Trends in hominin evolution

Question 1

what are the trends in hominin evolution

Answer 1

bipedalism, changes in limb structure, feet became longer and arched, brains enlarged, faces shortened and flattened, jaws and teeth became smaller

Question 2

what is the trend in bipedalism

Answer 2

7mya, our early ancestors walks on 4 legs, 5 mya walked on twp ;egs but retained features for climbing trees, 1.8 mya long legs and ability to run

Question 3

what is the evidence/consequences of bipedalism

Answer 3

foramen magnum, spine, angle of the femur, pelvis, foot efidence, longer legs and shorter arms

Question 4

foramun magnum

Answer 4

an opending on the underside of the cranium where the spinal cord enters the cranium

Question 5

how is the foramen magnum evidence of bipedalism

Answer 5

in bipedal organisms, the foramen magnum sits more towards the front of the cranium whereas in quadrupedal organisms, it sits more towards the back of the cranium

Question 6

how is the spine evidence for bipedalism/how has it changed

Answer 6

the lower part of the spine has become s shaped, therefore the head balances on top of the spine

Question 7

has has the spine changed in hominin evolution

Answer 7

the lower part of the spine has become s shaped so that the head balances on the top of the spine

Question 8

how has the femur changed in hominin evolution

Answer 8

the femur became more angeled out from the tibia which means that knees and feet are directly undr the bodys centre of gravity, gives balnce

Question 9

how have feet changed in hominin evolution

Answer 9

has arches, foott lost its prehensile capacity, developed heel that acts as a shock absorber

Question 10

how have changes iin our feet assisted in bipedelism

Answer 10

when a human foot preesses to the ground during walking, weight is transferred progressively forward and across the foot via the arches, the big toe then pushes off to lauch the next step

Question 11

how has the pelvis changed acroos hominin evolution

Answer 11

it has become shorter and bowl shapeed (wider)

Question 12

how does a short and wide pelvis assist in walking

Answer 12

the shape allows for balancing on one leg (required when walking) and allows for balance, straight walking

Question 13

what is the other consequence of a short and wide pelvis

Answer 13

a large pelvis means a longer gestation period, so babies are now born premature as they must be smaller

Question 14

what are the advantages of bipedalism/why did this develop

Answer 14

easier to view objects at a distance, reduced absorption of heat, ability to walk greeater distances when searching for food

Question 15

why does bidepalism result in reduced heat absorbtion

Answer 15

there is a smaller surface is exposed to direct sunlight (not full back)

Question 16

what were the changes in limb structure of hominins

Answer 16

longer legs and shorter arms

Question 17

why did hominins develop longer legs

Answer 17

longer legs were selected for in bipedals due to positively affecting affecting stride length and making walking more energy efficient

Question 18

why did hominins devvelop shorter arms

Answer 18

forelimbs were no longer in contact with the external environment during movement, freeing arms for other uses

Question 19

trends in the general morphology of skulls of hominins

Answer 19

centralised foramen magnum, increased cranial capacity, teeth, flattening of face, shrinking of sigital crest

Question 20

how has the cranial capcity of hominins changed

Answer 20

increased in size, for homo sapiens there cranial capacity is larger than what would be expected for their body mass

Question 21

what does an increased cranial capcity provid evidence of

Answer 21

increased brain size and therfore intelligence

Question 22

how has tthe cranial capacity increase been cotradicted

Answer 22

the average cranial capacity of the neanderthals was larger than that of modern humans

Question 23

how has the increased bidepalism been contradicted

Answer 23

because homo erectus were likely even more efficient bipeds than modern humans

Question 24

how have teeth changed across hominin evolution

Answer 24

gooot smaller, dental arcade is rounder not U shaped

Question 25

how has the face structure changed in hominins

Answer 25

flattening of face, decreased brow ridge, less protrouding chin