BackBook review: ‘Arrival of the Fittest’
Why man may find it difficult to win the fight against many disease-causing organisms
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People are no longer sick but “fighting an infection", or “battling cancer". Medicine, aided by antibiotics and chemotherapy, has vanquished resilient poxes but there are equally numerous casualties to insidious viruses such as HIV, stealthy drug-resistant bacteria and various formidable carcinoma. In the constant battle to stay alive, how do these brainless, bloodless, invisible critters outwit the vast collective knowledge that our species has patiently amassed through centuries of science?
Charles Darwin and biologists after him explain this as the sheer ruthlessness of nature selecting—or rather forcing—organisms to shore their defences against obliteration. From the outside, this “survival of the fittest" appears as if a magnificent intelligence is inventing unique defences just as free-market economists believe that an Invisible Hand guides market prices for goods.
Arrival Of The Fittest: Solving Evolution’s Greatest Puzzle by Andreas Wagner, an evolutionary biologist at the University of Zurich in Switzerland, builds the case that it isn’t intelligence, but plodding drudgery that nature uses to conjure up awesome diversity.
To understand “life" and “diversity", one must understand how the chemical reactions that help cells, the discernible building blocks of life, use raw materials from the environment to produce energy. There are roughly 60 molecules that can combine to produce 5,000 known fuels to power a cell and paradoxically, the more complex and “evolved" an organism, the fewer of these molecules it has, and the more dependent it is on simpler life forms. Thus people have far fewer molecules than the Escherichia coli bacterium, which has all 60 and, to borrow an elegant metaphor from Wagner, is “…a self-building, self-multiplying, self-healing race car that can run on kerosene, Coca-Cola or nail polish remover…"
The main reason why E. coli got that way is because it replicates itself much faster than people. It does this by trying out different permutations of molecules over generations, which helps it adapt as easily to river sludge as to human intestines. Wagner found that there were several, almost unimaginably many, ways for E. coli to make all the 60 molecules from just glucose, a vital sugar necessary for the metabolism of several other life forms.
To help the reader visually grasp this, Wagner uses a well-known trope in popular science, of the Universal Library, an idea invented in an entirely different context by Argentinian writer Jorge Luis Borges. Imagine a library made up of books, each about the size of the book being reviewed. Such a book contains about 500,000 letters and randomly choosing any of the 26 letters of the alphabet, you could get 26 multiplied by itself 500,000 times (or 1 followed by 700,000 zeroes) letter books. For the enormous gibberish that these many books contain, there will also be books that contain—by sheer chance—all of Shakespeare, the theory of relativity, every movie script that has ever been, and will be, written. Similarly, organisms too are written in the language of 5,000-odd chemical reactions and while smaller than the Universal Library, it’s still a massive combination of reactions (1 followed by 1,500 zeroes).
Though labyrinthine, one can hop from any point—in an infinite number of ways—to the other in the library along a predictable path and be forever surrounded by vastly similar, yet subtly different books. Steadily and tediously, nature too trudges along such libraries of reactions and proteins and hits upon novel combinations of known reactions while also conserving several successful combinations. While, on the one hand, it does seem that powerful computers can help us find new ways to discover drugs, it will still be a fraction of the ways that organism can outwit these.
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