Notes on various studies of animal sexual
behaviour
Dave Harris
[referred to in Bagemihl]
Kitamura K (1989) Genito-Genital
Contacts in the Pygmy Chimpanzee African
Study Monographs 10(2) 49--67
The abstract says that 'most of the contacts have
a typical pattern for each age -sex class
combination', although there also seem to be quite
unusual behaviour patterns. There is a
possible syntax of the analysis of interactions
There seems to be a lot of variable
copulation—females rub each other's genitals, one
male presents and the other one places his own
anal region in contact. There are also
'copulation like contacts'(49) and a great deal of
diversity. A particular focus here is on
ano-genital contacts.
It was based on a study lasting five months
focusing on particular groups which had been
'provisioned' by earlier researchers. They
were able to identify members of the group.
There is a lot of frigging. There are
difficulties in definition for example in age and
sex. A matrix displays the results with 206
categories and 10 forms of combination. 'It
may not be very meaningful to classify which sex
initiated each and every copulation' but we can
observe behaviour patterns like courtship
displays. One of these involves the male
having an erect penis. Different observers
have seen different frequencies. There do
not seem to be any bits of aggression, unlike
common chimpanzees where, for example '40 per cent
of the copulations were initiated by the approach
of the male with hair erect'. In pygmy
chimpanzees it is more common to find females
approaching those males with an erect penis.
There may be sharing. Sometimes the males
are annoyed by female approaches.
An extract from field notes follows [form of
anthropomorphism like one of the females begging,
or relenting]. Another extract has
exaggerated gestures. Males rarely ignored a
female solicitation but not the other way
about. There can be copulation 'without
active solicitation' [or rather it 'can be
imagined'] (52).
There can be different sorts of copulations.
267 episodes were observed, with 258 definite
identifications. 51 cases were ventral
dorsal, 34 of vetro ventra. Tthere was a
statistically significant correlation between the
maturity of the male and the choice of
posture. The actual position of the females
vagina 'may be reflected in the posture' (53).
There may be manipulation of the genitals by hands
and feet. On one occasion a female
manipulated her own genitals. Feet might be
used for example by lifting their own sexual skin
or standing on a scrotum. Age might be
significant. Other postures were observable
for example while copulating in a tree
Postures may change during copulation.
Savage and Bakeman 'have emphasized that a rather
complex communicative decision-making process is
necessary to achieve a compatible posture'.
Savage-Rumbaugh Et Al 'have shown that certain
gestures are followed by a particular postures 'at
statistically significant frequencies', although
observations in the field seem to be of lower
frequency and 'a complex process to determine the
copulatory posture may not occur
frequently'. There may be 'no clear
communicative gestures'. Only juvenile or
young adult males show the 'full postural
repertoire' (55).
Rubbing between mature females 'was observed 179
times'. It happens on the ground or in the
trees. It may be preceeded by other
activities including mutual eye contact. It
is not just simulated male female
copulations. It's not always easy to
synchronise the movements. There may be no
symmetrical embraces, and 'the chimpanzees
themselves seem to be aware of the difference
[because they] repeatedly present to one another
to determine which will have the lower
position'[supported by a field observation].
This choice of different positions 'indicates that
they clearly discriminate the two positions' that
there may be no predetermination
Males both mount each other and have this rump to
romp contact. [And then an abstract
discussion of possibilities]. They saw mounting 39
times and rump to rump contact 10 times. It
did not always involved penile insertion or even
pelvic thrusts. Deciding who mounts and who
is mounted involves the prior 'identity of the
participants' (57). There may be dominant
individuals who also use threatening
gestures. Sometimes 'both partners
simultaneously behave as the mountee [supported by
field notes again] The activity is 'often
preceded by aggressive chases'but there can be
other contexts.
There are no clear differences between
mature and immature males, although there is some
progressive development of chosen patterns.
Male infants can sometimes join in—in male cases
'the penis was always erect' [more or field
notes]. 'The infants made no attempt to gain
the females' consent'and there was often no
obvious reaction from the females.
Mature males can 'embrace and perform pelvic
thrusts with the infants of both sexes', with
erect penises, although there is no
insertion. There may be particular
activities during particular postures.
Infants may respond to a male display or even
solicit being mounted [field notes again].
There may also be food sharing.
There are other combinations. Most typical
interactions, for example the male always mounts
infant males, but there are some rare exceptions
when juvenile males either mount adults or embrace
others. There are other types of contacts
involving mature females.
There are some which could not be classified, were
observed 'only very few times' (62) and may
only have been observed by chance. Overall,
there seemed to be five types of combination
involving age sex and class. These describe
typical behaviour but not all behaviour.
There seem to be 'mutually exclusive sets' (63)
but some variation and sometimes no shared
pattern.
The piece goes on to compare other studies.
This piece does not used 'presumed function or
motivational states' or work with causes
(65). It claims to try to work with
understanding what is revealed about the
individuals and their social situation—'A "syntax"
analysis of interactions and a certain social
system'this implies that some interactions are
'entirely different' from others, although 'it
cannot be easily determined in what category and
observed interaction should be placed' and much
depends on the regularities of the pattern.
'The situations occur in an extreme form in human
society' (66) when people behave strictly
according to their roles. Behaviour patterns
may emerge independently of sexual behaviour, even
where 'it is almost indistinguishable'. He
is not classifying just on the level of behaviour
patterns. The emphasis is on dyadic
interaction. The method involves
accumulating data on frequency and then
'postulating several kinds of social relationships
for each dyad', but then interrelationships are
minimised in favour of 'a list'
Manson, J, Perry, S and Parish, A
(1996 ) Nonconceptive sexual behaviour in
Bonobos and Capuchins. International
Journal of Primatology, 18 (5). 767
-86.
There is an attempt to explain sexual behaviours
in terms of proposed functions like practice or
appeasement. They had observed sexual
behaviour in captive bonobo and wild
Capuchin. However, they found sexual
diversity, basically as much mounting and genital
contact among same sex and immature dyads. Bonobos
engaged in sexual behaviour 60 times as frequently
as Capuchins, and displayed more variety.
However, their sexual contact was 'concentrated
most heavily in socially tense situations in adult
female - female dyads'[among males for the
Capuchins]. They conclude that there is 'practice
sex'and 'paternity confusion', and more
communicative function for hetero Bonobos and male
homo Capuchins.
Sexual behaviour often occurs at higher
frequencies' 'than necessary to ensure conception
and or in nonconceptive forms or both'(768),
especially in primates, and between different
species of primates. They are interested in
data on 'temporal patterning… Sexual
positions'… Partner combinations and
contexts'. Then they want to go for explanations
[based on the five functional categories above,
explained 769 F]. Again Bonobos seem to be
particularly versatile. Their behaviour has
'been linked to differences in food distribution
and social structure...feeding and coalitions',
especially to strengthen females. There also
seems to be a link between sexual behaviour and
'socially tense situations' (770). Other
factors might include access to scarce fruit
sources and 'biased tolerance towards likely
offspring'
They did 2 data collection sessions over about
three weeks. 15 minute focal individual
observations in a random order. A total of
145 hours of focal data. No other data was
used. Dominance rankings were calculated
'for outcomes of agonistic interactions and
displacements' (771). The wild group
consisted of 21 capuchin living in a forest—they
followed the group from dawn till dusk for 25
sequential days per month. They assigned
them to age classes. There are 10 minute
focal 'individual follows'in which 'all the social
behaviours and the identities of the interactants
were recorded'. They discarded any data
where observers did not agree
They then counted different kinds of
contact. They already had some information
about ovulation, but noticed continuing
contact. Marvellously 'We combined
genito-genital contacts by each dyad to compute a
contact rate for ...contacts per hour of focal
observation' (773). They did some
statistical analysis of significance to see if
there were are differences between nonconceptive
contact rates and conceptive ones—there were
none. They noticed the importance of 'social
intense situations'which included aggression
Capuchins had lovely behaviour including making
'duck faces' (775), and dancing—highly ritualised
movements, deliberate and rhythmic.
'Ejaculation was difficult to discern'
There other dances as well as sexual. Nine
of 15 copulations took place while the female was
pregnant. They calculated 'a median rate of
0.05 copulations/hr' (776)
There was some connection with female reproductive
state, although some available females were not
courted at all. 'Olfactory cues' might have
been as important as behaviour, especially in
female urine(777). An immigrant male was
freely copulatid with, but also received more
aggression. There was a variable according
to whether the dyad was conceptive or not.
They calculated different rates of
mounting—'mounts per hour of focal observation of
the two individuals'. Nonconceptive mounting
rates were higher, although the difference is not
significant. There may also be a relation of
context and age - sex class. 42% occurred in
socially tense situations' including aggression,
especially homo ones, and one took place in a
period after a particular individual was deposed
as Alpha male. The others seem to show
'no discernible context' (778). Dominant
individuals could affect the interactions of
others.
So, overall 'a large fraction of sexual behaviour
is nonconceptive' in both species, but the data
'is consistent with the view that practice is one
function of this behaviour' (780). Age seems
to have been a factor especially with attraction
rates and the vigour of courtship. There is
also paternity confusion sex and general exchange
sex, more with Capuchins. Sometimes this led
to 'sexually selected infanticide'. Rates of
engagement were much higher for bonobo, although
the two groups vary according to whether they are
captive. Bonobo also showed much more
variety. There was no indication of
Capuchins exchanging sex for food. The main
purpose of nonconceptive sex seems to be to
ameliorate tension and forge cooperative social
links, hence their prevalence in socially tense
situations'the. Subordinates may need to be
appeased especially during feeding
competition. Capuchin males seem to need to
communicate more than females. Interation
occurred over a longer period of social tension
after rank reversal, and may have been down to
individual males wanting to ally against
rivals. Others have argued that baboons do
sexual interaction to develop commitment,
especially in resisting attacks, but there may
also be competitive ability between rivals.
Sex may serve to display social bonds, appease
potential aggressors, although there are
alternatives -- admitting that their data set is
small. They need more data on hormone
profiles and behaviours.
Bagemihl
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