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Genome
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.
You can purchase Genome from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
If you never thought you'd read a book about genetics, (or even if you have) then this is the book for you. Ridley shows how the genetic map that is being developed for us will lead us to many of the answers that we have sought about ourselves. He explains in basic terms how genetics and evolution works. The most amazing part of this book is that it is extremely enjoyable to read. While still in the second chapter I was contemplating reading it again. If you have any interest in how we got to be what we are and what the future may hold for us, (or if you want some great party trivia) then reading 'Genome' will be both entertaining and enriching.
-dk
Full disclosure: I consider myself a deeply religious person. I attend church twice a week, read the Bible, and send my children to a private religious school (at great expense).
However, I find Creationism utter nonsense. I do believe that God created man, but through the process of evolution. The evidence for evolution is so utterly overwhelming that Christians are left with two alternatives:
Whenever this subject comes up with the faithful, I try to change minds gently, and remember a quote (from whom I don't remember):
"A frantic orthodoxy is not rooted in faith, but in doubt."
If your bitterest enemies are people who hack the heads off civilians, then I would say you're doing something right.
"A frantic orthodoxy is not rooted in faith, but in doubt." can be attributed to Reinhold Niebuhr. FYI, 'not' should read 'never', but then I'm nitpicking.
There's a hell of a lot of data on calibration of C-14 dating. For some they used historical references, others they used tree-ring calibration. It's not far off, in most cases. If the parent to your post was trying to say that C-14 data gives dates >1 million years off, he/she's on crack: C-14 is only accurate up to 60K years or so. It's also almost definitely order-of-magnitude correct. The problem mostly stems from two sources:
:) The first one however can produce dates which drift significantly as you go farther and farther back in time, as the "C-14 timeline" will "compress" and "expand" - that is, certain stretches of "real time" will correspond to unequal portions of "C-14 time" based on the levels of C-14 in the atmosphere at those points.
1: Varying C-14 levels in the atmosphere over time (sunspots)
2: Point at which carbon-exchange ended in the object.
The first one is not that severe, honestly, and the second only applies to nonliving things. For living things we can pretty accurately assume that carbon exchange ended when it died.
Radiometric dating is very accurate if you know the ambient level throughout the period that isotope exchange was occuring, and then when the isotope exchange stopped. If you're off significantly on either one of those, you could have problems. But that's what cross-calibration is for.