Human Evolution

foramen magnum

positioned further under skull so that the head is balanced better on the spine

spine curves

thoracic is backwards, lumbar forwards, keeps trunk centered above the pelvis

pelvis

shaped more in form of basin, shorter and squatter

why is the pelvis shaped the way it is?

supports internal organs and stabilizes weight transmission

lower limbs

elongated, longer than arms

femur

angled inwards, keeping the legs more directly under the body

what is the angle on the femur called

valgus angle

big toe

enlarged and brought in line with the other toes

what does the big toe create

distinct longitudinal arch on feet

what is CP3

built in sharpener for canines, bottom premolars rub against the canine

do hominins have CP3

they have evidence of CP3 but it does not work

what are some benefits of bipedalism

energy efficient, can carry tools and infants, can travel between trees or see over grass, provisioning

how to recognize a hominin in the fossil record

jaw shape, bipedalism, no Cp3

pre-australopithecines, 7mya-4mya

all found in Africa, closest to the great apes will have closest traits to great apes

what is the earliest pre-australophithecine

sahelanthropus tchadensis

what is the second earliest pre-australopithecine

orrorin tugenesis

what is the third earliest pre-australopithecine

ardipethicus kadabba and ramidus

sahelanthropus tchadensis facts

oldest hominin, foramen magnum, large browridge, small brain size, no diastema

orrorin tugensis

has large, more ape-like canine, fragmentary cranial and post cranial remains

ardipithecus kadabba

has curvature finger bones, lived in wooded environment

ardipithecus ramidus

face is not as projecting as a chimp, but more projecting than later hominin, tree climber and bipedal

primitive

traits passed down by ancestors

derived

new traits in group

austrolopithecus group

only found in Africa, range in size from 64-100 lbs, moderate prognathism. mixture of primitive and derived traits

olduvai gorge

oldest archaeological site, used to have water

australopithecus anamensis

U shaped jaw, found in Kenya, not a lot of fossils but important parts

australopithecus afarensis

morphology of fossil is female (Lucy), 425 cc brain size

australopithecus garhi

primitive, small brain, large canines, sagittal crest, maybe early tool use

australopithecus africanus

only found in South Africa, 3.5-2.0 mya

homo habilis

“handy man”, earliest stone tool user, Oldowan tools

Oldowan tools

anything older than 1.7 mya

manuports

carried by man. carrying from place to place

hammerstone

stone used as a hammer. specific divets

core form

creates flakes

flakes

from core forms

Developed Oldowan Tool Industry

main difference is that tools are bifacial

homo erectus

1.8 mya, tall, long-limbed, pelvis narrow, increase in cranial capacity

Acheulian Tools

better made, more variety

gracile australopithecines cranial capacity

420 cc

robust australopithecine cranial capacity

520 cc

homo habilis cranial capacity

631 cc

homo erectus cranial capacity

900 cc

four pathways out of Africa

Morocco into Spain, Tunisia into Italy, Egypt into Israel, Ethiopia into Yemen

homo erectus MOST LIKELY

first meat eater and fire user

dispersal out of africa

demographic pressure, environmental change, opening of new niches, decrease in viable catchment sites

demographic change

unable to find food due to change, following resource

opening of new niches

uninhabitable land and environmental change equal habitable area.

decrease in viable catchmen sites

decrease in area with quality resources

how could they survive after leaving Africa

social groups, less specialized, Acheulian tools

habitat specific hypothesis

explains the appearance of adaptation due to the need to meet the demands of the environment

savannah hypothesis

expansion of savannah landscape

the ice age hypothesis

large and mini ice age can affect the way hominin survive

the woodland/forest hypothesis

expands/shrinks, different groups will survive

variability hypothesis

changes occur in species due to variability in the environment

short-term variability

adapt seasonally

long-term variability

adapt to long term change

homo heidelbergensis (archaic homo sapiens)

700,000 ya, Africa, Europe, and Asia.

homo heidelbergensis (archaic homo sapiens) DECREASES

size of molars, cranial robusticity, post-cranial robusticity

homo heidelbergensis (archaic homo sapiens) INCREASES

brain expansion, change in skull shape

bipedality is NOT

a trend

behaviours of archaic homo sapiens

built shelters, diverse diet, hunted, created hunting tools

Neandertals

400,00-40,000 ya. Only Europe and Western Asia

Neandertals traits

brain is larger than modern humans, possible they had speech, possible higher pain tolerance.

Neandertals physical traits

barrel chest, femurs more curved, bigger rib cage, more arch in feet

what did Neandertals do with their dead

they buried them, we know because we find them in peculiar positions

modern humans are

more culturally adept, usage of tools

modern humans have

more gracile skeleton, lessy heavy musculature, larger brain

cranial features

small teeth, high domed forehead, well arched parietals, no projecting nasal region

regional continuity model (least likely)

gene flow between populations, evolution to modern humans happened different times + places

why is regional continuity least likely

model does not work because homo erectus not in Europe, however, model can potentially explain genetic drift

potential replacement model (most likely)

modern humans evolved and left Africa at least 100,000 ya.

why is potential replacement model most likely

modern humans eventually replace archaic homo sapiens

Jebel Irhoud, Morocco

earliest homo sapies

Australia

populated at least 40,000 ya

Americas (New World)

greater than 13,000 ya

Pacific Islands

3500 ya