Finding expression in the face of the chacma baboon

The chacma baboon (Papio ursinus) is the largest (see and most southerly of monkeys. It is also exceptionally well-photographed, allowing us to illustrate its facial expressions.

There are at least four ways in which the face of the chacma baboon is so unlike the human face that we find difficulty in reading its expressions.

Males of the chacma baboon can fang-bare like carnivores ( However, the usual facial expression of masculine defensiveness and assertion is an exaggerated yawn, showing the pale eyelids ( and and and This is similar to a 'displacement activity' but serves to show the size and sharpness of the canines as a polite warning.

In the chacma baboon the expression of fear or appeasement is a grin/grimace (adult female: and

Whereas eye movements are extremely expressive in humans, they are extremely inscrutable in the chacma baboon. This is possibly because in humans status is gained mainly by sharing information, whereas in the chacma baboon status is gained mainly by withholding information ( and

The chacma baboon does possess pale ocular features, but these are located in keeping with a theme of non-divulgence and an avoidance of staring.

Firstly, adults of both sexes possess pale patches of fur on the otherwise bare rostrum, which seem designed to distract viewers from the eyes themselves. These can perhaps be thought of as 'false eyes' (see and and and and

Secondly, the pale eyelids are shown to express antagonism in both sexes. This can be the equivalent of a frowning stare but with the eyelids rather than the eyeballs doing the staring, or it can be a signal of appeasement. The half-closed eyes are accompanied by either raised eyebrows (assertive?) or flattened ears (submissive?). The following show the cringing expression in adult females: and

The 'neonatal makeup' of the chacma baboon ( and involves both a dark/pale contrast (blackish fur on the crown vs pale bare skin on the face of the newborn) and conspicuously reddish hues (particularly on the ears). This vivid colouration evokes the protective instinct of adults and juveniles so strongly that infants need no other facial expression for the first months of their lives.

Publicado por milewski milewski, 11 de septiembre de 2021


The following shows that pale eyelids are present already in infants:

Publicado por milewski hace 3 meses (Marca)

Baboons are not monkeys?

Publicado por dianastuder hace 3 meses (Marca)

Baboons belong to the same family as the vervet monkey of South Africa, and are indeed monkeys. The term 'baboon' refers to the genus level whereas the term 'monkey' refers to the family level.

However, now that we are on this topic, I notice in that what I might call 'cladistic derangement' has recently spread to include the term 'monkey'. You may previously have heard statements such as 'birds are dinosaurs' and 'whales are hoofed mammals'. These absurd claims arise in a kind of warped thinking in which one comes to conflate descendant with ancestor on the basis that a cladistic line of origination can be drawn between them. Birds are not dinosaurs, and humans are not monkeys - even though it is true that birds evolved from dinosaurs and humans evolved from monkeys.

The bottom line: the chacma baboon is a monkey in every biological sense but has a different vernacular name, much in the same way that the suni and the royal antelope are closely related but only one is called an antelope.

Publicado por milewski hace 3 meses (Marca)

@dianastuder What many may not realise is that the word 'baboon' is onomatopoeic, mimicking the well-known 'boggom' call ( So, next time you hear that familiar call resounding through a kloof in the Cape mountains, is it not an amusing thought that a monkey is shouting 'baboon' at you?

Publicado por milewski hace 3 meses (Marca)

We are primates with baboons.
Sadly Cape Town municipality is on a mission to kill off male baboons. We seldom see or hear them now. So many troops have been 'removed'.

Publicado por dianastuder hace 3 meses (Marca)

The following shows the maximum eyewhite visible in the chacma baboon: Compare this with

Publicado por milewski hace 3 meses (Marca)

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