Genome

Matt Ridley

Biologically and medically, times have never been more exciting or held more promise. Mankind now stands at the threshold of a genetics revolution that augurs the ability to reprogram human biology to eliminate many, and possibly most, diseases, to reduce pain and to extend health and prolong human life. Genetic engineering promises the ability to enable us to modify, remove, and replace genes, one at a time, even borrowing genes from other species to produce human proteins for drug development and cures or turning off negative genes; we are on the road to re-writing the genetic code to create things beyond existing biology (“synthetic biology”). We are on the cusp of an astonishing genetics revolution. Such is the topic of Matt Ridley’s timely book (1999), Genome. Ridley traces the genome from the dawn of life to today. The human genome is “the autobiography of the human species”.

The genome is all of the genes, the complete genetic code, of a living organism. A gene, like a piano key, plays the same note every time. A gene is a functional hereditary unit that occupies a fixed location in a chromosome (a DNA containing a cell capable of transmitting hereditary data). DNA (deoxyribose nucleic acid) in the gene instructs all cells in all living organisms; these instructions are known as the “genetic code”. The human genome is comprised of three billion base pairs that are organized into 50,000 to 80,000 genes. The genome is spelled out in a billion three-letter words which use a four-letter alphabet (A, C, G and T) of DNA, which work together in a computer-like fashion. Change one letter or the sequence and the result is totally different. We are the first generation to be able to read the DNA alphabet. How do we now identify a killer’s blood, a rapist’s semen, the biological father of a child or the type of bone marrow that it is needed to save the life of one dying from Leukemia and what promises the likelihood of mastering all manner of now incurable diseases and of postponing the aging process? DNA, all of us knew it! DNA was discovered in 1953 by James Watson and Francis Crick.

Repetitively, the author advises us, “GENES ARE NOT THERE TO CAUSE DISEASES.” The configuration of our genes, however, or the presence of too many or the absence of some, will cause or expedite some diseases, pain and death.

Life has evolved over a three to four billion-year period, emerging from primordial ooze (gases) to single cell to multi-cell to the “Flatish Round Worms” to tetrapods (a four-limbed, five-fingered-toed lizard) to mammals, etc. All living creatures flow from one source – which scientists call “Luca” (Last Universal Common Ancestor, who looked like a bacterium and lived in a warm pond and/or in a fissure below ground in hot igneous rocks, where she fed on sulphur, iron, hydrogen and carbon, and likely many of her roughly simultaneously emerged). As Luca’s progeny, of course, we share a similar genome (fn.1). Every living animal, creature, bug or blob shares a similar genetic code and, at early stages of development, many creatures appear

almost identical. With bacteria as a forbearer and seaweed as our distant cousins, and anthrax one of our advanced relatives, over the past 50 years of studying genome, we have learned that the unity of life is an empirical fact: “All life is one,” as Ridley, Gould and almost all scientists now agree . Despite the fact that humans are 99.9% identical, the tiniest differences in genes can predestine us to very different abilities, diseases and lives, although our conduct and the way that we think and feel can greatly influence our genome and our life’s experience. Being 99.9% identical, for better or worse, only a 0.1% DNA-difference fingerprints our identity as unique individuals.

The author, Matt Ridley, a long time science editor and researcher for The Economist and author of other related books, resides in England with his wife and family. He has read prodigiously in the genome field and offers us a solid overview of the subject, if, at times, a bit esoteric. Regardless, the subject matter is so close to us that it makes fascinating, edifying and, hence, very worthwhile reading. Shouldn’t all of us know “the autobiography of the human species”, a literal autobiography of our personal chemistry?

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1. The human genome is 97% identical to that of gorillas and 98% identical to that of a chimp; chimps’ genome, being only 97% identical to a gorilla, making chimps closer to humans than to gorillas. The genomes of humans and chimps are only 60% identical to the genome of fruit flies. We did not descend from modern apes, but we had a common ape-like ancestor; the human-chimp split is believed to have occurred between five and ten million years ago. While that exact creature has not yet been found, scientists have come very close with a little ape-man skeleton (“Ardipithecus”) who lived four million years ago. The human strain became meat eaters, and, with the extra protein, their brains grew larger and larger over the millennia. By 1.6 million years ago, our apelike human ancestors were using stone tools and walking as upright as do we.

2. See National Geographic, November 2006, pages 114 et seq. Compare photos of a fish, chicken and human (at one day, three days and 32 days, respectively); they look nearly identical and also true from photos at three days, 12 days and 56 days of the same three species. 3. See Gould’s Wonderful Life, Conway Morris’ Crucible of Creation, Bryson’s Brief History of Almost Everything, Greene’s Elegant Universe, etc. 4. See fn. 1.