Primate Anatomy : Primate Primates

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Primate Brains
The primate order to which we as humans belong can be divided into two sub-orders: the Strepsirrhini, also known across much literature as prosiminans, containing lemurs and lorises and the Haplorrhini containing tarsiers, monkeys and apes. The Strepsirrhini divide further into Lemuriformes and Lorisiformes, and the Haplorrhini divide into Tarsiiformes and Simiiformes, also known as anthropoids which consist of apes and humans. The Simiiformes divide into Platyrrhini (New World monkeys) and Catarrhini (Old World monkeys and hominoids), (Napier, 2014). Fig.1 attached shows the divisions of primate classification. Primates have various characteristics that identify them from other vertebrates such as, opposable thumbs, nails
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This has been suggested by many researchers to be related to their large neocortical area, which has expanded to produce a highly convoluted brain, (Aboitiz and Montiel, 2012).
The neocortex is part of the cerebral cortex which is the outermost layer of the brain in mammals, (Fleagle, 2013). Within primate evolution, this area of the brains seems to have undergone considerable change and growth. The neocortex in apes and humans equals between 65-76% of the total brain weight, (Dunbar, 1995). It appears to be involved in higher functions such as sensations, voluntary movements, memory, thought and interpretation. This strengthens the idea that a large neocortex infers intelligence amongst primates, (Fleagle, 2013).
The neocortex is thought to have originated about 160-300 million years ago and is suggested to play a role in helping the animal understand its complex environment to enable its survival. Therefore, it makes sense that much of the neocortex is involved in sensations and largely vision, (Allman, 1990). In fact it has been found that the brain of anthropoid primates is mostly dominated by this visual system found in the neocortex, (Aboitiz & Montiel, 2012). The primary visual cortex (part of the neocortex), is large across many anthropoid primates and it has been shown that for catarrhine primates, group size correlates with facial motor nuclei (which innervate muscles to control facial
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