Session A25e
Session
A1
Dynamics of human and
cultural dispersals
during the Neolithic
transition in Europe: Complex Systems and Prehistory
Silicious rock extraction and prehistoric lithic economies
Demic versus Cultural Diffusion in the
Neolithic
transition
in Europe
and
Title:
Flint mining,
handicraft,
and
the
southern
Africa
Neolithic
Revolution
Fort, Joaquim. Universitat de Girona ([email protected]);
Jerardino, Antonieta. Universitat Pompeu Fabra ([email protected]);
Isern, Neus. Universitat Autònoma de Barcelona ([email protected])
Acculturation
Cavalli-Sforza & Feldman (book 1979)
Boyd & Richerson (book 1985)
Fort (PNAS 2012)
Population numbers after (P’) and before (P)
cultural transmission (during 1 generation):
farmers
: =
+
hunter − gatherers
:
=
−
+
+
= intensity of cultural transmission
= preference of Hs to copy Fs rather than Hs (if
<1)
Lotka-Volterra eqs. ( =
+η
) are not realistic as:
· they are not derived from cultural transmission theory
· they yield, e. g. : if
→ ∞,
!"# $!"
then
!"
→ ∞ !!
2
Fort (PNAS 2012)
=
+
=
−
+
+
≈
+ %
≈
− %
%=
if
!"# $!"
= % is the
!"
!"# $!"
is not ,
!"
∞
≫
, then
number of Hs converted by farmer
in contrast to Lotka-Volterra eqs.
The front speed does not depend on and
'
separately, but only on % = .
(
3
Demic-cultural models
Fort (PNAS 2012)
Steps:
1. reproduction (logistic)
2. cultural transmission (horizontal/oblique)
3. dispersal (distance kernel)
The order of events does not change the speed
This cycle is repeated many times (once per generation)
4
Effect of acculturation intensity C
on the front speed in Europe
4.0
maximum
predicted
speed
3.5
s*
speed (km/yr)
3.0
EUROPE:
Dates
versus
distances
(great
circles &
shortest
paths)
minimum
predicted
speed
2.5
2.0
observed speed range
simulations
observed C range
1.5
1.0
Fort,
PNAS
(2012)
consistency between
predicted and
observed speeds
0.5
0.0
0.01
0.1
1
10
C
100
1000
10000
5
Ache hunter-gatherers (Paraguay)
Effect of cultural diffusion in Europe
Effect (%) = (speed – demic speed) /speed · 100
80
cultural effect (%)
70
minimum
predicted
speed
60
50
40
maximum
predicted
speed
40 ± 8 %
30
20
C range implied
10
by the consistency
(black) area in Fig. 1
0
0.01
0.1
1
10
C
100
1000
Fort,
PNAS
(2012)
10000
6
The Neolithic transition in southern Africa
Jerardino,
Fort,
Isern,
Rondelli,
submitted
(2014)
7
The Neolithic transition in southern Africa
speed= 2.4±1.0 km/yr →faster than in Europe
) = 0.77
) = 0.85 without sites 7,11,12
Jerardino,
Fort,
Isern,
Rondelli,
submitted
(2014)
8
Effect of acculturation intensity C
on the front speed in southern Africa
Faster
than in
Europe
Jerardino,
Fort,
Isern,
Rondelli,
submitted
(2014)
Stronger acculturation into
herding than into farming
9
Effect of cultural diffusion in southern Africa
Effect (%) = (speed – demic speed) /speed · 100
57 ± 7 %
Jerardino,
Fort,
Isern,
Rondelli,
submitted
(2014)
10
Local features in Europe
Fort,
J. R. Soc.
Interface
(2014)
11
Fort,
J. R. Soc.
Interface
(2014)
12
Fort,
J. R. Soc.
Interface
(2014)
13
6000 cal y BP
speed = 1000 km / 1000 y = 1 km/y
7000 cal y BP
speed = 400 km / 2000 y = 0.2 km/y
6000 cal y BP
8000 cal y BP
Fort,
J. R. Soc.
Interface
(2014)
speed = 400 km / 1000 y = 0.4 km/y
7000 cal y BP
14
Fort,
J. R. Soc.
Interface
(2014)
15
smoothing
1 time
10 times
Fort,
J. R. Soc.
Interface
(2014)
20 times
16
smoothing
40 times
(60 times→ same results)
No
smoothing
Fort,
J. R. Soc.
Interface
(2014)
17
smoothing
40 times
(60 times→ same results)
No smoothing
Fort,
J. R. Soc.
Interface
(2014)
18
smoothing
40 times
Fort,
J. R. Soc.
Interface
(2014)
No smoothing
19
Smoothing 40 times
→ mainly cultural
→ mainly demic
→ either mainly demic or
mainly cultural
Fort,
J. R. Soc.
Interface
(2014)
It would help a lot to measure prehistoric
dispersal kernels, if possible (Genetics?)
20