by Ben Miller
14 Well, almost. Quantum Mechanics shows us that even at absolute zero, a particle has a residual jiggly-ness, known as zero point energy.
15 The unit of energy called the joule (J) is named in his honor. The one used by physicists, anyway. Engineers use handier (i.e. much, much larger) units like the kWh, where 1 kWh = 3 600 000 J.
16 To be precise, Boltzmann’s formula is that for an ideal gas. This is a gas whose individual particles don’t interact with one another, so troublesome things like viscosity can be safely ignored.
17 By configured, of course, I mean where are they, what direction are they going in, and how fast?
18 No doubt you recognize this unit, the bit, as fundamental to computing. Bytes and bits are the dollars and cents of information, where 1 byte = 8 bits. When we ask for a 15 terabyte hard drive, we politely request the capacity to store a message with a Shannon entropy of 15 × 1012 × 8 bits.
19 Or “apple-stealing,” for those readers not familiar with this quaint British phrase.
20 In case that means nothing to you, then e is a number that crops up so often in math it is called the “natural number.” It’s irrational, meaning that it can’t be expressed precisely, and is roughly 2.718. Here’s just one of the ways e can be written: e = (1 + 1/n)n as n tends to infinity.
21 The chemist in me can’t help but point out that there is no such thing, really, as a lone proton in water. Protons react with water molecules to form hydronium ions, H3O+. The net result is the same, though, as hydronium ions repel one another, and will readily give a proton up so that it can pass back through the cell membrane.
22 Dying is an innovation of sexually reproducing complex organisms, with a division of labor between mortal “body” cells and immortal “reproductive” cells. Bacteria, for example, are entirely immortal, though it’s not a life I feel particularly envious of. There’s no escape though: Eventually the food will run out, and even bacteria will starve.
23 It will be a pretty big galaxy, though. The Milky Way is expected to collide with the Andromeda Galaxy in about four billion years, and in four hundred and fifty billion years’ time, the fifty-odd galaxies of the Local Group will have merged.
24 It will reach its maximum size in around 7.9 billion years’ time, at which point its surface will extend as far as the present orbit of Mercury.
25 That’s calculated for a black hole of twenty trillion solar masses. The largest black hole currently known is NGC 4889, which weighs in at twenty-one billion solar masses.
1 Darwin was such a secretive soul that his letters to Joseph Hooker form the backbone of all Darwin scholarship, and you can find a link to them at http://www.darwinproject.ac.uk/darwin-hooker-letters.
2 Often given the mnemonic CHNOPS. That’s if you can call a string of letters a mnemonic.
3 I feel like I should point out that there are tribalisms within the primordial soup theory. One favors self-replicating molecules first; one proteins; and one cell membranes. Sooner or later, of course, you are going to need all three.
4 To qualify that sweeping statement: To date, samples of amino acids have been found in Antarctic meteorites, and their spectra have been observed in comets and interstellar space. Nucleobases have also been found in Antarctic meteorites, and the spectrum of methanamide, their chemical precursor, has been identified in comets. The spectra of amino acids have been seen in interstellar space, but not–to my knowledge, at least–that of nucleobases or their precursors.
5 Microbial mat fossils 3.5 billion years old have been found at the Dresser Formation in the Pilbara region of Western Australia. Microbial mats are communities of bacteria.
6 The Isua Greenstone Belt in southwestern Greenland, dated at 3.7 billion years old, has carbon in it that seems to be of organic origin.
7 OK, cards on the table. I am not entirely sure that what builders call “serpentinite marble” has anything to do with serpentinite the mineral other than a similarity in appearance, which is to say both are green with a serpent-like pattern. In fact, I’m not altogether sure “serpentinite marble” has got anything to do with marble. It’s probably made in a factory from brick dust. Frankly, when you’re looking for synchronicities you take what you’re given.
8 In fact, the only example. Discovered in 2000, close to the Mid-Atlantic Ridge, the joint between the Eurasian and North American plates, at 30° north.
9 The acidity or alkalinity of a liquid is defined by its pH, being the logarithm to the base ten of the number of hydrogen ions (protons) per cubic meter.
10 Once it has given up its energy, ATP is converted to ADP, or adenosine diphosphate. It’s not as complex as it sounds. ATP is basically a blocky carbon molecule with three phosphate groups getting on each other’s nerves, so much so that one is happy to whizz off energetically, leaving the other two behind.
11 Thanks to anthropogenic carbon dioxide, this is changing, and the world’s oceans are becoming more acidic. In fact, their pH is changing ten to a hundred times faster than at any time in the past fifty million years. This will have positive and negative effects on marine life; we are all hoping that the positive outweighs the negative.
12 Ah yes–I forgot to mention. In the years since the Miller–Urey experiment, we’ve learned that, far from being full of ammonia, hydrogen, and methane, the early atmosphere was full of oxidized gases. How do we know this? Because of zircon crystals. The oldest are dated at 4.4 billion years old, and their chemical composition indicates that they were formed at moderate temperatures in water, in an atmosphere full of nitrogen, sulfur dioxide, and carbon dioxide. No oxygen of course; that came roughly 2.3 billion years ago, as a by-product of oxygenic photosynthesis. More about that in a moment.
13 Roughly a third of all proteins contain an embedded transition metal.
14 Chemists refer to an inorganic element’s “oxidation state,” being the number of electrons a neutral atom has either gained or lost. Iron is particularly obliging, and is happy to gain one or two electrons, or lose as many as six. We then say it is capable of oxidation states –2 to +6. For organic molecules, we define oxidation state slightly differently. C-C bonds are neutral, C-H bonds reduce the oxidation state by –1, and non-carbon atoms increase it by +1. The carbon in carbon dioxide (CO2), for example, is fully oxidized at +2; the carbon in methane (CH4) is fully reduced at –4. In an oxidizing atmosphere such as on Earth, methane is therefore chemically unstable compared to carbon dioxide. In a reducing atmosphere–in other words, one rich in hydrogen–it would be the other way around.
15 We currently think that oxygenic photosynthesis evolved around 2.7 bya in a single-celled organism called cyanobacteria. By 2.3 bya the build-up of oxygen in the atmosphere became significant, producing the Great Oxidation Event.
16 I know you’re gagging for some chemical formulae here, so methane is CH4, formate is HCO2–, and acetate is CH3CO2–.
17 This rigid structure makes it very stable. One of my favorite science facts is that real, working DNA has successfully been recovered from the toe bone of a 130,000-year-old Neanderthal found in a Siberian cave, enabling the sequencing of the Neanderthal genome, and making Jurassic Park seem like a real possibility. More about the Neanderthals later.
18 There are two main differences. Where RNA employs the nucleobase uracil, DNA uses its close relative thymine, and the ribose groups of DNA have had an oxygen atom removed when compared with those in RNA. Hence the names RiboNucleic Acid and DeoxyriboNucleic Acid.
19 Rocky planets tend to be small both because there’s not much rock to go around, and because their orbits are small so there’s a shorter path over which to hoover it up. The gas planets like Jupiter are in the sweet spot, where there’s lots of material and a large orbit. The ice planets have even larger orbits, of course, but not so much material, so tend to end up somewhere in the middle size-wise. Beyond the ice planets, orbits are enormous but material is even harder to come by, hence dwarf planets like Pluto.
20 It’s worth k
nowing that before DNA sequencing, life was divided into five kingdoms: animals, plants, fungi, protists, and prokaryotes. Within these various kingdoms, there were divisions into phylum, class, order, family, and, finally, genus and species. As Homo sapiens, for example, we sit within the kingdom of animals, in the phylum of vertebrates, in the class of mammals, in the order of primates, in the family of the great apes, in the genus of humans, in the species of modern humans.
21 Is it just me who finds it interesting that the US state with the highest number of Bigfoot sightings is the same one where flying saucers were first spotted?
22 Going back to the five kingdoms: animals, plants, fungi, and protists are all eukaryotes. In case you’re wondering, protists are single-celled eukaryotes, the most famous example being the amoeba.
23 Fatty acids are basically zigzag chains of hydrogenated carbon. Isoprenes are, too, but they also have side branches, also made of hydrogenated carbon atoms.
24 Other kinds of photosynthesis came first. In fact, one of the first indications we have of life on Earth are so-called “banded iron” formations, dated at 3.2 billion years old, caused by an early kind of photosynthesis that used iron instead of water.
25 We used to think the increase in oxygen “released the brakes” on evolution, and enabled the evolution of complex life. We now believe it was the other way around; the evolution of the Ediacaran biota helped oxygenate the oceans and sea bed through filter-feeding and burrowing.
26 Because there were relatively low oxygen levels (roughly 1 percent atmospheric) when the eukaryotic cell came into being, it seems likely that the very first mitochondria fermented glucose rather than burning it in oxygen. The progenitor of endosymbiont theory, Lynne Margolis (ex-wife of Carl Sagan, by the way), had a different view. She believed that the first mitochondria were aerobic (oxygen-burning) rather than anaerobic (fermenting), which is why the host archaeon liked them so much, given that the oceans were filling with free oxygen. Who’s right? As my father used to say, you pays your money and takes your choice.
27 Bilateral, as you might guess, means their left side mirrors their right side. The triploblast bit refers to the fact that they have a body cavity arranged about their digestive tract.
28 The Andean-Saharan lasted thirty million years, and spanned the Ordovician–Silurian extinction. The Karoo Ice Age lasted roughly sixty million years, and took place during the Carboniferous.
29 I know you want to know, so these are: the Ordovician–Silurian (the former pronounced “Ordo-vee-shan”), the Late Devonian, the Permian–Triassic, the Triassic–Jurassic, and the Cretaceous–Paleogene.
30 By now you may be getting the picture; geological periods are often defined by extinctions. Typically reddish oxygenated rocks like limestones and sandstones are followed by black, unoxygenated ones like slates and shales. They tend also to be named after the places where they were first discovered: The Cambrian, for example, is Latin for Wales; the Silurian is named after the Welsh tribe the Silures. The Jurassic gets its name from the Jura Mountains, close to CERN in Switzerland. And the Devonian is named after, well, Devon.
31 Other large creatures also managed to sneak through what is called the K-Pg extinction event, such as the crocodiles.
32 It’s possible that the rapid expansion of land plants sucked up so much carbon dioxide that they caused the Karoo Ice Age in the Carboniferous.
33 After an initial hot flush, the Cenozoic has seen a mighty cooling. We think the Antarctic first developed glaciers around thirty-four million years ago, then began to cool dramatically once it became isolated from South America, roughly twenty-three million years ago, eventually becoming covered in ice fourteen million years ago. The Arctic took a little longer, and iced over about 3.2 million years ago.
34 Also around at the time were Homo habilis and Homo ergaster, as well as Paranthropus robustus and Paranthropus bosei.
35 We aren’t completely sure how we are related to Homo erectus, but one of the most widely accepted hypotheses has it that the African branch of Homo erectus evolved into Homo heidelbergensis, which then spread to Europe and Asia, where it evolved into Homo neanderthalis. African Homo heidelbergensis then evolved into Homo sapiens.
36 A prime candidate is the Ordovician–Silurian, for which there seems to be no convincing climate event or meteor strike.
1 By then the father of invention may be global warming, but that’s a topic for another book.
2 See my handy guide to geological time.
3 The name means “Land of the Gonds”; the Gonds were an Indian tribe. The old name for Gondwana was “Gondwanaland,” meaning “Land of the land of the Gonds.”
4 While we’re on it, a quick refresher on recent geological time periods. The Cenozoic Era spans the sixty-six million years since the impact that wiped out the dinosaurs at the end of the Mesozoic Era, and is subdivided into the Paleogene, Neogene, and Quaternary Periods. The Paleogene was a hothouse, and the Neogene and Quaternary have been progressively colder. We divide the Paleogene into the Paleocene, Eocene, and Oligocene Epochs, and the Neogene into the Miocene and Pliocene Epochs. The Quaternary is divided into the Pleistocene and Holocene Epochs. Roughly speaking, primates evolved at the beginning of the Paleocene, and hominins at the end of the Pliocene. Anatomically modern humans emerged in the Pleistocene, and human civilization in the Holocene.
5 The last known New Zealand land mammal died out in the Miocene around 16mya. Interestingly, several species of bat have repopulated New Zealand, where they have started to fill the vacant niche of ground-dwelling shrews.
6 I should point out that, like New Zealand, the fossil record of Madagascar shows that it was once home to native mammals that died out. The recently (2014) discovered 66 million-year-old-fossil of Vintana sertichi, a strange-looking creature the size of a modern-day groundhog, is a case in point.
7 The classic example of the placental saber-toothed tiger is Smilodon fatalis, which first appeared in North America around 1.6 million years ago during the Pleistocene; along with the woolly mammoth and the dire wolf it belongs to an elite group of large mammals known as the Pleistocene megafauna. The marsupial tiger is the older Thylacosmilus atrox, which first appeared in South America in the late Miocene roughly eleven million years ago.
8 Shaw gave it the name Platypus anatinus, with Platypus meaning flat-footed and anatinus meaning duck-like. Sadly the genus Platypus turned out to have been already taken by a wood-boring beetle. Meanwhile, the German naturalist Johann Friedrich Blumenbach had independently named the same creature Orinthorhynchus paradoxcus (bird-snout, paradoxical). Compromise was then reached with Orinthorhynchus anatinus.
9 We used to say that the monotremes were therefore more “primitive” than the marsupials and placentals, but, of course, that isn’t the case at all. Monotremes have undergone just as much evolution as marsupials, for example; they continue to lay eggs because in Australia that’s what works.
10 The picture painted by phylogenetics shows placentals evolving first in Africa, and then spreading to Asia, North America, and eventually–once it joined via the Isthmus of Panama–South America.
11 The diversity of subfossil lemurs is astounding, and includes giant ape-like lemurs such as Megaladapis, as well as orangutan-sized forms, and large ground-dwelling Gorilla-sized species. They also convergently hit upon “sloths” (see Archaeoindris and others) with a wide array of sloth-like subfossil lemurs and giant Aye-ayes.
12 I know what you’re thinking: Crows can’t be that smart because they have tiny brains. Crucially, however, it’s not size that matters; it’s the ratio of size to body mass. A crow’s brain may be the size of a walnut, but its body is extremely light, giving it a so-called encephalization quotient, or EQ, on a par with apes. In fact, the western scrub jay, a particularly smart species of crow, has an EQ on a par with early hominins such as Australopithecus.
13 Meaning something that was capable of laying hard-shelled eggs on land. Amniotes then split int
o the synapsids and sauropsids. Synapsids eventually gave rise to mammals and sauropsids to reptiles and birds.
14 I know that sounds like I’m culling my data from Aesop’s Fables, but Sarah Jelbert at the University of Auckland actually did this experiment. In fact, if you put “crow and pitcher” into New Scientist’s YouTube channel you can watch a version for yourself.
15 Just for starters, and in no particular order: octopuses, dogs, cats, rats, whales, parrots, and pigs. The problem-solving abilities and tool use of octopuses is particularly significant, because they are about as far removed in animal evolution from the other examples as it is possible to be.
16 That’s not to say every species on Earth has become more complex, obviously. The vast majority of life on the planet is still single-celled, in the form of archaea and bacteria. Organisms can lose complexity as well as gain it, or even stay much the same. Like many cave-dwelling species, the Hawaiian Kaua’i cave wolf spider has lost its eyes, for example, and the coelacanth is doing a pretty good impression of other coelacanths that lived 400 million years ago. It’s average complexity that increases over time, which is why we would be so surprised to find a fossilized ichthyosaur with a brain-to-body ratio bigger than a bottlenose dolphin, or an Attine ant farm with elevators and designated parking spaces.
17 In 1041 a Chinese alchemist named Pi Sheng invented movable clay type, and in 1313 a Chinese magistrate named Wang Chen invented movable woodblock type.
18 It is the Islamic mathematician al-Khwarizmi (c. 780–850) who gives us the word “algebra,” being the Anglicized form of “al-jabr,” one of the mathematical operations he used to solve quadratic equations.
