Evolution of Hominids

what is a hominid

group of classification including all great apes past and present

what are some shared characteristics between all hominids

• large complex brains compared to other primates

• increased cognitive ability

• forward facing eyes

• dental formula of 2:1:2:3

• first digit opposable

What are the difference that occur in hominid species ( list)

• relative size of cerebral cortex

• mobility of digits

• locomotion

• prognathism

what is the trend seen with relative size of cerebral cortex

• cerebrum progessily increasing in size

• cranial capacity increases

what is the function of cerebral cortex and what is the effect of it getting larger

• cerebral cortex is responsible for higher functions such as vision,memory, manipulative ability …

• increase in cerebral cortex means increase in higher functions

compare the average craninal capacity of apes and humans

• apes = 450cm3

• humans = 1350 cm3

define brachiation

form of arboreal locomotion, where animal swings from branch to branch using arms

what has been the trend seen in skulls

• craniums have become more rounded as we go to advanced hominids

• reduced prognathism

• development of chin

what has been the trend seen with mobility of digits in hominids

• increasing ability to move digits independently of other digits

• increased opposability of thumb

why has opposability of big toe in hominins been lost

human foots has become weight bearing for bipedal motion rather than grasping

compare the spine of bipedal and quadrupedal movement

• bipedal is s shaped, positioning centre of mass over feet

• quadrupedal is c shaped, providing support and stability for horizontal movement

where is the foreman magnum located for bipedalism and quadrupedalism

• bipedal: central allowing for skull to balance of vertebral column

• quadrupedal: further back

what type of archs do hominins have compared to other hominids

• hominins have transverse and longitudinal arches

• other hominids only have longitudinal

what type of arch in feet allow of bipedalism

transverse arch

describe the shape of dental arcade of hominis and apes

• hominis have parabolic shape

• apes have u shaped

what has been the trend with prognathism and brow ridges

gradual drecrease in prognthism leading to flat nose and development of chin and prominent nose

describe the dental of an ape

• larger sharper canines that project

• large diastema to accommodate large lower caninces

describe the dental for hominins

• no projecting canines

• even sized canines and incisors

• rounding of teeth

what are the advantages of bipedalism

• more energy efficient

• increases exposure to breezes

• leaves hands free to use tools and carry items

• achieves greater height and ability to see further

what species falls under hominids

humans, chimpanzees, gorillas, bonobos and orangutans

what ape has the more recent shared ancestor with humans

chimpanzees and bonobos

what causes the difference between species of hominids

changes in nucleotide sequences