Frequencies
and contexts of gape yawn displays of
free-ranging Patas Monkeys
(Erythrocebus Patas)
E.L. Zucker, M.S. Gerald, and J.R.
Kaplan
Department of Psychology,
Loyola University, New Orleans, University of
California at Los Angeles; Wake Forest
University School of Medicine
While the patas monkey repertoire of
displays has been described, few quantitative
data have been published.
Here, the sequencies and contexts of gape
yawn displays of various age/sex classes are
presented and compared, based on 400 hours of ad
libitum data collected on a free-ranging group
[1 adult resident male (RM); 18 adult
females; 22 immatures] at La Parguera, PR
(1977-78).
The RM produced 75% (239/ 319) of the
gape yawns observed (0.60/hr), with 69% of his
total in the birth season (June-August) versus
in the breeding season (December-February);
adult females accounted for 17% of the total
(0.14/hr; 70% in the breeding season).
For the RM, 54 yawns (22% of his total) were
directed towards animate targets, suggesting an
agonistic function (6% towards group members, 9%
towards rhesus monkeys on the island, 7% towards
observers); the remaining displays occurred
while scanning or approaching and using the
feeding/drinking areas.
Four additional yawn displays occurred in
sexual contexts. Adult females and immatures
directed 40% of their total towards animate
targets (7.5% towards group members, 5% towards
rhesus, and 28% towards observers).
Thus, while the adult male emitted more
gape yawn displays than did other age/sex
class members, a significantly smaller
proportion were directed towards specific
targets (z = 4.82, p < .01), supporting
previous findings that male patas are socially
peripheralized and oriented towards extragroup,
generalized threats.
-Deputte BL
Study of yawning in two species of
Cercopithecidae, Cercocebus albigena albigena
gray and Macaca fascicularis raffles: Research
on causal and functional factors; A
consideration of socio-bioenergetic factors.
Thèse presentée devant
l'Universite de Rennes, pour obtenir le titre de
Docteur en Troisième Cycle, February
1978.
-Deputte BL
Revue sur le comportement de bâillement
chez les vertébrés Bull interne
société française pour
l'étude du comportement animal., 1,
26-35, 1974
-Deputte BL,
Fontenelle A Menace et bâillement chez
Macaca Fascicularis: intérêt de
l'étude électomyographique
comparée.Biology of behaviour
1980,5,47-54
-Deputte BL
Ethological study of yawning in primates
Ethology 98, 221-245, 1994
The
influence of age, sex, and rank on yawning
behavior in two species of macaques (M.
fascicularis and M. fuscata)
Troisi A; Aureli F; Schino, G; Rinaldi F;
and De Angeli N
Hypothesis:Three kinds of yawns
exist physiological yawns (during
transitions of waking to sleeping), stress or
anxiety yawns, and threat yawns involving canine
display.
Yawning is displayed more frequently in
males than females because of plasma levels
of androgens (see Redican, 1975 and Goy and
Resko, 1972). Male yawning increases through
adolescence and jumps dramatically as males
enter early adulthood (when plasma levels of
testosterone start to rise), whereas female
yawning increases only slightly, if at all,
after infancy.
The highest-ranking male in the dominance
hierarchy tends to yawn at a much higher rate
than other group members (Hadidian,
1980). These finding are expected to be
replicable in long-tailed and Japanese macaques
and this study set out to find if that is
true.
Method: Subjects of both species were
captive groups. Long tailed macaque data was
collected over five months for a total of 117
hours of observation. During 81 hours of this
observation behaviors other than yawns were
observed and so data may be an underestimation
as yawns may have been missed altogether by the
observer. Data on Japanese macaques was
collected over two periods, one 5 months the
other 4 months, and a total of 262 hours of
observation was made (107 and 155 hours
respectively). Differences of hourly rate of
yawning was assessed by two way ANOVA.
Correlations between dominance rank and
frequency of yawning were calculate by using
Spearmans correlation coefficient.
Results: Japanese macaques yawned
much more than long-tailed macaques. In the
long-tailed macaques, sex differences in
frequency of yawning emerged only after
sexual maturity; yawning rates increased
significantly in bothe males and females as they
approached sexual maturity; and, among males,
dominance rank was positively correlated with
frequency of yawning.
Differently, in the Japanese macaques,
males, both mature and immature, yawned more
than same-aged females; sexual maturity was
associated with an increase in yawning in males
only; and male rank did not correlate with the
frequency of yawning. Discussion: Age, sex, and
dominance rank exerted different effects on
yawning in the two species. Regardless of
interspecific differences, the overall results
supported only in part the finding that, in Old
World monkeys, yawning is largely influenced by
plasma concentrations of androgens.
There was evidence that social factors were
also important in influencing the age-sex class
distribution of yawning. Caldecott (1986) has
proposed two group classification of macaque
societies. Japanese macaques belong to one group
(M. mulatta, M. fuscata, M. nemstrina, and
M.selinu ) and are characterized by antagonistic
inter-male relationships and a multiple mount
copulation pattern. The other group (comprised
of M. sylvanus, M. radiata, M. arctoides and M.
tonkeana) show relaxed inter-male relationships
and a single mount copulation pattern. Long
tailed macaques display both single- and
multiple-mount copulations (Caldecott, 1986),
and agonistic behavior characteristic of both of
the groups but not more so one or the other
(Thierry, 1985), and are thus considered to be
an intermediate species between the two
groups.
A correlation between agonistic behavior
and yawning frequency is thus assumed
aswell. It is possible that most of the yawns
emitted by low ranking males were a result of
conflict or stress, whereas yawns by
high-ranking males were made as intimidating
displays. Conclusions: Macaque yawning has a
complex causation which is likely to result from
an interaction between hormonal and social
factors.
Derived
activities: their causation; biological
signifiance, origin and emancipation during
evolution
