THE JEWISH JOURNAL OF SOCIOLOGY VOLUME! NO.2 DECEMBER 1959 CONTENTS The Blood Groups of the Jews A. E. Mourant '55 The Resurgence of Hebrew Leon Roth '77 Two Iraqi Jewish Short Story Writers: A Suggestion for Social Research Emile Marmorstein 187 Aspects of the Social Life of Kurdish Jews Dma Feitelson 20! The Demography of the Jewish Community in Canada Louis Rosenberg 217 Cultural and Economic Problems of Jewish Migration in the Post-War World Julius Isaac 234 Trends in Occupational Structure and Distribution of Income among the Jewish Population in Israel A. Bonné 242 Max Weber on the Sociological Basis of the Jewish Religion L Schiper 250 Book Reviews Jacob Katz on Jewish Social History Joseph Agassi 261 Shorter Notices 266 Books Received 272 Notes on Contributors 273 / Chronicle P. Gli/cson 275 French Summaries 278 Hebrew Summaries 288 PUBLISHED TWICE YEARLY on behalf of the World Jewish Congress by William Heinemann Ltd, 1-16 Queen Street, London Wi Annual Subscription £'•'•° (post free)—Single Copies in 6d net Applications for subscription should be addressed to the Managing Editor, The Jewish Journal of Sociology, 55 J'Iew Cavendish Street, London Wi EDITOR Morris Ginsberg MANAGING EDITOR Maurice Freedman ADVISORY BOARD - R. Bachi (Israel) 0. Ktineberg (USA) André Chouraqui (France & Israel) Jacob Lestschinsky (Israel) S. N. Eisenstadt (Israel) Eugene Minkowski (France) Nathan Glazer (USA) Louis Rosenberg (Canada) J. Katz (Israel) H. L. Shapiro (USA) A. Tartakower (Israel) © THE WORLD JEWISH CONGRESS 1959 PRINTED IN GREAT BRITAIN BY BUTLER AND TANNER LTD FROME AND LONDON THE BLOOD GROUPS OF THE JEWS A. E. Mourant HERE IS NO DOUBT that the Jews of the Dispersion show differences, both cultural and physical, from the various popula- Ttions among whom they live. Opinions vary, however, as to the relative importance of the two kinds of difference. There is, moreover, a divergence of opinion not only as to the extent to which even the physical differences are environmental rather than inherited, but also as to how far inherited differences are derived from an original Israelite ancestry, how far from intermarriage in lands of tempofary sojourn, and how far from non-Jewish populations which have become converted to Judaism. It has also been suggested that there has been genetical self- selection of persons leaving the Jewish community through marriage or for other reasons. It is, however, unlikely that any such process has appreciably affected blood group frequencies. Before we can make specific comparisons between the Jews and their neighbours we must consider in general terms the nature of the evidence available• for corniaring populations with one another. Some of this cvidence is highly technical and it will be necessary to set out the theoretical considerations involved in some detail. Until a few years ago anthropologists, when comparing populations, depended almost entirely on observations and measurements of the external characters of the body. Differences in such characters are obvious to all observers but unless the observations are strictly controlled they are liable to be coloured by personal prejudices: we all have our own mental pictures of what a Frenchman or a Japanese should look like, and are liable to see our own picture in every Frenchman or every Japanese. Objective differences between individuals and between populations can, however, readily be demonstrated if observations of the size, shape and colour of the body and its parts are made which are strictly quanti- tative, but even these will not tell us whether the differences are due to '55 A.E. MOTJRANT environment or to heredity. The basic characteristics are certainly inherited, but the manifestation of the genes responsible may be con- siderably modified by the environmental history of the individual. Also, the genetics of the external characters have been very little studied, though it is certain that each of them, with one or two possible excep- tions, is the joint result of a considerable number of genes. The blood groups, on the other hand, are genetically very simple and well understood. The observed facts, that is to say the results of our tests on the red blood cells of the individual, constitute his or her blood group phenotype. The latter is very directly and simply related to the genotype, or genetical constitution, which is fixed for life at the moment of conception. As far as most tests are concerned the phenotype too is fixed by the time of birth, and for all tests by the age of about one year. Unlike the external characters, blood groups are therefore unaffected by the environment. They have the further practical advantage that their consideration is unaffected by such emotional accretions as have tended to attach themselves to discussion of the external features of the body. There are ten genetically independent or almost independent systems of blood groups, but in the present state of our knowledge only three of these, the ABO, the MNSs and the Rh or Rhesus systems, contribute appreciably to the solution of the problems of Jewish ancestry. The ABO blood groups constitute the best-known system and also the one which contributes most information about the Jews. It will therefore be convenient to use this system as the basis for a discussion of the general principles involved in the use of blood groups in popula- tion studies. As all blood donors know, there are four blood groups called 0, A, B, and AB; these are characterized by the presence or absence of either or both of the substances A and B on the red cells. These substances are polysacchandes, thus belonging, in a very broad sense, to the same class of compounds as starch and cellulose. They are present only in minute amounts and can be detected and distinguished from one another only by the use of serum reagents known as anti-A and anti-B. - If a suitable preparation of the red cells of a blood under test is treated with anti-A serum, cells containing the A substance (i.e. those of groups A and AB) will clump together or 'agglutinate'. Similarly those containing B (groups B and AB) will agglutinate in the presence of anti-B. The inheritance of the blood groups depends upon the existence of three kinds of allelomorphic (alternative) genes 0, A, and B, of which A and B give rise to the substances indicated by the same letters. Every human being has two of these genes, like or unlike, in his or her genetical constitution, one being inherited from the mother and one from the father. Thus people of group 0 have two 0 genes; group A people an 156 BLOOD GROUPS OF THE JEWS A and an 0 or two A's, group B people a B and an 0 or two B's, while group AB people have an A and a B. In applying the results of blood group surveys to population problems it is convenient to use the genes rather than the blood groups themselves and to think in terms of the frequencies or percentages of the three genes, 0, A, and B. When we speak of a person having an 0 and an A gene we mean in fact that every cell, or nearly every cell, of the body carries both of these genes. For statistical purposes, however, we attri- bute only a single pair of genes to each individual, namely, those present in the single fertilized cell from which the individual grew by repeated cell division. Thus the percentages of the genes in a given population may be regarded as the total numbers of each of the genes present in fifty people, who between them have one hundred genes. In the case of some of the blood group systems it is possible by direct serological tests to ascertain the precise genes carried by each indi- vidual. This as we have seen, is not in all cases possible for the ABO blood groups, but if we carry out tests on a sufficiently large number of people we can calculate without great difficulty the percentages of the genes present in the population. This may appear to be a roundabout procedure but it has several advantages. Firstly, we are dealing only with three quantities instead of four, and, since these three variables as a matter of simple arithmetic must add up to 100 per cent we can in fact specify any population in terms of the percentages of two only of these variables, the ones chosen being in practice the A and the B genes. Also, when we are considering the mixing of populations the percentages of the genes in the mixed population (as can simply be proved mathe- matically) are proportional to the contributions made by the respective ancestral populations. There is not such a simple proportion to be observed if we specify the populations in terms of the blood groups themselves. It should be added that, in the absence of selective survival or fertility, and of random fluctuations or drift such as may occur in very small populations, the frequencies of the three genes will tend to remain constant from generation to generation in a given population. The problem of natural selection is one which faces us whenever we try to compare populations, whether on the basis of blood groups, of skin colour, or of any other set of characters. If we accept the common ancestry of the whole human race then the differences now observed must, apart from random drift, be due to some form of natural selection, and this process, however slow it may be, must be continuing at the present time. The best that we can do for purposes of characterizing and comparing populations is to try to choose characters for which selection is slow.