Ch. 17 Primate Evolution Flashcards
define primate
a member of an order of mammals that includes the lemurs, lorises, tarsiers, monkeys, apes and humans
define binomial system
the system of naming organisms using generic (genus) and specific (species) names to describe a species
define hierarchy
: a series of groups that move from broad general categories to narrow specific ones
what are the movement of going down the hierarchal pyramid
Kingdom (Plant/Animal) > Phyla (Phylum) > Classes > Order
what were the early classifications of priamtes
o Prosimians (primitive primates) and anthropoids (monkeys, humans and apes)
what are the suborders of primates
o Strepsirrhini (non tarsier prosimians) and Haplorrhini (tarriers, monkeys, apes and humans)
what do most primate characteristics due to
arboreal lifestyle
what are the 8 common characteristics of primates
brain eyes smell teeth body limbs hand feet reproduction
What are the four areas of evolution of the digits
Mobility and opposability
tactile pads
nails
arrangement of hand
what does the fact that limbs are not specialed result in
diversity in use
what was the mobility trend of digits
increasing mobility ability to move digits independently of one another
what is prehensility important for primates
gripping trees
what is the most developed digit
- thumb and big toe
what does opposability mean and what does it depend on
o Opposable= ability to use thumb to touch the tips of each other digit on the hand
o Degree of opposability depends on relative length of first digits compared with other four
why did humans loose opposability of big toe
o All species bar humans= opposable big toe
♣ Lost opposability when human foot became a weight-bearing rather than grasping appendage
what does humans having longest thumb result in
o Humans= longest thumb of primates= contribute to ability to manipulate objects with our hands
explain tactile pads in evolution
- Ends of digits= sense receptors so that digits can grip and manipulate objects
- Nails and tactile pads on under surface= evolved together
o Pads developed small ridges to increase grip b/w ends of digit and object
♣ = friction ridges, finger prints= pattern varies b/w individuals and species
why did claws evolve into nails
- Claws limit grasping= prevent opposable surfaces from coming together
o Nails evolved from claws that became flattened
o Evolutionary less advanced primates still possess claws
explain had arrangement of humans
- Human hand compared to other primates= short and broad, with short straight fingers and long strong thumb
wha does the arrangement of the human hand allow
- This arrangement= great degree of freedom for thumb and can readily oppose other digits= allowing precision grip= one of the hallmarks of being human, though not unique to humans
- What is unique amount of contact b/w index and thumb
o Enables effective handling of small or delicate objects
o Precision grip also seen in old world monkeys (requires truly opposable thumb)
♣ These monkey= 2nd only to humans in manipulation abilities
What are the 4 areas of evolution for dentition
number of teeth
structure
diastema
cusps
what is the evolution of number of teeth
decrease- o Probs related to gradual reduction in size of face and jaw that has occurred in primates
explain dental comb
- Lemurs and lorises= unusual specialisation of incisor teeth= lower front incisors= slanted forward with crowns= narrow + closely spaced to form dental comb
o Used for grooming fur, only rarely for feeding/fighting
what is the trend in cusps
3 > 4 > 5
explain the olfactory/occiptial shift
- Arboreal life= emphasis on vision (with decreasing reliance on sense of smell, olfaction)
- = Shift in sensory orientation
what was the shift in vision accompanied by
- accompanied by overall change in shape of skull compared with other mammals
o I.e. decrease smell= reduced snout > allows for more forward facing eyes > better stereoscopic vision
how is observable behaviour linked to shift of vision
o E.g. lemurs= use their snout and teeth for what apes use eyes and hands for (investigating an object, grooming, communicating)
difference between mammals and primates in eye sockets
- Most mammals have eye socket that face sideways, but primates developed eye sockets that face forward
what does forward facing eyes allow
o Enables fields of vision of each eye to overlap= distances judged accurately
o = important adaption for a tree living animals
how do primates compensate for narrow vision
a highly mobile head and neck
explain eye socket and protection
- As eyes become more forward= bony eye socket developed to give protection
o Gradual change in eye socket clearly visible in fossil primate skulls
o As position of eye socket changed for eyes to face forward, bone gradually closed in side and rear of socket
what are the four areas of evolution for vision
shift
eyes
eye socket
visual area of brain
explain increase in area of vision in brain
- Increasing importance of vision= region of brain concerned with interpretation of visual information increased in size
o While that concerned with olfaction decreased - Unlike smell or hearing, reliance on vision to move about, locate and manipulate food generates large amount of complex sensory information that has to be processed and stored
what are the three areas of evolution of the cereal cortex
size
convolutions
cerebral cortex (higher order)
what are the five areas of evolution and gestation and parental care
single offspring
placental mammals
length of gestation
sexual maturity
what does increase length in development and delayed sexual maturity result in
- Enables ideas and techniques to be passed on from one generation to the next
- Delay in maturation + sexual maturity = reduce # of offspring female has in lifetime
o // each offspring important, + time and effort invested in care and survival
o Investment in prolonged parental care evolved because increases survival chances of offspring and provides a long period during which the young can learn from older members of the group
