Core Primate Characteristics In answer to the question

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Core Primate Characteristics In answer to the question “What is a primate? ”

Core Primate Characteristics In answer to the question “What is a primate? ”

Biological Classification: The Primate Order When scientists have sorted animals into taxonomic classes, going

Biological Classification: The Primate Order When scientists have sorted animals into taxonomic classes, going back to the Carolus Linnaeus the father of taxonomy, they key in on suites of shared physical attributes. An order is a very large grouping, e. g. the order Rodentia contains all rodents.

Primitive or Derived? • We further evaluate physical characteristics as to whether they are

Primitive or Derived? • We further evaluate physical characteristics as to whether they are primitive or derived. If they are primitive, they have been inherited from some ancestral group – for instance primates possess a clavicle and so do saurischian dinosaurs and amphibians. Retention of the clavicle is a core primate characteristic, and it is primitive. This Photo by Unknown Author is licensed under CC BY-SA

Derived Characteristics • A trait that is derived sets off an taxonomic group from

Derived Characteristics • A trait that is derived sets off an taxonomic group from other groups and is assumed to have newly evolved with the group’s ancestor. For instance, humans are the only primate and mammal that are habitual bipeds. This fact actually encompasses a suite of unique anatomical characteristics (non-opposable big toe, arch in foot, valgus angle, etc. ).

The relativity of the qualities of primitive and derived. • Whether a trait is

The relativity of the qualities of primitive and derived. • Whether a trait is primitive or derived depends upon the taxonomic class under consideration. For instance humans lack tails, but so do apes. Therefore if we are speaking of the genus Homo, lacking a tail is a primitive characteristic. However if we are speaking of the superfamily Hominoidea, a group that includes all apes and humans, then it is a derived characteristic.

The Core Primate Characteristics • Final note: a given primate will not possess all

The Core Primate Characteristics • Final note: a given primate will not possess all characteristics. But it will usually possess most of them. The Senses: Vision Color vision: ripe vs. unripe, depth perception. Stereoscopic/binocular vision: confers depth perception.

Sound and Smell • Enclosed auditory bullae (derived). • Sense of smell varies across

Sound and Smell • Enclosed auditory bullae (derived). • Sense of smell varies across the order, but the more evolved the primate the worse the sense of smell. Lemur’s sense of smell is acute, humans sense of smell is terrible. • In general primates depend more upon vison than the sense of smell.

Hands • Digit opposability (derived) • Independent mobility of digits (varies across the order,

Hands • Digit opposability (derived) • Independent mobility of digits (varies across the order, ours are the most mobile). • Nails instead of claws (derived). • Pentadactly – most primates have five digits. (primitive).

Habitual Posture will vary according to activity (e. g. we sleep horizontally) but “habitual”

Habitual Posture will vary according to activity (e. g. we sleep horizontally) but “habitual” means average posture when awake. • Tendency towards erect body posture. (derived)

The Brain • The neocortex of primates is larger than the same region in

The Brain • The neocortex of primates is larger than the same region in other mammals (derived). • Smelling region is smaller. Primate brains have high energy demands. This Photo by Unknown Author is licensed under CC BY-NC

Dependence upon Social Learning • Social primates are more numerous than solitary primates. Primates

Dependence upon Social Learning • Social primates are more numerous than solitary primates. Primates depend upon learned behavior more than any other animal, and learning happens socially (even virtual learning). Primates have the proven capacity to recognize and distinguish among large numbers of their own species.

Gestation Length Gestation = pregnancy. Two factors figure into gestation length: the size of

Gestation Length Gestation = pregnancy. Two factors figure into gestation length: the size of the animal and the complexity of its’ nervous system. Blue whales are pregnant longer than humans but are not as smart (I think). Humans should be pregnant for longer than they are, but like kangaroos we eject the fetus at nine months because of the limitations of the birth canal and the size of the infant’s head. Human babies are therefore altricial like kittens (but worse!).

Means of Fetal Nourishment • The primate placenta is geared towards delivering high quantities

Means of Fetal Nourishment • The primate placenta is geared towards delivering high quantities of oxygen, iron (necessary for normal brain development), and nutrients, due to the previous points about the brain and gestation. It has unique features that deliver hormones and maternal antibodies to the fetus as well (derived).

Single Births • Primates have evolved to give birth to a single infant (see

Single Births • Primates have evolved to give birth to a single infant (see the foregoing lecture on meiosis). • The reason is to be found in the ramifications of gestation length (preceding topic) and the period of infant dependency (foregoing topic).

Period of Infant Dependency • Given that primate learning occurs socially, given that there

Period of Infant Dependency • Given that primate learning occurs socially, given that there is much to learn, and given that primates take a long time to reach physical and mental maturity the period of an infant’s dependency upon its parents, though variable, is longer than that of other mammals. (derived, and how!). The more complex the nervous system, the longer the period of dependency. Currently both sons are with me now, even though both are in their 20’s, and I finally convinced one to get a checkbook! Both would not have cars if it were not for dear old dad!!!

Parental Investment • A concept in biology of key importance. Parental investment amounts to

Parental Investment • A concept in biology of key importance. Parental investment amounts to all energy that parents expend in an offspring between the formation of sex cells to the end of infant dependency. There is a clear relationship between parental investment and neural complexity.

K- selection and r-selection The brain, pregnancy, and behavioral factors discussed above are inter-related.

K- selection and r-selection The brain, pregnancy, and behavioral factors discussed above are inter-related. Biologists have recognized that this is a complex that varies uniformly across all living things, and constitutes a spectrum. Organisms of low or no neural complexity are said to be r-selected. They exhibit low parental investment, and as a consequence have to produce large numbers of potential offspring. This Photo by Unknown Author is licensed under CC BY-SA-NC

K-selection This Photo by Unknown Author is licensed under CC BY • Primates are

K-selection This Photo by Unknown Author is licensed under CC BY • Primates are the ultimate K-selected order, and within the primate order we are the ultimate K-selected species. We produce a small number offspring and invest huge amounts of energy in them. • These are the necessary pathways towards successfully achieving fitness. This Photo by Unknown Author is licensed under CC BY