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Handedness frequency over more than ten thousand years

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Although there are quite important geographical variations in the frequency of left-handers around the world, nothing is known about its temporal evolution. During the upper Palaeolithic (ca. 35,000-10,000 YBP), humans painted 'negative hands' by blowing pigments with a tube onto one hand applied on the rock in caves in Western Europe, by blowing pigments on their own hand through a tube held in the other hand. The frequency of left-handers prevailing during this period could thus be assessed. For comparison, the handedness of French university students has been observed for the same task. No difference was detected between the two proportions of left-handers, separated by more than 10,000 years. Implications for the evolution of the polymorphism of handedness are discussed.
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doi: 10.1098/rsbl.2003.0092
, S43-S45271 2004 Proc. R. Soc. Lond. B
Charlotte Faurie and Michel Raymond
Handedness frequency over more than ten thousand years
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Handedness frequency
over more than ten
thousand years
Charlotte Faurie
*
and Michel Raymond
Ge
´
ne
´
tique et Environnement, Institut des Sciences de l’Evolution de
Montpellier (UMR CNRS 5554), Universite
´
Montpellier II CC 065,
Place Euge
`
ne Bataillon, F-34095 Montpellier cedex 5, France
*
Author for correspondence ( faurie@isem.univ-montp2.fr).
Recd 02.06.03; Accptd 04.08.03; Online 25.09.03
Although there are quite important geographical
variations in the frequency of left-handers around
the world, nothing is known about its temporal evol-
ution. During the upper Palaeolithic (ca. 35 000–
10 000 YBP), humans painted ‘negative hands’ by
blowing pigments with a tube onto one hand applied
on the rock in caves in Western Europe, by blowing
pigments on their own hand through a tube held in
the other hand. The frequency of left-handers pre-
vailing during this period could thus be assessed.
For comparison, the handedness of French univer-
sity students has been observed for the same task.
No difference was detected between the two pro-
portions of left-handers, separated by more than
10 000 years. Implications for the evolution of the
polymorphism of handedness are discussed.
Keywords: Homo; polymorphism; stabilizing selection;
asymmetry; laterality; Palaeolithic
1. INTRODUCTION
Several studies indicate that the coexistence of both right-
and left-handed individuals has been maintained for a long
time in hominids. The oldest undisputed evidence is from
the middle (ca. 425 000–180 000 YBP) and early upper
Pleistocene (upper Pleistocene was 180 000–10 000
YBP), where marking on incisors indicates the existence
of Homo neanderthalensis individuals who were right- or
left-handed for sharp tool manipulation, while slicing meat
held between the front teeth and the other hand
(Bermu
`
dez de Castro et al. 1988; Lalueza & Frayer 1997).
In the Homo sapiens taxon, indications of handedness poly-
morphism come from studies of stone artefacts, hole-
making rotation movements in wood and wear marks on
spoons (e.g. Palaeolithic: Keeley (1977); Cornford (1986)
and Westergaard & Suomi (1996); Neolithic: Bocquet
(1978)). The oldest known evidence is from the upper
Palaeolithic, with the negative hand paintings in caves in
France and Spain (Groe
¨
nen 1997).
There is still today a polymorphism of handedness in
humans, in all populations so far investigated (e.g.
Connolly & Bishop 1992; Carrie
`
re & Raymond 2000).
The evolutionary significance of this polymorphism is
unclear. However, the heritability of this trait is clearly
established (e.g. Sicotte et al. 1999; McKeever 2000;
Francks et al. 2002). It is known that the frequency of left-
handers is variable across geographical areas (Raymond &
Pontier 2004), but nothing is known about its temporal
Proc. R. Soc. Lond. B (Suppl.) 271, S43–S45 (2004) S43 2003 The Royal Society
DOI 10.1098/rsbl.2003.0092
evolution. We propose to compare the proportion of left-
handers among the people who painted the negative hands
in the Palaeolithic with the current proportion.
Detailed studies suggest that negative hands were prob-
ably made by blowing paint onto the back of one hand
applied on the rock surface, the other hand holding a
blowing tube (Groe
¨
nen 1988). Thus a right negative hand
corresponds to a left-hander for the task of holding a tube
for paint blowing. These negative hands have different
sizes and are located at different heights, suggesting the
existence of different painters. Moreover, the caves are
often far apart in space, and the paintings were done over
a long period of time (30 000 to 10 000 YBP; Valladas et
al. 2001). They can thus be used to estimate the pro-
portion of left-handers in this period. Although we cannot
rule out the possibility that some individuals painted their
own hand more than once, the ratios should remain simi-
lar (all things being equal). In the following work, we use
experimentation to compare this proportion with the cur-
rent proportion.
2. METHODS
(a) Palaeolithic record
There are 507 known negative hands from the upper Palaeolithic
of France and Spain (10 000 to 30 000 YBP). Laterality can be
unambiguously determined for 343 of them (Groe
¨
nen 1997). There
are 79 right negative hands; this provides an estimate of 23% of
left-handers.
(b) Experiment
We placed our experimental subjects in hand-painting conditions
that were similar to the original situations. For comparison, we also
observed handedness for more usual tasks: throwing and writing
handedness were measured on the basis of performance.
(i) Subjects
The subjects were university students, attending the first and
second year in the University of Montpellier, France. They were
recruited on a voluntary basis, and were not told the purpose of the
study. They came one by one to the experimental room, so that they
did not have any opportunity to influence each other. The tests
were anonymous.
(ii) Throwing handedness
The subject was asked to pick up a ball placed on the middle of
a table in front of him and to throw it as close as possible to the
centre of a target 3.5 m distant. This way, the choice of the throwing
hand is not influenced by the configuration of the experiment. The
presence of the target increases the precision of the tasks, which
ameliorates the determination of the handedness of the individual
(Hopkins 1997).
(iii) Negative hand painting
The subjects were given a special pen that projects ink at one
extremity when they blow at the other (see www.blopens.com for
details). Each subject was instructed to paint a negative hand on a
blank paper. The technique is thus very similar to the pigment tube-
blowing technique attributed to the Palaeolithic artists.
(iv) Questionnaire
Subjects were asked to give the following information: age, sex and
writing hand.
(c) Data analysis
Three handedness variables were thus recorded: throwing hand-
edness, hand painted while holding the tube with the other hand,
and writing handedness. These qualitative variables have two possible
values: left or right.
The frequency of left and right negative hands obtained in our
experiment and as recorded in the caves were compared using a Fish-
er’s exact test. We tested with the same method the independence
between the three handedness variables. Non-parametric statistics
(Kendall’s
) were used to measure the correlations between vari-
ables. These analyses were performed with the SAS software, v. V8.
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S44 C. Faurie and M. Raymond Handedness frequency in the Palaeolithic
(a)(b)
Figure 1. (a) Right negative hand from the cave of Le Pech-Merle (Lot, France; photograph by J. Vertut). (b) Left negative
hand made by a subject in our experiment.
Table 1. Number of right and left negative hands recorded in
the caves and from university students.
negative hands
left right
Palaeolithic
a
264 (77.0%) 79 (23.0%)
Present 138 (77.1%) 41 (22.9%)
a
Data from Groe
¨
nen (1997).
3. RESULTS
One hundred and seventy-nine students participated in
the study (58 males and 121 females, aged 19.8 ± 1.1
years). Figure 1 shows a Palaeolithic negative hand, and
one made by one of the students. The percentage of them
that made a right negative hand was 22.9%. No effect of
sex was observed (Fishers exact test, p = 0.85). The
results of the experiment are compared with the Palaeo-
lithic record in table 1. There is no significant difference
between the frequency of right negative hands in our sam-
ple and in the Palaeolithic sample (Fishers exact test,
p = 0.99).
Left-handed writers and throwers were 8.9% and 7.8%,
respectively. The three measures of handedness are highly
dependent (Fishers exact test, p 0.0001). No effect of
sex was observed (Fishers exact test, p = 0.78 and
p = 0.77 respectively). The handedness for holding the
tube while making the negative hand is positively corre-
lated with writing (Kendalls
= 0.48, p 0.0001) and
throwing (
= 0.49, p 0.0001) handedness. Among sub-
jects who made a left negative hand, almost all (99.3%)
are right-handers for throwing. Among subjects who made
a right negative hand, however, only 31.7% are left-
handed for throwing.
4. DISCUSSION
The proportion of right and left negative hands in our
latterday experiment is not different from the proportion
recorded by Groe
¨
nen in the European caves. The absence
of significant variation in the frequency of left-handers (for
the task of holding a tube to paint the other hand) over
more than 10 000 years is surprising. It suggests that
Proc. R. Soc. Lond. B (Suppl.)
handedness is a trait under some functional constraint that
has not substantially changed since the upper Palaeolithic.
This is the first information, to our knowledge, on the
temporal variations of the frequency of left-handers for
one particular task. The only exception concerns the twen-
tieth century increase of left-handed writers in western
societies, probably explained by the relaxing of social
pressures (Porac et al. 1980). Studies based on human
subjects depicted in artworks sampled over 50 centuries
(Coren & Porac 1977) are irrelevant, because the conven-
tionaland often religiousrepresentation of a lateralized
human has no necessary link, in this respect, with a real
individual (Needham 1973).
To our knowledge, handedness for painting negative
hands has never before been measured in a contemporary
population. In the present sample, it is significantly corre-
lated with writing and throwing handedness. Surprisingly,
the correlation found is not as strong as the correlation
linking writing and throwing handedness: a substantial
proportion (17%) of right-handed throwers hold the tube
with the left hand. Inference on the frequency of left-
handed throwers during the upper Palaeolithic requires
the assumption that the level of the observed positive cor-
relation was already present at that time, which is difficult
to establish.
Negative hands are described in several locations
(Australia, South America, Indonesia). They all date from
Neolithic to contemporary times. The negative hands of
Western Europe are the most ancient (upper Palaeolithic;
Leroi-Gourhan et al. 1995).
The significance of the negative hands painted in caves
or shelters has long been a mystery. In some cultures (e.g.
in South Africa), traditional rock painting is still practised
(or was still practised very recently). The hand prints are
made by shamans and have a sacred meaning (Lewis-
Williams 1983). A comparative analysis indicated that the
negative hands from the upper Palaeolithic probably have
the same interpretation (Lewis-Williams & Dowson 1988;
Clottes & Lewis-Williams 1998). A more adequate sample
to estimate the present handedness would then be the
shamans themselves. A comparison of the frequency of
right and left negative hands from these locations would
be useful to know if the stability of the proportion of left-
handers over more than 10 000 years in Western Europe
is also found elsewhere.
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Handedness frequency in the Palaeolithic C. Faurie and M. Raymond S45
Acknowledgements
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Giriş ve Amaç: Bu araştırmada, İstanbul ilinde spor eğitimi veren yükseköğretim kurumlarındaki akademisyenlerin karanlık kişilik ve kişi-örgüt uyumları arasındaki ilişkinin incelenmesi amaçlanmıştır. Yöntem: Araştırmanın çalışma grubunu İstanbul ilinde bulunan üniversitelerin Beden Eğitimi ve Spor Yüksek Okulları ile Spor Bilimleri Fakültelerinde görev yapan 39 kadın 51 Erkek toplamda 90 akademisyen oluşturmaktadır. Araştırmada veri toplama aracı olarak araştırmacılar tarafından hazırlanmış “Kişisel Bilgi Formu”, akademisyenlerin karanlık üçlü özelliklerinin belirlenmesi amacıyla Jones ve Paulhus (2014) tarafından geliştirilen, Şahin, Ağralı Ermiş ve Demirus (2018) tarafından uyarlaması gerçekleştirilen “Kısa Karanlık Üçlü Ölçeği (SD3)” ve Netemeyer vd., (1997) tarafından geliştirilen, Turunç ve Çelik (2012) tarafından uyarlaması yapılan “Kişi-Örgüt Uyumu Ölçeği” kullanılmıştır. Elde edilen veriler SPSS-24 Paket Programı ile analiz edilmiştir. Aynı zamanda verilerin çözüm ve yorumlanmasında Pearson ve Spearman korelasyon analizleri, bağımsız örneklemler (Independent-Samples) t-testi analizi, One-Way ANOVA (Tek Yönlü Varyans Analizi), Mann-Whitney U Testi ve Kruskal-Wallis H Testi kullanılmıştır. Bulgular: Ölçeklere ait puan dağılımlarının homojen dağılıp dağılmadığına yönelik Levene istatistiği sonuçlarına bakıldığında kısa karanlık üçlü ölçeği toplamı ve psikopati alt boyutunun normal dağılım göstermediği, kısa karanlık üçlü ölçeği diğer alt boyutları olan makyavelizm ve narsizm ve kişi örgüt uyumu ölçeğinin normal dağılım gösterdiği tespit edilmiştir. Akademisyenlerin cinsiyetlerine göre kişi-örgüt uyumları arasında anlamlı farklılık bulunurken, kısa karanlık üçlü ölçeği toplamı ve alt boyutları arasında anlamlı bir farklılık bulunmamaktadır. Medeni durumlarına göre kişi örgüt uyumu, kısa karanlık üçlü ölçeği toplamı ve alt boyutları olan psikopati ve narsizm arasında anlamlı farklılık bulunmazken, kısa karanlık üçlü ölçeği diğer alt boyutu olan makyavelizm arasında anlamlı farklılık bulunmaktadır. Unvan, bölüm, üniversite türü ve idari göre olma durumuna göre kişi örgüt uyumu, kısa karanlık üçlü ölçeği toplamı ve alt boyutları arasında anlamlı bir farklılık bulunmadığı tespit edilmiştir. Anahtar Kelimeler: Kişilik, Karanlık Kişilik, Kişi-Örgüt Uyumu
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