Two and a half millennia after the idea's appearance, I'm still not ready. Evolution is the most explosive deflation of all time— the capstone of history's steady objectification of nature. I spend a day of quiet privacy spelling out how this unassuming model worked the most radical intellectual overhaul ever, how this near-tautology supplies the crucial cog that biology has aspired toward since its appearance. I trace every step in the synthesis, recheck, give the go-ahead to each subassembly. Still the complete machine lies one step outside credibility. I recapitulate evolution's four prerequisites in embryo:
1. Excess of issue. Surplus offspring. Seedlings rooting in the nook of an I-beam on the fiftieth floor of a two-year-old plate-glass skyscraper; maggots overrunning a scrap of meat. Viruses breeding under the electron microscope at Cold Spring Harbor, making Leo Szilard rush outside and pace the porch of his cabin to calm himself.
Precisely the state this evening finds me in.
2. Scarcity. Common currency from day one: no amount of goods are ever enough to go around. Not all surplus makes it; none makes good in every case. Death hones away, a missed heartbeat from home.
These first two innocuous tenets are reciprocal. Yet hiding in their sum is the larger part of Darwin's bugaboo. Too much divided into too little, and something's got to change. Some die faster than others, a conclusion as inescapable as its result.
3. Variation. Differential dying creates divergence. This is my sticking point tonight. I make the catch only slowly: variation is two-tiered. First: the ten thousand wrigglers in a pound of anchovy spawn are all different. Trivially individual. Even dyed-in-wool creationists admit that poodles differ from Great Danes, let alone wolves. Man too (whatever the nausea of knowing) is not an entity, but five billion disparate creatures with different eyes, hands, and minds. I fell in love with one whose hair, height, voice, fear, and protective narcissism made him unique. I loved one man distinct from all others, or at most, two. Already halfway to difference's second tier: the difference between Franklin and that anchovy spawn. A difference of some difference — where all the tempest still comes from.
4. Inheritance. Divergence depends on a means of conserving difference. Certain individuals in a varying population solve scarcity better than others. If their advantage is handed down disproportionately, that population changes. Mendel, a great admirer of Darwin's book, inexplicably never wrote the letter that would have conferred his results to his contemporary. His work, had it been communicated, might have shown far sooner that evolution harbored more than that tautology "Survivors survive."
Even had a letter been sent, the two great innovations in nineteenth century natural science still would have faced that paradox: more comes from less. Paring away compounds. Something new derives from the not-quite, under no more enlightened guidance than annihilation. The rub starts in that antithesis, conserved difference: the ability accurately to perpetuate lapses. To preserve infidelity faithfully, it has taken Dr, Ressler's death and Todd's variation on that theme for me to understand that the word "variation" itself, like "nihilism" and "ineffable," is among the best of Dr. Ressler's perpetually sought-after one-word contradictions in terms.
The resolution of the paradox that Mendel's unsent letter would have both clarified and compounded did not come until the demonstration that genes were nucleotide sequences. A rogue protein, synthesized by a slight variation in the master base string, was inheritable. And every variation across the spectrum — fish, fowl, lichen, redwood, redhead — is born in divergent protein. Characteristics stay intact from one generation to the next, but only within a margin of error. A few capriciously altered intervals produce a new tune, a song with crisp shocks of familiar difference hiding in its four notes.
Species' diverse qualities slip down the world's gradient unequally. The specific gravity of a place settles the trait-spread into new statistical parfaits. A forbidden secret: the Bible itself is versed in the linguistics of breeding. Only, scarcity prunes more efficiently than any artificial breeder. The gap between Chihuahua and Great Dane is negotiable; the same features are visible, just remixed along a sliding scale. A theist might concede microevolution and still not throw creation itself to the dogs. But variation has a wilder trick, tweaking the quantitative so far that it kicks out something qualitatively new — wolves and sheep from the same bolt of clothing.
In sexual reproduction, rearrangement of parental haplotypes produces a genotype different from either, although cut from the same constituent stuff. If all the carriers of a characteristic fail to reproduce, that trait is lost. But otherwise, it's a closed system, however unexplorably large. Alleles mix to create unimaginable variety, but the species material remains essentially unchanged. I can rearrange my furniture in countless ways, resulting in a surprise decorating scheme for every day I knew the man, but no new furniture ever enters my place.
Speciation, on the other hand, seems to contradict Mendel's perpetuated genes. But at molecular level, I trace it to a replicating system complex enough to suffer turbulence, to err. Something new can come about through recombination or mutation. I now have enough molecular biology to find the source of genetic novelty baldly assumed by Darwin: a G grabbing a T in its negative filament instead of its proper C, a sequence of nucleotides pinched Out or an intruder taken in and the whole program can change.
Terrifying, destructive anarchy, bumping blindly down dead ends and back alleys, when shaped by destruction, can shoot living things into undesignable places.
One changed nucleotide can profoundly alter the function of the protein it helps synthesize. The size of evolutionary steps, the exact scenario for speciation, is still debated. But all variants on the purposive molecule are hazards of evaluated chance. Without molecular mutation, there would be no amendment, no evolution. And yet, most bizarre to me of all, mutations are almost never beneficial. A message, carefully crafted over time, is altered at random. The text will almost certainly suffer, if it remains intelligible at all. The introduction of noise into a signal is much more likely to garble than improve. Failure is lots more probable than anything else going.
Typing too late at night, I begin to insert letters that distort my words diseasterously. Rereading, I piece some alterations back into partial sense. Only an infinitesimally few typos — the lucky comma that leaves a sentence more comprehensible — will produce clean, let alone enhanced final copy. Most swift kicks to my bum radio wreak havoc on its components. But once every few decades, I improve the signal. Mutations cause cancer, stillbirth, blindness, deafness, heart disease, mongolism — everything that can go wrong. Yet faulty copying is the only agency for change. Random tinkering, the source of all horrible mistakes, remains the "hopeful monster," the Goldschmidt variation.
We walked once in the drifted snow, the three of us, on a day written off, lost, abandoned to the world. Dr. Ressler, against the white background, speculated about the implausibility of those snow tracks, the creatures that made them. "Birds surely don't possess compositional sense, musical volition. They sing; that's all. A species' song is taught by parent to child. But every so many generations, something is lost in translation. A child muffs his riff, mislearns, wings it. If the mistake — highly unlikely — works a better attraction, this new melody will be taught to more chicks than flock average, and in time the twist becomes status quo. Insertions, deletions, transpositions: gaffs ratified or panned in performance. A species might, over considerable time, whistle its way from a G major scale into the Goldberg Base."