Transcript Human Evolution

Van Roekel IB BIO II
4/22/14
 Use
radioisotopes 14C, 40K, or 238U
 Living organisms and rocks contain
radioisotopes in small quantities
 Stop taking in new carbon products when
dead
 Over time, radioisotopes decay to stable
isotopes
 Using proportion of radioisotopes to
stable isotopes, we can determine the
age
 Half-life
is the amount of time it takes for
half the radioactive isotope in a
substance to decay
•
14C
– 1 half life = 5,730 years
 By
looking at proportion of isotopes, can
get an idea of age of fossils.
• More radioisotopes = younger
• Less radioisotopes = older
 Humans
possess physical features that
define primates
Opposable thumbs allow us to grasp objects
Long, thin, straight fingers to use tools
Finger pads and finger prints
Lack claws, have fingernails
Shoulder sockets increase movement in arms for
greater mobility
• Forward facing eyes which allow for
stereoscopic vision (3-D)
•
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 In
the skull
Anatomical Feature
Ape-like form
Human-like form
Position of the Foramen
Magnum
Towards back of skull
Towards center of base
of skull
Cranial Capacity
Small
Large
Canine Teeth
Long and sharp
Short and Dull
Molars
Long and narrow
Short and wide
Brow Ridge
Protruding
Flat
Face below brow
Protruding
Flat
Jaw
Tall and Thick
Small and Thin
 Ardipithecus
ramidus
• 4.4-5.8 million years ago in Ethiopia
• Close to split between humans and chimps
• Canines shorter, not sharp, less projecting
• Skull fragments indicate bipedalism
 Australopithecus
afarensis
• 2.5-4 million years ago in Eastern Africa
• “Lucy” dated 3.5 million years ago
• Tall lower jaw, large molar teeth, & projecting face
• Cranial capacity 380-430 cm3
 Australopithecus
africanus
• 2.5-3 million years ago in Southern Africa
• Tall, thick lower jaw, large molars and projecting
face
• Cranial capacity 435-530 cm3
 A. afarensis
 A. africanus
 How
do we measure the age of fossils? What
measurement is used and how is it read?
 Radioactive decay/Carbon dating
 Measure the proportion of radioactive
isotopes in a fossil compared to stable
isotopes.
 Then, using an isotope’s Half-life, which is
the amount of time it takes for half the
radioactive isotope in a substance to decay,
we can determine the relative age of the
fossil
 Homo
habilis
• 1.6-2.4 million years ago in Tanzania, Kenya,
Ethiopia, and South Africa
• Flatter face, larger molars, and cranial capacity
600 cm3
 Homo erectus
• 100,000-1.8 million years ago
in Europe, India, China,
Indonesia, and Africa
• Smaller Jaw, Receding
Forehead, large brow ridges,
and smaller molars
• Cranial Capacity 1000 cm3
• First migratory ancestor
because of the spread of
fossils
 Homo
neanderthalensis
• 30,000-200,000 years ago
in Europe and Western
Asia
• “Neanderthal man”
• Smaller jaw, lower
forehead, smaller brow
ridges, and smaller
molars
• Cranial capacity of 1600
cm3
 Homo sapiens
• Archaic forms 70,000-
140,000 years ago in
Africa, Europe, and Asia
• High Forehead, no brow
ridges, flat face, small
molars, very small jaws
• Cranial capacity 1300
cm3
• Developed art in the
form of cave paintings
and technology in form
of finely crafted tools
and weapons
 Dating
techniques show overlapping of
species on Earth
• A. afarensis and A. africanus approximately 3
million years ago
• H. erecuts, H. neanderthalensis, & H. sapiens
approximately 100,000 years ago.
 Gaps
and questions about human evolution
exist because of gaps in fossil record
• Many for some species, few for others
• Characteristics between males, females, and youths
are difficult to interpret
 Problems in accessing fossils
• Physically accessible
• Preservation
• Politically or legally accessible
 Leads to multiple hypothesis with
variations on evolution
different

Bigger brains = more energy
• More foods in diet
• Foods richer in energy and protein
Earliest hominids were foragers, and occasionally eat
meat
 Hominids evolved to hunt in groups and use more
sophisticated tools to increase meat in diet

• Large quantities of animal bones found at sites of early humans

Increase in meat in diet and complexity of tools show
direct correlation between changes in diet and brain
size
• High-protein, high energy foods fulfilled nutritional
requirements of demanding brains
• Bigger brains resulted in better tool making and hunting
techniques to supply more energy
• Practice of cooking food also improved diet and brain capacity
GENETIC EVOLUTION
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Inherited characteristics
passed from parent to
offspring
Body morphology (cranial
capacity, skull shape,
height, etc)
Number of chromosomes
Biochemicals such as blood
proteins
CULTURAL EVOLUTION
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Acquired knowledge and
characteristics passed
within a social group or
family
Language (spoken and
written)
Rituals (ethnic & religious)
Art (sculptures, pottery,
painting)
Technology (hunting,
comfort, food)
Species
Example of
Culture
Tools Developed
H. habilis
Oldowan
• Simple Choppers, scrapers,
and flakes of rock
H. erectus
Acheulian
• Hand axes, cleavers, and picks
H. neanderthalensis
Mousterian
• Large flakes of uniform size
produced from a core then
trimmed to desired tool
H. sapiens
Soultrian
• Delicate blades for knives, and
drills
• Other materials added, bone,
antler and ivory
• Some tools are ceremonial
 As
brain increased, so did complexity of
tools
 Genetic evolution precedes cultural
evolution
 Past 30,000 years, majority of evolution
has been cultural
• Few genetic evolutionary changes
• Many cultural evolutionary changes, such as
languages, rituals, arts, shelters, agricultures, as
well as using metals and obtaining energy
 Cultural
evolution can lag behind genetic
evolution
 Hominid’s brain has been roughly the
same size for 140,000 years
 Major cultural advances haven’t
appeared until 35,000 years ago
 Recently, most changes have been
cultural evolution with much greater
advances without any major genetic
changes.