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ad78a77
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One begins to wonder if all the most interesting problems in physics are now in biology.
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Nick Lane |
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bfcf159
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Nothing is more conservative than a bacterium.
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evolution
life
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Nick Lane |
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482e5a3
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Petty human squabbles over borders and oil and creed vanish in the knowledge that this living marble surrounded by infinite emptiness is our shared home, and more, a home we share with, and owe to, the most wonderful inventions of life.
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Nick Lane |
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1d7fa86
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If you resolve to give up smoking, drinking and loving, you don't actually live longer, it just seems longer.'1
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Nick Lane |
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35e10d8
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To visualize this dance, the transparent components of the cell had to be coloured using a stain. As it happened, the stains that were best able to colour the chromosomes were acidic. Unfortunately, these stains tended to dissolve the mitochondria; their obsession with the nucleus meant that cytologists were simply dissolving the evidence. Other stains were ambivalent, colouring mitochondria only transiently, for the mitochondria themselves..
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Nick Lane |
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41b4b46
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I shall argue that the distinction between a 'living planet' - one that is geologically active - and a living cell is only a matter of definition. There is no hard and fast dividing line. Geochemistry gives rise seamlessly to biochemistry. From this point of view, the fact that we can't distinguish between geology and biology in these old rocks is fitting. Here is a living planet giving rise to life, and the two can't be separated without s..
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Nick Lane |
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9b9528a
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We should not be too quick to dismiss our own [ocular] arrangement. As so often in biology, the situation is more complex.....we have the advantage that our own light-sensitive cells are embedded directly in their support cells (the retinal pigment epithelium) with an excellent blood supply immediately underneath. Such an arrangement supports the continuous turnover of photosensitive pigments. The human retina consumes even more oxygen than..
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evolution
science
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nick lane |
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755b72a
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If all these considerations are correct, then the appearance of eyes really could have ignited the Cambrian explosion. And if that's the case, then the evolution of the eye must certainly number among the most dramatic and important events in the whole history of life on earth.
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Nick Lane |
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63de9bc
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Radical feminists and evolutionists agree that males are a serious cost to society.
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Nick Lane |
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975a562
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Without programmed cell death, the bonds that bind cells in complex multicellular organisms might never have evolved.
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Nick Lane |
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0a9a1ad
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It seems that all eukaryotic cells either have, or once had (and then lost) mitochondria. In other words, possession of mitochondria is a sine qua non of the eukaryotic condition
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science
mitochondria
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Nick Lane |
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651503f
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Life itself turned our planet blue and green, as tiny photosynthetic bacteria cleansed the oceans of air and sea, and filled them with oxygen. Powered by this new and potent source of energy, life erupted. Flowers bloom and beckon, intricate corals hide darting gold fish, vast monsters lurk in black depths, trees reach for the sky, animals buzz and lumber and see. And in the midst of it all, we are moved by the untold mysteries of this crea..
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Nick Lane |
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4e287b1
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This was difficult to prove as most hydrogenosomes have lost their entire genome, but it is now established with some certainty.1 In other words, whatever bacteria entered into a symbiotic relationship in the first eukaryotic cell, its descendents numbered among them both mitochondria and hydrogenosomes.
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Nick Lane |
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ee709df
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Rather surprisingly, to anyone who is most familiar with textbook mitochondria, many simple single-celled eukaryotes have mitochondria that operate in the absence of oxygen. Instead of using oxygen to burn up food, these 'anaerobic' mitochondria use other simple compounds like nitrate or nitrite. In most other respects, they operate in a very similar fashion to our own mitochondria, and are unquestionably related. So the spectrum stretches ..
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Nick Lane |
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78a7a37
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The myosin in our own skeletal muscles is more closely related to the myosin driving the flight muscles of that irritating housefly buzzing around your head than it is to the myosin in the muscles of your own sphincters
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evolution
science
muscle
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Nick Lane |
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1bf5fc0
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Men are even worse: a hundred rounds of cell division are needed to make sperm, with each round linked inexorably to more mutations. Because sperm production goes on throughout life, round after round of cell division, the older the man, the worse it gets. As the geneticist James Crow put it, the greatest mutational health hazard in the population is fertile old men.
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Nick Lane |
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55570ce
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The point I want to make about methanogens is that they were the losers in the race through a bottleneck, yet nonetheless survived in niche environments. Similarly, on a larger scale, it is rare for the loser to disappear completely, or for the latecomers never to gain at least a precarious foothold. The fact that flight had already evolved among birds did not preclude its later evolution in bats, which became the most numerous mammalian sp..
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evolution
extinction
common-ancestry
common-descent
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Nick Lane |
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7358dfc
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At the level of their biochemistry, the barrier between bacteria and complex cells barely exists.
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Nick Lane |
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c4b67ca
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There's no greater insult in science than to say that an argument is 'not even wrong', that it is invulnerable to disproof.
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Nick Lane |
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7865536
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To doubt that life evolved, even if some of the details described in this book may yet prove wrong, is to doubt the convergence of evidence, from molecules to men, from bacteria to planetary systems. It is to doubt the evidence of biology, and its concordance with physics and chemistry, geology and astronomy. It is to doubt the veracity of experiment and observation, to doubt the testing in reality. It is, in the end, to doubt reality.
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Nick Lane |
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2d06fc3
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Thermodynamics is one of those words best avoided in a book with any pretence to be popular, but it is more engaging if seen for what it is: the science of 'desire'. The existence of atoms and molecules is dominated by 'attractions', 'repulsions', 'wants' and 'discharges', to the point that it becomes virtually impossible to write about chemistry without giving in to some sort of randy anthromorphism. Molecules 'want' to lose or gain electr..
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Nick Lane |
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fd3ef67
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Without a high flux of carbon and energy that is physically channelled over inorganic catalysts, there is no possibility of evolving cells. I would rate this as a necessity anywhere in the universe: given the requirement for carbon chemistry that we discussed in the last chapter, thermodynamics dictates a continuous flow of carbon and energy over natural catalysts. Discounting special pleading, that rules out almost all environments that ha..
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Nick Lane |
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df8b919
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All complex life shares an astonishing catalogue of elaborate traits, from sex to cell suicide to senescence, none of which is seen in a comparable form in bacteria.
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Nick Lane |
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8e0526e
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All life on our planet is related, and the readout of letters in DNA shows exactly how. By comparing DNA sequences, we can compute statistically how closely related we are to anything, from monkeys to marsupials, to reptiles, amphibians, fish, insects, crustaceans, worms, plants, protozoa, bacteria-you name it.
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Nick Lane |
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fb42865
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Buchner proposed that fermentation was carried out by biological catalysts that he named enzymes (from the Greek en zyme, meaning in yeast). He concluded that living cells are chemical factories, in which enzymes manufacture the various products.
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Nick Lane |
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7f39925
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Well, biology is not only about genes and environment, but also cells and the constraints of their physical structure, which we shall see have little to do with either genes or environment directly. The predictions that arise from these disparate world views are strikingly different.
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Nick Lane |
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7b66e28
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Pigments such as haemoglobin are coloured because they absorb light of particular colours (bands of light, as in a rainbow) and reflect back light of other colours. The pattern of light absorbed by a compound is known as its absorption spectrum. When binding oxygen, haemoglobin absorbs light in the blue-green and yellow parts of the spectrum, but reflects back red light, and this is the reason why we perceive arterial blood as a vivid red c..
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Nick Lane |
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5e781e8
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Our bodies are historical accidents of evolution and ultimately can only be understood from an evolutionary perspective: how things got to be the way they are. From this point of view, a good guys-bad guys philosophy is a woefully inadequate way of thinking about molecules as complex as NFKB. Even so, this is the norm. NFKB is usually portrayed as Janus-faced, capable of abrupt swings from the good to the bad and the ugly. Sometimes it dest..
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Nick Lane |
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a8af30d
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Core consciousness operates in the present, rebuilding itself moment by moment, mapping out how the self is altered by external objects, draping perceptions with feelings. Extended consciousness uses the same mechanisms, but now binds memories and language into each moment of core consciousness, qualifying emotional meaning with autobiographical past, labelling feelings and objects with words, and so on. Thus extended consciousness builds o..
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Nick Lane |
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44cb4eb
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When a molecule of vitamin C encounters a free radical, it becomes oxidised and thereby renders the free radical innocuous. The oxidised vitamin C then gets restored to its non-oxidised state by an enzyme called vitamin C reductase. It is like a boxer who goes into the ring, takes a hit to his jaw, goes to his corner to recover, and then does it all over again.
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Nick Lane |
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015d7a1
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We have established on thermodynamic grounds that to make a cell from scratch requires a continuous flow of reactive carbon and chemical energy across rudimentary catalysts in a constrained through-flow system. Only hydrothermal vents provide the requisite conditions, and only a subset of vents - alkaline hydrothermal vents - match all the conditions needed. But alkaline vents come with both a serious problem and a beautiful answer to the p..
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Nick Lane |
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58d29b8
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But whatever our beliefs, this richness of understanding should be a cause for marvel and celebration.
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Nick Lane |
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a386591
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Every day in the human body, some 10 billion cells die and are replaced by new cells. The cells that die do not meet a violent unpremeditated end, but are removed silently and unnoticed by apoptosis, all evidence of their demise eaten by neighbouring cells. This means that apoptosis balances cell division
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Nick Lane |
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cbec4c8
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With these new techniques, a new breed of evolutionist is emerging, able to capture the workings of evolution in real time. The picture so painted is breathtaking in its wealth of detail and its compass, ranging from the subatomic to the planetary scale. And that is why I said that, for the first time in history, we know. Much of our growing body of knowledge is provisional, to be sure, but it is vibrant and meaningful. It is a joy to be al..
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Nick Lane |