The Lazarus flower

The adage goes, "Extinction is forever."

It's a sobering thought.  There's been talk of "de-extinction" -- using intact DNA from well-preserved fossils to resurrect, Jurassic-Park-style, extinct animals -- but so far, the research in that vein has been tentative and not particularly promising.  Plus, there are the inevitable ethical questions about bringing back woolly mammoths, passenger pigeons, and dodos into a world where their environment has changed into something they couldn't survive in anyway.  It seems like recreating a few individuals of an extinct species, then having them live out their lives in zoos, is nothing more than generating a handful of entertaining curiosities at a very great cost.

There are, however, a few species that have been declared extinct which have turned out not to be.  The most famous of these is the coelacanth, a weird-looking fish that's one of the lobe-finned fish, the fish group with the closest relationship to amphibians.  It was thought that all the lobe-fins had become extinct along with the non-avian dinosaurs during the Cretaceous Extinction 66 million years ago, but then someone caught one in the Indian Ocean.  There are, in fact, two living species of coelacanth -- the West Indian Ocean coelacanth (Latimeria chalumnae) and the Indonesian coelacanth (Latimeria menadoensis).  This long-term survival of a species that was thought to be long gone has resulted in the coelacanth being labeled a "living fossil" or a "Lazarus taxon."

There are also the ones that have been declared extinct, but that a handful of true believers -- and sometimes some scientists, as well -- are convinced are still alive.  The last thylacine, or Tasmanian wolf (Thylacinus cynocephalus), which is neither a wolf nor restricted to Tasmania, died in a zoo in 1936 -- except there continue to be sightings of purported thylacines, both in Tasmania and adjacent South Australia.  In fact, there's a Facebook group devoted to alleged thylacine sightings, which so far, have either been anecdotal, or accompanied by photos of Bigfoot-level blurriness.

Then there's the ivory-billed woodpecker (Campophilus principalis), an enormous woodpecker species that used to live in swampy regions of the North American southeast.  The last confirmed sighting was in Louisiana in 1944, but there have been sporadic reports ever since -- most, probably, of the related (but smaller) pileated woodpecker (Dryocopus pileatus).  But a friend of mine, an employee of the Cornell Laboratory of Ornithology, was part of the team sent to investigate a cluster of alleged sightings, and she was one of the people who say they actually saw one.  Now, let me add that my friend is an accomplished and knowledgeable birder, and knew what she was looking for; she, and the other members of the team, would not mistake a pileated woodpecker for this bird.  Unfortunately, the only video they got was short and of poor quality, and although she and the rest of the team have serious credibility, it still amounts to a single anecdotal report, and a lot of folks are not convinced.

All of this is just by way of introducing a discovery that should give some hope to the thylacine and ivory-billed woodpecker aficionados.  Just last week, a paper in the journal PhytoKeys described the (re)discovery of a plant in the family Gesneriaceae, a tropical group most familiar to collectors of rare houseplants -- the best-known members are the African violet (Saintpaulia spp.),  Cape primrose (Streptocarpus spp.), and gloxinia (Gloxinia spp.).

The recent discovery was in the Centinela region of southern Ecuador, in the foothills of the Andes Mountains.  Centinela has been devastated by deforestation -- by some estimates, 97% of the original old-growth rain forest has been cleared or extensively damaged -- so it's to be expected that any species endemic to the region are gone.  That's what the botanists thought about a glossy-leaved, orange-flowered plant that grew in the humid understory; it was last seen in the 1980s.  By the time it was discovered and catalogued, it was gone.

That's why they named it Gasteranthus extinctus.

And then, a couple of months ago, some botanists studying what's left of Centinela found that it wasn't extinct after all.  Here's the plant:

[Photograph by Riley Fortier]

They took lots of photographs but were careful not to disturb the few remaining plants -- nor are they telling exactly where they found them.  This same strategy was adopted by the folks from Cornell looking for the ivory-billed woodpecker; the last thing they needed was a bunch of overenthusiastic amateurs stomping about the place (and you know they would).  But it is a hopeful thought, that some of the species we thought were gone forever might still be out there somewhere.  (For what it's worth, they're keeping the name Gasteranthus extinctus, and hoping that it doesn't one day become accurate in fact.)

"Rediscovering this flower shows that it’s not too late to turn around even the worst-case biodiversity scenarios, and it shows that there’s value in conserving even the smallest, most degraded areas," said Dawson White, a postdoctoral researcher at the Field Museum in Chicago, who was the paper's lead author.  "New species are still being found, and we can still save many things that are on the brink of extinction."

So that's today's optimistic news.  Me, I'm still hoping for the thylacine.  Those things were cool.  While thus far the evidence thus far has been less than convincing, it's certainly still a possibility that it -- and some of the other species most folks have given up on -- are still alive after all.

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Splitting the difference

One of the most misunderstood pieces of the evolutionary model is that natural selection is almost always a compromise.

Very few changes that could occur an organism's genes (and thus in its physical makeup) are unequivocally good.  (Plenty of them are unequivocally bad, of course.)  Take, for example, our upright posture, which is usually explained as having been selected for by (1) allowing us to see farther over tall grass and thus spot predators, (2) leaving our hands free for tool use, (3) making it easier to carry our offspring before they can walk on their own, or (4) all of the above.  At the same time, remodeling our spines to accommodate walking upright -- basically, taking a vertebral column that evolved in an animal that supported itself on all fours, and just kind of bending it upwards -- has given us a proneness to lower back injury unmatched in the natural world.  The weakening of the rotator cuff, due to the upper body no longer having to support part of our weight, has predisposed us to shoulder dislocations.

Then there are the bad changes that have beneficial features.  One common question I was asked when teaching evolutionary biology is if selection favors beneficial traits and weeds out maladaptive ones, why do negative traits hang around in populations?  One answer is that a lot of maladaptive gene changes are recessive -- you can carry them without showing an effect, and if you and your partner are both carriers, your child can inherit both copies (and thus the ill effect).  But it's even more interesting than that.  It was recently discovered that being a carrier for the gene for the devastating disease cystic fibrosis gives you resistance to one of the biggest killers of babies in places without medical care -- cholera.  It's well known that being heterozygous for the gene for sickle-cell anemia makes you resistant to malaria.  Weirdest of all, the (dominant) gene for the horrible neurodegenerative disorder Huntington's disease gives you an eighty percent lower likelihood of developing cancer -- offset, of course, by the fact that all it takes is one copy of the gene to doom you by age 55 or so to progressive debility, coma, and death.

So the idea of "selective advantage" is more complex than it seems at first.  The simplest way to put it is that if an inheritable change on balance gives you a greater chance of survival and reproduction, it will be selected for even if it gives you disadvantages in other respects, even some serious ones.

The reason the topic comes up is because of a cool piece of research out of the University of California - Santa Barbara into a curious genetic change in the charming little Colorado blue columbine (Aquilegia caerulea), familiar to anyone who's spent much time in the Rocky Mountains.

Colorado blue columbine (Aquilegia caerulea) [Image licensed under the Creative Commons Rob Duval, Heavycolumbinebloom, CC BY-SA 3.0]

Both the common name and scientific name have to do with birds; columba is Latin for dove, aquila Latin for eagle.  The reason is the graceful, backwards-curved tubular petals, which (viewed from the side) look a little like a bird's foot.  The tubes end in nectar glands, and are there to lure in pollinators -- mostly hummingbirds and butterflies -- whose mouthparts can fit all the way down the long, narrow tubes.

Well, the researchers found that not all of them have these.  In fact, there's a group of them that don't have the central petals and nectar spurs at all.  The loss is due to a single gene, APETALA3-3, which simply halts complete flower development.  So far, nothing too odd; there are a lot of cases where some defective gene or another causes the individual to be missing a structure.  What is more puzzling is that in the study region (an alpine meadow in central Colorado), a quarter of the plants have the defective flowers.

You would think that a plant without its prime method of attracting pollinators would be at a serious disadvantage.  How could this gene be selected strongly enough to result in 25% of the plants having the change?  The answer turned out to be entirely unexpected.  The plants with the defective gene don't get visited by butterflies and hummingbirds as much -- but they are also, for some reason, much less attractive to herbivores, including aphids, caterpillars, rabbits, and deer.  So it may be that the flowers don't get pollinated as readily as those of their petal-ful kin, but they are much less likely to sustain energy-depleting damage to the plant itself (in the case of deer, sometimes chomping the entire plant down to ground level). 

If fewer flowers get pollinated, but the ones that do come from plants that are undamaged and vigorous and able to throw all their energy into seed production, on balance the trait is still advantageous.

Even cooler is that the two different morphs rely on different pollinators.  Species of butterfly with a shorter proboscis tend to favor the spurless variant, while the original spurred morph attracts butterflies and hummingbirds with the ability to reach all the way down into the spur.  What the researchers found is that there is much less cross-pollination between the two morphs than there is between plants of the same morph.

For speciation to occur, there needs to be two things at work: (1) a genetic change that acts as a selecting mechanism, and (2) reproductive isolation between the two different morphs.  This trait checks both boxes.

So it looks like the Colorado blue columbine may be on the way to splitting into two species.

Once again, we have an example from the real world demonstrating the power and depth of the evolutionary model -- and one that's kind of hard to explain if you don't buy it.  This time, it's a pretty little flower that has vindicated Darwin, and shown that right in front of our eyes, evolution is still "creating many forms most beautiful and most wonderful."

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It's all becoming clear

The phenomenon of transparency is way more interesting than it appears at first.

I remember thinking about the concept when I was a kid, the first time I watched the classic horror/science fiction film The Invisible Man.  Coincidentally, I was in high school and was in the middle of taking biology, and we'd recently learned how the human eye works, and Claude Rains's predicament took on an added layer of difficulty when it occurred to me that if he was invisible -- including his retina -- not only would we not be able to see him, he wouldn't be able to see anything, because the light rays striking his eye would pass right through it.  Since it's light being absorbed by the retina that stimulates the optic nerve, and Rains's retinas weren't absorbing any light (or we'd have seen them floating in the air, which is kind of a gross mental image), he'd have been blind.

So an invisibility potion isn't nearly as fun an idea as it sounds at first.

It wasn't until I took physics that I learned why some objects are transparent, and why (for example) it's harder to see a glass marble underwater than it is in the air.  Transparency results from a molecular structure that neither appreciably absorbs nor scatters light; more specifically, when the substance in question has electron orbitals spaced so that they can't absorb light in the visible region of the spectrum.  (If not, the light passes right through it.)  Note that substances can be transparent in some frequency ranges and not others; water, for example, is largely transparent in visible light, but is opaque in the microwave region -- which is why water heats up so quickly when you put it in a microwave oven.

The second bit, though, is where it really gets interesting.  Why are some transparent objects still clearly visible, and others are nearly invisible?  Consider my example of glass in air as compared to glass under water.  You can see through both, but it's much harder to discern the outlines of the glass underwater than it is in air.  Even more strikingly -- submerge a glass object in a colorless oil, and it seems to vanish entirely.

The reason is something called the index of refraction -- how much a beam of light is bent when it passes from one transparent medium to another.  A vacuum has, by definition, an index of refraction of exactly 1.  Air is slightly higher -- 1.000293, give or take -- while pure water is about 1.333.  The key here is that the more different the two indices are, the more light bends when crossing from one to the other (and the more the light tends to reflect from the surface rather than refract).  This is why the boundary between air and water is pretty obvious (and why those amazing photographs of crystal-clear lakes, where you can see all the way to the bottom and boats appear to be floating, are always taken from directly overhead, looking straight down; even at a slight angle from perpendicular, you'd see the reflected portion of the light and the water's surface would be clearly visible).

Likewise, the more similar the indices of refraction are, the less light bends (and reflects) at the boundary, and the harder it is to see the interface.  Glass, depending on the type, has an index of refraction of about 1.5; olive oil has an index of 1.47.  Submerge a colorless glass marble in a bottle of olive oil, and it seems to disappear,

The reason all this comes up has to do with the evolution of transparency in nature -- as camouflage.  It's a pretty clever idea, that, and is used by a good many oceanic organisms (jellyfish being the obvious example).  None of them are completely transparent, but some are good enough at index-of-refraction-matching that they're extremely hard to see.  It's much more difficult for terrestrial organisms, though, because air's lower index of refraction -- 1, for all intents and purposes -- is just about impossible to match in any conceivable form of living tissue.

Some of them come pretty close, though.  Consider the "skeleton flower," Diphylleia grayi, of Japan, which has white flowers that become glass-like when they're wet:

The transparency of the flower petals is likely to be a fluke, as it's hard to imagine how it would benefit the plant to evolve a camouflage that only works when the plant is wet.  An even cooler example was the subject of a paper in the journal eLife last week, and looked at a group of butterflies called (for obvious reasons) "glasswing butterflies."  These are a tropical group with clear windows in their wings -- but, it turns out, they're not all closely related to each other.

In other words, we're looking at an example of convergent evolution and mimicry.

The study found that some of the clear-wings are toxic, and those lack an anti-glare coating on the "windows."  This makes the light more likely to reflect from the surface, rather than pass through; think about the glare from a puddle in the road on a sunny day.  Those flashes of light act as a warning coloration -- an advertisement to predators that the animal is toxic, distasteful, or dangerous.

The glasswing butterfly Greta oto of Central and South America [Image is licensed under the Creative Commons David Tiller, Greta oto, CC BY-SA 3.0]

The coolest part of last week's paper was in looking at the mimics; the species that had the transparent windows but weren't themselves toxic.  Unlike the toxic varieties, those species had evolved anti-glare coatings on the windows, so the mimicry was obvious in bright light -- but in shadow, the lack of glare made them seem to disappear completely.  In other words, the clear parts act as a warning coloration in sunshine, and as pure camouflage in the shade!

Even more amazing is that a number of only distantly-related species have stumbled on the same mimicry -- so this particular vanishing act has apparently evolved independently more than once.  A good idea, apparently, shouldn't just be wasted on one species.

So that's today's cool natural phenomenon, which I hope I've clarified sufficiently.  There seems truly to be no end to the way living things can take advantage of physical phenomena for their own survival -- as Darwin put it, to generate "endless forms most beautiful and most wonderful."

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It's kind of sad that there are so many math-phobes in the world, because at its basis, there is something compelling and fascinating about the world of numbers.  Humans have been driven to quantify things for millennia -- probably beginning with the understandable desire to count goods and belongings -- but it very quickly became a source of curiosity to find out why numbers work as they do.

The history of mathematics and its impact on humanity is the subject of the brilliant book The Art of More: How Mathematics Created Civilization by Michael Brooks.  In it he looks at how our ancestors' discovery of how to measure and enumerate the world grew into a field of study that unlocked hidden realms of science -- leading Galileo to comment, with some awe, that "Mathematics is the language with which God wrote the universe."  Brooks's deft handling of this difficult and intimidating subject makes it uniquely accessible to the layperson -- so don't let your past experiences in math class dissuade you from reading this wonderful and eye-opening book.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

The birds and the bees and the flowers and the trees

One of the most fascinating aspects of evolution, and one of the least appreciated (outside of the biology-nerd community, anyhow), is how insects and flowering plants have coevolved.

Coevolution occurs when two different species (or groups of species) reciprocally affect each other's evolutionary changes.  A commonly-cited example is the pair made up of cheetahs and impalas; the fastest cheetahs get more food than the slowest, and the slowest impalas get turned into food more than the fastest, so each species has a tendency to get faster and faster (at least until other considerations, like the limitations of physiology, kick in).  This specific type of coevolution is sometimes called an evolutionary arms race, and can occur not only with speed but with issues like toxicity (in the species being eaten) and toxin tolerance (in the species doing the eating).

The coevolutionary relationship between flowering plants and insects is a curious one.  Certainly, there are insects that eat (and damage, sometimes fatally) plants; witness the gypsy moths that this year have shredded trees in our part of New York state.  Fortunately for our apple and cherry trees and other susceptible species, most trees attacked by gypsy moths survive defoliation and are able to put out another set of leaves once the moths' caterpillars are gone, and because the moths are a "boom-and-bust" species, they seldom mount a serious infestation like this year's more than once a decade or so.

But there's a "nicer" side to coevolution between insects and flowering plants, and that has to do with pollination.  We all learned in elementary school how bees and butterflies pollinate flowers, but it's more complicated than that; insects and plants have in some senses opposite interests in pollination.  For insects, the more different species of flowers they can visit, the more potential nectar sources they can access; but that's actively bad for flowers, because if a bee visits (for example) a rose and then a clover blossom, any pollen transferred does the plant no good at all because the two species aren't cross-fertile.  That pollen is "wasted," from the plant's perspective.

A species peony from the Caucasus Mountains, Paeonia mlokosewitschii -- nicknamed "Molly-the Witch" because most people can't pronounce "mlokosewitschii" -- primarily pollinated by ants and wasps  [photo taken this spring in the author's garden]

Plants have adopted a variety of strategies for coping with this.  Some, such as wind-pollinated plants (oaks, maples, willows, grasses, and many others) produce huge amounts of pollen, because they don't have a carrier to bring it from one flower to the next, and much of the pollen never reaches its target.  (This is why wind-pollinated plants like ragweed are primary culprits in pollen allergies.)  The same thing is true of plants that are visited by many different kinds of pollinators, and for the same reasons.

But the other approach is specialization.  If a flower has a shape that fits the mouthparts of only one species of pollinator, the pollen picked up is almost certainly going to be transferred to a flower of the same species.  In stable ecosystems, like rainforests, there are flowers and pollinators that have coevolved together so long that both are completely dependent on the other -- the pollinator's mouthparts don't fit any other flower species, and the flower's shape isn't compatible with any other pollinator's mouthparts.

Anna's Hummingbird (Calypte anna) visiting Crocosmia flowers in San Francisco, California [Image licensed under the Creative Commons Brocken Inaglory, Humming flowers, CC BY-SA 3.0]

As my evolutionary biology professor put it, this strategy works great until it doesn't.  Specialists get hit hardest by ecological change -- all that has to happen is for one of the pair to decline sharply, and the other collapses as well.  Their specialization leaves them with few options if the situation shifts.

The topic comes up because of a paper this week in Biological Reviews that looks at plant species which try to do both at once -- attract various species of pollinators (increasing the likelihood that pollen gets widely distributed, and mitigating the damage if one species of pollinator disappears) while encouraging those pollinators to feed exclusively on the flowers of that species only (decreasing the likelihood that the pollen will be transferred to a flower of an unrelated species).

A trio of researchers -- Kazuharu Ohashi (of the University of Tsukuba), Andreas Jürgens (of Technishe Universität Darmstadt), and James Thompson (of the University of Toronto) found that this complicated "hedging your bets" strategy is more common than anyone realized.  Some of the solutions the plants happen on are positively inspired; the goat willow (Salix caprea) has evolved to be pollinated by two different pollinators, bees and moths -- and the flowers actually change scents, producing one set of esters (chemicals associated with floral fragrance) during the day, and a different one at night, to attract their diurnal and nocturnal visitors most efficiently.  Cardinal shrub (Weigela spp.) flowers change scent as they age -- young flowers have fragrances attracting bees and butterflies, older ones attracting species like drone flies.

"[Y]ou'd expect that flowers would mostly be visited by one particular group of pollinators," said study lead author Kazuharu Ohashi, in an interview with Science Daily.  "But flowers often host many different visitors at the same time and flowers appear to meet the needs of multiple visitors.  The question we wanted to answer is how this happens in nature... Most flowers are ecologically generalized and the assumption to date has been that this is a suboptimal solution.  But our findings suggest that interactions with multiple animals can actually be optimized by minimizing trade-offs in various ways, and such evolutionary processes may have enriched the diversity of flowers."

Evolution is more subtle than a lot of us realize, happening on solutions to ecological problems that nearly defy belief.  The bucket orchid of South America (Coryanthes spp.) has a flower with a complex "trap" that only appeals to one species of bee -- and is so convoluted that when I explained its function to my biology students, I had to assure them more than once that I wasn't making it all up to fool the gullible.  The strategies vary dramatically from species to species, but always fall back to that tried-and-true rule -- evolution is the "law of whatever works."

So there's something to think about when you're working in your garden.  The birds and the bees and the flowers and the trees are a lot more complicated and interconnected than they may seem.  Many of the sophisticated mechanisms they use to assure survival and reproduction are only coming to light now -- and papers like Ohashi et al. give us a new lens into how beautiful and intricate the natural world is.

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Most people define the word culture in human terms.  Language, music, laws, religion, and so on.

There is culture among other animals, however, perhaps less complex but just as fascinating.  Monkeys teach their young how to use tools.  Songbirds learn their songs from adults, they're not born knowing them -- and much like human language, if the song isn't learned during a critical window as they grow, then never become fluent.

Whales, parrots, crows, wolves... all have traditions handed down from previous generations and taught to the young.

All, therefore, have culture.

In Becoming Wild: How Animal Cultures Raise Families, Create Beauty, and Achieve Peace, ecologist and science writer Carl Safina will give you a lens into the cultures of non-human species that will leave you breathless -- and convinced that perhaps the divide between human and non-human isn't as deep and unbridgeable as it seems.  It's a beautiful, fascinating, and preconceived-notion-challenging book.  You'll never hear a coyote, see a crow fly past, or look at your pet dog the same way again.

[Note: if you purchase this book from the image/link below, part of the proceeds goes to support Skeptophilia!]

The flora of prehistory

I grew up around plants.  Well, everyone does, more or less, but my parents were dedicated gardeners and naturalists.  My dad grew show-quality tea roses and taught me how to recognize the trees of my native Louisiana from the shapes of the leaves and texture of the bark when I was still in elementary school.  My mom's flower gardens more than once had people pulling over to take photographs.

Regular readers of Skeptophilia are well aware of my fascination with prehistoric animals -- like many kids I grew up with books on dinosaurs (and posters of dinosaurs and models of dinosaurs...).  So it shouldn't have been a surprise that I was thrilled when I found out that just like the animals of prehistory, the plants of prehistory were different than the ones we have today.  But I recall that my interest was mixed with shock -- if I went back to the Cretaceous Period, not only would there be T. rexes and triceratopses stomping about, but the plants through which they'd have been stomping wouldn't have been the familiar oaks and ashes and hollies and camellias that were so familiar, but an entirely different flora in which I doubt there'd have been a single species I could have identified.

Well, maybe a couple, if not to species, at least to family.  Some of the earliest flowering plants were magnolias, and from the fossilized flowers, they look pretty much like... magnolias.  Ferns have been around for a long, long time (far predating the dinosaurs, in fact), and conifers like the common pines, cedars, and cypresses I saw every day were plentiful all the way back in the Triassic Period, 240-odd million years ago.  

But that's about it.  And although some of the groups were there, the species themselves would have been different ones than what we see around us today.  Imagine it: forests of plants with huge and wonderful biodiversity, in which you wouldn't recognize a single one that's familiar.

The reason I'm thinking about all this floral prehistory is a link to some cool research that showed up last week in Geology that a friend and frequent contributor to Skeptophilia sent me, about a discovery of a phenomenally well-preserved flower in hundred-million-year-old amber from Myanmar.  

Valviloculus pleristaminis, flower in lateral view.  Image credit: Poinar, Jr. et al., doi: 10.17348/jbrit.v14.i2.1014.

Dubbed Valviloculus pleristaminis (the genus name comes from the Latin valva -- "a folding door" -- and loculus -- "compartment;" the species name means "lots of stamens"), the little flower is only distantly related to any extant species.  Botanists think that Valviloculus might be allied to one of two rather obscure families of plants native to the Southern Hemisphere -- Monamiaceae and Atherospermataceae -- but that's only a preliminary analysis.

Atherosperma moschatum, an Australian species that may be one of the closest living cousins to Valviloculus [Image is in the Public Domain courtesy of photographer Peter Woodard]

"This isn't quite a Christmas flower but it is a beauty, especially considering it was part of a forest that existed 100 million years ago," said emeritus professor George Poinar, Jr., of Oregon State University, who led the research into the newly-discovered species.  "The male flower is tiny, about two millimeters across, but it has some fifty stamens arranged like a spiral, with anthers pointing toward the sky.  Despite being so small, the detail still remaining is amazing.  Our specimen was probably part of a cluster on the plant that contained many similar flowers, some possibly female."

What's even more mind-blowing is something I've pointed out before; given how difficult it is to form a good fossil and then have it survive intact for millions of years, the species we know about (both animal and plant) probably represent about 1% of what was actually alive back then.  The vast majority of species came and went, leaving no traces.  So if we were to travel back to the mid-Cretaceous, when Valviloculus was living and flowering in the prehistoric forests, not only would we see it, but literally hundreds of other long-gone species as varied, attractive, weird, and fascinating as the ones we have today.

Imagine the colors, shapes, and scents, plants from tiny sprigs all the way to towering trees, and none of which we still have with us now.  Truly, in Darwin's words, evolution produced -- and continues to produce -- "endless forms most beautiful and most wonderful."

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This week's Skeptophilia book recommendation is apt given our recent focus on all things astronomical: Edward Brooke-Hitching's amazing The Sky Atlas.

This lovely book describes our history of trying to map out the heavens, from the earliest Chinese, Babylonian, and Native American drawings of planetary positions, constellations, and eclipses, to the modern mapping techniques that pinpoint the location of stars far too faint to see with the naked eye -- and objects that can't be seen directly at all, such as intergalactic dust clouds and black holes.  I've always loved maps, and this book combines that with my passion for astronomy into one brilliant volume.

It's also full of gorgeous illustrations showing not only the maps themselves but the astronomers who made them.  If you love looking up at the sky, or love maps, or both -- this one should be on your list for sure.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]