five yearsearlier。 trawlers are sometimes now as big as cruise ships and haul behind them nets bigenough to hold a dozen jumbo jets。 some even use spotter planes to locate shoals of fish fromthe air。
it is estimated that about a quarter of every fishing net hauled up contains 鈥渂y…catch鈥濃�攆ishthat can鈥檛 be landed because they are too small or of the wrong type or caught in the wrongseason。 as one observer told the economist： 鈥渨e鈥檙e still in the dark ages。 we just drop a netdown and see what es up。鈥潯erhaps as much as twenty…two million metric tons of suchunwanted fish are dumped back in the sea each year； mostly in the form of corpses。 for everypound of shrimp harvested； about four pounds of fish and other marine creatures aredestroyed。
large areas of the north sea floor are dragged clean by beam trawlers as many as seventimes a year； a degree of disturbance that no ecosystem can withstand。 at least two…thirds ofspecies in the north sea； by many estimates； are being overfished。 across the atlantic thingsare no better。 halibut once abounded in such numbers off new england that individual boatscould land twenty thousand pounds of it in a day。 now halibut is all but extinct off thenortheast coast of north america。
nothing； however； pares with the fate of cod。 in the late fifteenth century； the explorerjohn cabot found cod in incredible numbers on the eastern banks of north america鈥攕hallowareas of water popular with bottom…feeding fish like cod。 some of these banks were vast。
georges banks off massachusetts is bigger than the state it abuts。 the grand banks offnewfoundland is bigger still and for centuries was always dense with cod。 they were thoughtto be inexhaustible。 of course they were anything but。
by 1960； the number of spawning cod in the north atlantic had fallen to an estimated 1。6million metric tons。 by 1990 this had sunk to 22；000 metric tons。 in mercial terms； thecod were extinct。 鈥渇ishermen；鈥潯rote mark kurlansky in his fascinating history； cod； 鈥渉adcaught them all。鈥潯he cod may have lost the western atlantic forever。 in 1992； cod fishingwas stopped altogether on the grand banks； but as of last autumn； according to a report innature； stocks had not staged a eback。 kurlansky notes that the fish of fish fillets and fish sticks was originally cod； but then was replaced by haddock； then by redfish； and lately bypacific pollock。 these days； he notes drily； 鈥渇ish鈥潯s 鈥渨hatever is left。鈥�
much the same can be said of many other seafoods。 in the new england fisheries offrhode island； it was once routine to haul in lobsters weighing twenty pounds。 sometimes theyreached thirty pounds。 left unmolested； lobsters can live for decades鈥攁s much as seventyyears； it is thought鈥攁nd they never stop growing。 nowadays few lobsters weigh more thantwo pounds on capture。 鈥渂iologists；鈥潯ccording to the new york times； 鈥渆stimate that 90percent of lobsters are caught within a year after they reach the legal minimum size at aboutage six。鈥潯espite declining catches； new england fishermen continue to receive state andfederal tax incentives that encourage them鈥攊n some cases all but pel them鈥攖o acquirebigger boats and to harvest the seas more intensively。 today fishermen of massachusetts arereduced to fishing the hideous hagfish； for which there is a slight market in the far east； buteven their numbers are now falling。
we are remarkably ignorant of the dynamics that rule life in the sea。 while marine life ispoorer than it ought to be in areas that have been overfished； in some naturally impoverishedwaters there is far more life than there ought to be。 the southern oceans around antarcticaproduce only about 3 percent of the world鈥檚 phytoplankton鈥攆ar too little； it would seem； tosupport a plex ecosystem； and yet it does。 crab…eater seals are not a species of animal thatmost of us have heard of； but they may actually be the second most numerous large species ofanimal on earth； after humans。 as many as fifteen million of them may live on the pack icearound antarctica。 there are also perhaps two million weddel seals； at least half a millionemperor penguins； and maybe as many as four million ad茅lie penguins。 the food chain isthus hopelessly top heavy； but somehow it works。 remarkably no one knows how。
all this is a very roundabout way of making the point that we know very little about earth鈥檚biggest system。 but then； as we shall see in the pages remaining to us； once you start talkingabout life； there is a great deal we don鈥檛 know； not least how it got going in the first place。
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19 THE RISE OF LIFE
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in 1953； stanley miller； a graduate student at the university of chicago； took twoflasks鈥攐ne containing a little water to represent a primeval ocean； the other holding amixture of methane； ammonia； and hydrogen sulphide gases to represent earth鈥檚 earlyatmosphere鈥攃onnected them with rubber tubes； and introduced some electrical sparks as astand…in for lightning。 after a few days； the water in the flasks had turned green and yellow ina hearty broth of amino acids； fatty acids； sugars； and other organic pounds。 鈥渋f goddidn鈥檛 do it this way；鈥潯bserved miller鈥檚 delighted supervisor； the nobel laureate haroldurey； 鈥渉e missed a good bet。鈥�
press reports of the time made it sound as if about all that was needed now was forsomebody to give the whole a good shake and life would crawl out。 as time has shown； itwasn鈥檛 nearly so simple。 despite half a century of further study； we are no nearer tosynthesizing life today than we were in 1953 and much further away from thinking we can。
scientists are now pretty certain that the early atmosphere was nothing like as primed fordevelopment as miller and urey鈥檚 gaseous stew； but rather was a much less reactive blend ofnitrogen and carbon dioxide。 repeating miller鈥檚 experiments with these more challenginginputs has so far produced only one fairly primitive amino acid。 at all events； creating aminoacids is not really the problem。 the problem is proteins。
proteins are what you get when you string amino acids together； and we need a lot of them。
no one really knows； but there may be as many as a million types of protein in the humanbody； and each one is a little miracle。 by all the laws of probability proteins shouldn鈥檛 exist。
to make a protein you need to assemble amino acids （which i am obliged by long tradition torefer to here as 鈥渢he building blocks of life鈥潱n a particular order； in much the same way thatyou assemble letters in a particular order to spell a word。 the problem is that words in theamino acid alphabet are often exceedingly long。 to spell collagen； the name of a montype of protein； you need to arrange eight letters in the right order。 but to make collagen； youneed to arrange 1；055 amino acids in precisely the right sequence。 but鈥攁nd here鈥檚 anobvious but crucial point鈥攜ou don鈥檛 make it。 it makes itself； spontaneously； withoutdirection； and this is where the unlikelihoods e in。
the chances of a 1；055…sequence molecule like collagen spontaneously self…assembling are；frankly； nil。 it just isn鈥檛 going to happen。 to grasp what a long shot its existence is； visualize astandard las vegas slot machine but broadened greatly鈥攖o about ninety feet； to be precise鈥攖o acmodate 1；055 spinning wheels instead of the usual three or four； and with twentysymbols on each wheel （one for each mon amino acid）。
1how long would you have topull the handle before all 1；055 symbols came up in the right order？ effectively forever。 evenif you reduced the number of spinning wheels to two hundred； which is actually a moretypical number of amino acids for a protein； the odds against all two hundred ing up in a1there are actually twenty…two naturally occurring amino acids known on earth； and more may await discovery；but only twenty of them are necessary to produce us and most other living things。 the twenty…second； calledpyrrolysine； was discovered in 2002 by researchers at ohio state university and is found only in a single type ofarchaean （a basic form of life that we will discuss a little further on in the story） called methanosarcina barkeri。
prescribed sequence are 1 in 10260（that is a 1 followed by 260 zeroes）。 that in itself is a largernumber than all the atoms in the universe。
proteins； in short； are plex entities。 hemoglobin is only 146 amino acids long； a runt byprotein standards； yet even it offers 10190possible amino acid binations； which is why ittook the cambridge university chemist max perutz twenty…three years鈥攁 career； more orless鈥攖o unravel it。 for random events to produce even a single protein would seem astunning improbability鈥攍ike a whirlwind spinning through a junkyard and leaving behind afully assembled jumbo jet； in the colorful simile of the astronomer fred hoyle。
yet we are talking about several hundred thousand types of protein； perhaps a million； eachunique and each； as far as we know； vital to the maintenance of a sound and happy you。 andit goes on from there。 a protein to be of use must not only assemble amino acids in the rightsequence； but then must engage in a kind of chemical origami and fold itself into a veryspecific shape。 even having achieved this structural plexity； a protein is no good to you ifit can鈥檛 reproduce itself； and proteins can鈥檛。 for this you need dna。 dna is a whiz atreplicating鈥攊t can make a copy of itself in seconds鈥攂ut can do virtually nothing else。 so wehave a paradoxical situation。 proteins can鈥檛 exist without dna； and dna has no purposewithout proteins。 are we to assume then that they arose simultaneously with the purpose ofsupporting each other？ if so： wow。
and there is more still。 dna； proteins； and the other ponents of life couldn鈥檛 prosperwithout some sort of membrane to contain them。 no atom or molecule has ever achieved lifeindependently。 pluck any atom from your body； and it is no more alive than is a grain of sand。
it is only when they e together within the nurturing refuge of a cell that these diversematerials can take part in the amazing dance that we call life。 without the cell； they arenothing more than interesting chemicals。 but without the chemicals； the