he 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’t exist。
to make a protein you need to assemble amino acids （which i am obliged by long tradition torefer to here as “the building blocks of life”） in 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—and here’s anobvious but crucial point—you don’t 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’t going to happen。 to grasp what a long shot its existence is； visualize astandard las vegas slot machine but broadened greatly—to about ninety feet； to be precise—to 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—a career； more orless—to unravel it。 for random events to produce even a single protein would seem astunning improbability—like 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’t reproduce itself； and proteins can’t。 for this you need dna。 dna is a whiz atreplicating—it can make a copy of itself in seconds—but can do virtually nothing else。 so wehave a paradoxical situation。 proteins can’t 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’t 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 cell has no purpose。
as the physicist paul davies puts it； “if everything needs everything else； how did themunity of molecules ever arise in the first place？” it is rather as if all the ingredients inyour kitchen somehow got together and baked themselves into a cake—but a cake that couldmoreover divide when necessary to produce more cakes。 it is little wonder that we call it themiracle of life。 it is also little wonder that we have barely begun to understand it。
so what accounts for all this wondrous plexity？ well； one possibility is that perhaps itisn’t quite—not quite—so wondrous as at first it seems。 take those amazingly improbableproteins。 the wonder we see in their assembly es in assuming that they arrived on thescene fully formed。 but what if the protein chains didn’t assemble all at once？ what if； in thegreat slot machine of creation； some of the wheels could be held； as a gambler might hold anumber of promising cherries？ what if； in other words； proteins didn’t suddenly burst intobeing； but evolved 。
imagine if you took all the ponents that make up a human being—carbon； hydrogen；oxygen； and so on—and put them in a container with some water； gave it a vigorous stir； andout stepped a pleted person。 that would be amazing。 well； that’s essentially what hoyleand others （including many ardent creationists） argue when they suggest that proteinsspontaneously formed all at once。 they didn’t—they can’t have。 as richard dawkins arguesin the blind watchmaker； there must have been some kind of cumulative selection processthat allowed amino acids to assemble in chunks。 perhaps two or three amino acids linked up for some simple purpose and then after a time bumped into some other similar small clusterand in so doing “discovered” some additional improvement。
chemical reactions of the sort associated with life are actually something of amonplace。 it may be beyond us to cook them up in a lab； à la stanley miller and haroldurey； but the universe does it readily enough。 lots of molecules in nature get together to formlong chains called polymers。 sugars constantly assemble to form starches。 crystals can do anumber of lifelike things—replicate； respond to environmental stimuli； take on a patternedplexity。 they’ve never achieved life itself； of course； but they demonstrate repeatedly thatplexity is a natural； spontaneous； entirely monplace event。 there may or may not be agreat deal of life in the universe at large； but there is no shortage of ordered self…assembly； ineverything from the transfixing symmetry of snowflakes to the ely rings of saturn。
so powerful is this natural impulse to assemble that many scientists now believe that lifemay be more inevitable than we think—that it is； in the words of the belgian biochemist andnobel laureate christian de duve； “an obligatory manifestation of matter； bound to arisewherever conditions are appropriate。” de duve thought it likely that such conditions would beencountered perhaps a million times in every galaxy。
certainly there is nothing terribly exotic in the chemicals that animate us。 if you wished tocreate another living object； whether a goldfish or a head of lettuce or a human being； youwould need really only four principal elements； carbon； hydrogen； oxygen； and nitrogen； plussmall amounts of a few others； principally sulfur； phosphorus； calcium； and iron。 put thesetogether in three dozen or so binations to form some sugars； acids； and other basicpounds and you can build anything that lives。 as dawkins notes： “there is nothingspecial about the substances from which living things are made。 living things are collectionsof molecules； like everything else。”
the bottom line is that life is amazing and gratifying； perhaps even miraculous； but hardlyimpossible—as we repeatedly attest with our own modest existences。 to be sure； many of thedetails of life’s beginnings remain pretty imponderable。 every scenario you have ever readconcerning the conditions necessary for life involves water—from the “warm little pond”
where darwin supposed life began to the bubbling sea vents that are now the most popularcandidates for life’s beginnings—but all this overlooks the fact that to turn monomers intopolymers （which is to say； to begin to create proteins） involves what is known to biology as“dehydration linkages。” as one leading biology text puts it； with perhaps just a tiny hint ofdisfort； “researchers agree that such reactions would not have been energeticallyfavorable in the primitive sea； or indeed in any aqueous medium； because of the mass actionlaw。” it is a little like putting sugar in a glass of water and having it bee a cube。 itshouldn’t happen； but somehow in nature it does。 the actual chemistry of all this is a littlearcane for our purposes here； but it is enough to know that if you make monomers wet theydon’t turn into polymers—except when creating life on earth。 how and why it happens thenand not otherwise is one of biology’s great unanswered questions。
one of the biggest surprises in the earth sciences in recent deca