Top critical review
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Interesting material but flawed scientific reasoning
on April 18, 2007
This book deals with a fascinating topic, of how to use genetics to understand history. It is very timely, since it is an area of research in rapid development. The prose is excellent, and a pleasure the read.
Content wise, the book consists of two types of material. One is description of a large number of recent scientific studies. This is fascinating stuff to read. The studies are well chosen and well described, showing the authors great skills as a science writer.
The other type of material is the authors own scientific reasoning, conclusions and speculations, which are spread throughout the book. Unfortunatly, his logic and scienific reasoning is often very weak. Here are just three examples:
On page 96, Wade uses the fact it is possible to use a genetic test to determine where in Iceland a persons grand-parents came from, as "striking proof of the human tendency to develop local genetic variations" in as little as 1000 years. That argument assumes that the Icelandic population was genetically homogeneous 1000 years ago, which is not at all obvious, since different parts of Iceland may have been settled by people from different parts of Norway and Ireland. If that was the case, the regional genetic differences were there from the start.
ARGUMENT WITH JARED DIAMOND
On page 199, he criticizes Jared Diamond (author of Guns, Germs and Steel), for attributing early European advance on "their geography" with for example a greater number of plants and animals suitable for domestication, providing them a head start on the farming revolution.
Wade writes: "In attributing western advance solely to geography, while tacitly excluding the genetic explanation . . . Diamond focuses on the development of agriculture. But . . ., archeologists now believe that the NearEast sedentism came long before agriculture: the first people settled down, abandoning the foraging way of life. They tehn took to cultivating plants. . . . The critical step was not domestication, but sedentism. This finding would seem to undercut an important part of Diamond's case because, unlike the case with agriculture, it's harder to see any geographical reason why sedentism should have risen in one society and not another."
Some problems with Wades argument above are:
1. It is very easy to see geographical reasons for sedentism, namely, a geographically concentrated supply of continuously available food.
2. Wades give no explanation why sedentism rather than agriculture was the critical step (for the development of western civilization). Sedentism might have been a critical step for domestication/agriculture, but agriculture was obviously a critical step for western civilization. As long as agriculture was one of possible sevral critical steps, Diamonds arguments have not been undercut.
I am not trying to prove Diamonds thesis, nor disprove genetic explanations for many things. It is just one illustration of the weak scientific reasoning used by Wade when he leaves the realm of published scientic research.
THE SYKES FAMILY
On page 238 Wade discusses the issue of wheather Englisg surname has a single or multiple progenitors (originators). He argues that since 50% of a sample of men with the surname Sykes have the same Y-chromosome, "there where was just one real Sykes Y chromosome. All men who carried it were presumably descendend from the first bearer of the surname. That meant that the surname had been assigned only once or, if more than once, all other lines had ended without male heir and no longer existed". Wade explains the 50% who did not carry the Sykes Y chromosome, by "nonparity events" where the biological father is difefrent from the husband of the mother.
Here are two problems with the scientific reasoning:
1. There may very well be multiple Sykes Y-chromosomes, each originating with a difefrent Sykes progenitor. It is just that one have prolifirated a lot, while others have not, while others may be extinct. The theory of branching processes tells us that that is a likely outcome if there are multiple progenitors, and we would not expect to see an equal amount of each Y-chromosome in the current population.
2. Even if there were only one Sykes progenitor, those with the "Sykes Y-chromosome" may not at all be decendant of him. If there was an early "nonparity event", within a few generations after the first Sykes, none of them may be a paternal line decendant of him.
So, my advice is, enjoy the book when it describes established scientific work, but ignore the authors own conclusions and speculations.