For two hundred years, scientists have believed that the eyespots of butterflies and moths evolved to look like large eyes in order to frighten off predators. A bird might think that the bright eyespots are the eyes of a concealed cat, for example.

It sounds logical, but there is a hidden assumption: We are assuming that a predator such as a bird pays attention to the same features that we would. But does it?

Cambridge behavioral ecologist Martin Stevens and his team decided to test the longstanding assumption: They nailed paper moths to trees in Cambridgeshire, with a mealworm stuck to each one, to attract birds.

Some of the paper moths also had bright spots that looked like eyes, but others had bright spots such as bars and squares that did not look like eyes.

The researchers reasoned that if the longstanding assumption was correct, then birds such as blackbirds, and house sparrows would avoid the moths whose spots looked most like big eyes.

But that is not what happened.

Birds came to eat the "moths" at the same rate, whether their spots looked like eyes (at least to a human) or not.

However, paper moths that had lots of spots were attacked 30% less often than others. Also large spots were more effective than small ones.

The researchers concluded that the theory that eyespots evolved to look like eyes has no experimental support. Rather, the spots deter birds just by being colourful and conspicuous.

Dr. Stevens offers a suggestion as to why conspicuous spots deter predators: They suggest that the insect might be poisonous. He told New Scientist, "Predators tend to stay away from highly conspicuous prey, possibly because most conspicuous objects in nature are toxic," says Stevens. "We think this is the primary eyespot effect."

He does not rule out the idea that some eyespots evolved to look like eyes. He offers the hawkmoth caterpillar, whose eyes may look like snakes, as an example.

See also

• Butterfly "stare" doesn't intimidate birds (New Scientist, March 8, 2008)
• Insect "eyespots" don't mimic eyes, study says" by Anne Casselman (National Geographic News, February 22, 2008)
• "Zoologists Challenge Longstanding Theory That 'Eyespots' Mimic The Eyes Of Predators' Enemies" ScienceDaily (Feb. 28, 2008)

Journal reference: Conspicuousness, not eye mimicry, makes ‘‘eyespots’’ effective antipredator signals (Martin Stevens, Chloe J. Hardman, and Claire L. Stubbins) Behavioral Ecology doi:10.1093/beheco/arm162

Abstract: Many animals bear colors and patterns to reduce the risk of predation from visually hunting predators, including warning colors, camouflage, and mimicry. In addition, various species possess paired circular features often called "eyespots," which may intimidate or startle predators preventing or postponing an attack. Most explanations for how eyespots work assert that they mimic the eyes of the predators own enemies. However, recent work has indicated that spots may reduce the risk of predation based purely on how conspicuous they are to a predator's visual system. Here, we use a field technique involving artificial prey marked with stimuli of various shapes, numbers, and sizes, presented to avian predators in the field, to distinguish between the eye mimicry and conspicuousness theories. In 3 experiments, we find that the features which make effective antipredator wing markings are large size and higher numbers of spots. Stimuli with circles survived no better than those marked with other conspicuous shapes such as bars, and changing the spatial construction of the spots to increase the level of eye mimicry had no effect on the protective value of the spots. These experiments support other recent work indicating that conspicuousness, and not eye mimicry, is important in promoting avoidance behavior in predators and that eyespots on real animals need not necessarily, as most accounts claim, mimic the eyes of other animals.

Key words: antipredator, conspicuousness, eyespots, mimicry, predation, vision.

(Note: The image of a, common Buckeye found at Toronto Island, is from the Government of Canada's online listing of the butterflies of Canada. The insect is pictured with both wing faces.)

A  passage from Daniel Levitin's This Is Your Brain On Music notes the complexity of the human mind, as relates to thought and music processing, in a way that students can understand":

It is difficult to appreciate the complexity of the brain because the numbers are so huge they go well beyond our everyday experience (unless you are a cosmologist). The average brain consists of one hundred billion (100,000,000,000) neurons. Suppose each neuron was one dollar, and you stood on a street corner trying to give dollars away to people as they passed by, as fast as you could hand them out- let's say one dollar per second. If you did this twenty-four hours a day, 365 days a year, without stopping, and if you had started on the day that Jesus was born, you would by the present day only have gone through about two thirds of your money. Even if you gave away hundred-dollar bills once a second, it would take you thirty-two years to pass them all out. This is a lot of neurons, but the real power and complexity of the brain (and of thought) comes through their connections. Each neuron is connected to other neurons- usually one thousand to ten thousand others. Just four neurons can be connected in sixty-three ways, or not at all, for a total of sixty-four possibilities. As the number of neurons increases, the number of possible connections grows exponentially...The number of combinations becomes so large that it is unlikely we will ever understand all the possible connections in the brain, or what they mean. The number of combinations possible- and hence the number of possible different thoughts or brain states each of us can have- exceeds the number of known particles in the entire known universe." (Levitin, pp.85-86)

Most of us, far from overestimating our brains, probably underestimate them. It's not magic, but it is reality.

Students' brains will not do everything they (or we) want, but they will do far more than they sometimes expect.

A fascinating article by Judith Thurman, "First Impressions: What does the world’s oldest art say about us?" (June 23, 2008) in The New Yorker explores the attempts we make to understand the artworks left by humans drawing on the walls of caves thousands of years ago. She reflects on the Chauvet paintings found in south central France. These oldest known paintings predate the Lascaux and Altamira friezes by fifteen to eighteen thousand years. The history of interpretation of older artworks has suffered from too-ready assumptions about "primitive" people, in particular that, as mud slowly morphed into mind, art would gradually become more sophisticated. For example,

He had also made the Darwinian assumption that the most ancient art was the most primitive, and [i]n that respect, Chauvet was a bombshell. It is Aurignacian, and its earliest paintings are at least thirty-two thousand years old, yet they are just as sophisticated as much later compositions. What emerged with that revelation was an image of Paleolithic artists transmitting their techniques from generation to generation for twenty-five millennia with almost no innovation or revolt. A profound conservatism in art, Curtis notes, is one of the hallmarks of a “classical civilization.” For the conventions of cave painting to have endured four times as long as recorded history, the culture it served, he concludes, must have been “deeply satisfying”—and stable to a degree it is hard for modern humans to imagine.

Also, curiously in the light of the notion of the "violent brute" cave man,

No human conflict is recorded in cave art, although at three separate sites there are four ambiguous drawings of a creature with a man’s limbs and torso, pierced with spearlike lines. More pertinent, perhaps, is a famous vignette in the shaft at Lascaux. It depicts a rather comical stick figure with an avian beak or mask, a puny physique, and a long skinny penis. He and his erect member seem to have rigor mortis. He is flat on his back at the feet of an exquisitely realistic wounded bison, whose intestines are spilling out. The bison’s glance is turned away, but it might have an ironic smile. Could the subject be hubris? Whatever it represents, some mythic contest—and the struggle of prehistorians to interpret their subject is such a contest—has ended in a draw.

Her descriptions are beautiful,

A great frieze covers the back left wall: a pride of lions with Pointillist whiskers seems to be hunting a herd of bison, which appear to have stampeded a troop of rhinos, one of which looks as if it had fallen into, or is climbing out of, a cavity in the rock. As at many sites, the scratches made by a standing bear have been overlaid with a palimpsest of signs or drawings, and one has to wonder if cave art didn’t begin with a recognition that bear claws were an expressive tool for engraving a record—poignant and indelible—of a stressed creature’s passage through the dark.

and I will spoil no more of them for you. A fierce controversy rages over how exactly to interpret the art and its purpose - or whether one should attempt to interpret it at all. One archaeologist defended his interpretation as follows:

Clottes was hurt and outraged by the rancor of the attacks that greeted “The Shamans of Prehistory” (“psychedelic ravings,” one critic wrote), and the authors defended themselves in a subsequent edition. “You can advance a scientific hypothesis without claiming certainty,” Clottes told me one evening. “Everyone agrees that the paintings are, in some way, religious. I’m not a believer myself, and I’m certainly not a mystic. But Homo sapiens is Homo spiritualis. The ability to make tools defines us less than the need to create belief systems that influence nature. And shamanism is the most prevalent belief system of hunter-gatherers.”

Influence nature, yes, but we also need to understand and interpret nature. Probably the most important thing that the cave paintings tell us about ourselves is that the mind seems to have emerged rather suddenly, not by a long series of increments, a point that Mario Beauregard and I discuss in The Spiritual Brain. Tour the caves, courtesy France's culture ministry. The image above is but one of many you can click on. Also tour Lascaux here (at Virtual visit) and view Altamira images here.

Historically, we have always assumed that an amputated finger, for example, could not be regenerated. However, medical scientists are now finding that certain cells actually have the necessary information for regeneration. The can even share this capability with other cells, tissues, and organs. The secret is coaxing them to do it, and this informative CBS report highlights significant advances: Here is the YouTube link and here's the Tube:

The scientists, it should be noted, are not creating this ability; the information was there in the cell already, but special techniques are required to enable it to be used.

In "First Detailed Map of the Human Cortex" in MIT's Technology Review, Emily Singer notes, "A new imaging technique reveals previously hidden brain structures, including the central hub" and explains,

The first high-resolution map of the human cortical network reveals that the brain has its own version of Grand Central Station, a central hub that is structurally connected to many other parts of the brain. Scientists generated the map using a new type of brain imaging known as diffusion imaging. The technique maps the largely inaccessible tangle of the brain's white matter--the long, thin fibers that ferry nerve signals between cells.

and we also learn,

Conventional imaging techniques, such as structural magnetic resonance imaging (MRI), reveal major anatomical features of the brain. But in humans, the brain's finer architecture--the neural projections that connect its different parts--has, until recently, remained hidden. "The brain we've been looking at with conventional MRI or CT scans all these years is not the real brain," says Van Wedeen, a neuroscientist at Massachusetts General Hospital, in Boston, who was also involved in the study. "We're just seeing a shadow of its surfaces."

The notion of the "real" brain vs. "a shadow of its surfaces" is an intriguing one.

Probably, we will never find the "real" brain for the same reasons as we never find the "real" Grand Central Station or the real Canada. There is a physical reality that corresponds to Grand Central Station and one that corresponds to Canada. But usually, what we find is a series of overlapping material and immaterial things whose "reality" can only be understood as a series of generalities - the reality is not any one of the generalities nor even all of them together, nor only in specific things we can point to. Perhaps it will always be much easier to find the answers to specific questions about the brain than to find - and take in - the "real" brain.

Here’s another great animation of life inside the body and the cell, from Hybrid Medical Animations.

They enter the realm of high art, achieving a combination of Truth and Beauty ... - from an unidentified endorsement

The music is well suited too. I wrote to the friend who drew it to my attention,

Medical animations are quite helpful because many people still believe the “brick theory of the cell.” = that the body is built out of cells as a wall is of bricks, with the brick being less organized than the wall.

 But the cell is something between a factory and a supercomputer.

The remarkable thing is that the wretched caterpillar I found on a rosebud and threw to the wolf spider was like that. As is the spider itself.

One realizes that Darwin’s explanation for how all this came to be is not even relevant. Darwin argued that it all happened because the stronger life form survives to breed.

That, of course, is doubtless true, but it is not going to give you a supercomputer! – d.

(Note: The video starts a couple of seconds after you access the page.) Note to teachers: Teachers may wish to point out to students who have questions in this area that scientists in Darwin's and Huxley's day thought that the cell was a very simple unit that related to the body as the brick does to a wall. They thought that the question they needed to answer was, How might a structure like a wall might be built? The question we really need to answer is, how might a structure like a supercomputer be built? You will find the chapter on "specified complexity" in The Design of Life helpful in introducing students to "information" as a science concept.

British physicist David Tyler points to a recent paper by L. Vogt in the journal Cladistics which explains why attempts to construct a tree of life are generally unfalsifiable:

Putting this in more popular language, cladists have adopted a variety of rationales to justify giving weight and credence to their evolutionary trees, but these rationales do not survive critical scrutiny if the test is Popper's demarcation criterion for science.

[ ... ]

The debates within evolutionary circles are always about specifics: the broader issues are not debated because they have an axiomatic status. So, evolutionary theorists do not have the mental tools that would allow them to disprove common ancestry, or whether design inferences are warranted. Consequently, it is not unreasonable to conclude, from the perspective of empirical science, that proposed evolutionary scenarios represent not "scientific but metaphysical hypotheses".

The Vogt paper suggests that the common science criterion that a theory should be falsifiable (able to be shown to be incorrect) be abandoned where evolution is concerned.

At the Molecular and Cell Biology Learning Center, you will find a Virtual Cell Animation Collection:

In addition to Virtual Cell's online game modules, animations have been developed to introduce students to new concepts. By walking through the still images and movies included for each topic, viewers can easily choose between either studying a specific step from one of the processes or taking a more immersive look at the process in it's entirety. In order to better serve all levels of educational interest, each topic is being offered with a choice between two approaches:

A great way to learn about protein traffic, photosynthesis, and transcription of genes.