Previous - 133. Necessitarianism
Proust was... - George Eliot cont.
The Literary Genomep44 ...As soon as the Human Genome Project began decoding our substrate, it was forced to question cherished assumptions of molecular biology. The first startling fact... was the dizzying size of our genome. While we technically need only 90 million base pairs of DNA to encode the 100,000 different proteins in the human body, we actually have more than 3 billion base pairs. Most of this excess text is junk. In fact, more than 95 percent of human DNA is made up of what scientists call introns: vast tracts of repetitive, noncoding nonsense.
How certain can they be of this? How can you determine what is "junk" and what has meaning? And what about our bacteria? No one ever talks about their genomes. And couldn't you say the same thing about In Search of Lost Time if you were thinking of it as a novel driven by a standard plot?
But by the time the Human Genome Project completed its epic decoding, the dividing line between genes and genetic filler had begun to blur. Biology could no longer even define what a gene was. The lovely simplicity of the Central Dogma collapsed under the complications of our genetic reality, in which genes are spliced, edited, methylated, and sometimes jump chromosomes (these are called epigenetic effects). Science had discovered that, like any work of literature, the human genome is a text in need of commentary, for what Eliot said of poetry is also true of DNA: "all meanings depend on the key of interpretation."
What makes us human, and what makes each of us his or her own human, is not simply the genes that we have buried in our base pairs, but how our cells, in dialogue with our environment (and bacteria?), feed back to our DNA, changing the way we read ourselves. Life is a dialectic...
p45 By demonstrating the limits of genetic determinism, the Human Genome Project ended up becoming an ironic affirmation of our individuality. By failing to explain us, the project showed that humanity is not simply a text. It forced molecular biology to focus on how our genes interact with the real world. Our nature, it turns out, is endlessly modified by our nurture. This uncharted area is where the questions get interesting (and inextricably difficult).
...the mouse brain contains roughly the same number of genes as the human brain... scientists have found that there is little correlation between genome size and brain complexity. (Several species of amoeba have much larger genomes than humans.) This strongly suggests that the human brain does not develop in accordance with a strict genetic program that specifies its design.
...our plastic neurons are designed to adapt to our experiences. Like the immune system, which alters itself in response to the pathogens it actually encounters... the brain is constantly adapting to the particular conditions of life. This is why blind people can use their visual cortex to read Braille...
p46 ...The invention of neural plasticity, which is encoded by the genome, lets each of us transcend our genome...
The best metaphor for our DNA is literature. Like all classic literary texts, our genome is defined not by the certainty of its meaning, but by its linguistic instability, its ability to encourage a multiplicity of interpretations. What makes a novel or poem immortal is its innate complexity, the way every reader discovers in the same words a different story...
The Blessing of Chaos
p47 ... Molecular biology, confronted with the unruliness of life, is also forced to accept chaos. Just as physics discovered the indeterminate quantum world [that's as close as we get] -- a discovery that erased classical notions about the fixed reality of time and space -- so biology is uncovering the unknown mess at its core. Life is built on an edifice of randomness.
p48 ... According to [Motoo] Kimura's calculations, the average genome was changing at a hundred times the rate predicted by the equations of evolution. In fact, DNA was changing so much that there was no possible way natural selection could account for all of these so-called adaptations.
... Pure chance. The dice of mutation and the poker of genetic drift [was driving this evolution of our genes according to Kimura]... Your genome is a record of random mistakes.
p49 ...Neuroscientist Fred Gage has found that retrotransposons -- junk genes that randomly jump around the human genome -- are present at unusually high numbers in neurons. In fact, these trouble making scraps of DNA insert themselves into almost 80 percent of our brain cells, arbitrarily altering their genetic program... Gage... realized that all these genetic interruptions created a population of perfectly unique minds... In other words, chaos creates individuality. Gage's new hypothesis is that all this mental anarchy is adaptive, as it allows genes to generate minds of almost infinite diversity.
p50 ...As Darwin observed in On the Origin of Species, "The more diversified the descendents from any one species become in structure, constitution and habits, by so much will they be better enabled to seize on many and widely diversified places in the polity of nature."...
Like the discovery of neurogenesis and neural plasticity, the discovery that biology thrives on disorder is paradigm-shifting... Chaos is everywhere. As Karl Popper once said, life is not a clock, it is a cloud. Like a cloud, life is "highly irregular, disorderly, and more or less unpredictable." ...
p51 ...What we need now is a new view of life, one that reflects our indeterminacy. We are neither fully free not fully determined. The world is full of constraints, but we are able to make our own way.
This is the complicated existence that Eliot believed in... her novels... are ultimately celebrations of self-determination.
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