Traits
Mammalian Characteristics
- females give birth to live young
- having hair/fur
- females breastfeed young
all mammals have these traits from a common ancestor
1. Forward Facing Eyes
(as opposed to, for example, eyes at the side of your head)
eyes at the front of your face ---> no peripheral vision, but we do have overlapping visual fields that give depth perception
6. Smell
Energy trade-off with vision: Primate vision is very detailed, meaning more energy is spent on vision and smell is of lesser importance
we have smaller snouts in comparison to other animals
Life History
speed of aging, reproduction, growth; usually correlated to body size
for primates:
- long juvenile period allows for learning things like social behaviors rather than just reliance on instincts that other animals have
- single births rather than litters allow for high probability of survival into adulthood due to attention given to young
Diurnal vs. Nocturnal vs. Cathemeral
Diurnal: active during the day
Nocturnal: active during the night
Cathemeral: active throughout the 24h cycle
Primitive Traits
Ancestral traits; traits a TAXON inherits from a common distant ancestor
Ex: body hair in primates
2. Postorbital Bar
A bony ring that surrounds the eye socket, protects eyes from chewing muscles
7. Evolutionary Trade-Offs
when lots of energy is spent on one trait, others will be a bit neglected
Ex: smell in humans
Heterodont vs. Homodont
Heterodont: having multiple types of teeth for specific purposes
Homodont: having one type of tooth
1. Vertical Clinging and Leaping
when animal holds vertical branch and them jumps to another vertical branch using back legs to push off
because of this, they usually have longer legs than arms, and large hands for grasping trees
Derived Homologies vs. Autapomorphies
DH: Traits that have been recently evolved (indicating common ancestry)
Ex: humans walking upright on two feet
Auta: traits unique to a taxon
3. Trichromatic Vision
Ability to see reds, yellows, blues, greens
(most animals are dichromatic, or only see blues + greens, which is great for night vision rather than day)
This is an evolutionary trade-off, as primates are either trichromatic (to see how ripe fruit is) or nocturnal (eat insects))
Arboreal vs. Terrestrial
Arboreal: (to do with trees) primates generally spend a lot of time in trees, this evolved hands + feet for a 3D environment
Terrestrial: (on the ground) like dogs/horses and their paws/hooves
Not just primates vs. non-primates! some are terrestrial
Canine Size
often sexually dimorphic, meaning that males have bigger canines than females
2. Quadrupedalism
Most common among primates
walking on all fours
because of this, legs and arms are of equal length, and they use tail for balance
Generalized Traits
Traits that are useful in many ways, for many things
Ex: thumbs that bend in a different way to the rest of the fingers
4. Brain Size
we have relatively large brain size, when compared to total body size (twice as large as expected for our body size)
Opposable Thumbs/Toes
ability to touch pad of thumb to any other finger, which gives the ability to grasp things, which in turn gives the ability to climb and make and use tools
Also evolved because primates grab food and bring it to our mouths rather than just eating like a horse
Furgivores
Primate diet that consists of mostly fruit for sugar + vitamins, gets protein from seeds, insects, leaves
Are medium sized, as that is the growth the caloric intake can support
3. Brachiation
only apes do this
swinging from horizontal branch to horizontal branch
long arms, flexible shoulders and wrists, short lower back, no tail
Specialized Traits
Traits that serve one purpose
Ex: our teeth were developed to much more easily chew food
5. Neocortex
front part of brain, where the more complex brain functions take place (like decision making)
Primates have very complex (wrinkly) brains, allowing for much more to go on up there)
Folivore
Primate diet that consists of mostly leaves
Usually the largest primates, as they spend most of the time digesting difficult to break down, semi-poisonous leaves with their complex digestive systems and stomachs
Insectivores
Primate diet that consists mainly of insects
Trade-off: they have to chase and catch insects, they don't want to spend more energy that they can obtain, thus they are small in size as insects can only provide so much nutrients
4. Bipedalism
moving upright on two feet
humans are the only primates that are habitually bipedal