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Natural Selection and Morphological Variability: The Case of Europe From Neolithic to Modern
Times [and Comments and Reply]
Author(s): Maciej Henneberg, Janusz Piontek, Jan Strzalko, Kenneth L. Beals, Della Collins
Cook, John Huizinga, Trinette S. Constandse-Westermann, Christopher Meiklejohn, Frederick
S. Hulse, Frank B. Livingstone, Roland Menk, Michael Pietrusewsky, Francisco Rothhammer,
Francisco M. Salzano, G. Richard Scott, C. Susanne, Milan Thurzo and Andrzej Wierciński
Reviewed work(s):
Source:
Current Anthropology,
Vol. 19, No. 1 (Mar., 1978), pp. 67-82
Published by: The University of Chicago Press on behalf of Wenner-Gren Foundation for Anthropological
Research
Stable URL: http://www.jstor.org/stable/2741152 .
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CURRENT ANTHROPOLOGY
Vol.
19,
No.
1,
March
1978
? 1978
by The Wenner-Gren
Foundation for
Anthropological
Research
0011-3204/78/1901-0003$01.85
Natural
Selection
and
Morphological
Variability:
The
Case
of
Europe
from
Neolithic
to
Modern
Times'
by
Maciej
Henneberg,
Janusz
Piontek,
and
Jan
Strzalko
THE
QUESTION OF
THE
INTRASPECIFIC differentiation
of
mankind
may be
answered
in two
ways.
The first
answer is a
typological
one,
based on
the
assumption
that
evolutionary
forces,
especially
natural
selection,
do not
act upon
man now
that he
is
equipped
with
culture as
an
adaptive
mechanism.
Hence
the
human
"races"
developed
in the
Paleolithic have
remained
unchanged
up to our
time,
and all
the
changes in the
phenotypic
charac-
teristics
of
populations are
due to
gene
flow and
environmental
factors
only. The
second
answer takes into
account all
the
phenomena
known to
population
genetics,
as well
as
knowledge
of
cultural
evolution and the
interrelations
between man and
the
environment
he creates. It is
obvious that in this
concept
there is
no room
for
speculation about
an
absence of
biological
evolution
caused
by cultural
development. Man is
continuously
adapting
to his
environment, both
biologically
and
culturally,
but
cultural change is at the same time
change in the environ-
ment, demanding further adaptation.
Hence he has to adapt
biologically
both to the
natural
environment and to the envi-
ronment created by socioeconomic progress.
It
seems
that natural
selection
is
the main
mechanism respon-
sible
for
the origin and maintenance of
man's variability.
Although
numerous
attempts have been
made to show substan-
tial effects
of
genetic drift
or
inbreeding on
human populations,
only a few
rather
exceptional cases of
isolates,
on
islands,
in
high mountains, etc.,
have been found.
Obviously
these
popu-
lations are not typical for our species at
any level of cultural
development. Moreover,
it
seems
that
considerable
exchange
of
genes
between
populations
is the
normal state
of human breed-
ing groups and
isolation is
mostly relative,
due to
distances
(cultural and/or geographic) separating
population
clusters.
Hence
in
this paper we will deal with the
effects
of
natural
selection on inter- and intragroup variability
in
man.
The
operation
of natural
selection
on man
may
be
arbitrarily
MACIEJ
HENNEBERG is
Adjunct
in
Anthropology
in
the
Depart-
ment of
Anthropology,
A.
Mickiewicz
University (ul.
Fredry
10,
61-701
Poznafi,
Poland).
Born in
1949,
he
received his doctorate
in
natural
sciences,
anthropology, from
A.
Mickiewicz
University
in
1976.
His
research
interests
are
human
population
biology
and,
in
particular,
the
influence
of
cultural
phenomena
on
gene
pools.
His
publications
include
"Comments
on
the
Studies of
Natural
Increase
and
Biological
Dynamics
of
Earlier
Human
Populations"
(Anthropos
[Athens]
2:31-39);
"Reproductive
Possibilities
and
Estimations
of
the
Biological
Dynamics
of
Earlier Human
Populations"
(Journal
of Human
Evolution
5:41-48);
and
"Bio-
logical
Dynamics
of a
Polish
Rural
Community
in
the
19th
Century"
(Przeglad
Antropologiczny
43:67-89
and
in
press).
JANUSZ
PIONTEK
is
also
Adjunct in
Anthropology
at
A.
Mickiewicz
University,
where he
received
his
doctorate in
natural
sciences,
anthropology,
in
1970. He
was born
in
1945.
His
research
interests
are
methods
of
investigation
of
prehistoric
populations
(especially
from
cremated
human
bones),
mechanisms of
inter-
and
intragroup
differentiation,
and
the
paleobiology
of
pre-
and
early
Slavonic
groups.
Among
his
publications
are
"Problems of
the
Morphologi-
cal
Differentiation
and
the
Determination
of
Interdependence
of
Traits
in
the
Structure
of
Vertebrae
in
Man"
(Glasnik
Antro-
poloskog
Drustva
Jugoslavije
10:13-20);
"Polish
Methods
and
Results
of
Investigations
of
Cremated
Bones
from
Prehistoric
Cemeteries"
(Glasnik
Antropoloskog
Drustva
Jugoslavije
12:23-34);
and
"Natural
Selection
and
Microevolutionary
Changes
in
Non-Metrical
Traits
in
Medieval
Populations
from
Poland"
(Studies in
Physical
Anthropology
[Wroclaw], in
press).
JAN
STRZALKO
is
Docent in
Anthropology
in
the
Department
of
Anthropology
of A. Mickiewicz
University.
Born in
1943,
he
received his
doctorate in
natural sciences,
anthropology,
in 1968
and his habilitation
in 1974
from that
university. His
research
interests are
the morphogenesis
and evolution
of the
human
skeleton, formal
and populational
problems
in
somatotypology,
and
the
methodological
aspects
of
biocultural
evolution. His
publications
include
"Role
of
the
Temporal
Muscle
in
the Mor-
phogenesis
of the Skeleton
of the Face"
(Przeglhd
Antropologiczny
36:3-24);
with A. Malinowski, "The Muscles
of
Mastication
and
Cranial Proportions
in
Primates"
(Folia
Morphologica [Warszawa]
31:207-13);
and "Variability
of Human
Internal Organ
Size and
Their Connection
with
Body-Build Type" (Przeglad
Antropolo-
giczny
40:217-49).
The
three
authors
have worked
together
since
1974 in
a research
program on
the biological
history of human
populations,
the
details
of
which
are
spelled
out
in
"Anthropology
and
Biological
Changes
of Human
Populations,"
by
Strzalko,
Piontek,
and
Henneberg
(Przeglad Antropologiczny
41:159-72).. Other
joint
products
of the program
include
"Theoretico-Methodological
Presuppositions
and Possibilities
of Investigating
the
Biology
of
Prehistoric Populations
in
Central
Europe," by Henneberg
and
others (Przeglad
Archeologiczny
23:187-231),
Wstep do
ekologii
populacyjnej
czlowieka (Introduction
to Human Populational
Biology),
by Strzalko, Henneberg,
and
Piontek (Poznant,
1976),
and
"Durability
of
Living
Systems: Origin
and
Role
of
Culture"
(Poznaniskie
Studia z
Filozofli
Nauki,
in
press).
The
present
paper,
submitted
in
final
form
10
v
77,
was
sent
for comment
to 50 scholars.
The responses
are printed
below
and
nre fnollwe1l
bv a renlv
hv
the aiithnrcs
'This
work is
part of
Section
IA of
the
Biological
History of
Human
Populations
Research
Programme.
Vol. 19
*
No. 1
*
March
1978
67
divided
into
two modes:
differential
mortality
and
differential
fertility
(Crow
1958).
In a
previous
paper
(Henneberg
and
Piontek
1975) we have
discussed the
importance of
these
two
modes.
Here
it
will be
sufficient to
mention
only
that
during
the
vast
majority
of our
evolution,
cultural and
natural
regula-
tion of
selective
forces was
effectuated
mainly
by
the
regulation
of
mortality;
fertility
regulation,
although
present
in
all
populations,
did
not
have
much
connection
with
the
genetic
endowment
of
parents
or
children.
The
only reasonable
way
to
measure
total
selection
intensity
in earlier
human
populations
is
to
observe
the
opportunity
for
selection
resulting
from
mortality.
For
this
purpose,
the
biological-state index
(IbS)
is
useful.
The
concept of
biological
state and the
details of its
measurement
have
been
discussed
elsewhere
(Henneberg
1975,
Henneberg
1976a,
Ward and
Weiss
1976).
Here
we
will
give
only a
brief
definition
and
the
formula
for
calculation of the
index.
The
notion of
biological
state
relates to the
notion of
average
fitness.
We have defined it
as
follows
(Henneberg
and
Piontek
1975:193): The
biological
state
of
a
population
is
equivalent to
the
general
intensity
of
selection
pressures
acting
through
mortality
on
all its
individuals.
A
measure of
biological
state,
thus
understood,
is
provided
by
a
quantity
expressing
what
fraction
of a
given
generation has
a
chance
to
participate
fully
in
producing
the
next
generation
under given
mortality
condi-
tions.
This is
a
measure
of
the
chance of
reproductive success of
the
population as
a whole
or,
equivalently,
of its
average
in-
dividual. The
greater the
probability,
in
a
given
population,
of
complete
reproduction
of
an
average
genotype,
the
better is
the
population's
adaptation
to the
complexity of its
environ-
mental
conditions.
Biological
state
is
thus
an
expression
of
adaptation,
taken as
the
totality
of
biological and
cultural
characteristics that
permit,
though
they
do not
necessarily
cause,
the
reproductive success
of a
population.
With
regard
to
man
we can
speak
only
of
the chance to
reproduce,
not
of
the
absolute
reproductive
intensity,
as a
good
measure
of
biological
state. This
is
because of
man's
capacity,
unique
in
the
world of
living
beings, for
conscious birth
control.
The
measure
lbS
combines
mortality
structure
with
the
shape
of the
fertility function.
This
shape
is
expressed
in
the
form
of
s-
coefficients-the
relative,
cumulative
numbers
of births for
age
x
subtracted
from
unity.
Thus
the
sx
coefficient
expresses
the
probability
that
the
average individual of
age
x does
not
have all the
progeny
attainable
throughout
his/her
entire
reproductive life
span. It should
be stressed
that
the relevant
s-
values
are
practically
identical
in
all
non-Malthusian
popula-
tions,
despite
differences
in
total
fertility rates
among
these
populations
(Henneberg
1975).
Obviously,
as
follows from the
definition, the values of
s for x
=
0-14 years are
in
fact
1,
and
for
ages
after
the
cessation
of
reproductive
activity
(i.e.,
after
about 50
years
of
age)
they
approach
0, while
throughout
the
reproductive
life
span
the
values
decrease
logistically with
age.
The
formula for
lbs
is
x=w
lbs
1
dx
x=O
where
d.
=
death
frequency by
age and w
=
the
age
at death
of
the
oldest
member of
the
group.
The
similarity
of
s-
coefficients
in
populations not
practicing
birth
control
in the
modern
form
allows
us to use for
skeletal
material the
one
"standard"
series of
s.
coefficients
established
on
data for
living
non-Malthusian
populations
(Henneberg
1975).
Through
the use of
this
index,
we
have
found, for
Europe
and
its
environs,
that
average
intensity of
selective
pressures
consistently
dropped
from
the Paleolithic
to modern
times.
On
the
basis of
these
observations,
we have
formulated
two
hypotheses
concerning
changes
in inter-
and
intrapopulational
variability
in the
last
few
millennia.
In formulating
these
hypotheses,
we
have
assumed
that
intensity
of
natural
selection
is the most significant factor responsible for morphological
changes as revealed by anthropometric studies. Effects of migra-
tion seem less important, because throughout the period studied
the isolation of human groups in Europe was only relative and
gene flow was constantly present in such a range of intensity
that the influence of changes in it on trends of morphological
variability may be ignored.
The hypotheses are as follows:
1. Decrease in the intensity of natural selection resulted in
an increase in intragroup variability of characters with a
polygenic mode of inheritance.
2.
Decrease in the intensity of natural selection, together
with
growing similarity of cultural demands under conditions
of incessant
gene exchange, resulted in a decrease in inter-
populational differences-decrease in intergroup variability of
average values
of
characters with a polygenic mode of inheri-
tance and greater morphological similarity of various groups.
Hypotheses such as these are acceptable on the following
methodological premises: If one is aiming at the formulation of
a rule
describing a general natural regularity, one should first
specify the variables in the order of their significance (this
stage
is
called the construction of a hierarchy of essentiality)
and then
select
the
variable of the supposed greatest significance
for the
regularity
in
question, ignoring the rest (this procedure
is
called idealization). The idealized formulation of the rule is
then tested against an "experimental" situation. Obviously, the
corroboration will be
only approximate because of the com-
plicated structure of reality. When the corroboration, even
admitting
its
approximate character,
is not
satisfactory, the
investigator must take into account other variables of decreas-
ing significance and
make
appropriate amendments
in
the
formulation of the rule (this process of diminishing the degree
of
idealization
is
called
concretization).
This reformulated
hypothesis
is
again
tested
in
an
empirical
situation. The idealized
formulation
of a
rule
can
be
taken as a
good description
of
reality
when
predictions
derived from it do not
significantly
differ from
phenomena
observed in
empirical
situations
(for
methodological details,
see
Nowak 1975).
The aim of this
paper is,
in
accordance with
this
methodologi-
cal
approach,
to corroborate the
two
hypotheses just presented
with
regard
to skeletal materials from
Europe through
the
use
of
routine
anthropometric techniques.
We
have taken a
random
sample
of data
on skeletal
materials
from
typical anthropologi-
cal
publications concerning
collections
of excavated
skeletons.
Since
published
metric
data
on
skeletal
materials
very
often do
not
contain
sufficient information
on
mortality parameters
and
good paleodemographic analyses
are
often
unaccompanied by
morphological descriptions,
we
are
forced
to
adopt
an indirect
approach.
This
method,
instead
of
observing
correlations
of
lbs
with metric
data
variability
for the
same
groups,
assumes
that,
omitting effects
of
mass
migrations, average intensity
of
selec-
tive
pressures
and
average
statistical
parameters
for metric
characters
are
typical
for
a
given territory
in a certain
period.
Hence lbS
and
morphological
characters
may
be observed
separately
on different local
groups
from the same
period,
culture,
and,territory
without
serious
risk of
obtaining
biased
conclusions
concerning
the
hypotheses
tested.
The choice
of material
for
study
was
made
according
to
certain
rules:
1.
Each
series of
cranial
measurements
must
represent
a
single breeding population.
2. The influence
of random
factors
on statistical
measures
of
dispersion
must
be minimal
(e.g.,
the series
must
be
sufficiently
large).
3. The
numbers
of series
representing
various
periods
should
be similar and their territorial distribution representative for
Europe and its environs.
4. Individuals in the series, and series as units, must be
selected randomly as representative of breeding
populations,
cultures,
and territories.
68
CURRENT
ANTHROPOLOGY
Henneberg,
Piontek, and
Strzalko:
SELECTION
AND
VARIABILITY
Applying
these
rules,
we took from the literature
data on
58
series
(table
1).
We chose
for
analysis
the
following
cranial
measurements:
skull
length
(g-op),
breadth
(eu-eu),
and
height
(ba-b), upper
face
height
(n-pr),
bizygomatic
breadth
(zy-zy),
minimum frontal
breadth
(ft-ft),
length
of nose
(n-ns),
breadth
of nasal
aperture
(BAP),
breadth
of orbit
(mf-ek),
and
height
of
orbit
(HO).
In some
series
the data were
incomplete,
so
for
almost
all
characters we
have
slightly
different numbers
of
observations.
This is
mainly
because
of
the
requirement
that,
in
a
given
series,
the number
of
individuals
with a
certain
character
be more than ten of each
sex-only
the data
meeting
this
condition
were considered. More
serious difficulties
arose
as
to the
choice
of series
representing
modern
populations,
because
collections
of skeletons do not
represent
local
groups,
and,
on the other
hand,
not all the cranial
characters
analyzed
here
can be
measured
on
living
individuals.
Moreover,
data
from
national
anthropological
surveys
usually
cover too
large
a
territory
to
represent
a
single
breeding
population.
In
the
end,
we considered
for
analysis
only
six
measurements
(g-op,
eu-eu,
zy-zy,
n-pr,
n-ns,
ft-ft)
on
living
adults
from modern
local
groups.
As
may
be
seen in
figure 1,
the
geographical
distributions
of
series
are
similar
in
all
periods,
the
mean distance between
series
in
each period
varying
from
1,000
to
2,000
km.
The
smaller
number of series
representing
Bronze
and
Early
Iron
Ages
is
obviously due to the fact that
cremation was
widespread
in
those
periods.
Since the rate
of
decline of selective
pressures
depends
on
progress
in
culture, but not
on
geological
time,
we have used
a
time
scale
on which
equal
values
are
assigned
to the
distances
between the
following
periods
of
cultural
development:
Neo-
lithic, Bronze, and
Early
Iron
Ages, Early
Middle
Ages,
15th
to
18th
century,
Modern Times.
Application
of
such a time
scale
allows
us
to obtain
linear correlations
between
time,
intensity
of
selective
pressures,
and
variability.
Our
first
hypothesis
states
that
intragroup
variability
of
polygenic
characters
increases
with
decrease
in
selective
pressures
acting through
mortality.
To
test
this, for all
analyzed
characters
jointly,
we
have
computed
for each
series
separately
for
males and
females an
average, standardized
value of
ob-
served
standard
deviations,
m(8). The
standardization was
accomplished
according
to the
following
formula:
k
1
I
sij
-Si
k()
='=
- FL
where k
=
number
of
characters in
a series
j;
i,=
standard deviation of
an ith
character
in the
jth series;
s=
mean standard deviation of
the ith
character
in
the
whole
sample
of
series
N
=
LSij;
and
o,
=
standard deviation of
s;t values
=
iN E
(sii
-
s)2
The
correlation of
m(s) values
with
cultural time
(fig. 2) is
very
clear:
r
=
+0.452
(significant at
the 0.01
level). From
table
2
it can
be seen
that
almost all
characters,
analyzed
separately,
behave in
accordance
with the
general
statement.
Because of
the
relatively small
number
of series
analyzed,
only
a few characters
have
statistically
significant,
positive
coefficients of
correlation,
but even
among characters
insig-
nificantly
correlated
the surplus of plus
over
minus signs
is
considerable
and not random
(significant
at the 0.01
level).
TABLE
1
SERIES
OF
SKELETAL MATERIALS ANALYZED
PERIOD AND
SERIES NUMBER
SOURCE
Neolithic
12
(Russe)....
Boev
1972
16.
...........
Galasinska-Pomykol
and
Szewko-
Szwaykowska 1967
18
(Kara
Depe)
.........
Ginzburg
and
Trofimova 1972
19
(Geoksjur)
.........
.
Ginzburg
and
Trofimova
1972
29 (ceremika sznurowa).
. Miszkiewicz 1958
30
(undeformed skulls)...
Ozbek
1974
31
..
.............
Parenti 1965
32
...............
Patte
1971
38 .Rakowsky and Roudenko
1914
44
(Bilcze Ziote)
.
Stojanowski
1948
46
.
..............
Surnina 1963
54
(Helwan)
............
Wierci'ski 1965
57.
.............
ejmo-Zejmis
1938
Bronze and Early Iron Ages
3
(Staryje
kiski).....
...
Akimova 1968
4
(Kamysly-Tamakskij
mogilnik)
............
Akimova
1968
23 .
........ .....
Kapica
and Tuczak
1971
25
(Turan
II)
.........
.
Kozincev
1972
49
..............
Ullrich
1972
56
(girokinskij
mogilnik).
Zinievic and Kruc 1968
Early
Middle
Ages
2
(Birskij mogilnik)...
Akimova 1968
7
(Wiatycze I).
... .. Aleksiejewa
1966
8
.............
..
D'Amore
and
Moraldo 1973
9
..
.. ..........
Bach and
Bach 1971
10
............. ...
.
Bartucz and Farkas
1958
13 .Bottyan 1972
14
Chodzajov
1969
15
.ry
1967
26
.Liptak
and Farkas 1967
35
.Popovici
1972
40
.Salivon
1971-72
41
.Schott 1967
43.
Stloukal
and Hanakova
1974
45.
.
Strzalko
1970
50
.Toth
1964
51
.Thurzo
1972
52
........
....
Vladarova-Mojie6va
and
Hanulik
1970
55
....
Wokroj
1973
15th
to
18th
century
1
(Mavljutovskij
mogilnik)
............
Akimova
1968
5
(Siebiez)
.............
Alekseev
1969
6
(Durbe)
............
Alekseev
1969
11
.............
.
Belniak
et al.
1961
20
..............
Gralla
and
Krupinski
1966
21
..............
Hanulik and
Placha
1965
22
.............
Kaczanowski
1965
27
.............
Lotterhof 1968
33
........ .....
Popovici
1973
34
............. Popovici
1973
37
.............
Rabischong
and
Engel
1970
39
..............
Salivon 1971-72
Modern times
17
(Glozan)
.............
Gavrilovic,
Stajic,
and Rumenic
1965-
66
24
(Walsers I)
.. . Kaufmann, Hagler,
and
Lang
1958
28
.............
Malinowski 1975
36
(Irakleios)
...........
Poulianos
1971
42
(Zyglin)
............
Sikora
1956
47
.............
Susanne
1971
48.
.............
Swornowski
1975
53
(Izvoarele)
...........
Vladescu
1973
58
(Konin)
.............
authors'
unpublished
data
NOTE: Where only one of several series was taken from a given
source, the
Vol.
19 * No.
1 March
1978 69
A~~~~~
A6
BRONZE+ EARLY IRON
A.
o
EARLY
MIDDLE
A.
XV
-
XVIII C.
o
MODERN
FIG. 1.
Geographic
distribution
of
the series
analyzed.
rn(S)
5
m(s)- ~~~~~~~~~~~~~~~~~~~~58
+1.0
.9
.8-
37
47
.7
.6
08
14
17
.5
-
13
20
.4
48
3
29
4352
9
22
32
4
.2 19 56 10
53
.1
25
40
2
O
-
41
11
05
.1-
16
45
27 08
.1
~~~~~ ~ ~~~~~~15
33
28
.2-
/
36
13
/18
01
.3.
0407
.4- 124
04
26
42
.5-
38
54
03
51
.6
-
.7-
.8
-
.9
31
44
-1.0
NEOLITHIC
BRONZE
A
EARLY EARLY
XV -XVIII
C. MODERN
IRON
A
MIOOLE A
FIG.
2.
Correlation
between
standardized
measures of
intragroup
variability
(mi(,))
and
time. Numbers
refer to
series listed
in table 1.
The
mean
values
of
m(,)
and
of
Ibs,
shown
in
figure
3, strongly
suggest
a
coincidence
between increase
in
intragroup
variability
and
decrease
in the
intensity
of
natural
selection,
as stated
in
the
first
hypothesis.
For
some
of the
cranial characters
analyzed, there
are well-
known
directional
changes
of mean values
over the
centuries
that are
imprecisely
labelled
"secular
trends." For
at least two
TABLE
2
PRODUCT-MOMENT CORRELATION
COEFFICIENTS
OF
STANDARD
DEVIATIONS
FOR CRANIAL
CHARACTERS, WITH
TIME
EXPRESSED IN
UNITS OF CULTURAL
CHANGE
MALES
FEMALES
CHARACTER
N
r N
r
-op
.........
58
+0.256*
46 +0.075
eu-eu
.........
57
+0.164
44 +0.160
n-pr
..........
49
+0.370**
38 +0.456**
zy-zy
.........
49
-0.215
37 +0.057
n-ns
..........
50
+0.180
38 +0.212
BAP
.........
43
+0.292
32 +0.194
HO
.........
45
+0.348*
34
+0.250
mf-ek
.........
42
+0.300*
33 +0.134
ba-b
..........
39 +0.229 30
-0.128
ft-
ft..........
53
+0.292*
42
-0.002
NOTE:
N
=
number of groups;
* =
significant
at the 0.05 level;
** = sig-
nificant
at the
0.01
level.
of
these-head
length
and breadth-there
is good evidence
that
the
process
(brachycephalization)
is caused
by
the
operation
of
natural selection (Bielicki
and Welon
1964, Henneberg
1976b).
Briefly, we
may suspect
that the average
values
of cranial
characters
will change under the operation
of natural
selection
in
two ways:
Firstly, if
developing culture
changes the
direction
of selective
pressures
in
the majority of
breeding populations
in
the
same
way,
a
so-called
secular trend
will occur. Secondly,
if
cultural development
is relaxing selective
pressures,
gene
exchange
among populations
is
present,
and
the cultural
demands
on
particular
populations
tend
to be similar
but
population
means
of
given
characters are
close
to
the
optimum
value for a
given eco-cultural
situation,
there will
be
only
an
increase in
morphological
similarity
among populations-a
decrease
in
intergroup
variability
of mean values without any
directional
change.
For
purposes
of analysis,
we have
taken
mean
values
of
characters
in
separate
series
as individual data
and
computed,
for
each period,
means
(Xx)
and standard
deviations
(sj).
In
70 CURRENT ANTHROPOLOGY
Henneberg,
Piontek, and
Strzalko:
SELECTION AND
VARIABILITY
order
to
maintain
large enough samples, we have
been
forced
to
group
data for
Neolithic, Bronze,
and
Early
Iron
Ages.
When
looking
for a trend in mean
values,
it
is
better
to calculate
the crude
mean of
arithmetic means
for
separate
series
than
the
weighted
mean for the
period, because
the
numbers
of
particular
series of data do not
correspond
in the
slightest
degree with
actual
sizes
of
living populations. From table 3,
it
may be seen
that directional
change occurs
in
three dimensions
of the brain
case
(g-op, eu-eu, ba-b)
and
upper face height
in
both sexes
and
in
bizygomatic
breadth in
males
Qnly;
in
the
other
charac-
ters examined, there are no significant changes in
mean values
over time.
In almost all characters, however,
there is a clear
decrease
in
intergroup variability:
si
values decrease
with time.
One
may suspect
that the
decrease is simply a result of the
increase in series size, which diminishes the
proportion of
mr(S)
lbs
+1.0
1.0
0
-1.0 .
0
PALEOL. NEOLITHIC
BRONZE A.
EARLY EARLY
XV-
XVIIIC.
MODERN
IRON
A
MIDDLE A.-
FIG.
3.
Concordance between
changes
of mean values
of
m(s)
and
Ibs
-4th
time
random-error
variance
(size
of the
standard
error of
particular
mean
values)
in the total
variance
observed
as
sF2.
To
eliminate
the
influence
of
this fact,
we have
computed
a correcting
factor
in the
form of the average
squared standard
error of
mean
values
for
each
period and,
by subtracting
this factor
from
si,
have
obtained
estimations
of the
"pure"
variance
of mean
values,
SY.
These
values,
together
with the results
of the
F test,
are given
in table
4.
In
order to
combine
the results
for all
characters
in a
single
numerical value,
indices
R;
were
computed:
sX
(p)
S.X(Neol.)
Both the results
of
the F test and the
mean
Rs
values
show that
interpopulational
variability
of cranial
characters
decreases
with
time,
in
accordance
with
our expectations.
We
are
well aware that
the indirect method
applied
here
permits
us to
draw conclusions
only with
a certain degree
of
probability.
In
such
a
situation,
all
possible
systematic
factors
which could
influence
trends
of
variability
without
changes
in
the operation
of natural selection
should be controlled
for
in
further
investigations.
The
trends
of
variability
revealed
in this
study,
if natural
selection
does not
fully
account
for
them,
might
be caused
by
the increasing
mobility
of
people
with cultural
progress.
In our
sample
of series,
the influence
of
gene
exchange
on
the
observed
trends
is
scarcely probable,
because
even abundant
gene
flow
among
groups
existing
in similar
cultural
and natural conditions
cannot
result
in
any
considerable
increase
in
the
range
of
variability
in a
breeding
population.
Being
subject
to the
same
eco-cultural
conditions,
these
populations
exist
under
similar
selective pressures.
At
the
same
time,
interpopulational
ex-
change
of
genes,
undoubtedly present
in
the
series
analyzed,
probably
acted
against
the effects
of
genetic
drift,
inbreeding,
etc., phenomena
which may
influence
the
variability
of
poly-
genic
characters.
TABLE
3
INTERGROUP
VARIABILITY
AND MEAN VALUES
OF
CRANIAL
CHARACTERS WHEN ARITHMETIC
MEANS
FOR SEPARATE
SERIES ARE TREATED
AS UNITS
OF
STATISTICAL
OPERATIONS
NEOLITHIC, BRONZE,
EARLY
15TH TO 18TH
AND EARLY IRON
AGES
MIDDLE AGES
CENTURY
MODERNa
N
XY
Si
N
XF
s9
N Xs
si
N
xi
Si
Males
g-op....
19
188.1
4.75
18
184.9
2.81
11
181.4
3.66
9
189.1
3.68
eu-eu
...
18
139.3
3.67
18 140.7
3.39
11 144.0
3.09
9 156.7
2.93
n-pr
....
15
70.0 2.02 16
69.5
2.04
11
68.9 1.35
- -
-
zy-zy
..
13 131.9
4.22
15 133.3
1.71 11 134.1 1.74
9
141.4 1.11
n-ns
....
15 51.3
1.27 15
51.2
1.26
10 51.2
0.94
7
52.5 1.07
BAP....
16
25.2 0.78 16 25.0
0.53
10
25.2
0.30
- -
-
HO.....
17
32.5 0.83 16 32.6
0.64
10
32.7 0.87
- - -
mf-ek...
16 42.1 1.10
15
41.1
1.28
10 41.4
1.05
ba-b....
12
136.7
2.67
17 134.6
1.65 9
133.2
2.22
-
-
-
ft-ft....
19
96.8 1.58 17 97.3 1.36
10
97.8
0.90
6
110.2 1.72
Females
g-op....
13
180.2 4.86 17
176.6 2.74
10 173.4
3.42
6 181.7 1.82
eu-eu...
12
135.9
4.01
17 137.0
3.16 9
139.5 3.00
6
151.6
2.25
n-pr....
9
66.5 2.58
16
64.9
1.87
9
64.8 1.68
-
-
-
zy-zy...
6 125.6
3.78
16 125.3
2.20 9
125.5 1.66
6 133.8
1.33
n-ns....
9
48.4 1.89 15 48.6
1.39
8
48.4 0.43
4
48.4
0.70
BAP....
7 24.1
0.68
16 24.4
0.66 8
24.0
0.39
-
- -
HO.. 11
32.2 0.86
15 32.6 0.64
8
32.4
0.46
- -
-
mf-ek...
10 40.3
1.44
14 39.5
1.06 8
40.1 0.82
-
-
ba-b....
7 131.4 3.62
15
129.1 1.46
8 126.8
2.02
-
-
ft-ft. 13
94.3
1.96 17
94.3
1.76
8 94.5
1.46
4 107.2
1.49
NOTE:
N
=
number of series.
a
Measurements
on living individuals,
not corrected
for thickness
of soft tissues (all
characters).
Vol.
19 * No. 1
*
March 1978
71
TABLE
4
INTERGROUP VARIABILITY IN
VARIOUS
PERIODS AS EXPRESSED BY STANDARD DEVIATIONS OF MEAN
VALUES
FOR SEPARATE SERIES, CORRECTED FOR POSSIBLE
INFLUENCE
OF
SERIES SIZE
NEOLITHIC,
BRONZE,
AND
EARLY 15TH TO 18TH
EARLY IRON AGES MIDDLE AGES CENTURY MODERN
sx-
Rs
sx
RS,
si
RS,
si
RS,
F
Males
g-op
.........
4.49
1.00
2.56
.57 3.51 .78 3.64 .81
3.07*
eu-eu
........
3.48
1.00
3.24
.93
3.00
.86 2.89
.83 1.37
n-pr
.........
1.69 1.00
1.93 1.14 1.13
.67
- -
2.82*
zy-zy
........
3.98 1.00 1.30
.33
1.50
.38 .98 .25
15.89*
n-ns
.........
.93
1.00
1.15
1.24 .79 .85
1.01 1.09 2.04
BAP
........
.65
1.00
.42
.65
.00 .00
-
-
2.37*
HO
........
.68
1.00
.50
.74 .78 1.15
-
-
2.52
mf-ek........
.99
1.00
1.22
1.23
1.00 1.01
-
-
1.52
ba-b
.........
2.33 1.00
1.22
.52 2.06
.88
-
-
3.75*
ft-ft.........
1.22 1.00 1.13 .93 .62 .51 1.65 1.35 3.74*
mean
RS.
1.00
.83
.71 .87
Females
g-op
.........
4.65 1.00 2.45 .53 3.18 .68 1.68 .36 6.93*
eu-eu
........
3.80
1.00 2.99
.79 2.92 .77
2.18 .57
2.76
n-pr
.........
2.41
1.00
1.67 .69 1.52
.63
- -
2.52
zy-zy
........
3.62 1.00 1.88 .52 1.44 .40 1.23 .34 8.69*
n-ns
.........
1.77 1.00
1.22
.69
.00
.00
.58
.33
o
*
BAP.........
.54
1.00
.51
.94
.27
.50
-
-
4.25*
HO
........
.69 1.00 .52 .75
.33
.48
- -
4.08*
mf-ek........
1.35
1.00 1.00
.74 .77
.57
- -
3.01
ba-b
........
3.23
1.00 .91
.28 1.92 .59
-
-
13.67*
ft-ft.........
1.61
1.00
1.57
.98
1.33 .83
1.44
.89 1.39
mean
Rs
. .
.
1.00
.69 .55
.50
NOTE:
Rs denotes the relative
value of
Si
in
a
period when
Si
for the Neolithic is taken as 1.00. Italicized values of
&y
were tested for significance
of
differences
between
them; statistically significant
F
values are marked
with
an
asterisk
(0.05 level).
It
may
be concluded that
the
influence
of natural
selection on
intra-
and
interpopulational
variability
of
morphological char-
acters,
although
shown
only
indirectly,
seems
important.
Furthermore, the observed trends of
variability,
whatever their
causes,
have
to
be
considered
in
future
investigations.
They
have
practical
significance
for
interpopulational
comparisons
in
ethnogenetic
investigations,
especially
those made
with
the
aid
of
multivariate methods
for
computing
"distances"
between
sets of
quantitative
characteristics
representing
populations.
It
seems
that in all
kinds
of
microtaxonomic work
it
will be easier
to define
a number of
distinguishable
Neolithic
"racial types"
than a number of
modern ones. In
other words,
because
of
changes
in
the
operation
of
natural
selection due to
the
develop-
ment of
culture,
and also to
some extent
because of
migrations,
differences
between
human races
are
continuously
disappearing.
Comments
by
KENNETH L.
BEALS
Department
of
A
ntharopology,
Oregon
State
University, Corvallis,
Ore.
97331,
U.S.A 5
ix
77
There is
a
time for
new ideas to
arrive.
After years of
preoccupa-
tion with
stereotypic
and
typological
norms,
it
is
exciting to
witness
a
rise of
interest
in
variation
itself. The
task
of an-
thropology is
to
explain
human variation
through
time and
space,
for
both
biological
and
cultural traits.
Such variation
has
dispersion as
well as
central tendency.
Why
groups differ in
within-group
and
between-group
heterogeneity is
fully as
important
as (and
probably
more
interesting than)
why they
vary
in
central
tendency.
I
have
a
few
quibbles about
the
analysis and
semantics of the
present
contribution. For
example, socioeconomic
"progress"
implies
a
systematic
improvement of
the human
condition.
Since
the process
is
often
disruptive,
the more objective
phrase
"cultural
evolution"
is preferable.
The important
thing
is
the
hypothesis
concerning
the
pat-
terns
of
heterogeneity.
My colleagues
and
I
have
been
evaluat-
ing the
hypothesis
for
several
years
with
data
collected
from
hundreds
of ethnic
groups
around
the
world.
Some
of this
is
not
yet published;
I
will,
however,
mention
our general
conclusions
so
that
we
can
share with
the present
authors
the rapid
feedback
which CURRENT
ANTHROPOLOGY
offers.
Our interpretive
dif-
ference
appears
to
concern
the
relative
role
of selective
(con-
trasted with
cultural)
causation.
Kelso (1974)
anticipates
the
trends
in question
to
apply
to
both
time and
space
and throughout
the
world-at
least as
a
statistical
generality.
The
basis
of this is
the Law of
Biocultural
Evolution:
as
culture
evolves,
the
variance
within
groups
in-
creases
while
the
variance
between
groups
decreases.
In
1975,
Kelso
and
I tested
the law
with
heterozygosity
among
three
blood groups.
We
organized
ethnic groups
by stage
of
social
organization
(from
band,
tribe,
chiefdom,
and
state)
and
demonstrated
that
the
expected
patterns
were
indeed
empiri-
cally
observable.
We
also
provided
arguments
that selection
could
not
reasonably
account
for
such
observations.
Anthropometric
traits
may
well
be
different.
In fact,
any-
thing
related
to the
size
and
shape
of
the
body
is
part
of
its
surface-area/mass
ratio,
and climate is
known
to be a selective
agent
which
creates
evolutionary
trends
among
a
wide
variety
of related
morphological
traits:
head
form,
cranial
capacity,
body
build,
nose shape,
and
so
forth.
To
agree
that
anthro-
pometrics
are
influenced
by selection
does
not,
however,
provide
evidence
that selection
is
responsible
for the
patterns
of
varia-
tion
reported.
More generally,
trend
analysis
by
itself will
not
separate
the effects
of natural
selection
from those
of nonrando
m
mating.
As
culture
evolves,
the
probability
of
mating
between
dif-
ferent
genotypes
increases.
It creates
an
expanding
population
structure
in
which
different
alleles, genotypes,
mating types,
72 CURRENT ANTHROPOLOGY
Henneberg,
Piontek,
and
Strzaiko: SELECTION
AND
VARIABILITY
morphological
traits,
languages,
and behaviors
are more
likely
to be combined. It is a
process
of
isolation
breakdown,
the in-
evitable
consequence of
which is to create
the observed
patterns
of
heterogeneity.
Europe from Neolithic
to modern times
has some
cultural
features which
generally
typify
the entire world:
(1)
an
increase
in
population
size
(which
would reduce
the coefficient
of
in-
breeding),
(2)
more
advanced systems
of transportation
(which
increase
the
mobility
of
individuals),
and
(3)
increased
"im-
perialism"
(by
means of which variable
populations
come
increasingly
under
centralized
political
control).
If these
ele-
ments
of culture
change
are
present,
the result is
theoretically
expected
to
be
as
Henneberg, Piontek,
and Strzalko
have
dis-
covered.
The culture
change
is
independent
of
selection
but
produces
evolutionary
trends with
central
tendency
and
dis-
persion.
Observing
the trend from
empirical data,
one
would
probably
be
tempted
to
conclude
that
selection was the
cause.
It may be;
it
may
not be.
To
demonstrate
the
affirmative
re-
quires,
however,
that the effect of cultural
evolution
be
analyt-
ically
separated.
We
have
just
completed
two
additional
studies
on the
same
topic. From
the
first,
we
discovered
that
polygenic
characters
are
generally
correlated with
cultural
evolution
around
the
world
despite
the
large
number
of
overriding
influences which
are
probably
present.
In
the
second,
we
applied
the
theory
to
individual social
behaviors
but found
no
association
whatever.
Our
interpretive
difference with
the authors seems to be
only
a
matter of
emphasis.
They stress
selection,
while we
stress
the
cultural factors involved. We
all
recognize
some
interaction
between
them. We are
actually
dealing
with
a
broader
phe-
nomenon of
biocultural
evolution
in
which population
structure,
social
organization,
and
natural
selection are
intimately
con-
nected. The
present
study has a direct
relevance to
a
better
understanding of this
phenomenon.
by
DELLA
COLLINS COOK
Department
of
Anthropology,
Indiana
University,
Bloomington,
Ind.
47401,
U.S.A.
15
ix
77
This
paper is
innovative
in
its use of
osteological data
to address
questions
of
broader
interest than the local
archeological se-
quences it
includes. The
authors
demonstrate time
trends in
both
selection
intensity
and
variability.
The causal link
they
hypothesize
between these
trends is
difficult to
accept without
further
analysis of
morphological and
archeological
data. Other
attempts at
demonstrating relaxed
selection
with
time
(Brace
and
Mahler
1971) and with
relative
cultural
complexity (Post
1964, 1966)
are similarly
limited. In
all
three
instaThces, it is
possible that
other models
may provide
plausible
explanations for
the observed
trends. An
example of
such
an
alternative model
omitting
reference to selection
follows:
Increasing
social
and
technological
complexity, as
reflected in
"cultural
time," results in
increased
community size
through the
aggregation
of isolates;
the breakdown
of isolates
results in in-
creased
within-group
variability and
decreased
between-group
variability
through the
effects of sample
size on the
sampling of
a
heterogeneous
distribution. Under
these
hypotheses, the
observed
correlation of
variance with
selection
intensity may be
viewed as the
spurious
result of joint
correlations
with time.
Similar
alternative models
centering on
effective size of
breeding
populations,
social
stratification,
mechanisms of
group forma-
tion,
and
the
like are
possible. Any
effective
demonstration of
relaxed
selection
must
eliminate the
more plausible
among these
alternative
models
through an
examination of the
relationship
of
other
possible causal
variables and
time or
cultural com-
plexity.
The authors suggest
that selection
is the only
important
com-
ponent
of morphological
variability
in the series they
employ.
However,
other components
are demonstrable
and
may
well
be useful in explaining
the trends
they observe.
Variance as
re-
flected
in
bilateral
asymmetry
can
be shown
to result from en-
vironmentally mediated
deviation from the
canalization of de-
velopment (Bailit et
al. 1970, Doyle and Johnston
1977) inde-
pendent
of
the
genetic
components of variability
and hence of
selection.
Work on the Yanomamo
has demonstrated
that with-
in-group homogeneity
and between-group heterogeneity
reflect
lineage effect
in
the
formation of new communities
rather than
the effects
of
selection
per se (Chagnon 1972,
Spielman, Migliaz-
za, and Neel 1974).
Since a series spanning
the Neolithic-to-
Modern
period
also spans the shift from tribal
to state organi-
zation,
such effects may be expected to decrease with
time,
hence increasing
within-group variability.
Similarly, the
variance
of
anthropometric
measures in the
living can be ex-
pected
to exceed
the
variance
of
skeletal measures
on the same
individuals,
in
that the added effect of soft-tissue
variability
is included. Reexamination
of the results presented
here omit-
ting the living samples
might be profitable.
A
broader problem
is presented by the
assumption that
skeletal collections
adequately represent the
variability present
in
the breeding population.
The use of samples
as small as ten
individuals permits
questioning of the stability
of variance esti-
mates. Furthermore,
skeletal collections from
archeological sites
are frequently
modest
in
size even when the
community they
represent
was
large.
They are seldom representative
of the
range
of
disposal
contexts
used by
the
community
or of the
social
groups present
within
the
community.
In
many instances
excavations may
be biased toward the inclusion
of related
in
dividuals, through
inclusion of family plots,
or toward particu-
lar classes, moieties,
or economic
groups.
From Neolithic to
Modern
times,
European
communities can be
expected
to have
changed
dramatically
in
size,
effective size
of the
breeding popu-
lation,
social
stra?tification, mortuary practices,
and,
most
im-
portantly, the degree
to which residence
and
burial were
kin-
ship-based.
All
these
factors limit
the
appropriateness
of
vari-
ance
in
a
skeletal collection
as
a
measure
of variance
in
the
population it represents.
It is by
no
means obvious
that
these
effects will operate similarly
in
all the time
periods
sampled.
A
discussion of archeological
information
on
the
samples included
in
this study, encompassing
sample size,
community size,
and
nature of mortuary
units and practices, could
clarify
the
impor-
tance
of
these effects
through
time. Such
a
discussion
could
strengthen
the
interesting argument
the authors
present.
by JOHN HUIZINGA,
TRINETTE
S.
CONSTANDSE-WESTERMANN,
and
CHRISTOPHER
MEIKLEJOHN
Institut
voor
Antropobiologie, Rijksuniversiteit
Utrecht,
Achter
de Dom
24,
Utrecht
2501,
The
Netherlands.
12
ix
77
The
study
of
Henneberg
and
colleagues
raises
both
analytical
and
theoretical questions.
The
results
obtained
are not
clearly
related to
the
reasons
given.
We
would
like to raise some
ques-
tions about
the
analysis
and
then turn
to some
of
the
theoretical
assumptions.
The
nature
of the
samples
used
raises
two
points: Firstly,
whether
they represent
single breeding populations
remains
to
be
proven.
Such
proof
is said to be
necessary
but is
not
attempt-
ed
here.
Secondly,
while the
various
periods
are
said
to
be
represented by samples
of
equal
territorial
coverage,
this
is
not
apparent when the samples
are
examined.
No
fewer
than
four
of
the
thirteen
Neolithic
samples
are
non-European, compared
to one
of
the
forty-five
later
samples.
The
effect
of
these
non-
European samples
can
be
expected
to
increase
the
range
of
variability
in
the Neolithic
sample,
thus
biasing any
results
obtained. If
proof
for
the
hypothesis
is
required,
why
not use
a
set
of
strictly
localized
populations
such
as
those
from
the
Ukraine
recently published
by
Konduktorova
(1974)?
In
the
analysis,
the
assumption
is
made that
selective
pres-
sures are linearly correlated with cultural
progress. Further-
Vol.
19
*
No.
1
*
March
1978
more, the
periods treated
are seen as
involving
equal
degrees
of
cultural
change, and therefore
of selective
pressure.
Such
a
model
of cultural
development
is
acceptable
to few
prehistori-
ans.
Not only are
the
periods
of
unequal
length,
but
the
techno-
logical
changes
are far
from
equivalent.
For
example,
the
acqui-
sition
of bronze
by
a
community
is
generally
seen
as
having
had
little
effect
on the
life-style
of the
average
community
member.
In
many
cases, so-called
Neolithic
and Bronze
Age
technologies
existed side
by
side in the same
community.
If
the
cultural levels used
in the
paper
are
not of
equal
magnitude,
the
linear correlation
(fig. 2)
between
cultural
development
and
the value of
m(8)
ceases to have obvious
meaning.
Furthermore,
the
plotted
correlation
(r)
is
dependent
upon
the series
used,
and
the
overlap
in
the values
of
m(8)
for
varying
time
intervals
is great
(the
Bronze
Age
sample
falls
totally
within
the
range
of the
Modern
sample).
Other
questions
are also related
to
analytic
matters.
Is
the
brachycephalization
noted under the control of
natural
selec-
tion,
as
stated,
and
therefore, by
definition, genetic?
Studies
going
back
to
the classic
Hawaiian work of
Shapiro
and
Hulse
(1939)
bring
this
into
question.
The
complexity
of
this
problem
can
be
seen
in the
work of
Huizinga-
(1958).
Is
there
increased
mobility
with cultural
progress
over time? How
far
back could
such
an
idea be
pushed?
Pre-Neolithic
populations
with
low
densities
can be
expected
to
show
mobility
related to
areal con-
straints
on the number
of
people required
to
maintain
an
opera-
tional
breeding population
(Meiklejohn
n.d.,
Wobst
1976).
Neolithic
populations
of
increasing
density
would
be
expected
to
show
increasingly
less
mobility
over time.
The localized
population
structure
of
agrarian
populations
has been
demon-
strated
on
Bougainville
by
Friedlaender
(1975)
and in
Oxford-
shire
by
Harrison
and
Boyce
(1972).
Increased
mobility
is
hard
to
document
except
in
those
populations
which have
become
urbanized.
Even in
Western
urban
society
such
mobility
is
strongly
related
to social
class
and
is
thereby
restricted
to a
small
section
of
society.
This
last
point
directs the
discussion
towards
more theoreti-
cal
aspects
of
the
paper. The
paper is based
upon
a
number of
assumptions
that
are
critical to
the
interpretation of
the
analysis.
Gene flow
is
assumed
to
be
relatively
constant
across
cultural
levels;
this
has been
queried
above.
Gene
flow,
closely
related
to
the factor of
density just
noted,
may be
critical
in
explaining
morphological
variability
in
space at
differing
cultural
levels
(Meiklejohn
1974).
Further,
it
is
assumed
that
selection
occurs
mainly
through
mortality
rather
than
through
fertility and
that an
individual's
ability to
reproduce is
related
primarily to
mortality. The
latter
point
underestimates cultural
factors, such
as
polygyny,
which
affect
the
relative
genetic
success
of
different
individuals
in a
population
(Chagnon
1972).
Polygyny is
more
likely to be
seen
in
developed
societies and is
therefore of
growing
importance
over
time
(Meiklejohn
1974).
Simple
reproductive
ability is
countered
by
such
cultural
systems,
irrespective
of any
mor-
tality
profile.
Even
more
important is
the
apparent
under-
rating of
the
place
of
fertility in
selection.
Recent work
sug-
gests that
fertility
may be a
central
concern
in the
development
from
pre-Neolithic
through
Neolithic and
later
systems
(Cohen
1977).
Lee
(1972)
argues for
birth
spacing
as a
major
factor in
population
control at
the
band
level.
Howell
(1976)
has
indi-
cated
that
physiological
mechanisms
related to
Frisch's
work
on
critical
weight
may be
involved. If
anything,
it
may be
fertility rather
than
mortality that
is
critical to
understanding
of
the
period
under
consideration,
thus
considerably
blurring
the
distinction
made
between
(theoretical)
Malthusian
and
(em-
pirical)
non-Malthusian
populations
(discussed
further by
Henneberg
1976a).
This will
affect
the meaning
of the
parame-
ter S(x)
and thereby
the
conclusion
that there
is a drop
in
the
average
intensity of
selection
pressure over
time.
Further
assumptions
surround
the importance
of
natural
se-
lection
in the
maintenance
of morphological
variation
and
the
ignoring
of
changes
in
the
rate of
gene
flow. Probable
changes
in the
rate
of gene
flow
over
time
have
been
mentioned.
The
efficacy
of gene
flow
has
been
well
demonstrated
by
Brues
(1972).
We
also
query
whether
local
populations
during
the
earlier
periods
involved
here
would
have
been large enough
for
selection
to outweigh
random
changes
in gene
frequency.
It is
possible
to develop
an
alternate
model
in
which
natural
selec-
tion increases
in
intensity
while
gene flow decreases
during
the
time period
under consideration.
This might
produce
an
end
product
opposite
to that predicted
in
the article.
A final
important
assumption
is that
a decrease
in the
in-
tensity
of
natural
selection
will
result
in
increasing
variability
in measurable
polygenetic
characters.
This
may not
be
as simple
as
it seems.
Bailit (1966)
has
demonstrated
that
variability
in
individual
characteristics
is
not
related
to
genetic
vari-
ability
and
probably
involves complex
interaction
with
environ-
mental
buffering.
Such
an
observation
can
also be
seen
in
early
work on
the
variability
of hybrid populations
(see Muller
1936,
Trevor
1953).
Furthermore,
Bulmer
(1976)
has
demonstrated
that
genetic
variability
will be
affected differently
depending
upon
whether
selection
is
disruptive
or
stabilizing.
Selection
can,
in
some
cases,
increase
genetic
variability.
It thus
seems
unwise
to
predict
that
decreasing
natural selection will
result,
ipsofacto,
in
increased
morphological
variability.
It
also
remains
to
be
demonstrated
that
selection pressures
affecting
later cul-
tures
are
both
lessened
and
increasingly
similar over
large
geo-
graphic
areas.
In conclusion,
it is
difficult to
agree
that
the
results
obtained
are necessarily
due
to
the
factors
suggested.
In addition,
the
tabular
data
are not
in all
cases
consistent
between
males
and
females,
and
the statistical
manipulations
are
not
always
clear.
The
decrease
noted
in
intergroup
variability
may
be related
simply
to the inclusion
of
non-European
samples
in
the Neo-
lithic
group.
Finally,
if
Neolithic
racial
"types"
are easier
to
define
than
modern ones-a
doubtful exercise
in
any
case-
this
may
indicate
localized
genetic
isolation
present
in
the later
Neolithic
and
post-Neolithic
but
absent
in
pre-Neolithic
as
well
as
in
modern
urban populations.
by
FREDERICK
S. HULSE
Department
of
Anthropology,
University
of
Arizona,
Tucson,
Ariz.
85721,
U.S.A.
27
viII
77
At the
present
time,
it is
more
difficult
to
distinguish
between
Europeans
from
different
areas
than
it
used
to
be
a
long
time
ago.
This,
at
any
rate,
is
the conclusion
of
Henneberg,
Piontek,
and
Strzalko,
and I
wouldn't
be
surprised
if
they
were correct;
but
I
searched
their
article
in vain
for
positive
'vidence
that
this is due
to
natural selection
rather
than
population
admix-
ture. Increased variability
within
local
populations,
for
some
of
the cranial
traits
considered,
seems
to
be
a
widespread
trend.
The
authors
attribute
this
to
a decline
in
selective
pressures
due
to
improving
technology,
but
it
could
just
as
readily
be
explained
by
increased
miscegenation
as
improving
technology
made
travel
easier.
The
authors
state
quite
frankly
that
they
assume
natural
selection
to
be
the
most
significant
factor
in
morphological
change.
They
dismiss
the effects
of
migration
and
gene
flow
on
the
grounds
that,
within Europe,
isolation
between
human
groups
has
never been
absolute
since
the
Paleolithic.
This is
of
course
true,
but
there
are
many
steps
between
total
isolation
and
no isolation
whatever.
We
know that
even such
simple
technological
changes
as
the
introduction
of
bicycles
greatly
in-
creases
the
area
within
which
people
search
for mates.
It
seems
shocking
to
ignore
the
influence
of
migrations,
which
have
be-
come
easier
with each
improvement
in transport
and
with
each
expansion
of
empire.
Quite properly,
the
authors
state that
"each
series
of
cranial
measurements
must represent
a single
breeding
population."
C
CURRENT
ANTHROPOLOGY
Henneberg,
Piontek,
and
Strzalko:
SELECTION AND
VARIABILITY
We have no means of
knowing, however,
how
they
were able
to
assure
themselves
that
all,
or even
any,
of the cranial series
they
use do
really
meet
this
requirement.
All of
us who have
worked
with American Indian skeletal material
realize the
difficulty
of
knowing
anything
of the sort. And how can we
know that, in times and places
where cremation was
widespread
(but
not
universal),
the noncremated remains we
find don't
represent
some
unusual, nontypical group? Perhaps
they were
enslaved
captives,
or members of a lower
caste.
It
seems to me that Henneberg, Piontek,
and Strzalko
have
made
a
very ingenious
attempt
to demonstrate the continued
operation
of natural selection
upon
our
species,
at least in
Europe.
I have little doubt that this
proposition
is
correct,
but
their
assumptions
are
shaky
and their data are dubious. Were
I
a
skeptic,
I would
not
be convinced.
by
FRANK B.
LIVINGSTONE
Department of
Anthropology, University of
Michigan,
Ann
Arbor, Mich. 48109,
U.S.A.
22
viII
77
For the authors'
results
to
be due
to
selection,
it
is
necessary
to
make the
questionable
assumption
that the
amount
of
gene
flow
has been the
same
for
all
these
periods.
If
gene
flow has
increased through time,
it could
have
produced
the same
re-
sults
of
decreased
interpopulational
variation
and
increased
in-
trapopulational variation
that
they
attribute
to
selection.
My
own
work on
hemoglobin
variants
has
convinced
me that a
very
small amount
of
long-distance
gene
flow is of
great
importance
in
determining genetic
variation.
It
seems
obvious
to me
that,
with the
great migrations
of the
Middle
Ages
in
Europe
and
the
subsequent
invasions
and
crusades,
both
the
amount
and
the
range
of
migration
changed considerably. Population
size
also influences genetic
variation through gene drift,
but Henne-
berg
et al. do not
discuss
the
very
certain
changes
in
population
size
through
time.
Finally,
the models
of
Malecot
and
Wright,
as
applied
to
human
populations
by Morton
and
others, clearly
demonstrate
that
migration
pressure for most human
popula-
tions is
so
much greater
than selection pressure for
most human
loci that the effects of
selection on human variation
are too
small
to
detect.
Thus,
although
I
still
think
most human
genetic
variation
is due to natural
selection, the effects of
the latter
cannot
be
measured by
studies of genetic variation
among hu-
man
isolates. The noise
is greater than the signal.
by ROLAND MENK
Departement
d'Anthropologie,
Universite
de
Geneve,
Geneva,
Switzerland.
15
Ix
77
Henneberg, Piontek, and
Strzalko are to be congratulated
for
their
attempt
to
introduce
an
indicator of the eco-adaptational
success
of
historic (and
prehistoric) populations.
An indicator
such as their Ibs represents
a long awaited methodological
link
between
physical anthropology
and paleodemography,
which
will
help to establish, eventually,
a more in-depth collaboration
between
these two branches,
which-despite large
zones of
common
interest-have
never really reached a level
of essential
information interchange
and mutual enrichment of
research.
It
seems
necessary,
however, to formulate two
points of
criticism aimed
at the
oversimplified approach to
phenotype
evolution-its description
as well as the explanation
of its
causality-during the last
few millennia.
First,
it
must be stressed
that the patterns of morphological
evolution are much more
complex than the authors
seem to
suggest. This remark
applies to the purported
"directional"
changes of general skull
morphology, as well as to
the time-
dependent behavior of
its intergroup variability.
A more in-
depth analysis of the European Neolithic (covering
more
than
4,000 years, and therefore equivalent to the time
span of the
authors' material) shows
three time-dependent phenomena
(Menk 1975): (1) gracilisation-degracilisation; (2)
brachyceph-
alisation,
and
(3)
increase
of
intergroup
variability.
These
facts
are clearly
in
contradiction
with
the authors'
results
and
hypotheses.
The
instability
(or
reversibility)
of the
purported
directional
changes
(morphological
trends
as
well
as
oscillation
of
intergroup
variability