Books, Brochures, and Chapters>Book:  Dawkins, Richard (2010-08-24), The Greatest Show on Earth: The Evidence for Evolution, Free Press, Retrieved on 2011-05-19
Folksonomies: evolution science

Memes

19 MAY 2011

 Two Meanings of the Word "Theory"

Theory, Sense 1: A scheme or system of ideas or statements held as an explanation or account of a group of facts or phenomena; a hypothesis that has been confirmed or established by observation or experiment, and is propounded or accepted as accounting for the known facts; a statement of what are held to be the general laws, principles, or causes of something known or observed. Theory, Sense 2: A hypothesis proposed as an explanation; hence, a mere hypothesis, speculation, conjecture; an ide...
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How scientists use it versus it's use in everyday life.

19 MAY 2011

 Conjecture versus Theorem

Mathematicians use the idea of proof to make a distinction between a 'conjecture' and a 'theorem', which bears a superficial resemblance to the OED's distinction between the two senses of 'theory'. A conjecture is a proposition that looks true but has never been proved. It will become a theorem when it has been proved. A famous example is the Goldbach Conjecture, which states that any even integer can be expressed as the sum of two primes. Mathematicians have failed to disprove it for all eve...
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in mathematics and how it applies to scientific "theory".

19 MAY 2011

 What is Sufficient Evidence for Something to Become a Fact

A scientific theorum has not been - cannot be - proved in the way a mathematical theorem is proved. But common sense treats it as a fact in the same sense as the 'theory' that the Earth is round and not flat is a fact, and the theory that green plants obtain energy from the sun is a fact. All are scientific theorums: supported by massive quantities of evidence, accepted by all informed observers, undisputed facts in the ordinary sense of the word. As with all facts, if we are going to be peda...
Folksonomies: theory evidence fact
Folksonomies: theory evidence fact
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How much evidence is necessary to make evolution a fact?

19 MAY 2011

 People Freed by DNA Evidence

...there is a distressingly long list of people who have been wrongly convicted on eye-witness testimony and subsequently freed - sometimes after many years - because of new evidence from DNA. In Texas alone, thirty-five condemned people have been exonerated since DNA evidence became admissible in court. And that's just the ones who are still alive. Given the gusto with which the State of Texas enforces the death penalty (during his six years as Governor, George W. Bush signed a death warrant...
Folksonomies: evidence dna csi
Folksonomies: evidence dna csi
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It's shocking how many people have been falsely imprisoned.

19 MAY 2011

 Many Hypotheses Become Theories

The distinction between the two dictionary meanings of 'theory' is not an unbridgeable chasm, as many historical examples show. In the history of science, theorums often start off as 'mere' hypotheses. Like the theory of continental drift, an idea may even begin its career mired in ridicule, before progressing by painful steps to the status of a theorum or undisputed fact. This is not a philosophically difficult point. The fact that some widely held past beliefs have been conclusively proved ...
Folksonomies: evolution theory fact
Folksonomies: evolution theory fact
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Beliefs about things are often proven false, but evolution and heliocentric theory are here to stay.

19 MAY 2011

 The Difficulty of Defining Species

The Platonist regards any change in rabbits as a messy departure from the essential rabbit, and there will always be resistance to change - as if all real rabbits were tethered by an invisible elastic cord to the Essential Rabbit in the Sky. The evolutionary view of life is radically opposite. Descendants can depart indefinitely from the ancestral form, and each departure becomes a potential ancestor to future variants. Indeed, Alfred Russel Wallace, independent co-discoverer with Darwin of e...
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The Platonist view of species defines all members as imperfect examples of a perfect example of the species, when in reality, there is a bell curve of examples that blend into other species.

19 MAY 2011

 Mendelian Genes are All-Or-Nothing

A Mendelian gene is an all-or-nothing entity. When you were conceived, what you received from your father was not a substance, to be mixed with what you received from your mother as if mixing blue paint and red paint to make purple. If this were really how heredity worked (as people vaguely thought in Darwin's time) we'd all be a middling average, halfway between our two parents. In that case, all variation would rapidly disappear from the population (no matter how assiduously you mix purple ...
Folksonomies: genes inheritance mendel
Folksonomies: genes inheritance mendel
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Genes are on-off switches, carrying either mother or father's version of it, not a blend of the two.

19 MAY 2011

 Everyone is a Choosing Agent

1 Humans deliberately choose attractive roses, sunflowers etc. for breeding, thereby preserving the genes that produce the attractive features. This is called artificial selection, it's something humans have known about since long before Darwin, and everybody understands that it is powerful enough to turn wolves into chihuahuas and to stretch maize cobs from inches to feet. 2 Peahens (we don't know whether consciously and deliberately, but let's guess not) choose attractive peacocks for bree...
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Sexual selection, breeding selection, and survival of the fittest selection.

19 MAY 2011

 Experiment is the Ultimate Test

The ultimate test of a scientific hypothesis is experiment. Experiment specifically means that you don't just wait for nature to do something, and passively observe it and see what it correlates with. You go in there and do something. You manipulate. You change something, in a systematic way, and compare the result with a 'control' that lacks the change, or you compare it with a different change. [...] If your hypothesis is that the non-random survival of random genetic variation has import...
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You don't wait for something to happen, you must test it.

19 MAY 2011

 Animals Can't Be Perfect in all Characteristics

We can expect bodies to be well equipped to survive, but this does not mean they should be perfect with respect to any one dimension. An antelope might run faster, and be more likely to escape a leopard, if its legs were a little longer. But a rival antelope with longer legs, although it might be better equipped to outsprint a predator, has to pay for its long legs in some other department of the body's economy. The materials needed to make the extra bone and muscle in the longer legs have to...
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Energy and materials put into one characteristic means less for another; therefore, species must find balance.

19 MAY 2011

 Hitler Wasn't Inspired by Darwin

The popular canard about Hitler being inspired by Darwin comes partly from the fact that both Hitler and Darwin were impressed by something that everybody has known for centuries: you can breed animals for desired qualities. Hitler aspired to turn this common knowledge to the human species. Darwin didn't. His inspiration took him in a much more interesting and original direction. Darwin's great insight was that you don't need a breeding agent at all: nature - raw survival or differential repr...
Folksonomies: politics history evolution
Folksonomies: politics history evolution
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...but by the science of breeding.

19 MAY 2011

 Carbon Dating

Of all the elements, carbon is the one that seems most indispensable to life - the one without which life on any planet is hardest to envisage. This is because of carbon's remarkable capacity for forming chains and rings and other complex molecular architectures. It enters the food web via photosynthesis, which is the process whereby green plants take in carbon dioxide molecules from the atmosphere and use energy from sunlight to combine the carbon atoms with water to make sugars. All the car...
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How it works.

19 MAY 2011

 Carbon Dating

Of all the elements, carbon is the one that seems most indispensable to life - the one without which life on any planet is hardest to envisage. This is because of carbon's remarkable capacity for forming chains and rings and other complex molecular architectures. It enters the food web via photosynthesis, which is the process whereby green plants take in carbon dioxide molecules from the atmosphere and use energy from sunlight to combine the carbon atoms with water to make sugars. All the car...
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How it works.

19 MAY 2011

 Science is a Public Activity

One of the nice things about science is that it is a public activity. Scientists publish their methods as well as their conclusions, which means that anybody else, anywhere in the world, can repeat their work. If they don't get the same results, we want to know the reason why. Usually they don't just repeat previous work but extend it: carry it further.
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Open to scrutiny and reproducible.

19 MAY 2011

 Species Divisions are Complicated

Zoologists have traditionally divided the vertebrates into classes: major divisions with names like mammals, birds, reptiles and amphibians. Some zoologists, called 'cladists',* insist that a proper class must consist of animals all of whom share a common ancestor which belonged to that class and which has no descendants outside that group. The birds would be an example of a good class. All birds are descended from a single ancestor that would also have been called a bird and would have sha...
Folksonomies: evolution species taxonomy
Folksonomies: evolution species taxonomy
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The ancestors are birds are reptiles, but in the fossil record where do we draw the line between them?

19 MAY 2011

 The Unimaginative Naming of an Ancestor

Raymond Dart, then, gave the name Australopithecus to the Taung Child, the type specimen of the genus, and we have been stuck with this depressingly unimaginative name for our ancestor ever since. It simply means 'southern ape'. Nothing to do with Australia, which just means 'southern country'. You'd think Dart might have thought of a more imaginative name for such an important genus. He might even have guessed that other members of the genus would later be discovered north of the equator. S...
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The name for Australopithecus is non-descriptive and unfortunate.

19 MAY 2011

 consequence of omphalogical reasoning

A more sophisticated consequence of omphalogical reasoning would be that stars whose distance from us is more than a few thousand light years must have been created with ready-made light beams stretching almost all the way to us - otherwise we wouldn't be able to see them until the distant future!
Folksonomies: astronomy omphalogical
Folksonomies: astronomy omphalogical
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Is that the stars were made with light beams stretch lightyears toward us.

19 MAY 2011

 The Wonder of Birds Flocking

What is remarkable about the starlings' behaviour is that, despite all appearances, there is no choreographer and, as far as we know, no leader. Each individual bird is just following local rules. The numbers of individual birds in these flocks can run into thousands, yet they almost literally never collide. That is just as well for, given the speed at which they fly, any such impact would severely injure them. Often the whole flock seems to behave as a single individual, wheeling and turnin...
Folksonomies: biology wonder emergence
Folksonomies: biology wonder emergence
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Emergent behavior without collisions.

19 MAY 2011

 DNA is not a Blueprint

Textbooks of biology repeat time and again that DNA is a 'blueprint' for building a body. It isn't. A true blueprint of, say, a car or a house embodies a one-toone mapping from paper to finished product. It follows from this that a blueprint is reversible. It is as easy to go from house to blueprint as the other way around, precisely because it is a one-to-one mapping. Actually, it's easier, because you have to build the house, but you only have to take some measurements and then draw the blu...
Folksonomies: biology dna
Folksonomies: biology dna
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You cannot reverse engineer DNA from the animal it appears within.

20 MAY 2011

 An Experiment With a Tadpole's Development

An early classic experiment by the Nobel Prize-winning embryologist Roger Sperry illustrates the principle perfectly. Sperry and a colleague took a tadpole and removed a tiny square of skin from the back. They removed another square, the same size, from the belly. They then regrafted the two squares, but each in the other's place: the belly skin was grafted on the back, and the back skin on the belly. When the tadpole grew up into a frog, the result was rather pretty, as experiments in embryo...
Folksonomies: biology experiments
Folksonomies: biology experiments
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Taking a piece of skin from the belly and switching it with a piece from the back caused the frog to scratch its belly when you tickle its back.

20 MAY 2011

 Caenorhabditis elegans

Caenorhabditis elegans was chosen in the 1960s as an ideal experimental animal by the formidably brilliant South African biologist Sydney Brenner. He had recently completed his work, with Francis Crick and others at Cambridge, on cracking the genetic code, and was looking around for a new big problem to solve. His inspired choice, and his own pioneering research on its genetics and neuro-anatomy, has led to a worldwide community of Caenorhabditis researchers that has grown into the thousands....
Folksonomies: biology experiments
Folksonomies: biology experiments
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A species in which we know every cell in its body, making it an excellent experimental specimen.

20 MAY 2011

 There Are Many Types of Islands

IMAGINE a world without islands. Biologists often use the word 'island' to mean something other than just a piece of land surrounded by water. From the point of view of a freshwater fish, a lake is an island: an island of habitable water surrounded by inhospitable land. From the point of view of an Alpine beetle, incapable of flourishing below a certain altitude, each high peak is an island, with almost impassable valleys between. There are tiny nematode worms (related to the elegant Caenorh...
Folksonomies: evolution science
Folksonomies: evolution science
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Creating many ways for species to evolve divergently.

20 MAY 2011

 Genes are Under Constant Attack

Every animal and plant genome is subject to a constant bombardment of deleterious mutations: a hailstorm of attrition. It is a bit like the moon's surface, which becomes increasingly pitted with craters due to the steady bombardment of meteorites. With rare exceptions, every time a gene concerned with an eye, for example, is hit by a marauding mutation, the eye becomes a little less functional, a little less capable of seeing, a little less worthy of the name of eye. In an animal that lives i...
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Constantly bombarded by things that mutate them so that the moment the expression is no longer used, it becomes ruined, thus we have blind animals living in caves.

20 MAY 2011

 Our Sinuses are Upside Down

Another consequence of our own shift from quadruped to biped concerns the sinuses, which give such grief to many of us (including me at the moment of writing) because their drainage hole is in the very last place a sensible designer would have chosen. Williams quotes an Australian colleague, Professor Derek Denton:* 'The big maxillary sinuses or cavities are behind the cheeks on either side of the face. They have their drainage hole in their top, which is not much of an idea in terms of using...
Folksonomies: evolution vestigial
Folksonomies: evolution vestigial
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Like back pains, its a product of our former quadrupedal nature.

20 MAY 2011

 The Natural Economy is Solar Powered

The natural economy is solar-powered. Photons from the sun rain down upon the entire daytime surface of the planet. Many photons do nothing more useful than heat up a rock or a sandy beach. A few find their way into an eye - yours, or mine, or the compound eye of a shrimp or the parabolic reflector eye of a scallop. Some may happen to fall on a solar panel - either a man-made one like those that, in a fit of green zeal, I have just installed on my roof to heat the bathwater, or a green leaf, ...
Folksonomies: nature biology sun
Folksonomies: nature biology sun
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All life on Earth deals in exchanges of sunbeams.

20 MAY 2011

 Evolutionary Arms Race Produces Tall Trees

Look at a single tall tree standing proud in the middle of an open area. Why is it so tall? Not to be closer to the sun! That long trunk could be shortened until the crown of the tree was splayed out over the ground, with no loss in photons and huge savings in cost. So why go to all that expense of pushing the crown of the tree up towards the sky? The answer eludes us until we realize that the natural habitat of such a tree is a forest. Trees are tall to overtop rival trees - of the same and ...
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As they compete for sunlight.

20 MAY 2011

 The Boundary of Life

The harder we look at the border between life and non-life, the more elusive does the distinction become. Life, the animate, was supposed to have some sort of vibrant, throbbing quality, some vital essence - made to sound yet more mysterious when dropped into French: elan vital. Life, it seemed, was made of a special living substance, a witch's brew called 'protoplasm'. Conan Doyle's Professor Challenger, a fictional character even more preposterous than Sherlock Holmes, discovered that the ...
Folksonomies: history life
Folksonomies: history life
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Different attempts to define it over the years.

20 MAY 2011

 The Fact of Our Own Existence

The fact of our own existence is almost too surprising to bear. So is the fact that we are surrounded by a rich ecosystem of animals that more or less closely resemble us, by plants that resemble us a little less and on which we ultimately depend for our nourishment, and by bacteria that resemble our remoter ancestors and to which we shall all return in decay when our time is past. Darwin was way ahead of his time in understanding the magnitude of the problem of our existence, as well as in t...
Folksonomies: nature wonder natural law
Folksonomies: nature wonder natural law
  1  notes

An eloquent rebuttal to the Anthropogenic principle.

20 MAY 2011

 The laryngeal nerve's haphazard course through the body

A favourite example, ever since it was pointed out to me by Professor J. D. Currey when he tutored me as an undergraduate, is the recurrent laryngeal nerve.* It is a branch of one of the cranial nerves, those nerves that lead directly from the brain rather than from the spinal cord. One of the cranial nerves, the vagus (the name means 'wandering' and it is apt), has various branches, two of which go to the heart, and two on each side to the larynx (voice box in mammals). On each side of the n...
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Another example of poor biological design.

20 MAY 2011

 The Idiotic Design of the Eye

Hermann von Helmholtz, the great nineteenthcentury German scientist (you could call him a physicist, but his contributions to biology and psychology were greater), said, of the eye: 'If an optician wanted to sell me an instrument which had all these defects, I should think myself quite justified in blaming his carelessness in the strongest terms, and giving him back his instrument.' One reason why the eye seems better than Helmholtz, the physicist, judged it to be is that the brain does an am...
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Wired backwards with a blind spot.

20 MAY 2011

 Transforming Species Through Mathematics

In 1917 the great Scottish zoologist D'Arcy Thompson wrote a book called On Growth and Form, in the last chapter of which he introduced his famous 'method of transformations'. * He would draw an animal on graph paper, and then he would distort the graph paper in a mathematically specifiable way and show that the form of the original animal had turned into another, related animal. You could think of the original graph paper as a piece of rubber, on which you draw your first animal. Then the tr...
Folksonomies: evolution evidence
Folksonomies: evolution evidence
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D'Arcy Thompson showed how one species could be transformed into another by sketching it on graph paper and distorting it.

20 MAY 2011

 Skeletal Similarities in Mammals

What a piece of work is the mammalian skeleton. I don't mean it is beautiful in itself, although I think it is. I mean the fact that we can talk about 'the' mammalian skeleton at all: the fact that such a complicatedly interlocking thing is so gloriously different across the mammals, in all its parts, while simultaneously being so obviously the same thing throughout the mammals. Our own skeleton is familiar enough to need no picture, but look at this skeleton of a bat. Isn't it fascinating ho...
Folksonomies: evolution evidence
Folksonomies: evolution evidence
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There are corresponding bones across species, evolved into other functions.

19 MAY 2011

 We Recapitulate Evolution in Nine Months

Evolution sceptic: Professor Haldane, even given the billions of years that you say were available for evolution, I simply cannot believe it is possible to go from a single cell to a complicated human body, with its trillions of cells organized into bones and muscles and nerves, a heart that pumps without ceasing for decades, miles and miles of blood vessels and kidney tubules, and a brain capable of thinking and talking and feeling. JBS: But madam, you did it yourself. And it only took you ...
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...to build a complete human being.

19 MAY 2011

 The Taung Child's Horrible Demise

The first Australopithecine to be discovered, and the type specimen of the genus, was the so-called Taung Child. At the age of three and a half the Taung Child was eaten by an eagle. The evidence is that damage marks to the eye sockets of the fossil are identical to marks made by modern eagles on modern monkeys as they rip out their eyes. Poor little Taung Child, shrieking on the wind as you were borne aloft by the aquiline fury, you would have found no comfort in your destined fame, two and ...
Folksonomies: history evolution
Folksonomies: history evolution
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Killed by a bird of prey.

20 MAY 2011

 DNA as an Archive of the Past

Each individual's genome, in any one generation, will be a sample from the species database. Different species will have different databases because of their different ancestral worlds. The database in the gene pool of camels will encode information about deserts and how to survive in them. The DNA in mole gene pools will contain instructions and hints for survival in dark, moist soil. The DNA in predator gene pools will increasingly contain information about prey animals, their evasive trick...
Folksonomies: history evolution dna
Folksonomies: history evolution dna
  1  notes

A repository of ancestral survival techniques.

19 MAY 2011

 The Term "Higher Animals"

So glibly do the phrases 'higher animals' and 'lower animals' trip off our tongues that it comes as a shock to realize that, far from effortlessly slotting into evolutionary thinking as one might suppose, they were - and are - deeply antithetical to it. We think we know that chimpanzees are higher animals and earthworms are lower, we think we've always known what that means, and we think evolution makes it even clearer. But it doesn't. It is by no means clear that it means anything at all. Or...
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Is meaningless and confuses people.

19 MAY 2011

 Animals Evolved onto the Land and Took the Ocean With them

If you go back far enough, everything lived in the sea - watery, salty alma mater of all life. At various points in evolutionary history, enterprising individuals from many different animal groups moved out on to the land, sometimes eventually to the most parched deserts, taking their own private sea water with them in blood and cellular fluids. In addition to the reptiles, birds, mammals and insects we see all around us, other groups that have succeeded in making the great trek out of life's...
Folksonomies: evolution
Folksonomies: evolution
  1  notes

In their blood.

19 MAY 2011

 The Evolution of Whales from Land to Sea

Whales were long an enigma, but recently our knowledge of whale evolution has become rather rich. Molecular genetic evidence (see Chapter 10 for the nature of this kind of evidence) shows that the closest living cousins of whales are hippos, then pigs, then ruminants. Even more surprisingly, the molecular evidence shows that hippos are more closely related to whales than they are to the cloven-hoofed animals (such as pigs and ruminants) which look much more like them. This is another example ...
Folksonomies: evolution species
Folksonomies: evolution species
  1  notes

The opposite of sea animals evolving to live on land.

19 MAY 2011

 Guppies Evolve Their Spots in Experimentation

Guppies are popular freshwater aquarium fish. As with the pheasants we met in Chapter 3, the males are more brightly coloured than the females, and aquarists have bred them to become even brighter. Endler studied wild guppies (Poecilia reticulata) living in mountain streams in Trinidad, Tobago and Venezuela. He noticed that local populations were strikingly different from each other. In some populations the adult males were rainbow-coloured, almost as bright as those bred in aquarium tanks. H...
Folksonomies: evolution experimentation
Folksonomies: evolution experimentation
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Spots are attractive to females, but also attractive to predators.

19 MAY 2011

 Antibiotics Evolve Bacteria in the Gut

New antibiotics have been coming out at frequent intervals since then, and bacteria have evolved resistance to just about every one of them. Nowadays, the most ominous example is MRSA (methycillin-resistant Staphylococcus aureus), which has succeeded in making many hospitals positively dangerous places to visit. Another menace is ' C. diff.' ( Clostridium difficile). Here again, we have natural selection favouring strains that are resistant to antibiotics; but the effect is overlain by anothe...
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As the bacteria adapt to the hostile environment.

19 MAY 2011

 Theory of Evolution Predicts the Existence of a Species

Both Darwin and his co-discoverer of natural selection, Wallace, called attention to an amazing orchid from Madagascar, Angraecum sesquipedale (see colour page 4), and both men made the same remarkable prediction, which was later triumphantly vindicated. This orchid has tubular nectaries that reach down more than 11 inches by Darwin's own ruler. That's nearly 30 centimetres. A related species, Angraecum longicalcar, has nectar-bearing spurs that are even longer, up to 40 centimetres (more tha...
Folksonomies: evolution science prophecy
Folksonomies: evolution science prophecy
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The existence of an orchid means there must be a species adapted to reaching its nectar.

19 MAY 2011

 Dog Breeding and Evolution

Another familiar example is the sculpting of the wolf, Canis lupus, into the two hundred or so breeds of dog, Canis familiaris, that are recognized as separate by the UK Kennel Club, and the larger number of breeds that are genetically isolated from one another by the apartheid-like rules of pedigree breeding. Incidentally, the wild ancestor of all domestic dogs really does seem to be the wolf and only the wolf... [...] The main point I want to draw out of domestication is its astonishing ...
Folksonomies: evolution species breeding
Folksonomies: evolution species breeding
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Dog breeding demonstrates how quickly animals can evolve, even if it's under artificial selection.

19 MAY 2011

 Missing Links Make Defining Species Possible

As we trace the ancestry of modern Homo sapiens backwards, there must come a time when the difference from living people is sufficiently great to deserve a different specific name, say Homo ergaster. Yet, every step of the way, individuals were presumably sufficiently similar to their parents and their children to be placed in the same species. Now we go back further, tracing the ancestry of Homo ergaster, and there must come a time when we reach individuals who are sufficiently different fro...
  1  notes

Without missing links, species would blur into each other.

19 MAY 2011

 The Empty Space in an Atom

A favourite analogy portrays the nucleus as a fly in the middle of a sports stadium. The nearest neighbouring nucleus is another fly, in the middle of an adjacent stadium. The electrons of each atom are buzzing about in orbit around their respective flies, smaller than the tiniest gnats, too small to be seen on the same scale as the flies. When we look at a solid lump of iron or rock, we are 'really' looking at what is almost entirely empty space. It looks and feels solid and opaque because o...
Folksonomies: wonder atom analogy model
Folksonomies: wonder atom analogy model
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Our senses are not adapted to experience the empty space between atoms.

20 MAY 2011

 How a Swim Bladder Works

The swim bladder is perhaps the major key to the teleosts' success, and it is well worth a digression to explain it. It is an internal bladder filled with gas, which can be sensitively adjusted to keep the fish in hydrostatic equilibrium at any desired depth. If you ever played with a Cartesian Diver as a child you'll recognize the principle, but a teleost fish uses an interesting variant of it. A Cartesian Diver is a little toy whose business part is a tiny upended cup, containing a bubble o...
Folksonomies: biology adaptation
Folksonomies: biology adaptation
  1  notes

A crucial adaptation for life in the sea.

20 MAY 2011

 An Origami Metaphor for Fetal Development

The sheets of tissue that fold, invaginate and turn inside out in a developing embryo do indeed grow, and it is that very growth that provides part of the motive force which, in origami, is supplied by the human hand. If you wanted to make an origami model with a sheet of living tissue instead of dead paper, there is at least a sporting chance that, if the sheet were to grow in just the right way, not uniformly but faster in some parts of the sheet than in others, this might automatically cau...
  1  notes

Cells divide and fold into new forms, just as origami structures become other structures through new folds.