Jacobi
Absolute Generations Scale 1)
Absolute Generations Scale 1)
Chanan
Rapaport
Rapaport
(Deputy
Chair of IIJG and a close collaborator of Paul Jacobi)
Chair of IIJG and a close collaborator of Paul Jacobi)
A major goal of the International Institute for Jewish Genealogy
and Paul Jacobi Center is to develop scientific research tools and technologies
for the use of Jewish genealogists and social scientists generally.
and Paul Jacobi Center is to develop scientific research tools and technologies
for the use of Jewish genealogists and social scientists generally.
One such tool for which there has long been a compelling need, is
a standard chronological system to record generations on family trees.
Additionally, there has been a need for a system that permits the
synchronization of generations within kinship groups and their harmonization
with other family trees, whether related or unrelated, and with wider
frames of reference, both historical and societal.
a standard chronological system to record generations on family trees.
Additionally, there has been a need for a system that permits the
synchronization of generations within kinship groups and their harmonization
with other family trees, whether related or unrelated, and with wider
frames of reference, both historical and societal.
The "Jacobi Absolute Generations Scale", devised by the
late Dr. Paul Jacobi almost half a century ago, which fully answers
these various needs (and) is thus recommended by the Institute for
general use.
late Dr. Paul Jacobi almost half a century ago, which fully answers
these various needs (and) is thus recommended by the Institute for
general use.
This paper begins by addressing areas illustrating some of the
problematics involved, both in enumerating the generations using the “Relative
Generations” system and in identifying individuals bearing identical names
within them.
problematics involved, both in enumerating the generations using the “Relative
Generations” system and in identifying individuals bearing identical names
within them.
A. "Relative Generations"
The simplest way to register generations on a family tree is to
define the length of a generation as 25 or 30 years, and then to tie individuals
on the tree to a recognized dating system, such as the Julian, Gregorian,
Hebrew or Muslim calendars. Unfortunately, this arbitrary approach is
inadequate from a number of perspectives, starting with the fact that it
depends on knowledge of years of birth and death of individuals on the tree,
and these facts often are unknown. As a result, family historians, in grappling
with the problem, often adopt a different approach. They opt to designate
generations by the number of generations known to them, generally
assigning the number 1 to the earliest generation recorded on their particular
tree.
define the length of a generation as 25 or 30 years, and then to tie individuals
on the tree to a recognized dating system, such as the Julian, Gregorian,
Hebrew or Muslim calendars. Unfortunately, this arbitrary approach is
inadequate from a number of perspectives, starting with the fact that it
depends on knowledge of years of birth and death of individuals on the tree,
and these facts often are unknown. As a result, family historians, in grappling
with the problem, often adopt a different approach. They opt to designate
generations by the number of generations known to them, generally
assigning the number 1 to the earliest generation recorded on their particular
tree.
Despite the prima
facie logic of this system of “relative generations,” it can lead to
confusion, inconsistencies and even errors. One obvious danger may be
demonstrated in the case of a family historian who fixes the third generation
back (the earliest known to him) as number 1, while another researcher of the
same family, who has traced the common lineage further back in time, assigns
the number 1 to the fifth or even the fifteenth generation back. The resultant
confusions are self- evident.
facie logic of this system of “relative generations,” it can lead to
confusion, inconsistencies and even errors. One obvious danger may be
demonstrated in the case of a family historian who fixes the third generation
back (the earliest known to him) as number 1, while another researcher of the
same family, who has traced the common lineage further back in time, assigns
the number 1 to the fifth or even the fifteenth generation back. The resultant
confusions are self- evident.
However, the potential pitfalls associated with this system run
deeper. To cite but two problem areas:
deeper. To cite but two problem areas:
1. Homonymous individuals
In certain Ashkenazi Jewish traditions, it is customary to
memorialize deceased relatives by calling new-born children after them. While
several considerations may come into play in selecting given names, a first son
is very often named after his grandfather or, if the latter is still alive,
after his great grandfather. Other children, both male and
female, are named in accordance with various conventions and, in some
communities, in a well-accepted (though not iron-cast) order. These customs
lead to regular, consistent naming patterns, usually repeating themselves in
every third generation and often throughout parallel branches within the same
family.
memorialize deceased relatives by calling new-born children after them. While
several considerations may come into play in selecting given names, a first son
is very often named after his grandfather or, if the latter is still alive,
after his great grandfather. Other children, both male and
female, are named in accordance with various conventions and, in some
communities, in a well-accepted (though not iron-cast) order. These customs
lead to regular, consistent naming patterns, usually repeating themselves in
every third generation and often throughout parallel branches within the same
family.
Since family historians frequently use naming patterns as a
guiding light to fix generations in time and to determine
the relationships between individuals, the recurrence of people with the same given name – known as
“homonymous individuals” - in a single family lends itself to
misidentification and outright mistakes. The problem may be compounded when the same
naming pattern is found in another, unrelated family that bears the same
surname, sometimes in the same community.
guiding light to fix generations in time and to determine
the relationships between individuals, the recurrence of people with the same given name – known as
“homonymous individuals” - in a single family lends itself to
misidentification and outright mistakes. The problem may be compounded when the same
naming pattern is found in another, unrelated family that bears the same
surname, sometimes in the same community.
Among Sephardim, especially Ladino-(Judeo-Spanish) speaking Jews,
it has been, and to an extent it still is, the custom (is) to name a
child in honor of maternal and paternal grandparents, even while
they are still alive. Again, the same names may appear many times within a single
timeframe, and not in clearly defined generations, thereby increasing the risk
of errors in identity.
it has been, and to an extent it still is, the custom (is) to name a
child in honor of maternal and paternal grandparents, even while
they are still alive. Again, the same names may appear many times within a single
timeframe, and not in clearly defined generations, thereby increasing the risk
of errors in identity.
2. Married names
In Jewish usage, women tend to be recorded as
“so-and-so” the daughter of “so-and-so” [her father], wife of “so-and-so.” Although in some
cases this form of appellation may help identification, it frequently leads to
confusion, given the multiplicity of the same masculine name in repeated
generations within a given family. The problem is compounded by the propensity for cousins
to marry cousins in certain Jewish societies.
“so-and-so” the daughter of “so-and-so” [her father], wife of “so-and-so.” Although in some
cases this form of appellation may help identification, it frequently leads to
confusion, given the multiplicity of the same masculine name in repeated
generations within a given family. The problem is compounded by the propensity for cousins
to marry cousins in certain Jewish societies.
These factors complicate and hinder comparisons
between independently produced family trees, especially where the
"relative-generations" system is used for recording purposes.
Harmonizing such trees and reconciling inconsistencies between them is far from
easy, while the establishment of complex family relationships becomes all the
more difficult the longer the lineages. Errors are hard to spot and
"skipped generations" may be overlooked, with all the attendant genealogical
blunders likely to arise therefrom.
between independently produced family trees, especially where the
"relative-generations" system is used for recording purposes.
Harmonizing such trees and reconciling inconsistencies between them is far from
easy, while the establishment of complex family relationships becomes all the
more difficult the longer the lineages. Errors are hard to spot and
"skipped generations" may be overlooked, with all the attendant genealogical
blunders likely to arise therefrom.
In brief, the "relative generations" system can become
an obstacle to serious genealogical research. Attempts to synchronize the
arbitrarily numbered generations with a standard time-line may not lead to
accurate correlations. Hence, the historical background and cultural context surrounding
an individual may be skewed and marred by anachronisms or the opposite
(“prochronisms”). Equally, the influences on his behavior and life choices, his
educational and occupational opportunities, residential possibilities, communal
affiliations and societal networks, and migrational decisions, to mention but a
few aspects of life relevant to the genealogist, may be improperly understood
and even totally misinterpreted.
an obstacle to serious genealogical research. Attempts to synchronize the
arbitrarily numbered generations with a standard time-line may not lead to
accurate correlations. Hence, the historical background and cultural context surrounding
an individual may be skewed and marred by anachronisms or the opposite
(“prochronisms”). Equally, the influences on his behavior and life choices, his
educational and occupational opportunities, residential possibilities, communal
affiliations and societal networks, and migrational decisions, to mention but a
few aspects of life relevant to the genealogist, may be improperly understood
and even totally misinterpreted.
B. "Absolute Generations"
Aware of these difficulties, the late Dr. Paul Jacobi (1911-1997)
developed an alternative system for registering generations, now known
as the Jacobi “Absolute Generations Scale (JAGS). In this
system, genealogists employ an absolute time line that is stable,
recognized and linked directly to the years as enumerated in the accepted
system in use in the Western world today (“BC” and “AD”, or, for Jews and some
others, “BCE” and “CE”).
developed an alternative system for registering generations, now known
as the Jacobi “Absolute Generations Scale (JAGS). In this
system, genealogists employ an absolute time line that is stable,
recognized and linked directly to the years as enumerated in the accepted
system in use in the Western world today (“BC” and “AD”, or, for Jews and some
others, “BCE” and “CE”).
On the basis of his extensive genealogical knowledge
and experience, Jacobi determined the average span of a single generation as 75
years, with each successive generation set to follow the previous one at
intervals of 30 years. Thus, on the basis of the Common Era dating system:
and experience, Jacobi determined the average span of a single generation as 75
years, with each successive generation set to follow the previous one at
intervals of 30 years. Thus, on the basis of the Common Era dating system:
•“Generation 1” is fixed as 2040–1965 (a period of 75
years).
years).
•Working backwards, “Generation 2” begins 30 years
earlier and covers the period 2010-–1935.
earlier and covers the period 2010-–1935.
•Successive generations are counted retrogressively
every 30 years prior to 2010.
every 30 years prior to 2010.
With the designation of the current generation as “Generation 0,”
Jacobi’s absolute generational scale for the last 900 years is as follows:
Jacobi’s absolute generational scale for the last 900 years is as follows:
0 | = | 1995-2070 | 11 | = | 1665-1740 | 2 | = | 1335-1410 | ||||
1 | = | 1965-2040 | 12 | = | 1635-1710 | 23 | = | 1305-1380 | ||||
2 | = | 1935-2010 | 13 | = | 1605-1680 | 24 | = | 1275-1350 | ||||
3 | = | 1905-1980 | 14 | = | 1575-1650 | 25 | = | 1245-1320 | ||||
4 | = | 1875-1950 | 15 | = | 1545-1620 | 26 | = | 1215-1290 | ||||
5 | = | 1845-1920 | 16 | = | 1515-1590 | 27 | = | 1185-1260 | ||||
6 | = | 1815-1890 | 17 | = | 1485-1560 | 28 | = | 1155-1230 | ||||
7 | = | 1785-1860 | 18 | = | 1455-1530 | 29 | = | 1125-1200 | ||||
8 | = | 1755-1830 | 19 | = | 1425-1500 | 30 | = | 1095-1170 | ||||
9 | = | 1725-1800 | 20 | = | 1395-1470 | 31 | = | 1065-1140 | ||||
10 | = | 1695-1770 | 21 | = | 1365-1440 | 32 | = | 1035-1110 | ||||
Jacobi consciously drew his scale back to “Generation 32”
(1035-1110) which corresponds with the life of the great Jewish biblical and
Talmudic commentator, Rashi (1040-1105).
(1035-1110) which corresponds with the life of the great Jewish biblical and
Talmudic commentator, Rashi (1040-1105).
Theoretically, Jacobi’s scale could be extended back
to the dawn of recorded history, or indeed of history itself, but Jacobi
preferred not to be drawn into unnecessary theoretical discussions over when
history began and, according to whose historical tradition. As a practical
matter, he regarded it as sufficient to use the scale as it is, since
scientific Jewish genealogy scarcely pre-dates Rashi.*
to the dawn of recorded history, or indeed of history itself, but Jacobi
preferred not to be drawn into unnecessary theoretical discussions over when
history began and, according to whose historical tradition. As a practical
matter, he regarded it as sufficient to use the scale as it is, since
scientific Jewish genealogy scarcely pre-dates Rashi.*
An individual, who lived the larger part of his life
within the time-frame of a given generation, is designated as belonging to that
generation. Thus, the outstanding Jewish scholars Samuel Eliezer ben Judah
Halevi Edels (1555-1631) [the “Maharsha”] and Maimonides (1135-1204) [the
“Rambam”] belong to generations 15 and 29, respectively. Within each absolute
generation, the scale allows for flexibility. On occasion, it is necessary—and possible—to
split a generation or to skip one. For example:
within the time-frame of a given generation, is designated as belonging to that
generation. Thus, the outstanding Jewish scholars Samuel Eliezer ben Judah
Halevi Edels (1555-1631) [the “Maharsha”] and Maimonides (1135-1204) [the
“Rambam”] belong to generations 15 and 29, respectively. Within each absolute
generation, the scale allows for flexibility. On occasion, it is necessary—and possible—to
split a generation or to skip one. For example:
Ø •A man lived
from 1725 to 1755 and had a son who lived from 1744 to 1790. Both belong to
Generation 9. For the sake of clarity, however, the father should be assigned
to Generation 9b and the son to Generation 9a.
from 1725 to 1755 and had a son who lived from 1744 to 1790. Both belong to
Generation 9. For the sake of clarity, however, the father should be assigned
to Generation 9b and the son to Generation 9a.
Ø A woman
lived from 1775 to 1830 and had a daughter who lived from 1815 to 1890. The
mother belongs to Generation 8, but the daughter to Generation 6—hence the need
to skip a generation in this case.
lived from 1775 to 1830 and had a daughter who lived from 1815 to 1890. The
mother belongs to Generation 8, but the daughter to Generation 6—hence the need
to skip a generation in this case.
When the need eventually arises, the scale can be extended forward
in time by adding Generation–1 (2100–2025), Generation–2 (2130–2055), and so
on.
in time by adding Generation–1 (2100–2025), Generation–2 (2130–2055), and so
on.
Conclusions
Several advantages arise from adopting the Jacobi
Absolute Generations Scale (JAGS).
Absolute Generations Scale (JAGS).
·
First and foremost, the JAGS offers a standard
chronological system to record generations on family trees and to synchronize
them within kinship groups.
First and foremost, the JAGS offers a standard
chronological system to record generations on family trees and to synchronize
them within kinship groups.
·
Every individual on a specific family tree—and
on parallel trees drawn up independently–can be assigned to an absolute
generation.
Every individual on a specific family tree—and
on parallel trees drawn up independently–can be assigned to an absolute
generation.
·
An individual’s generational position is
identical on all trees, thereby providing positive identification when trees
are compared, merged or interchanged.
An individual’s generational position is
identical on all trees, thereby providing positive identification when trees
are compared, merged or interchanged.
·
The JAGS minimizes the possibility of
misidentification and of coalescing discrete individuals bearing the same given
name and patronym.
The JAGS minimizes the possibility of
misidentification and of coalescing discrete individuals bearing the same given
name and patronym.
·
The JAGS readily illustrates anomalies,
requiring further investigation, such as a married woman whose father was born
in generation 12, but whose supposed husband was born 100 years earlier, in
generation 15.
The JAGS readily illustrates anomalies,
requiring further investigation, such as a married woman whose father was born
in generation 12, but whose supposed husband was born 100 years earlier, in
generation 15.
·
It sometimes suggests solutions to these
anomalies because facility in using JAGS leads to an ability to place an
individual in his correct generation, even in the absence of precise dates of
birth and death for the individual concerned.
It sometimes suggests solutions to these
anomalies because facility in using JAGS leads to an ability to place an
individual in his correct generation, even in the absence of precise dates of
birth and death for the individual concerned.
·
The JAGS indicates the precise time-frame in
which a person lived the majority of his life and thereby places him in the
correct historical context, even when some vital genealogical information is
lacking.
The JAGS indicates the precise time-frame in
which a person lived the majority of his life and thereby places him in the
correct historical context, even when some vital genealogical information is
lacking.
·
Assignment of an absolute generation to all
family members reveals who an individual’s contemporaries were, both within his
own family and beyond. The JAGS permits the reconstruction of generational
relationships even when full genealogical information is missing. For instance,
if an individual can be located in generation 26, one may reasonably assume
that his father belonged to generation 27, his children to generation 25 and
his grandchildren to generation 24. The subsequent discovery of a critical
piece of vital statistical information almost invariably substantiates these
assumptions, proving the reliability and value of the scale.
Assignment of an absolute generation to all
family members reveals who an individual’s contemporaries were, both within his
own family and beyond. The JAGS permits the reconstruction of generational
relationships even when full genealogical information is missing. For instance,
if an individual can be located in generation 26, one may reasonably assume
that his father belonged to generation 27, his children to generation 25 and
his grandchildren to generation 24. The subsequent discovery of a critical
piece of vital statistical information almost invariably substantiates these
assumptions, proving the reliability and value of the scale.
·
Finally, use of Jacobi's Absolute Generations
Scale points the way to the creation of a common terminology and chronology
between genealogists and researchers from other scientific disciplines, as well
as scholars from diverse cultures, speaking different languages.
Finally, use of Jacobi's Absolute Generations
Scale points the way to the creation of a common terminology and chronology
between genealogists and researchers from other scientific disciplines, as well
as scholars from diverse cultures, speaking different languages.
In the light of these advantages, the Genealogical Institute
highly recommends that Jacobi’s scale be adopted as widely as possible.
highly recommends that Jacobi’s scale be adopted as widely as possible.
Dr. Neville Lamdan, the Director of the Institute, contributed to
this article.
this article.
--------------
* For those seeking greater historical depth, herewith the Jacobi
Absolute Generations Scale drawn from “Generation 0” to “Generation 101”,
during which time (-1049 – -970), according to tradition and to many Biblical
archaeologists, King David is held to have lived.
Absolute Generations Scale drawn from “Generation 0” to “Generation 101”,
during which time (-1049 – -970), according to tradition and to many Biblical
archaeologists, King David is held to have lived.
0 = 1995 - 2070 | |||
1 = 1965 - 2040 | 26 = 1215 - 1290 | 51 = 465 - 540 | 76 = -285 - -210 |
2 = 1935 – 2010 | 27 = 1185 - 1260 | 52 = 435 - 510 | 77 = -315 - -240 |
3 = 1905 - 1980 | 28 = 1155 - 1230 | 53 = 405 - 480 | 78 = -345 - -270 |
4 = 1875 - 1950 | 29 = 1125 - 1200 | 54 = 375 - 450 | 79 = -375 - -300 |
5 = 1845 - 1920 | 30 = 1095 - 1170 | 55 = 345 - 420 | 80 = -405 - -330 |
6 = 1815 - 1890 | 31 = 1065 - 1140 | 56 = 315 - 390 | 81 = -435 - -360 |
7 = 1785 - 1860 | 32 = 1035 - 1110 | 57 = 285 - 360 | 82 = -465 - -390 |
8 = 1755 - 1830 | 33 = 1005 - 1080 | 58 = 255 - 330 | 83 = -495 - -420 |
9 = 1725 - 1800 | 34 = 975 - 1050 | 59 = 225 - 300 | 84 = -525 - -450 |
10 = 1695 - 1770 | 35 = 945 - 1020 | 60 = 195 - 270 | 85 = -555 - -480 |
11 = 1665 - 1740 | 36 = 915 - 990 | 61 = 165 - 240 | 86 = -585 - -510 |
12 = 1635 - 1710 | 37 = 885 - 960 | 62 = 135 - 210 | 87 = -615 - -540 |
13 = 1605 - 1680 | 38 = 855 - 930 | 63 = 105 - 180 | 88 = -645 - -570 |
14 = 1575 - 1650 | 39 = 825 - 900 | 64 = 75 - 150 | 89 = -675 - -600 |
15 = 1545 - 1620 | 40 = 795 - 870 | 65 = 45 - 120 | 90 = -705 - -630 |
16 = 1515 - 1590 | 41 = 765 - 840 | 66 = 15 - 90 | 91 = -735 - -660 |
17 = 1485 - 1560 | 42 = 735 - 810 | 67 = -15 - + 60 | 92 = -765 - -690 |
18 = 1455 - 1530 | 43 = 705 - 780 | 68 = -45 - + 30 | 93 = -795 - -720 |
19 = 1425 - 1500 | 44 = 675 - 750 | 69 = -75 - 0 | 94 = -825 - -750 |
20 = 1395 - 1470 | 45 = 645 - 720 | 70 = - 105 - -30 | 95 = -855 - -780 |
21 = 1365 - 1440 | 46 = 615 - 690 | 71 = -135 - -60 | 96 = -885 - -810 |
22 = 1335 - 1410 | 47 = 585 - 660 | 72 = -165 - -90 | 97 = -915 - -840 |
23 = 1305 - 1380 | 48 = 555 - 630 | 73 = -195 - -120 | 98 = -945 -870 |
24 = 1275 - 1350 | 49 = 525 - 600 | 74 = -225 - -150 | 99 = -975 - -900 |
25 = 1245 - 1320 | 50 = 495 - 570 | 75 = -255 - -180 | 100 = -1005 - -930 |
101 = -1035- -960 |
1) The above
paper was written for "The International Institute for Jewish Genealogy
and
paper was written for "The International Institute for Jewish Genealogy
and
It was published in the International Journal for Jewish
Genealogy "AVOTAYNU",
Genealogy "AVOTAYNU",
Volume XXV, Number 4.
Winter 2009, Washington,
DC.
Winter 2009, Washington,
DC.
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