Shared Traits of Primates Professor Janaki Natalie Parikh

Primate Derived Traits 1. Stereoscopic vision: overlapping field of vision from both eyes due to placement, what type of image? 3-D image, depth perception Since primates rely most heavily upon sense of vision, we have skeletal protection surrounding the eyes

Primate Derived Traits cont’d 2. reduced prognathism: reduced snout 3. Prehensile hands, feet & (sometimes) tail: What is prehensility? Grasping ability 4. reduction of claws to fingernails 5. increased complexity of cerebral cortex Results in: -increased intelligence

Primate derived traits (Results in cont’d) (increased complex. of cerebral cortex offshots cont’d) -increased play behavior -extended gestation, meaning? -REALLY long pregnancies relative to sz. of newborn, comparison w/ blue whale (9 ½ mos. vs. ~12mos.) To support this longer pregnancy, it would require? -increased development of the placenta 6. decreased litter size: (typically singletons)

Evolutionary reproductive strategies K-selection: organism has FEW offspring, but tremendous parental investment (environ. near carrying capacity) r-selection: organism invests energy into production of MANY offpsring, ltl or no parental investment Humans (& primates in gen. utilize which of these?) K-selection (w/ the following poss. exception…) R-selecting organisms? r-selectionK-selection

Primate derived traits cont’d 7. altricial young: what can our newborns do? Not much! They’re rather helpless & have a long period of infant dependancy 8. live in complex social groups: not simply a “bonus”, social interaction is actually crucial for our young to survive & thrive

Selection theories (derived traits) 1. Arboreal hypothesis (splat hypoth.) : arbor means? Tree. Suggests that primate derived traits provided an advantage to adapting to & living in the trees. Sounds plausible. Prob’s/Criticisms? Tree squirrels: well adapted to the trees, but don’t have the derived features of primates 2. Visual Predation hypothesis: focuses on what earliest primates were doing in the trees…hunting

Shared ancestral traits (not used as basis of taxonom. classification) 1. pentadactyly: penta means? Five. presence of 5 digits on hands & feet 2. generalized dentition: we’re heterodonts, meaning? Many different kinds of teeth in our mouths, how many? Primates have 4. As opposed to sharks (homodonts) Those 4 are called? Incisors.

Ancestral traits cont’d Incisors: Canines: Premolars: Molars. Dental formula: how many of ea. kind per quadrant 2:1:2:3. Full set in humans = 32 (once “wisdom” teeth have come in) 3. clavicle: commonly referred to as? Collarbone. Maintains distance btwn the scapula (shoulder blade) & sternum

Socio-ecology of primates: diet & size Primates are homeotherms: narrow range of internal body temp. comfort, (slight change considered?) As organism gets bigger, it’s ratio of surface area to volume decreases…(implications in plain English) Larger animals: produce more body heat Smaller animals: more surface area, thus body heat escapes quickly, have prob’s keeping warm Has implications in terms of relative quantity of food Who eats more (relatively speaking?)

Smaller animals eat more in order to pwr their metabolisms, which generate heat to keep warm. They eat less in absolute terms, but more in relation to size (may consume its own weight in food in a day!) Smaller animals also require foods that are higher in calories, while larger animals can’t process the calories 26_FinFat&utm_content=003A000000ommjJIAQ&utm_source=VerticalResponse&utm_m edium= &utm_term=read%20the%20whole%20report&utm_campaign=How%20fat %20is%20{State|your%20state}%3F 26_FinFat&utm_content=003A000000ommjJIAQ&utm_source=VerticalResponse&utm_m edium= &utm_term=read%20the%20whole%20report&utm_campaign=How%20fat %20is%20{State|your%20state}%3F