important such as crops, water, or fire. While larger, sedentary civilizations often worshiped entities responsible for protecting elements like human affairs [e.g., a god of war – LG].

But the larger these communities grew, . . .

Continue reading.

Written by LeisureGuy

31 March 2016 at 11:27 am

Posted in Evolution, Religion, Science

Cornell study finds some people may be genetically programmed to be vegetarians

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Ariana Eunjung Cha reports in the Washington Post:

Why is it that some people can stay healthy only by sticking to a strict vegetarian diet? Why is it that others can eat a steak a day, remain slim, avoid heart disease and feel like a million dollars? The answers may lie in your heritage.

Cornell University researchers have found a fascinating genetic variation that they said appears to have evolved in populations that favored vegetarian diets over hundreds of generations. The geography of the vegetarian allele is vast and includes people from India, Africa and parts of East Asia who are known to have green diets even today.

Researcher Kaixiong Ye said that the vegetarian adaptation allows people to “efficiently process omega-3 and omega-6 fatty acids and convert them into compounds essential for early brain development.”

Omega-3 is found in fish, whole grains, olive oil, fruits and vegetables, while omega-6 is found in beef, pork products and many packaged snack foods such as cookies, candies, cakes and chips, as well as in nuts and vegetable oils.

Nutritionists believe that getting a good balance of these two types of fatty acids in the diet is essential to staying healthy. The body can’t produce these substances naturally, so it must get them from food.

Omega-3 is anti-inflammatory and helps regulate metabolism, which affects a wide range of functions in the body. In recent years, supplements rich in omega-3 have been trendy, based on the idea that it may reduce risk of heart disease. (The Food and Drug Administration says the evidence supports this theory but isn’t conclusive.) Omega-6 contributes to inflammation and plays an important role in skin and hair growth, bone health and reproductive health. Inflammatory responses are essential to our survival. They help fight off infections and protect us from injury. But if the response is excessive, it can lead to all kinds of problems and may contribute to a higher risk of heart disease, cancer and Alzheimer’s disease.

Studies have suggested that humans evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids of 1:1 but that the Western diet has a ratio that is closer to 15 or 16:1. The Mediterranean diet, in contrast, is closer to having an equal balance of the two and is recommended by many doctors.

But this new study, funded by the National Institutes of Health and the U.S. Department of Agriculture, shows that different people may need radically different ratios of the substances in their diet depending on their genes, and it supports the growing evidence against a one-size-fits-all approach to nutrition and for highly personalized advice.

The existence of the vegetarian allele implies that, for people with this variation, straying from that diet — by eating a lot of red meat, for example — may make them more susceptible to inflammation, because their bodies were optimized for a different mix of inputs.

The research, published Wednesday in the journal Molecular Biology and Evolution, involved two parts. . .

Continue reading.

Written by LeisureGuy

30 March 2016 at 11:42 am

Evolution skeptics will be pleased at living transitional species of the move to land

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One standard argument from those who don’t understand and thus disbelieve evolution is that they would believe if any transitional species could be discovered—e.g., of the transition of the ancestors of modern whales moving from land-dwelling to sea-dwelling. Of course, whenever such fossils are found, the goalposts are moved, and some additional thing must be found.

One biggie, of course, which is of interest to believers in evolution as well as skeptics of it, would be the discovery of fossils showing the transition of vertebrates from sea-dwelling species to land-dwelling species, and lo! such a species has been found still living.

Obviously, this small (5-cm) fish is not the ancestor of current land-dwelling vertebrates, but it exemplifies the evolutionary transition from swimming in water to walking on land. It’s a fascinating discovery, reported in the NY Times by Carl Zimmer:

It’s one of the most famous chapters in evolution, so familiar that it regularly inspires New Yorker cartoons: Some 375 million years ago, our ancestors emerged from the sea, evolving from swimming fish to vertebrates that walked on land.

Scientists still puzzle over exactly how the transition from sea to land took place. For the most part, they’ve had to rely on informationgleaned from fossils of some of the intermediate species.

But now a team of researchers has found a remarkable parallel to one of evolution’s signature events. In a cave in Thailand, they’ve discovered that a blind fish walks the way land vertebrates do.

The waterfall-climbing cave fish, Cryptotora thamicola, has even evolved many of the skeletal features that our ancestors did for walking, including a full-blown pelvis.

“It’s really weird,” said John R. Hutchinson, a biologist at the Royal Veterinary College at the University of London who was not involved in the new study. “It’s a good example of how much fish diversity there’s left to be discovered.”

Drop an ordinary fish on the ground, and it will flop around helplessly: Its fins are adapted for pushing against water, not fighting gravity.

The early land vertebrates, known as tetrapods, evolved adaptations that enabled them to move efficiently over solid ground. A pelvis joined their hind limbs to their spines, for example. Their vertebrae grew flanges so that they interlocked, helping the spine hold itself stiff and straight even when being pulled down by gravity.

These adaptations led tetrapods to walk in a distinctive fashion, moving their forelegs and hind legs together in a cycle. Early tetrapods probably walked much the way salamanders do today, bending their trunk from side to side as they traveled.

All tetrapods descend from a single ancestor — a single lineage of fish that managed to spread on land. Some other fishes evolved vaguely similar ways of moving around.

On coral reefs, for example, frogfish can push off surfaces with their fins. They have a gait that looks something like a slow-motion walk. But they can manage this movement only underwater.

Other fish can move on land, although none of them use a tetrapod gait to do so. Some simply squirm, while others, like mudskippers, rely on their front fins as crutches. In Hawaii, the Nopili rock-climbing goby climbs up rock faces by using its mouth as a suction cup.

The waterfall-climbing cave fish is leaps ahead of them, it turns out. Pale and blind, the two-inch-long fish feeds on microbes and organic matter growing on the cave walls. It was discovered in 1985, deep inside a system of caves in northern Thailand, and has been found nowhere else.

While other fish in the caves enjoy a life in quiet pools, the waterfall-climbing cave fish clambers up slick rocks as water crashes over it. . .

Continue reading. At the link, a GIF of the little guy in action.

Obviously the transition this little fish represents was long ago accomplished, but evolution doesn’t care: evolution is blind. The variations that result in a survival advantage will have more progeny, and that’s the story of evolution: the process never stops and never is directed at any particular goal. It just churns away and the survival advantages produce the pressure that helps the variations that have such an advantage. If conditions change, which variations are helpful also change.

I have to say I simply cannot grasp the logic (if any) if those who disbelieve in evolution. I do not see how they can have the slightest grasp of modern biology, which shows evolution’s work on every hand. It must be that such skeptics simply are ignorant of biology, which of course makes one wonder how they can believe that they are in a position to judge the reality of evolution. I suppose it’s the Dunning-Kruger effect at work: great confidence because the level of knowledge is so tiny.

Written by LeisureGuy

24 March 2016 at 9:18 am

Posted in Evolution, Science

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