For example the average speaker knows 20-35K English words, and yet we can produce an infinite variety of works. ↩ Since the process of natural selection is one of extracting useful information from the environment and encoding it in the genes, there is a sense in which you can look on the human genome as four billion years’ worth of accumulated learning. Arguably, more damage has been done by false negatives (true genes that have been prematurely ruled out on inadequate data) than by false positives (suspicions of a link that later prove unfounded). Genome has been reviewed in scientific journals including Nature [1] and in medical journals such as the New England Journal of Medicine, where Robert Schwartz notes that Ridley speculates, "sometimes wildly". [7] The book is a "gambol" through the human chromosomes. All the same, Schwartz writes, the book is "instructive, challenging, and fun to read. I envy Ridley's talent for presenting, without condescension, complex sets of facts and ideas in terms comprehensible to outsiders." [7]

a b Kealey, Terence (2000). "Book Review Genome:The Autobiography of a Species in 23 Chapters". Nature. 24 (21): 21. doi: 10.1038/71638. PMID 10615121. Despite the title, each chapter does not go into a detailed account of the function of each set of chromosomes. Good thing, too, since each chromosome serves a variety of different functions. Instead, each chapter is divided up into themes. For example, the chapter Fate, which I found the most fascinating, sought to prove that a good portion of our lives is written in our genetic code. Ridley uses Huntington’s Disease to prove this point: he explains how Huntington’s is caused, why it happens in some people and not in others, and describes in detail how a repeating sequence of CAGs can determine at what age you start to show symptoms. What I appreciated the most, though, was that Ridley also pushes further to describe the ramifications of the disease—should doctors tell a patient that they have the disease and that they will develop symptoms at a certain age? Should patients inquire about whether or not they have the incurable, unavoidable disease? There are plenty of inherited diseases, and contagious diseases in which inheritance determines susceptibility — cholera being a now classic case — but the notion that an infectious particle could somehow travel through the germline seemed to break all the rules of biology. Chromosome 21 – Eugenics Genes are not there to cause diseases. Most genes are not ‘broken’ in any of us, they just come in different flavours. The blue-eyed gene is not a broken version of the brown-eyed gene, or the red-haired gene a broken version of the brown-haired gene. They are different alleles – alternative versions of the same genetic ‘paragraph’, all equally fit, valid and legitimate. They are all normal; there is no single definition of normality. The impact of stress on the human body is described starting with the creation of hormones by the CYP17 gene on chromosome 10. Ridley points out the relationship between cholesterol, steroidal hormones such as progesterone, cortisol, aldosterone, testosterone and oestradiol.The analogy between a homeobox and a plug is quite close: the homeobox is the bit by which the protein made by the gene attaches to a strand of DNA to switch on or off another gene. All homeotic genes are genes for switching other genes on or off. Book Genre: Biology, Evolution, Genetics, Health, History, Medical, Medicine, Nonfiction, Popular Science, Science Genes need to be switched on, and external events – or free-willed behaviour – can switch on genes. Far from us lying at the mercy of our omnipotent genes, it is often our genes that lie at the mercy of us. The conclusion that all these studies converge upon is that about half of your IQ was inherited, and less than a fifth was due to the environment you shared with your siblings – the family. The rest came from the womb, the school and outside influences such as peer groups.

Ridley delves into other contentious political topics as well, such as media hysteria over Mad Cow Disease, eugenics, genetic screening, sex, evolutionary psychology, and luddism. Ridley has a unique, but extremely compelling views on all these topics, and that's where this book really shines. One of the points Ridley quite clearly makes in a couple of places is that your genes belong to you alone, and you alone have the right to decide who you want to share it with. However, you really have to wait for the last few chapters of the book for his to really get started. Blood groups can give us insights into the history of human migrations and since 1990 they have found an entirely new role: they promise understanding of how and why our genes are all so different. They hold the key to human polymorphism. Anticipation: it has been known for some time that those with a severe form of Huntington’s disease or fragile X are likely to have children in whom the disease is worse or begins earlier than it did in themselves. Anticipation means that the longer the repetition, the longer it is likely to grow when copied for the next generation. We know that these repeats form little loopings of DNA called hairpins. When the hairpins unfold, the copying mechanism can slip and more copies of the word insert themselves. Chromosome 5 – Environment Paternal cells, by contrast, are comparatively scarce in the brain, but much commoner in the muscles. Where they do appear in the brain, however, they contribute to the development of the hypothalamus, amygdala and preoptic area. These areas comprise part of the ‘limbic system’ and are responsible for the control of emotions. Is the end of the story? In evolutionary terms, no. Genes which reduce the cost of crying will increase in frequency, until one of the inequalities is broken. At this point, the cost of a not hungry child crying and getting a larger meal share is feasible, and the existing rule system (crying gets larger meal share) no longer works. At this point, parents may begin to base feeding decisions based on some threshold of the intensity of crying to discern whether their offspring are truly hungry. However, the intensity of infants’ crying will continue to escalate, and parents will continue to demand a higher threshold due to this arms race. What’s important to remember is that this evolutionary arms race is not occurring between cheetah and gazelle running speed genes, but on the human genome itself! Genes are selfish.

Most of the striatum, cortex and hippocampus of the mouse brain are consistently made by these maternal cells, but that such cells are excluded from the hypothalamus. The cortex is the place where sensory information is processed and behaviour is produced. Recall dear reader that we humans are genetically diploid (two matching pairs of chromosomes - male sex chromosome aside), and have twenty-two autosomal chromosomes plus one pair of sex chromosomes. Our total chromosome count is one less than our apish cousins, but nine more than a Tasmanian devil. Keep in mind that ones chromosome count tells one nothing about the sophistication of a species: barley has fourteen chromosomes but oats have fourty-two, for example. ↩ The genome's been mapped. But what does it mean? Matt Ridley’s Genome is the book that explains it all: what it is, how it works, and what it portends for the future I found the chapter on free will particularly interesting. I had thought of DNA as making proteins for cells, but I had never thought that it would be possible for our decisions to be determined by the genetic code that we are born with. Ridley discusses the arguments in such an interesting way that I couldn’t help but read more about it. Each chapter gives such an amazing introduction to each topic that every time I read a chapter I wanted to find out more about it before continuing. This is how I found another book by Ridley, Nature via Nurture, which I would also recommend, since it is a very similar book discussing the genes vs. environment debate in a simple and fascinating way.

Evidence suggests that such people took up a pastoral way of life first, and developed milk-digesting ability later in response to it. It was not the case that they took up a pastoral way of life because they found themselves genetically equipped for it. This is a significant discovery. It provides an example of a cultural change leading to an evolutionary, biological change. The genes can be induced to change by voluntary, free-willed, conscious action. By taking up the sensible lifestyle of dairy herdsmen, human beings created their own evolutionary pressures. Chromosome 14 – Immortality This was an interesting and understandable survey of human genetic heritage. There were a few boring pieces that recounted things I'd been taught repeatedly in biology classes - I can see the utility of this as not all readers would have taken those classes, I just didn't enjoy reading about those things again as much as I enjoyed the more specific examples. The last few chapters contained some biased language (calling people who tore up GM crops "eco-terrorists" rather than simply "vandals," for example, is using a contested definition of terrorism) and drew some political conclusions that, whether I agreed with them or not (and there were some of each) neither fit well with the reasonably objective structure established by the preceding chapters nor were especially well defended. We are spectacularly resistant to brainwashing. No matter how hard their parents or their politicians tell them that smoking is bad for them, young people still take it up. Indeed, it is precisely because grown-ups lecture them about it that it seems so appealing. We are genetically endowed with a tendency to be bloody-minded towards authority, especially in our teens, to guard our own innate character against dictators, teachers, abusing step-parents or government advertising campaigns.This chapter examines the so-called "immortality" of the genetic code - i.e. how is it that genetic code can remain as precise as it has been for 50 billion copyings since the dawn of life? Part of the answer is in the protein enzyme telomerase, lying on chromosome 14 and coded by the gene TEP1. The typical chimpanzee’s hardware can be put together in the womb of a foreign species, but its software would be a little awry. Huntington's chorea is used to discuss the use of a particular sequence on Chromosome Four to cause traumatic health consequences. The search for the chromosomal source of this and other related diseases is discussed through the work of Nancy Wexler, someone who may have inherited the gene but who turns to scientific work to study it in others.

I expected there to be a bit of overlap between them, but I actually found them each to be very different. Mukherjee and Kean focus a lot on the history, while Ridley stays more on the science and less about the history. Kean is a great storyteller, while Mukherjee tries hard to make a grand philosophical message, which falls flat, in my opinion, compared to Ridley. Evolution has no pinnacle and there is no such thing as evolutionary progress. Natural selection is simply the process by which life-forms change to suit the myriad opportunities afforded by the physical environment and by other life-forms.

Genome

The O group has just a single spelling change compared with A, but instead of a substitution of one letter for another, it is a deletion. In people with type O blood, the 258th letter, which should read ‘G’, is missing altogether. The effect of this is far-reaching, because it causes what is known as a reading-shift or frame-shift mutation, which is far more consequential.