Creation (29 page)

2
. For example, Aristotle declares that some fish are neither male nor female, and these are prone to spontaneous generation, unlike their sexed brethren. We now know that all fish are sexual beasts, to the extent that many, such as clownfish and wrasses, display hermaphroditism—they switch sex when their environments demand it.

3
. The notion that lemmings are suicidal is equally fantastic, a myth derived from images of mass migration, possibly staged, in the 1958 Disney film
White Wilderness
.

4
. As every biologist who has worked with them knows, gestation for the common house mouse is indeed around three weeks, but, more important, mice are sneaky, small, and hungry: where there is grain, you'll find mice.

5
. Robert Brown is most famous for Brownian motion, which describes the haphazard microscopic pathway that particles make in a gas or solution when bombarded by atoms or molecules.

6
. While Brown certainly named it, the prize for the first observation of the nucleus goes, yet again, to Antonie van Leeuwenhoek. In a letter to Robert Hooke dated 1682, he describes smaller bodies within the red blood cells of a fish. Admittedly, it's an incomplete description, and doesn't imply any of the subsequent importance of the nucleus. But an unnamed modern editor at the Royal Society, where these letters are kept, casually scrawled in the margin, “Discovery of the cellular nucleus.”

7
. For the record, Virchow was not a bad guy, even though this looks like the act of a backstabbing rat. Throughout his career he was tremendously politically active, fought social injustice, and drove civic reform in Germany and Prussia with great success. One legend has it that his liberal views annoyed the Prussian prime minister Otto von Bismarck enough that he challenged Virchow to a duel. As the challenged, Virchow had the right to choose weapons. He selected sausages: one cooked, the other loaded with roundworm. Bismarck, the sausage-fearing Iron Chancellor, withdrew.

8
. To further prove his point that contaminants were in the air, he repeated this experiment in different locations: some in dusty rooms, others in the relative sterility of over two thousand feet in altitude on Mont Blanc. The results were consistent: clean air, no growth.

9
. Darwin was ultimately prompted to publish by another explorer-biologist, Alfred Russel Wallace, who came up with effectively the same idea and described it in writing to Darwin. A kind and generous gentleman, Darwin suggested they present the idea together, which they did in 1858.

10
. As a result of Darwin's being a scrupulous note taker, writing down pretty much everything he saw and did, his important life has been documented in meticulous detail. There is an ongoing leviathan project to digitize everything he ever wrote, scribbled, jotted, and doodled, and publish it electronically at
The Complete Work of Charles Darwin Online
. There you can read about everything from his experimental bassoon playing to earthworms to the wooden slide he had built for the central staircase in Down House to keep his many children entertained. As a result of his coming up with pretty much the best idea anyone ever had, the body of literature about evolution is deservedly both gargantuan and wondrous.

11
. Darwin's idea has really upset a lot of people over the years, despite being self-evidently true, demonstrably true, experimentally true, and on all counts robustly so. Opposition to his radical but thorough argument was immediate and forthright, but so was support. “How extremely stupid not to have thought of that,” said Thomas Huxley, Darwin's most pugnacious contemporary defender. It's a flattering sentiment, but masks the fastidious detail and stack of work that Darwin put into his opus. Conversely, cell theory appears to have upset exactly no one. It was observed, refined, and then has simply remained true. The laws of natural selection, the laws of genetics, and the workings of DNA (which we will come to shortly) are taught, fittingly, as absolute cornerstones of biology. But the principles of cell theory are simply assumed, and assumed to be correct. It's an odd oversight, but I suppose it's one that we shouldn't complain about.

1
. Mendel went on to become abbot, but history does not record how good he was at monking.

2
. Mendel performed his key experiments between 1856 and 1863, and in 1866 published them in a minor parochial journal,
Proceedings of the Natural History Society of Brünn
. Mendel scholars have determined that 115 copies of the paper were distributed; many writers have described how one of them made its way to Darwin himself, and how it was discovered in his library after his death in 1882. But oh, the heartbreak of it all! The pages of this manuscript were uncut. Darwin never even opened it. Imagine the fusion of these great ideas, the two great biological geniuses finally uniting their work into one all-encompassing law, the mode and the mechanism of inheritance. . . . Alas, this story is fully untrue, a “what if . . . ?” myth. There was no copy of Mendel's pea paper in Darwin's library, cut or uncut. Indeed, according to the custodians of his library, Darwin had no published work authored by Mendel in his vast collection at all. Where this charming fiction has come from is unknown.

3
. Although we tend to think of DNA as the elegant double helix, in action inside cells it is very dynamic, constantly shuffling, twisting, splitting, folding, and remolding as it performs its myriad duties. When extracted in labs for experiment, DNA resembles pale, stringy mucus.

4
. Biology is full of caveats and exceptions, and the exception here is a rather important one. During the process of sperm or egg production, a slightly different form of cell division occurs, called meiosis. This results in cells with half the total genetic material. There is a return to the full complement when sperm meets egg at conception.

5
. That sequence, from the retinal gene Chx10 above, folds into the shape of a grip that fixes onto short, unique stretches of DNA and instructs the cell to activate this gene, rather like using a word in the index to seek out a particular sentence.

6
. In a world that began to reject dogma during the Enlightenment, it is perhaps a pity that this pivotal process for all living things should have been named thusly. It was Francis Crick who called it dogma, and years later he expressed regret that his intended meaning with this word was perhaps not the same as everyone else's. Over the years, as with all rules and laws in science, it has been refined and modified, so although it remains utterly true, it's not quite as dogmatic as its moniker suggests. All the same, that's what it's called.

7
. The naming conventions that determine whether a chiral molecule is left or right are murky and not very helpful. In general, naturally occurring amino acids are referred to as
L
-amino acids, and they make left-handed proteins.

8
. Pasteur was French, and therefore, I imagine, was probably jolly interested in wine. In fact, he developed the technique that bears his name—pasteurization—to sterilize not just milk but wine, too.

9
. There is a website dedicated to outing depictions of DNA that spirals the wrong way, the Left Handed DNA Hall of Fame, for which I qualify alongside most of the major science journals and websites, not to mention newspapers, and many, many advertisements and films. There is one organization whose logo features the alien lefty screw, and that is the Astrobiology Society of Britain, composed of researchers whose work concerns the existence of life in the rest of the universe. Whether that was a design error or a deliberate play on the fact that they are primarily concerned with unearthly biology is unknown. As far as I'm concerned, it's quite clever.

10
. It's not just the fossilized bones that tell us our past. Trace fossils are also crucial. The upright footprints set in soft ash 3.4 million years ago in Laetoli in Tanzania by
Australopithecus afarensis
are stunning evidence of our unique gait, but the truth is that we don't really know if these apelike people were our direct ancestors. The fossil record for human evolution is desperately uneven.

11
. A gene called
Pax6 is a beautiful example, and one on which I once worked. In humans, this gene encodes a protein whose role is to dictate that an area of the developing brain will mature in eyes. It does the same job in mice and zebrafish, whose version of Pax6 only differs by four out of a hundred amino acids, despite having a common ancestor around four hundred million years ago. The conservation is such that in the fruit fly beloved of genetics researchers, Pax6 also specifies where an eye is going to grow, even though it is a fly eye, not a mammalian one.

12
. It is precisely this behavior by which so-called superbugs have become such an infectious problem in hospitals. Within a few years of the introduction of penicillin in the 1940s, a previously undetected strain of the bacteria
Staphylococcus aureus
was described that was resistant to penicillin. What this means is that in the presence of the otherwise lethal antibiotic, a random mutation appeared in one bacterium that rendered penicillin ineffective. As bacteria reproduce with alarming speed, soon this penicillin-immune microbe had spread. So we invented methicillin, another antibiotic that would still prove lethal to the penicillin-resistant ones. Guess what? Within a few years, methicillin-resistant
Staphylococcus aureus
(MRSA) were found. Evolution has provided the mechanism for survival, and bacteria use it with tenacious vigor. Once a bacterium has randomly developed resistance to an antibiotic, it is more than happy to share it not just with its descendents but with its neighbors. They extend a thin bridge, a
pilus,
which brings two bacteria together, and through a tiny pore sections of DNA can be transferred from donor to recipient. This vastly speeds up the spread of an advantageous trait. It means that a population doesn't necessarily have to wait for a random resistant mutation to arise and to be passed from parent to offspring. It might be that the resistance is already in place, unused, and is deployed throughout the population as soon as they are exposed to the antibiotic. It's a familiar story: we try to control an organism, it evolves to survive. Humans waging war against bacteria is a bold gesture. Here, and elsewhere, the words of the great chemist Leslie Orgel resound: his so-called second law states that “evolution is cleverer than you are.”

13
. Amazingly, this hasn't settled the matter. A Japanese team has published a response that says this analysis is not sufficient to reject the idea of multiple origins. That's not to say they or other critics are advocating a multiple-origin hypothesis, just that this particular study doesn't prove its own conclusions. Scientists can be a quarrelsome lot.

1
. Pluto, once the ninth, is no longer considered a fully fledged planet, as it is one of several similar-size bodies in that area of our solar system.

2
. The source of the earth's water remains controversial. The absence of an atmosphere and its position in space so close to the sun may have caused much water on Earth to evaporate. Yet perhaps the shape of the rocks that first accreted to form this planet held water in their crannies. Another idea that some scientists promote is that most of the water on Earth was delivered in one or several icy comets whose frozen payload melted on delivery.

3
. I say “less controversial,” as some scientists contest that stromatolites could form from a nonbiological process—abiogenesis. Nevertheless, the consensus leans heavily toward these rocks being strong evidence for an Archean world thronging with microbial life.

4
. Darwin's handwriting was extraordinarily sloppy, to say the least, and the original letter is barely legible.

1
. For an even more reduced stock of animal behavior, a more memorable but less specific list is sometimes referred to as the four Fs: Feeding, Fighting, Fleeing, and . . . reproduction.

2
. The word
inanimate
is unsatisfactory, as it implies inaction, which chemistry most certainly is not. The opposite of living—dead—is also unhelpful for the same reasons.
Undead
seems a fitting way to describe what is more correctly called prebiotic chemistry: fizzing, active reactions that form the pathway to life.

3
. They've been doing this for a while. In the 1970s, NASA sent the Viking missions to Mars, two insect-shaped spaceships that sampled the Martian surface looking for the signatures of life, and found none. In August 2012,
Curiosity,
a rover the size of a VW Beetle, gracefully plummeted to the surface, with one item on its ongoing mission being to scratch around in the red rocks looking for traces of what once might have been life on Mars. It is the freakiest show.

4
. Joyce's research into this area is utterly crucial, as he deals with the very origins of this process of descent with modification, and we'll come to it in the next chapter.

5
. No relation.

6
. Schrödinger is best known for putting an imaginary cat in a box, and then poisoning it to death. Or maybe not. His famous thought experiment was a way of understanding the effect of observation on the quantum world and how it might affect the classical physical world. The cat, invisible to our observation, would be killed by the poison gas that has a random chance of being released. But we have no way of knowing whether or not the cat is dead until we open the box. According to quantum physics, until that point, the cat paradoxically occupies two simultaneous states: alive and dead, only to be selected upon observation. Perhaps less mind-bending was his attempt to focus on the first of those states.