Category Archives: Natural World

Caesar’s Last Breath. The Epic Story of the Air around us – Sam Kean. 

The ghosts of breaths past continue to flit around you every second of every hour, confronting you with every single yesterday.

Short of breathing from a tank, we can’t escape the air of those around us. We recycle our neighbors’ breaths all the time, even distant neighbors’. Just as light from distant stars can sparkle our irises, the remnants of a stranger’s breath from Timbuktu might come wafting in on the next breeze.

Our breaths entangle us with the historical past. Some of the molecules in your next breath might well be emissaries from 9/11 or the fall of the Berlin Wall, witnesses to World War I or the star-spangled banner over Fort McHenry. And if we extend our imagination far enough in space and time, we can conjure up some fascinating scenarios. For instance, is it possible that your next breath, this one, right here, might include some of the same air that Julius Caesar exhaled when he died?

How could something as ephemeral as a breath still linger? If nothing else, the atmosphere extends so far and wide that Caesar’s last gasp has surely been dissolved into nothingness by now, effaced into the æther. You can open a vein into the ocean, but you don’t expect a pint of blood to wash ashore two thousand years later.

Your lungs expel a half liter of air with every normal breath; a gasping Caesar probably exhaled a full liter, a volume equivalent to a balloon five inches wide. Now compare that balloon to the sheer size of the atmosphere. Depending on where you cut it off, the bulk of the atmosphere forms a shell around Earth about ten miles high. Given those dimensions, that shell has a volume of two billion cubic miles. Compared to the atmosphere at large, then, a one-liter breath represents just 0.00000000000000000001 percent of all the air on Earth. Talk about tiny: Imagine gathering together all of the hundred billion people who ever lived, you, me, every last Roman emperor and pope and Dr. Who. If we let those billions of people stand for the atmosphere, and reduce our population by that percentage, you’d have just 0.00000000001 “people” left, a speck of a few hundred cells, a last breath indeed. Compared to the atmosphere, Caesar’s gasp seems like a rounding error, a cipher, and the odds of encountering any of it in your next breath seem nil.

Consider how quickly gases spread around the planet. Within about two weeks, prevailing winds would have smeared Caesar’s last breath all around the world, in a band at roughly the same latitude as Rome, through the Caspian Sea, through southern Mongolia, through Chicago and Cape Cod. Within about two months, the breath would cover the entire Northern Hemisphere. And within a year or two, the entire globe.

The same holds true today, naturally, any breath or belch or exhaust fume anywhere on Earth will take roughly two weeks, two months, or one or two years to reach you, depending on your relative location.

While on some level (the human level) Caesar’s last breath does seem to have disappeared into the atmosphere, on a microscopic level his breath hasn’t disappeared at all, since the individual molecules that make it up still exist.

So in asking whether you just inhaled some of Caesar’s last breath, I’m really asking whether you inhaled any molecules he happened to expel at that moment.

One liter of air at any sort of reasonable temperature and pressure corresponds to approximately 25 sextillion (25,000,000,000,000, 000,000,000) molecules.

When you crunch the numbers, you’ll find that roughly one particle of “Caesar air” will appear in your next breath. That number might drop a little depending on what assumptions you make, but it’s highly likely that you just inhaled some of the very atoms Caesar used to sound his cri de coeur contra Brutus. And it’s a certainty that, over the course of a day, you inhale thousands.

Nothing liquid or solid of Julius Caesar remains. But you and Julius are practically kissing cousins. To misquote a poet, the atoms belonging to his breath as good as belong to you.

You could pick anyone who suffered through an agonizing last breath: the masses at Pompeii, Jack the Ripper’s victims, soldiers who died during gas attacks in World War I. Or I could have picked anyone who died in bed, whose last breath was serene—the physics is identical. Heck, I could have picked Rin Tin Tin or Jumbo the giant circus elephant. Think of anything that ever breathed, from bacteria to blue whales, and some of his, her, or its last breath is either circulating inside you now or will be shortly.

Why not be more audacious? Why not go further and trace these air molecules to even bigger and wilder phenomena? Why not tell the full story of all the gases we inhale? Every milestone in Earth’s history, you see—from the first Hadean volcanic eruptions to the emergence of complex life—depended critically on the behavior and evolution of gases. Gases not only gave us our air, they reshaped our solid continents and transfigured our liquid oceans. The story of Earth is the story of its gases. Much the same can be said of human beings, especially in the past few centuries. When we finally learned to harness the raw physical power of gases, we could suddenly build steam engines and blast through billion-year-old mountains in seconds with explosives. Similarly, when we learned to exploit the chemistry of gases, we could finally make steel for skyscrapers and abolish pain in surgery and grow enough food to feed the world. Like Caesar’s last breath, that history surrounds you every second: every time the wind comes clattering through the trees, or a hot-air balloon soars overhead, or an unaccountable smell of lavender or peppermint or even flatulence wrinkles your nose, you’re awash in it. Put your hand in front of your mouth again and feel it: we can capture the world in a single breath.

This includes the formation of our very planet from a cloud of space gas 4.5 billion years ago. Later a proper atmosphere emerged on our planet, as volcanoes began expelling gases from deep inside Earth. The emergence of life then scrambled and remixed this original atmosphere, leading to the so-called oxygen catastrophe (which actually worked out pretty well for us animals). Overall the first section explains where air comes from and how gases behave in different situations.

Human beings have, well, harnessed the special talents of different gases over the past few centuries. We normally don’t think of air as having much mass or weight, but it does: if you drew an imaginary cylinder around the Eiffel Tower, the air inside it would weigh more than all the metal. And because air and other gases have weight, they can lift and push and even kill. Gases powered the Industrial Revolution and fulfilled humanity’s ancient dream of flying.

Our relationship with air has evolved in the past few decades. For one thing, we’ve changed the composition of what we breathe: the air you inhale now is not the same air your grandparents inhaled in their youth, and it’s markedly different from the air people breathed three hundred years ago.

You can survive without food, without solids, for weeks. You can survive without water, without liquids, for days. Without air, without gases, you’d last a few minutes at most. I’ll wager, though, that you spend the least amount of time thinking about what you’re breathing.

Caesar’s Last Breath aims to change that. Pure air is colorless and (ideally) odorless, and by itself it sounds like nothing. That doesn’t mean it’s mute, that it has no voice. It’s burning to tell its story. Here it is.

Caesar’s Last Breath. The Epic Story of the Air around us. by Sam Kean

get it from Amazon

How Color Vision Came to the Animals – Nick Stockton. 

ANIMALS ARE LIVING color. Wasps buzz with painted warnings. Birds shimmer their iridescent desires. Fish hide from predators with body colors that dapple like light across a rippling pond. And all this color on all these creatures happened because other creatures could see it.

The natural world is so showy, it’s no wonder scientists have been fascinated with animal color for centuries. Even today, the questions how animals see, create, and use color are among the most compelling in biology.

Until the last few years, they were also at least partially unanswerable—because color researchers are only human, which means they can’t see the rich, vivid colors that other animals do. But now new technologies, like portable hyperspectral scanners and cameras small enough to fit on a bird’s head, are helping biologists see the unseen. And as described in a new Science paper, it’s a whole new world.

Visions of Life

The basics: Photons strike a surface—a rock, a plant, another animal—and that surface absorbs some photons, reflects others, refracts still others, all according to the molecular arrangement of pigments and structures. Some of those photons find their way into an animal’s eye, where specialized cells transmit the signals of those photons to the animal’s brain, which decodes them as colors and shapes.

It’s the brain that determines whether the colorful thing is a distinct and interesting form, different from the photons from the trees, sand, sky, lake, and so on it received at the same time. If it’s successful, it has to decide whether this colorful thing is food, a potential mate, or maybe a predator. “The biology of color is all about these complex cascades of events,” says Richard Prum, an ornithologist at Yale University and co-author of the paper.

In the beginning, there was light and there was dark. That is, basic greyscale vision most likely evolved first, because animals that could anticipate the dawn or skitter away from a shadow are animals that live to breed. And the first eye-like structures—flat patches of photosensitive cells—probably didn’t resolve much more than that. It wasn’t enough. “The problem with using just light and dark is that the information is quite noisy, and one problem that comes up is determining where one object stops and another one starts. ” says Innes Cuthill, a behavioral ecologist at the University of Bristol and coauthor of the new review.

Color adds context. And context on a scene is an evolutionary advantage. So, just like with smart phones, better resolution and brighter colors became competitive enterprises. For the resolution bit, the patch light-sensing cells evolved over millions of years into a proper eye—first by recessing into a cup, then a cavity, and eventually a fluid-filled spheroid capped with a lens. For color, look deeper at those light-sensing cells. Wedged into their surfaces are proteins called opsins. Every time they get hit with a photon—a quantum piece of light itself—they transduce that signal into an electrical zap to the rudimentary animal’s rudimentary brain. The original light/dark opsin mutated into spin-offs that could detect specific ranges of wavelengths. Color vision was so important that it evolved independently multiple times in the animal kingdom—in mollusks, arthropods, and vertebrates.

In fact, primitive fish had four different opsins, to sense four spectra—red, green, blue, and ultraviolet light. That four-fold ability is called tetrachromacy, and the dinosaurs probably had it. Since they’re the ancestors of today’s birds, many of them are tetrachromats, too.

But modern mammals don’t see things that way. That’s probably because early mammals were small, nocturnal things that spent their first 100 million years running around in the dark, trying to keep from being eaten by tetrachromatic dinosaurs. “During that period the complicated visual system they inherited from their ancestors degraded,” says Prum. “We have a clumsy, retrofitted version of color vision. Fishes, and birds, and many lizards see a much richer world than we do.”

In fact, most monkeys and apes are dichromats, and see the world as greyish and slightly red-hued. Scientists believe that early primates regained three-color vision because spotting fresh fruit and immature leaves led to a more nutritious diet. But no matter how much you enjoy springtime of fall colors, the wildly varicolored world we humans live in now isn’t putting on a show for us. It’s mostly for bugs and birds. “Flowering plants of course have evolved to signal pollinators,” says Prum. “The fact that we find them beautiful is incidental, and the fact that we can see them at all is because of an overlap in the spectrums insects and birds can see and the ones we can see.”

Covered in Color

And as animals gained the ability to sense color, evolution kickstarted an arms race in displays—hues and patterns that aided in survival became signifiers of ace baby-making skills. Almost every expression of color in the natural world came about to signal, or obscure, a creature to something else.

For instance, “aposematism” is color used as a warning—the butterfly’s bright colors say “don’t eat me, you’ll get sick.” “Crypsis” is color used as camouflage. Color serves social purposes, too. Like, in mating. Did you know that female lions prefer brunets? Or that paper wasps can recognize each others’ faces? “Some wasps even have little black spots that act like karate belts, telling other wasps not to try and fight them,” says Elizabeth Tibbetts, an entomologist at the University of Michigan.

But animals display colors using two very different methods. The first is with pigments, colored substances created by cells called chromatophores (in reptiles, fish, and cephalopods), and melanocytes (in mammals and birds). They absorb most wavelengths of light and reflect just a few, limiting both their range and brilliance. For instance, most animals cannot naturally produce red; they synthesize it from plant chemicals called carotenoids.

The other way animals make color is with nanoscale structures. Insects, and, to a lesser degree, birds, are the masters of color-based structure. And compared to pigment, structure is fabulous. Structural coloration scatters light into vibrant, shimmering colors, like the shimmering iridescent bib on a Broad-tailed hummingbird, or the metallic carapace of a Golden scarab beetle. And scientists aren’t quite sure why iridescence evolved. Probably to signal mates, but still: Why?

Decoding the rainbow of life

The question of iridescence is similar to most questions scientists have about animal coloration. They understand what the colors do in broad strokes, but there’s till a lot of nuance to tease out. This is mostly because, until recently, they were limited to seeing the natural world through human eyes. “If you ask the question, what’s this color for, you should approach it the way animals see those colors,” says Tim Caro, a wildlife biologist at UC Davis and the organizing force behind the new paper. (Speaking of mysteries, Caro recently figured out why zebras have stripes.)

Take the peacock. “The male’s tail is beautiful, and it evolved to impress the female. But the female may be impressed in a different way than you or I,” Caro says. Humans tend to gaze at the shimmering eyes at the tip of each tail feather; peahens typically look at the base of the feathers, where they attach to the peacock’s rump. Why does the peahen find the base of the feathers sexy? No one knows. But until scientists strapped to the birds’ heads tiny cameras spun off from the mobile phone industry, they couldn’t even track the peahens’ gaze.

Another new tech: Advanced nanomaterials give scientists the ability to recreate the structures animals use to bend light into iridescent displays. By recreating those structures, scientists can figure out how genetically expensive they are to make.

Likewise, new magnification techniques have allowed scientists to look into an animal’s eye structure. You might have read about how mantis shrimp have not three or four but a whopping 12 different color receptors and how they see the world in psychedelic hyperspectral saturation. This isn’t quite true. Those color channels aren’t linked together—not like they are in other animals. The shrimp probably aren’t seeing 12 different, overlapping color spectra. “We are thinking maybe those color receptors are being turned on or off by some other, non-color, signal,” says Caro.

But perhaps the most important modern innovation in biological color research is getting all the different people from different disciplines together. “There are a lot of different sorts of people working on color,” says Caro. “Some behavioral biologists, some neurophysiologists, some anthropologists, some structural biologists, and so on.”

And these scientists are scattered all over the globe. He says the reason he brought everyone to Berlin is so they could finally synthesize all these sub-disciplines together, and move into a broader understanding of color in the world. The most important technology in understanding animal color vision isn’t a camera or a nanotech surface. It’s an airplane. Or the internet.


The Asteroid that finished the Dinosaurs. A grain of sand hitting a bowling ball. – Liz Dunphy. 

The asteroid impact that doomed the dinosaurs to extinction had such a devastating effect on Earth by pure chance, scientists say.

If it had struck 30 seconds later – or 30 seconds sooner – it would have caused far less damage and the dinosaurs would probably have survived.

As a result, man might never have become the planet’s dominant species, a BBC documentary reveals tonight, according to Daily Mail.

The asteroid struck 66million years ago 24 miles off the Yucatan Peninsula in Mexico, causing a crater 111 miles wide and 20 miles deep. Scientists who drilled into the crater found the rock was rich in sulphur compounds.

The impact of the asteroid vaporised this rock, filling the air with a cloud of dust similar to that created by a catastrophic volcanic eruption.

This blocked out the sun and cooled the planet dramatically – below freezing for a decade – wiping out most life.

Those dinosaurs not killed by fumes, molten rock falling from the sky or tsunamis would have starved as their food ran out.

Yet if the asteroid, which is estimated to have been nine miles across and travelling at 40,000mph, had arrived a few seconds sooner or later, it could have landed in deep water in the Atlantic or Pacific.

That would have meant that mostly sea water would have been vaporised, causing far less harm. Instead, the effect of the impact of a comparatively tiny asteroid was magnified catastrophically.

Sean Gulick, professor of geophysics at the University of Texas at Austin, who organised the drilling with Professor Joanna Morgan, of Imperial College London, said: “That asteroid struck Earth in a very unfortunate place.”

Professor Morgan said research suggests 100billion tons of sulphates were thrown into the atmosphere, adding: “That would be enough to cool the planet for a decade and wipe out most life.”

The asteroid’s impact was so huge that the blast led to the extermination of three quarters of all life on Earth, including most of the dinosaurs.

But this chance event allowed smaller mammals – and ultimately humans – the chance to thrive.

Had the asteroid crashed seconds earlier or later it would have hit the ocean, potentially causing much less vaporisation which may have allowed the dinosaurs to survive, scientists now believe.

Professor Joanna Morgan of Imperial College London has co-led a major new study with Sean Gullick, professor of geophysics at the University of Texas, Austin into the the impact of this earth-changing asteroid.

The results of this major study will be revealed in a new BBC documentary called The Night the Dinosaurs Died which will be screened in the UK tomorrow and is presented by Professors Alice Roberts and Ben Garod.

In the study, researchers have drilled into the peak ring of the Chicxulub crater in the Gulf of Mexico where the asteroid hit.

Their research has unearthed insights into how impacts can help shape planets and possibly even provide habitat for new origins of life.

It also established a new understanding of how violent asteroid impacts cause a planet’s surface to behave like a fluid – previous scientific analysis suggested that such impacts deform the surface by melting most of the rock around the impact.

Prof Gullick said that the asteroid struck the earth at a very unfortunate place – a concentration of sulphur-rich rock which vaporised, catapulting a light-reflecting cloud into the air.

Prof Gullick explained that sulphate particles reflect light, which effectively shaded the earth from the sun, dramatically cooling the planet, limiting plant growth and ultimately cutting off food supplies.

This caused the decline and death of the dinosaurs as a species which had dominated earth for 150m years.

According to Professor Joanna Morgan, the samples suggest that more than 100bn tons of sulphates were thrown into the atmosphere with extra soot from the fires that followed.

“That would be enough to cool the planet for a decade and wipe out most life,” Prof Morgan said as reported by The Times.

But this dark day for the dinosaurs provided an opportunity for mammals and ultimately humans to evolve.

“Just half a million years after the extinction of the dinosaurs, landscapes had filled with mammals of all shapes and sizes. Chances are, if it wasn’t for that asteroid we wouldn’t be here today,” scientist and BBC presenter Prof Alice Roberts told The Times.

Rock analysis has allowed scientists to calculate the size of the impact which indicates that the asteroid was approximately nine miles wide and hit the planet at 40,000mph.

This would make the asteroid equivalent to a grain of sand hitting a bowling ball.


The 30 seconds that sentenced dinosaurs to their doom: New BBC documentary reveals the moment an asteroid NINE-MILES long hit the earth and wiped out an entire species. 

Daily Mail