How do random mutations in our genes really create the kind of diversity of life we see in the world today? Charles Darwin certainly had no idea, since the genetic revolution happened long after he died.
Now, researcher and evolutionary biologist Dr. Andreas Wagner has written a book explaining how life can adapt in a way that’s much faster than simple random variations. It’s called Arrival of the Fittest:
In the excerpt below, Wagner explains the concept of the “Universal Library”:
Imagine standing in a room crammed with books from floor to ceiling. The bookshelves barely leave space for the door you see on each of the four walls. You start leafing through the books and realize that they all have the same number of pages. Each page contains the same number of lines. And each line has the same number of characters. But — this is strange — the books are full of gibberish. Each line of each page of each book contains mostly arbitrary strings of letters — “hsjaksjs…,” “zvaldsoeg…,” and so on — occasionally separated by spaces and punctuation. Only rarely do you find a meaningful English word — “cat,” “teapot,” “bicycle” — islands in a vast sea of more gibberish.
After a while you tire of these books, which do not make sense. You step through one of the doors and find yourself in another room just like the first one. It is equally packed with bookshelves that crowd in on four doors. And its books make no more sense than those in the first room.
Another door leads you to yet another identical room, and from there you begin to wander through room after room after room, and realize that you are in an endless maze of rooms, identical except for the books that inhabit them. These books form a library that is as gigantic as it is bizarre. As you wander through this library, you encounter fellow travelers who help you grasp the enormity of this place.
The rooms form a universal library, home to all conceivable books.
That is, its books contain all possible strings of characters — twenty-six letters and a few punctuation marks. Most of the strings are the nonsense you already read. But occasionally a book will contain a meaningful word, sentence, or paragraph. More than that, somewhere in this library dwell books that contain no gibberish whatsoever. Because the library contains all possible books, it also contains each meaningful book ever written. All possible novels, short stories, poetry collections, biographies (of people real or imagined), philosophical treatises, religious books, books of science and mathematics, all conceivable books written not only in English but in all languages, books that reveal everything that is true, but also spin terrible lies, books that talk about other books, about the library itself and where it came from, books, some true, others false, about your life’s story, how it began and how it will end, and the book you are reading right now. All of them are contained in this library — a library enormous almost beyond imagining.
To get of an idea how large this library is, let us say that every book in it contains 500,000 characters. (That’s not very long — in the same ballpark as the book you are reading right now.) Excluding punctuation marks, there are 26 possibilities (A through Z) for each of these 500,000 characters. That is, there are 26 possibilities for the first character, 26 for the second, 26 for the third, and so forth. To estimate the number of books, we thus need to multiply 26 by itself 500,000 times. Mathematicians would write this number as 26 raised to the power of 500,000, or 26500000. This is a very large number, amounting to a 1 with more than 700,000 zeroes behind it, more zeroes than this book has letters. And far greater than the number of hydrogen atoms in the universe. It is a hyperastronomical number.
The deepest secrets of nature’s creativity reside in libraries just like this: all-encompassing and hyperastronomically large. Only instead of being written in human language, the texts in these libraries are written in the genetic alphabet of DNA and the molecular functions that DNA encodes.
Human books can capture entire universes — everything that human language can utter — but they have nothing on the chemical language of what may be life’s oldest library of creation, the one devoted to metabolism. Every one of the trillions of living things on earth can be described by human prose or poetry. But creating any one of them requires the chemical language of metabolism, the chemical reactions that create the building blocks of life and thus ultimately all living matter. The library’s chemical language can express life itself — all of it.
To date, we have discovered more than five thousand different chemical reactions that some organism, somewhere on our planet, uses to produce the building blocks of life I mentioned in chapter 2, the nucleotides that make up DNA and RNA, and the amino acids from which proteins are constructed. The reactions that occur in E. coli — more than a thousand — are among them, as are all known chemical reactions that take place in any bacterium, fungus, plant, or animal — including humans. When your body extracts energy from sugar or any other food, it uses such reactions. It also uses them when healing the few hundred skin cells covering a scraped knee, and when replenishing the millions of red blood cells that die every day.
… just as the universal library contains all meaningful books, the library of metabolisms contains all “meaningful” metabolisms — those that allow an organism to survive — and many more, because not all metabolisms are meaningful, just as not all books are. Some metabolisms cannot procure energy, or they fail to manufacture important molecules. These are like books where some chapters, paragraphs, or sentences are coherent but the book as a whole does not make sense. And many other metabolic texts are gibberish. These are metabolisms with disjointed reaction sequences dead-ending on molecules useless to life, the equivalent of books containing only meaningless character strings.
Arrival of the Fittest is in bookstores and online beginning today.
Reprinted from Arrival of the Fittest: Solving Evolution’s Greatest Puzzle by Andreas Wagner with permission of Current, a member of Penguin Group (USA) LLC, A Penguin Random House Company. Copyright (c) Andreas Wagner, 2014.