Genome

No One You Know writes "I just finished reading an excellent book by Matt Ridley called Genome. The book is divided into 23 chapters, one for each chromosome. The author picks a significant gene from each chromosome to focus on, and explores a myriad of topics such as why we age, how life forms assemble themselves into full-grown adults starting from a blob of cells, how we form and store new memories, and how gene therapy works. I found the book very well-written, highly interesting, and quite accessible. Anyone that is interested in knowing more about themselves and all life on Earth would do themselves a service to read it." Read on below for the remainder of NOYK's review. Genome author Matt Ridley pages 352 publisher Harper-Collins rating Excellent reviewer No One You Know ISBN 0060932902 summary The author selects one gene from each chromosome, and uses it to explain who we are and where we came from.

One thing Ridley discusses is how closely related humans are to many other species that seem quite unrelated. We share 99% of our genetic code with chimpanzees, which is more or less common knowledge. But we are also very similar to many other organisms, such as fruit flies. By comparing the genomes of different life forms, we can tell not only what creatures (and plants) we are related to, but historically when the genome split. Ridley explores possible explanations and ramifications of this knowledge (it's pretty hard to refute evolution with the facts he presents).

One of my favourite chapters in the book deals with self-assembly. How in God's green Earth do we develop into full-grown adults with a trillion cells, having started out as a tiny blob of a handful of cells? There are some really surprising discoveries here, such as the fact that the genes that lay out the general physical form of the body are laid out in order -- the gene for the head first, then the upper body, etc., ending with the rear. Another interesting fact is that the genes that define the front and back of a fruit fly also exist in humans, but are switched around. So the gene that defines the back of a fruit fly defines the front of a human, and vice versa. This means that at some point in our evolutionary history, one creature decided to walk on its front, and another decided to walk on its back.

Another chapter deals with why we age. Less than 50 cell divisions are required for us to grow into adults, but throughout life cell divisions are necessary for maintenance and repair. Each cell contains a complete copy of the genome; when a cell divides, it must make another copy for the new cell. However, the very beginning and end of each chromosome are not copied. In order to not lose important data, each chromosome has a long string of junk at the beginning and end. But with each cell division, a little more of the junk is lost and you get closer to cutting off the real data in the middle. In this way we've got a kind of built-in obsolescence; we are designed to live just long enough to bear and rear children.

One chapter is devoted to memory: how we create new memories and how we store them. Also discussed is the difference between instinct and learned knowledge, and why we need both. It turns out that language is a genetic thing; we have an instinctive capacity for language and we pick it up very easily as we develop. But then why is the vocabulary of a language not in our genes? Vocabulary is learned knowledge because if it weren't, it would be difficult for us to incorporate new words since they wouldn't be instinctive. Basically, as I understand it, static knowledge is often recorded in our genes (therefore becoming instinct), while dynamic knowledge must be learned.

Ridley dedicates one chapter to gene therapy and modification: how it works and the ethical concerns. I was curious as to how injecting a new or repaired gene into the cell of an organism could affect anything but that one cell. It turns out there are enzymes that will replicate the new DNA strand and go around distributing it to other cells -- a virus! Geneticists use the code from a virus that causes replication (leaving the bad stuff of course) and combine it with the DNA they want to repair or replace in an animal. They then "infect" the animal with the new code.

In short, I found Matt Ridley's "Genome" a fascinating book. The mapping of the human genome was a huge milestone in human history, and Ridley does an excellent job of using it to explain in layman's terms who and what we are. What we don't know about the genome dwarfs what we do know of course, and Ridley makes no bones about that point. But the bit that we do know just makes you sit back in awe. Ridley has a talent for translating his own enthusiasm for the subject to the written word.

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