While a homologous area is present in monkeys and apes, ours has much broader interconnections and is uniquely involved with speech comprehension. At what point our ancestors began to speak is a highly contested topic but the archaeological record provides some clues see Chapters 23 and Great ape social organization varies by species.
Philopatry refers to the sex that remains in their natal group , i. This type of social organization is seen in some ripe fruit specialists, such as the chimps and bonobos of Africa and the New World spider monkeys. Since fruit is an ephemeral resource, females cannot cooperatively defend it. Groups of related males cooperatively defend a home range against outsider males.
Females emigrate from their natal community and join a different community when they reach sexual maturity. Group members come together intermittently into larger aggregations wherein they may interact. This grouping pattern is termed fission-fusion. Since males patrol and protect the area and females are relatively large and powerful and can climb, the danger of predation is relatively low and they therefore have less of a need to congregate.
The mating pattern is termed polygynandry , meaning that males and females are promiscuous and may have multiple sexual partners. Males may attempt to monopolize and coerce females to mate but females are adept at getting around bullying males and may even mate with males outside of their group. Orangutans are considered to be solitary foragers and their prominent mating pattern is polygyny males have multiple mates , wherein females in a given area usually mate with the resident, large, dominant male.
Smaller males who are sexually mature but lacking the pronounced secondary sexual characteristics, such as facial pads termed flanges and an enlarged throat sac for loud calls, may try to forcibly copulate with females. Gorillas live in one-male groups, except for the mountain gorillas, where two males may reside, an older dominant and younger subordinate. Both sexes tend to leave their natal group. Females join a male who may or may not already have other female mates.
Thus the mating system is also polygynous. Males defend their females and offspring from outsider males who may be infanticidal. In mountain gorillas, females are thought to prefer groups with two males as they provide better protection for her offspring. It can thus be seen that there are characteristics of the human sexes in all three great ape genera plural of genus : male defense and mate-guarding, female choice for dominant males and good genes, male philopatry with females maximizing resources for themselves and offspring in chimps and bonobos, etc.
The following terms are used to delineate characteristics in cladistics: Plesiomorphy —a primitive trait that is present in the ancestor as well as descendent species, for example, pentadactyly five digits in primates is an ancient trait seen in amphibians and reptiles.
Apomorphy —a derived trait that is not found in the ancestor but is present in descendent species, for example, nails in primates. Autapomorphy —a unique derived trait present in member species of a particular grade, for example, the lack of a tail in apes. Synapomorphy —a trait inherited by members of two or more grades from their common ancestor, wherein the trait was an apomorphy, for example, bipedalism in the various grades within our tribe, Hominini.
Orders within the class Mammalia. Presence of a clavicle that allows greater mobility. Lemuriformes lemurs. Lemuridae true lemurs. Madagascar and Comoro Islands for some species. Cheirogaleidae dwarf lemurs. Lorisiformes lorises.
Haplorrhini haplorrhines: primates with dry noses. Tarsiiformes 2 tarsiers. Philippines, Borneo, Celebes Islands, and Sumatra.
Simiformes anthropoids. The Simiiformes again divide into two clades, Platyrrhini and Catarrhini, alternatively classified as parvorders or, sometimes, left unranked there is much dissension about unranked taxonomic systems; in the opinion of most taxonomists, ranks are useful, especially if tied to some time-depth scheme. The Platyrrhini retain the primitive three premolars, inflated bulla and ring-like tympanic, and it has proved difficult to find any derived character states which they share, although molecular research confirms their monophyly; most recently, however, it has been shown that contact between parietal and zygomatic malar bones is a truly derived platyrrhine condition [ 7 ].
The Platyrrhini are the New World monkeys; all of them occur in South America, some of them extending north into Central America, even as far as southern Mexico. There are three families of Platyrrhini: Cebidae including the marmosets and tamarins, at one time assigned to their own family , Atelidae and Pitheciidae Figures 4 — 6.
Colombian night monkey, Aotus griseimembra , a member of the Cebidae. Pied Tamarin, Saguinus bicolor , a member of the Cebidae. Northern red howler monkey, Alouatta seniculus , a member of the Atelidae. The Catarrhini all live in the Old World. There are three families of Catarrhini: Cercopithecidae, belonging to the superfamily Cercopithecoidea the Old World monkeys Figure 7 , and the Hylobatidae gibbons, of Southeast Asia Figure 8 and Hominidae great apes and humans Figures 9 and 10 , these latter two belonging to the superfamily Hominoidea.
Molecular calculations of the separation time of the two families of Hominoidea tend to fall in the late Early Miocene, well below the criterion laid down by Goodman et al. A female olive baboon, Papio anubis , from Kenya a member of the Cercopithecidae , filling her cheek pouches with food. Kloss gibbon, Hylobates klossii. Sumatran orangutan, Pongo abeli.
Western Gorilla, Gorilla gorilla. There are many more species of lemurs that had previously been appreciated [ 10 ], and the list is still growing. Similarly, the number of species in some platyrrhine genera is growing see, for example, [ 11 ] , and there are many more species of Asian primates than had previously been recognised [ 12 ]. This brings us to ask the important question: what actually is a species?
Species thus have a real existence. This definition has three strands:. Species are populations or aggregations of populations.
They are not, for example, segments of populations. This can generally be observed in the field, though in the museum or on the laboratory bench it must be inferred. The differences are heritable. They may thus be differences observable in the genome; or they may be differences in morphological characters or in behavioural characters, in which case a heritable genetic basis is only inferential, although such a basis tends to be very strongly implied.
The differences are fixed. That is to say, the two populations are absolutely diagnosably different. The work of Christian Roos and his colleagues has shown that, in fact, there has been very widespread interbreeding and gene exchange between different species during their evolution see, for example, [ 16 ].
The strepsirrhines, the tarsiers and the platyrrhines have been subjected to critical taxonomic revision over the past 15 years or so. What of the catarrhines? The Asian catarrhines gibbons, the orangutan, colobines and the genus Macaca have in most cases been carefully examined taxonomically, and work on them continues [ 12 ].
The macaques and langurs, especially, both need further attention. New species of macaques have been described, and the question of the gene flow between the long-tailed macaque Macaca fascicularis and the rhesus macaque Macaca mulatta , where their ranges meet in mainland Southeast Asia is an ongoing focus of research. This leaves the African catarrhines, particularly the Old World Monkeys superfamily Cercopithecoidea, family Cercopithecidae.
The Cercopithecidae are divided into two subfamilies. The African members of the subfamily Colobinae the leaf eating monkeys need further attention, both genetically and morphologically.
Within the other subfamily, Cercopithecinae omnivorous monkeys with cheek pouches , the taxonomy of the baboons Papio , of the tribe Papionini, is receiving continual attention and has already yielded unexpected insights [ 17 ].
The related genera Cercocebus , Lophocebus , Rungwecebus , Theropithecus and Mandrillus mangabeys, geladas and mandrills remain to be investigated in depth. Enhancement of free mobility of the digits, especially of the pollux and hallux both used for grasping. Demonstration - and maybe get them to take off their shoes to try their feet. Replacement of sharp, compressed claws by flat nails; development of very sensitive tactile pads on the digits. Progressive shortening of the snout.
Elaboration of the visual apparatus, with the development of varying degrees of binocular vision. Reduction of the olfactory apparatus. These 3 are all linked and progress from prosimian through monkeys to humans.
Loss of certain elements of the primitive mammalian dentition. Preservation of a simple molar cusp pattern. Tooth formula reduction: primitive mammal 3. Note, that it is the anterior 2 premolars that we have lost. Progressive expansion and elaboration of the brain, especially of the cerebral cortex.
Progressive and increasingly efficient development of gestational processes. And this has been further expanded by Napier and Napier Prolongation of postnatal life periods. Progressive development of truncal uprightness leading to a facultative bipedalism. Problems At first view, this seems OK apart from the dreadful language which makes the whole thing read like a life insurance document. But there are problems with this definition: Firstly, there is no unique characteristic that defines a primates.
Do humans fit P43 PM? Primate taxonomy is one such area: Prosimians and Simians First primate like animals appeared in the Palaeocene 70 mya , perhaps even late Cretaceous. These are described as early prosimians. Features Tooth comb from incisors Locomotor specializations: vertical clinging and leaping, slow quadrupedalism Wet noses Dog-like faces Nocturnal well, often Orbital bar Ectotympanic ring Epitheliochorial placenta Tapetum Tarsiiformes As you saw from the diagram, there is a big split between the prosimians on the one hand and the anthropoids on the other, with tarsiers somewhere in the middle.
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