EMBA RGOE D UNTI L 2PM U. S. EAST ERN TIME ON THE THURSDAY B EF ORE T HI S DAT E: PERSPECTIVE When the World s Population Took Off: The Springboard of the Neolithic Demographic Transition Jean-Pierre Bocquet-Appel During the economic transition from foraging to farming, the signal of a major demographic shift can be observed in cemetery data of world archaeological sequences. This signal is characterized by an abrupt increase in the proportion of juvenile skeletons and is interpreted as the signature of a major demographic shift in human history, known as the Neolithic Demographic Transition (NDT). This expresses an increase in the input into the age pyramids of the corresponding living populations with an estimated increase in the total fertility rate of two births per woman. The unprecedented demographic masses that the NDT rapidly brought into play make this one of the fundamental structural processes of human history. A fter the membe rs of the genus Homo had been living as foragers for at least 2.4 mil- lion years, agriculture began to emerge in seven or eight regions across the world, almostsimultaneously at the beginning of the Holocene: in the Levant, in North and South China, in New Guinea and Ethiopia, and in eastern North Amer- ica, Mesoamerica, and South America, all during the chron olog ical window from 11 ,500 to 3500 years ago (1). In world archaeological sequences, the emergence of agriculture coincides with a con- siderable increase in artefact remains, which was lon g int erpre ted as ind icat ing a spu rt in demo grap hic growth. The world s population on the eve of the emer genc e of agricul ture is esti mat ed to ha ve bee n around 6 million ( 2) individuals as against almost7 bi lli on tod ay , mul tip ly ing by 12 00 in ju st 11,0 00 years. The shift from forager to producer societies is known as The Neolithic Revolution ( 3). Th e ma- jor change that arose from this revolution was, in evo luti ona ry time , the number of potential mouths it was possible to feed per km 2 , i.e., the weight ofth e po pu lat io n, 0.05 peo ple per km 2 wit h the foraging system as against 54 today and, perhaps, 70 to 80 by 2050. The archaeological data, such as the increasing density of settlement sites during the transition, are too imprecise to express the de- mograp hic shift. Cemetery data prov ide a more direct reflectio n of demographic process es, and itis from cemet eri es that th e si gn al of a ma jo r de mo - graphic shift can be observed in world archaeo- logica l sequen ces in the North ern Hemisphere (Fi g. 1). Th is sig na l is chara cte riz ed by a rel ati vel y abr up t inc rea se in the pro porti on of 5- to 19-year -ol d juven iles in cemet eries during the econ omi c tran - sition from foraging to farming. This proportion (called 15 p 5 in demogr aphic notation) leveled off 1000 years after the advent of the farming system locally (dt= 1000 years). This expresses an increase in the input into the age pyramids ofthe corresponding living populations ( 4, 5),with an estimated increase in total fertility rate oftwo births per woman. What, in the agricultural economy, had an im- pact on human biology that ultimately determined the growth of the population? The increase in natural maternal fertility, through a reduction in the birt h inte rval , is main ly dete rmin ed by the energy balance and the relative metabolic load (6). It implies a positive return of the postpartum energy balance, which occurred earlier in farming than in foraging societies due to the energy gain from the high-calorie food of sedentary farmers (wheat, lentils, peas, maize, rice, and millet) com- pared to the low-calorie food of mobile foragers (mainly game), coupled with a decrease in the energy expenditure of carrying infants. This signal is interpreted as the signature of a major demo- CNRS (National Center for Scientific Research), UPR2147 and EPHE (Practical School of High Studies), 44, rue de l'Amical Mouchez, Paris 75014, France. E-mail: jean-pierre.bocquet- [email protected]0.0 0.1 0.2 0.3 0.4 0.5 - 4 0 0 0 - 3 0 0 0 - 2 0 0 0 - 1 0 0 0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 0 dt(years) 1 5 p 5 Fig. 1. The proportion of 5- to 19- year-old skeletons (to all skeletons 5 or more years old) (vertical axis: 15 p 5 ) in 133 cemeteries across the North- ern Hemisphere during the transition from foraging to farming (horizontal axis: dt). The horizontal axis d trepre- sents the time that elapsed between the advent of farming at that partic- ular location, aligned at dt= 0 [from ( 25)]. (Below) The population explo- sion of the Neolithic Demographic Tran- sition, detectable in ceme teri es, was unprecedented in the history of Homo sapiens . Neolithic gallery grave of La Chaussée Tirancourt, France (~4500 years before the present). 29 JUL Y 2 011 VOL 333 SCIENCE www.sciencemag.org 560 [ P H O T O C L . M A S S E T ]
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EMBARGOED UNTIL 2PM U.S. EASTERN TIME ON THE THURSDAY BEFORE THIS DATE:
PERSPECTIVE
When the World’s Population Took Off:The Springboard of the Neolithic
Demographic TransitionJean-Pierre Bocquet-Appel
During the economic transition from foraging to farming, the signal of a major demographic shift can beobserved in cemetery data of world archaeological sequences. This signal is characterized by an abruptincrease in the proportion of juvenile skeletons and is interpreted as the signature of a major demographicshift in human history, known as the Neolithic Demographic Transition (NDT). This expresses an increasein the input into the age pyramids of the corresponding living populations with an estimated increasein the total fertility rate of two births per woman. The unprecedented demographic masses that the NDTrapidly brought into play make this one of the fundamental structural processes of human history.
A
fter the members of the genus Homo had
been living as foragers for at least 2.4 mil-
lion years, agriculture began to emerge inseven or eight regions across the world, almost
simultaneously at the beginning of the Holocene:
in the Levant, in North and South China, in New
Guinea and Ethiopia, and in eastern North Amer-
ica, Mesoamerica, and South America, all during
the chronological window from 11,500 to 3500
years ago (1). In world archaeological sequences,
the emergence of agriculture coincides with a con-
siderable increase in artefact remains, which was
long interpreted as indicatinga spurt in demographic
growth. The world’s population on the eve of the
emergence of agriculture is estimated to have been
around 6 million (2) individuals as against almost
7 billion today, multiplying by 1200 in just 11,000years. The shift from forager to producer societies
is known as The Neolithic Revolution (3). The ma-
jor change that arose from this “revolution” was, in
evolutionary time, the number of potential mouths
it was possible to feed per km2, i.e., the weight of
the population, 0.05 people per km2 with the
foraging system as against 54 today and, perhaps,
70 to 80 by 2050. The archaeological data, such
as the increasing density of settlement sites during
the transition, are too imprecise to express the de-
mographic shift. Cemetery data provide a more
direct reflection of demographic processes, and it
is from cemeteries that the signal of a major demo-
graphic shift can be observed in world archaeo-
logical sequences in the Northern Hemisphere
(Fig. 1). This signal is characterized by a relatively
abrupt increase in theproportion of 5- to 19-year-old
juveniles in cemeteries during the economic tran-
sition from foraging to farming. This proportion
(called 15 p5 in demographic notation) leveled
off 1000 years after the advent of the farming
system locally (dt = 1000 years). This expres
an increase in the input into the age pyramids
the corresponding living populations (4, 5),w
an estimated increase in total fertility rate
two births per woman.
What, in the agricultural economy, had an i
pact on human biology that ultimately determin
the growth of the population? The increase
natural maternal fertility, through a reductionthe birth interval, is mainly determined by
energy balance and the relative metabolic lo
(6 ). It implies a positive return of the postpartu
energy balance, which occurred earlier in farmi
than in foraging societies due to the energy g
from the high-calorie food of sedentary farm
(wheat, lentils, peas, maize, rice, and millet) co
pared to the low-calorie food of mobile forag
(mainly game), coupled with a decrease in t
energy expenditure of carrying infants. This sig
is interpreted as the signature of a major dem
CNRS (National Center for Scientific Research), UPR2147 andEPHE (Practical School of High Studies), 44, rue de l'AmicalMouchez, Paris 75014, France. E-mail: [email protected]
0.0
0.1
0.2
0.3
0.4
0.5
- 4 0 0 0
- 3 0 0 0
- 2 0 0 0
- 1 0 0 0
1 0 0 0
2 0 0 0
3 0 0 0
4 0 0 0 0
dt (years)
1 5 p 5
Fig. 1. The proportion of 5- to 1
year-old skeletons (to all skeletonor more years old) (vertical axis: 15
in 133 cemeteries across the Norern Hemisphere during the transitfrom foraging to farming (horizonaxis: dt ). The horizontal axis dt repsents the time that elapsed betwethe advent of farming at that partular location, aligned at dt = 0 [fr( 25)]. (Below) The population expsion of the Neolithic Demographic Trsition, detectable in cemeteries, wunprecedented in the history of Ho sapiens. Neolithic gallery grave ofChaussée Tirancourt, France (~45