human bio - evidence for evolution + hominid evolutionary trends

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103 Terms

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nuclear DNA

  • all living things use same DNA code

  • seq of bases varies

  • species more distantly related, more diffs in seq

  • species closely relates, less diffs in seq

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DNA sequencing

The determination of the precise order of nucleotides in a sample of DNA

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introns

  • non coding seqs of DNS that have no apparent function + seem to serve no purpose

  • e.g endogenous retroviruses

  • more closely related species, have more introns in common

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endogenous retroviruses

a viral sequence that has become part of an organism’s DNA

  • store genetic info as RNA

  • RNA genome copied into DNA when it enters a cell in reverse transcription

  • DNA becomes inserted into one host cells chromosome + passed to next gen

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mitochondrial DNA

  • small, circular molecules

  • inherited only from mum

  • mtDNA comparisons uses to compare organisms w/in a species or closely related species

  • closely related may share identical mtDNA

  • if very diff, last common maternal ancestor lived long ago

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autonomy as an ethical consideration for genetic info

respect for the right to be self-determining + to choose whether or not to be tested and, if tested, to know + share the info. It also includes the right of an individual to decide their own future, independent of genetic info

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confidentiality as an ethical consideration for genetic info

the use of genetic information is treated sensitively, + is accessed only by those who are authorised.

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equity as an ethical consideration for genetic info

the right to fair + equal treatment regardless of genetic information.

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privacy as an ethical consideration for genetic info

the right to be ‘left alone’ + to make decisions regarding genetic testing + the resulting information, independent of others

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comparative protein studies

comparison of types + seqs of A.A making up a protein

  • longer the period of time, greater the no. of A.A that would be diff

  • animals of same species have identical A.A seq

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ubiquitous proteins

one of a group of proteins that appears to be in all species from bacteria to humans e.g cytochrome C

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cytochome C

  • has changed v little over millions of years

  • 104 A.A in humans

  • 37 of the A.A in cytochrome C found in same spot of every sequenced cytochrome C, regardless of species

  • more similar the A.A seq, more recently they evolved from a C.A

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bioinformatics

use of computers to describe the molecular components of living things

  • it is a multidisciplinary field

  • uses biochemical analysis to gain info abt DNA + proteins + computer software to store + analyse it

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multidisciplinary field

combines all areas of biological science w/ computer science, engineering, statistics + applied mathematics to help understand biological processes

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what is bioinformatics used for

  • Useful in tracing the evolution of a large no. of organisms by measuring changes in their DNA

  • more similar the genes, more closely related

  • can compare entire genomes

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how are genes in a DNA seq identified in bioinformatics

through a process called annotation which needs to be computerised as more genomes are too large to be annotated by hand

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fossil

any preserved trace left by an organism that lived long ago e.g bones, teeth

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what can fossils show

how species evolved + determine relatedness

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what conditions are required to create a fossil

  • soil w/ no oxygen, as oxygen allows preservation

  • alkaline soil, as it allows minerals in bones to not be dissolved

  • rapid burial that prevents decomposition + no invasion from micro organisms

  • hard body parts

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examples of places where fossilisation can occur

  • being buried by drifting sand, mud deposited by rivers + volcanic ash

  • if a cave wall containing limestone collapses and covers bodies of animals

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problems w/ the fossil record

  • incomplete due to specific conditions needed for fossilisation

  • fossils may not have formed + most fossils are undiscovered

  • dating fossils is challenging; carbon dating only accurate up to 60000 years + other methods require specific surrounding conditions

  • fossils finds often incomplete which requires reconstruction + fragments are subject to interpretation

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relative dating

determining the age of a fossil or artefact in comparison to smth else

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stratigraphy

the study of layers/strata of rock

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principle of superposition

layers at the top of sedimentary rock are younger than those beneath them

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correlation of rock strata

the process of matching layers of rock from diff locations

  • movement of earth’s crust makes this difficult

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index fossils

fossils of organisms that were widely distributed + were present on earth for only a limited period of time

  • will only be found in 1 rock strata

  • these fossils are used to correlate strata

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absolute dating

determining the actual age of the specimen years

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isotope

atoms w/ the same no. of proteins but diff no. of neutrons

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radioactive isotopes

atoms that contain an unstable combo of neutrons + protons or excess energy in their nucleus

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radioactive decay

atoms w/ an unstable nucleus regain stability by excess particles + energy in the form of radiation

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half life

the time required for half of the radioactive material to decay into stable non radioactive material

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potassium argon dating

  • K-ar dating is based on the decay of potassium 40 to form calcium + argon 40

  • slow but steady decay

  • half life = 1.25 billion years

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limitations of potassium argon dating

  • can only date volcanic rock or rock that contains potassium

  • can only date volcanic rocks older than 200000 years

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carbon 14 dating

  • the decay of carbon 14 to nitrogen 14

  • half life is 5730 ± 40 years

  • ratio of C14 to C12 can be estimated + the age of the sample can be calculated

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limitations of carbon 14 dating

  • normal method requires at least 3g of organic material (AMS radiocarbon dating has enabled samples as small as 100 micrograms)

  • cannot be used to date back more than 60000 years

  • must contain organic compounds

  • ratio of C14 to C12 in atmosphere was thought to be constant but we now know amount of C14 in atmosphere varies

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phylogenetic tree

a diagram showing evolutionary relationships between related organisms

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characteristics of phylogenetic tree

  • ancestral organism = base of the tree

  • organisms derived from ancestor = branches

  • closer related = branches close to one another

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what are phylogenetic trees useful for

representing relationships as well as organising knowledge of genetic diversity + structural classifications

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what order are humans

primates

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what family are humans

hominid

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what tribe are humans

hominin

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what genus are humans

homo

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what species are humans

sapiens

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characteristics of primates

  • pentadactyl

  • nails

  • grasping fingers + toes, w/ friction ridges for gripping

  • opposable thumb

  • forward facing 3D vision

  • most able to distinguish colour

  • very poor sense of smell

  • 4 incisors in lower + upper jaw

  • large + complex brain

  • cerebrum size inc as primates evolve more

  • rhythmical sexual cycle

  • long period of parental care

  • usually one offspring at a time

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why was there a change from quadrupedalism to bipedalism

  • climate become cooler + dryer

  • trees became widely separated

  • had to leave the trees and move across great grasslands to seek out resources

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how has the foramen magnum evolved

  • from apes to humans it has moved forward to become more central

  • this allows skull to balance on top of vertebral column

  • apes used large neck muscles to hold brain in place, but we use vertebral column, so it needed to become more central

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how has the curvature of spinal column evolved

  • apes had a C shaped curve

  • now we have a S shaped curve

  • the lumbar have become wedge shaped to allow the S shape

  • this allows an upright position + head to balance on top of neck

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evolution of the jaw

  • apes had a prognathic jaw

  • humans have a flatter face w/a smaller jaw + reduced prognathism

  • this is to allow skull to balance on top of spine + achieve balance

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evolution of the pelvis

  • apes had a long + narrow pelvis

  • humans have a short, broad + bowl shaped pelvis

  • this is to support abdominal organs + foetus during pregnancy

  • also provides stability for bipedal locomotion

  • broad hip bone also allows attachment of buttock muscles to move the legs + keep upper body erect

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the femur/carrying angle in apes

  • femur attached directly to pelvis

  • has a very little carrying angle

  • weight tends to not fall outside of femur

  • less stability when standing bipedally

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the femur/carrying angle in humans

  • head of femur fits into acetabulum of the pelvis

  • femur tends to converge towards the knees

  • this creates a carrying angle, which allows weight distribution to stay close to the central axis of the body

  • allows weight of body to be transferred from pelvis to legs

  • allows greater stability in upright posture + when walking enables body to be rotated at lower leg + foot and each step has a straight line

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acetabulum

hip socket of the pelvis

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the knee in apes

  • body weight transmitted to inside of the knee

  • this is less strong, so the medial condyle (inside) serves as a stronger point

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the knee in humans

  • body weight transmitted down the outside of the knee

  • this makes the lateral condyle (outside) become stronger

  • this produces a joint that requires no energy to support body in a standing position + body weight

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the foot in apes

  • abducted/splayed big toe

  • flat foot w/only longitudinal arch

  • relatively smaller calcaneous (heel) + talus (ankle) bones

  • this does not support bipedalism

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the foot in humans

  • adducted, robust big toe

  • the metatarsals are arranged in a way to form a longitudinal + transverse arch

  • this enables bipedalism

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apes centre of gravity

  • arms longer than legs

  • higher centre of gravity at the chest

  • this allows for quadrupedalism

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humans centre of gravity

  • legs longer than arms

  • this increases the length of the stride when walking

  • this lowers the centre of gravity to the pelvis

  • this allows stability when moving bipedally or standing erect

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humans muscle tone

the muscles that move the spine, hip, knee + ankle are partially

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muscle tone

the partial contraction of skeletal muscles

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apes striding gait

  • apes lack wide pelvis + carrying angle

  • this means they sway from side to side when walking bipedally so that the weight is over each leg in turn

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humans striding gait

  • when the foot hits the ground, weight transmitted from the heel along the outside of the foot via the transverse arch

  • at final moment of walk, whole weight of body is propelled by big toe via longitudinal arch

  • forward arm swinging keeps shoulders at right angles + red energy expelled

  • foot steps follow a straight line

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striding gait

walking upright in a way that the hip + knee are fully extended

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advantages to bipedalism

  • is a more energy-efficient means of moving.

  • leaves the hands free to use tools.

  • leaves the hands free to carry items.

  • The upright stance achieves greater height, thus the ability to see further.

  • The upright stance means that less of the body is exposed to sunlight.

  • The upright stance inc exposure to breezes, inc cooling mechanisms.

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relative size of cerebal cortex evolution

  • brain size has inc due to inc size of cerebrum

  • would have inc due to nat selection of using visual + tactile perception in arboreal env’t to locate food

  • brains of hominids are highly convoluted which inc S.A, and therefore cerebral cortex

  • inc in size of cerebral cortex also allows greater variety of behaviours to meet env’t problems e.g interactions w/allies + grooming

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mobility of digits evolution

  • pentadactyl limbs

  • digits are highly mobile

  • prehensile digits were essential for climbing in arboreal env’t

  • however, has evolved into inc ability to move digits independently of one another

  • thumb is opposable but not our big toe as we are weight bearing

  • having opposable thumbs allow precision (e.g holding pencil) + power grip

  • however, apes only have power grip as they have short thumbs

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how have digits evolved

  • claws of primates have flattened to become nails

  • this assts w/grasping action

  • development of fingerprints also occurred which inc sensitivity + gripping ability

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locomotion evolution

change from quadrupedalism to bipedalism

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prognathism + dentition in apes

  • primitive mammals had 44 teeth + dental formula of 3:1:4:3, meaning 3 incisors, 1 canine, 4 premolars + 3 molars on each side of jaw

  • some old monkeys used to have large canines + a diastema

  • teeth were in a U shape

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prognathism + dentition in humans

  • have 32 teeth + dental formula of 2:1:2:3, meaning 2 incisors, 1 canine, 2 pre molars + 3 molars on either side of jaw

  • no diastema

  • has evolved into a parabolic shape

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prognathism + brow ridges in apes

  • had a forward cutting, prognathic jaw + a distinct brow ridge

  • brow ridge located above the eye sockets

  • tooth size was a lot larger

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prognathism + brow ridges in humans

  • prognathic jaw has dec over time

  • teeth have become smaller, leading to a flatter face + development of a chin + prominent nose

  • inc size of the frontal lobe means the cranium is extended forward, dec brow ridges

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brachiation

form of arboreal locomotion where by the arms are used to swing from one hold to another

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brachiation - shoulders

  • Shorter clavicle = greater mobility + rotation of the shoulder joint

  • Movement of scapulae (shoulder blades) from side of chest to the back + higher up = larger range of shoulder motion

  • Shoulder socket faces towards the back = allows the humerus to rotate freely in multiple directions = enhances the ability to reach out in various angles + absorb the forces of swinging

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brachiation - arms

  • Longer arms = inc reach, allowing brachiators to span greater distances between branches

  • Flexible elbow joint = allows for smooth extension + flexion during the swing cycle, helping to adjust grip + momentum mid-swing

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brachiation - hands

  • Robust, flexible wrist joint = absorbs the impact forces during branch contact, allows for quick adjustments in hand position, aiding in stability + control

  • Long, curved fingers = grasping branches 

  • Short thumb = red interference during swinging, makes it easier to hook fingers around branches

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how long ago did australopithecines live on earth

3.56 million years

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who discovered the australopithecines fossil + when

Raymond Dart in south Africa in the 1920’s

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features of the australopithecines fossil that indicate bipedal

  • deep impression showing heel hit ground first + where toe used to push off

  • big toe parallel to other digits

  • well developed longitudinal arch

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features that indicate ‘Lucy’ is australopithecus afarensis

  • dental arcades

  • size of canines

  • prominence of cusps on cheek teeth

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features of australopithecines

  • teeth like a hominin

  • canines short + projecting

  • incisors + canines make a row of cutting teeth w/no gap

  • parabolic shape

  • low forehead

  • jaw more upper + lower projecting than modern humans

  • brain size 480cm³

  • body weight 1/3 gorilla

  • brain size between chimpanzees + humans

  • bipedal gait

  • femur, pelvis + carrying angle similar to humans

  • pelvic + foot bone has a non opposable big toe

  • foramen magnum more forward than other apes

  • S shaped spine

  • thumb short + less mobile for arboreal lifestyle

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features of australopithecus afarensis

  • 3.9 and 2.8 million years ago

  • East Africa

  • Female: 105–110 cm

  • Males: 150 cm

  • brain size 430 cm3

  • Low, sloping forehead

  • Prominent brow ridges

  • Short sagittal crest in males

  • Prognathic jaw

  • Small canine teeth (but larger than

    A. africanus)

  • Diastema present

  • Big toe not opposable

  • Long arms, shorter than the legs

  • Long curved fingers + toes

  • Short and wide pelvis

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features of australopithecus africanus

  • 3.2 to 2 million years ago

  • Southern Africa

  • Female: 110 cm

  • Males: 135 cm

  • brain = 480 cm3

  • Slightly arched forehead

  • Smaller brow ridge

  • Prognathic jaw

  • Shorter + smaller incisors + canines

  • Large molar + premolars

  • No diastema

  • Big toe not opposable

  • Long arms, shorter than the legs

  • Some curvature of finger + toe bones

  • Short + wide pelvis, less rounded than in modern humans

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skull characteristics in apes

  • Thicker bones forming cranium

  • Face large compared to cranial size

  • Smaller cranial capacity

  • Heavier brow ridges

  • No forehead or sloping forehead

  • Lower cranium

  • Less prominent cheek bones

  • Possible saggital crest on top of skull

  • Foramen magnum towards back of skull

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skull characteristics in humans

  • Thinner bones forming cranium

  • Face small compared to cranial size

  • Larger cranial capacity

  • Brow ridges red or absent

  • Inc larger + more vertical forehead

  • More dome-shaped cranium

  • More prominent cheek bones

  • No crest on top of skull

  • Foramen magnum under centre of skull

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mandible + teeth characteristics in apes

  • More prognathic jaw

  • Larger jaw

  • Heavier, thicker mandible

  • No chin

  • Larger teeth, especially molars

  • Diastema present

  • Canine teeth more prominent

  • Difference between size of incisors and

molars

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mandible + teeth characteristics in humans

  • Flatter face

  • Smaller jaw

  • More slender, thinner mandible

  • Inc definite chin

  • Smaller teeth

  • No diastema

  • Canine teeth less prominent

  • More even teeth/little diff in size of incisors + molars

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torso characteristics in apes

  • narrower pelvis

  • back vertebrae less wedge shaped

  • wide, barrel shaped rib cage

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torso characteristics in humans

  • broader pelvis

  • lumbar vertebrae more wedge shaped

  • smaller ribcage

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upper limbs characteristics in apes

  • shorter thumb that is less mobile

  • fingers longer + more curved

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upper limbs characteristics in humans

  • longer thumb with inc opposability

  • fingers straighter + shorter

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lower limbs characteristics in apes

  • femurs more parallel

  • arms longer than legs

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lower limbs characteristics in humans

  • femurs sloping inwards towards the knee

  • arms shorter than legs

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when was the paranthropus robustus fossil found

in 1938 by robert broom

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features of paranthropus robustus

  • females' height of approximately 1 m + males’ height of

    approximately 1.2 m

  • existed 1.8 to 1.2 million years ago

  • found in south africa

  • cranial capacity of 520 cm3

  • large sagittal crest for attachment of strong chewing muscles

  • very large molars and premolars, with small incisors and

    canines by comparison

  • prognathism, although less than australopithecines

  • wide, dish-shaped face with large zygomatic arches

  • heavy brow ridges

  • structures for bipedalism.

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when was homo habillis found

in 1964 by Dr Louis Leakey

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features of homo habillis

  • existed 2.3 to 1.5 million years ago

  • found in south africa

  • females’ height of 110 cm + males’ height of 130 cm

  • brain size of 610 cm3

  • rounder skull

  • small brow ridge

  • central foramen magnum

  • moderate prognathism

  • teeth arranged in a rounder arc

  • relatively short legs and long arms

  • slightly curved finger bones, indicating a

    strong power grip

  • able to form a precision grip

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when was homo erectus found

in 1927 by Dr Davidson Black. first fossil found to show modern human like bodies

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features of homo erectus

  • existed 1.9 mill years ago to 110000 years ago

  • in africa, asia + maybe europe

  • varied height, ranging from 145 cm to 185 cm

  • short, stocky body with thicker bones, suggesting a demanding lifestyle

  • average cranial capacity of 1050 cm3

  • low, sloping forehead

  • defined brow ridges

  • large, thick jaw without a chin

  • red size of molars

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when was homo neanderthalensis found

in 1856 in neander valley