Curse and blessing of the ghetto

“Curse and Blessing of the Ghetto” by Jared Diamond

Reading Guide

Subheading—The subheading tells us that the article is about Tay-Sachs, that Tay-Sachs is a genetic

disease that is more common among Eastern European Jews than other populations, and that by

using TS as an example, we can learn something in general about how genetic diseases evolve.

¶1-2: These two paragraphs set up a narrative introduction to the article, focusing on the personal experience of Diamond and his wife getting tested for TS. ¶3: Offers some basic information about TS.

¶4: Back to Diamond’s personal narrative, explaining why he and his wife were high risk

candidates. This paragraph ends with the sentence, “Second, both she and I are of Eastern European

Jewish ancestry, the population with by far the world’s highest Tay-Sachs frequency.” This is a key

transition sentence to the next paragraph and works to establish the main focus of the article.

¶5: Discusses the rate of TS in the general global population and among Eastern European Jews

(also known as the Ashkenazim). For the Ashkenazim, TS occurs 100 times more frequently than

other groups. This paragraph ends with a clear statement of the question this article is asking,

“What is it about this one group of people that produces such an extraordinarily high risk of this

disease?” This is the question Diamond will answer in this article.

¶6-7: Discuss how some genetic diseases are more common in some populations than others and

that by studying TS, we can learn something about the evolution of genetic diseases, in general.

¶8: The discovery and naming of TS.

¶9-10: This is extremely important information about the disease itself. These two paragraphs

address protein synthesis, heredity, and incomplete dominance, all topics we have covered. This

article connects these basic biological processes to evolution, to human variation, and to the

biocultural nature of the human experience.

¶11-13: Provide a brief discussion of the history of the Ashkenazim, starting with very early

migrations and dispersals to tracing the settlement of Jews in Europe by the 8th and 9th centuries

under the Carolingians and ultimately the post-WWII diaspora that led to major settlement of the

Ashkenazim in the United States and Israel in the 20th century. The experience of Jews in Europe

over will be central to understanding Diamond’s argument.

¶14-15: A little discussion of the genetic history of the Ashkenazim to help set up the next section.

¶16: Another clear statement of the question, “Can history help explain why the Tay-Sachs gene in

particular is so much more common in Ashkenazim that in their non-Jewish neighbors or in other

Jews?” Diamond tells us that, yes, history can help explain this. He then explicitly tells us he is going

to present 4 possible explanations, 4 competing hypotheses, for the high rate of TS among Eastern

European Jews. This is a huge thing. He is telling us he will present 4 arguments and we can infer,

then, that 3 of them will be counterarguments or hypotheses that he rejects and 1 of them will be

his thesis, his argument, the hypothesis he suggests is the best explanation. It is in the presentation

of the counterarguments and his thesis that the modern synthesis comes into the article.

¶17: “First,…” This is the first counterargument Diamond presents and it focuses on mutation. He

refutes this.

¶18: “As a second possibility,…” This is the second counterargument Diamond presents and it

focuses on gene flow and population history. He refutes this.

¶19-28: “The third hypothesis…” This is the third counterargument Diamond presents and it

focuses on the founder effect and genetic drift. In ¶21 Diamond presents two examples where

founder effect is in fact the best explanation for the high rate of TS in two other populations—

Pennsylvania Dutch and French Canadians—BUT he ultimately refutes this possibility as the best

explanation for the high rate of TS among the Ashkenazim in ¶24-28.

¶29: “All these facts bring us to the fourth possible explanation…” THIS is where Diamond starts to

present his thesis, his argument, the hypothesis he suggests is the best explanation for the high rate

of TS in Eastern European Jews: “something about them favored accumulation of GM2 ganglioside

and related fats.” This starts to get at the first part of his argument.

¶30: Just a short analogy to make the point suggested in the last sentence of ¶29.

¶31: This starts to establish the heart of his argument and make the connection to natural selection.

He talks about heterozygous advantage and the most well-known example of this, sickle-cell trait in

African blacks as an adaptation to malaria.

¶32: He restates and refines the question and emphasizes an important point about the genetics of

TS: infants born with TS have to be homozygous recessive, meaning both of their parents have to be

heterozygous for the allele associated with TS.

¶33-41: Establishing some key elements of the evidentiary basis for his argument—history matters

and the specific historical conditions the Ashkenazim experienced matterexposure to TB coupled

with anti-Semitic laws preventing land ownership and free migration. PAY CLOSE ATTENTION.

¶42: Here Diamond shows he is a good scientist. He notes that the evidence is speculative, that

there is still work that needs to be done to demonstrate more support for his argument, particularly

in the underlying biochemical mechanism for what he is proposing, but he is not invalidating his

argument and this is NOT a counterargument. It is an acknowledgement of the work that still needs

to be done.

¶43-47: Concluding thoughts that connect understanding TS to the broader question of

understanding the evolution of genetic diseases and why some are more prevalent in some ethnic

groups than others.