ANTH 1 Examples of Study Guides

Tags Physics, Gravity

ANTH 1Introduction to Physical Anthropology
Study Guide #3

Last Updated: May 8, 2006

Physics of Stability:

relationship of height of center of gravity (CG) of body relative to width/size of base of support
High CG and small Base = unstable (e.g., ballerina, some floor lamps)
Low CG and large Base = stable (e.g., sumo wrestler, high-chair, some table lamps)

Biomechanical constraints on arboreal locomotion:

branches are narrow, so base of support for a primate is limited
can modify height of CG by: having shorter legs or flexing legs at elbow and knees
can modify width of base of support by moving legs/feet onto a nearby branch

Lack of biomechanical constraints in terrestrial environment:

ground is continuous, so base of support for a primate is unlimited
because there are no limits to the base of support, animals can afford to heighten CG;
Can heighten CG by lengthening legs
advantage of long legs is that speed is a function of:
rate of stride (how often legs move)
length of stride (distance covered by one leg)

Characteristics of all humans (living and fossil) compared to other apes:

The distinctive difference between humans and apes relates to locomotion: humans are bipedal, whereas apes are quadrupedal.

Modifications of skeleton for bipedal walking include:

vertebral column S-shaped with anterior lumbar curve
consequence of curvature is to bring body mass directly above knees and feet at midline
hip modified to balance body over one supporting foot
pelvis curved anteroposteriorly rather than along back of body or from side to side, so
gluteus maximus muscle functions as an extensor of the hip
gluteus medius and minimus are abducters of trunk, keeping the trunk from falling to the unsupported side; in apes these muscles are extensors of the hip
femur modified to bring knees to midline
thus humans have a "carrying angle" that does not equal 90 degrees, whereas in apes the carrying angle=90 degrees
large calf muscles compared to apes
foot modified to bear total body weight, rather than body weight being shared by four limbs as in apes
transverse arch, as seen in all primates, and
longitudinal arch, unique to bipedal hominids
very short toes (not needed for grasping)
big toe bound/adducted to other toes

Another distinctive difference relates to the loss of the honing triad
honing triad:
canines large and projecting;
upper canine honed against lower anterior premolar and lower canine; so worn on anterior and posterior sides
lower canine fits into diastema between upper canine and lateral incisor;
anterior premolar is unicuspid;
large canines in non-human primates used in male-male competition and in establishing dominance heirarchies
human canine complex:
canines look like incisors (incisiform)
canines occlude apically (at top), so worn only apically
no diastema
lower anterior premolar is bicuspid

Plate Tectonics:

Structure of Earth: Core, Mantle, Crust (divided into plates)
Convection currents in mantle, in part, drive movements of plates
In Mesozoic all continents joined into Pangaea - earth warm all over
Division of Pangaea into Gondwanaland and Laurasia; then division of Gondwanaland into S. America & Africa by opening of S. Atlantic, Madagascar breaks off, India heading North towards Laurasia; Laurasia splits into N. America and Eurasia by opening of N. Atlantic; then India smacks into belly of Asia, uplifting Himalaya Mts.

Dating methods:

Assumptions:
Principle of Superposition
strata higher in a column are younger than those lower in the sequence
Principle of Uniformitarianism

Relative methods

Biostratigraphy
Use biological organisms within strata to correlate different sites
Paleomagnetism
the position of the poles have changed through time; we are currently in a Normal Chron but there have also been Reversed Chrons
Flourine dating
bones that are buried at the same time should have equal amounts of flourine in them
used to prove that Piltdown Man was a hoax

Chronometric (aka Absolute) methods

Non-radiometric
dendrochronology (tree ring dating)
1 ring = 1 year
date fossil trees
Varves
lake sediments
varve made up of 2 bands: bottom coarse-grained; top fine-grained
1 varve = 1 year
Radiometric methods
atomic structure
atom made of central nucleus and surrounding shells
nucleus = protons (+ charge) and neutrons (0 charge)
shells = electrons (- charge)
protons and neutrons have mass/weight whereas electrons do not
elements differ from each other in that their atoms have a different number of protons in their nucleus (i.e., atomic number)
the atoms of a particular element (e.g., oxygen, carbon etc.) have the same number of protons (atomic number), but may have different number of neutrons (yielding different atomic weights); if there are variants of an atom they are called ISOTOPES
some isotopes may be unstable and disintegrate over time in to the atom of another element; disintegration occurs by protons capturing an electron and becoming a neutron or by neutrons breaking into protons and electrons; in either case the number of protons changes in the nucleus
the HALF-LIFE of radioactive isotopes refers to the amount of time it takes for one-half of the atoms to decay in to the atoms of another element
Potassium/Argon (40K/40Ar)
half-life = 1.3 by
date volcanic rocks, not fossils themselves
when volcanic rock is hot all the argon in the rock "evaporates" off, so that when the rock cools there is no argon in it; thus, whatever argon is found in a volcanic rock is there because it was produced by potassium decaying in to argon
used to date age of Earth as well as hominid localities
examine the ratio of 40K to 40Ar
Carbon 14 (14C)
half-life = 5730 years
date fossils, not rocks
plants absorb equal amounts of 14C and 12C during their lives; when plants die 14C decays in to nitrogen while 12C remains stable
used to date organic things up to 50 kya
examine the ratio of 14C to 12C

Climate Reconstruction:

Oxygen Isotope Analysis
18O is heavier than 16O; therefore, water (H2O) with 18O is lower in the water column than is water with 16O
microscopic organisms that live in the water column use oxygen in constructing their exoskeletons (shells);
during cold periods when glaciers exist, water is bound up in the ice and the sea level drops
by examining the type of oxygen in the shells of organisms that live near the top of the water column, we can tell whether the period during which they lived was cold or warm

Major Events in Primate Evolution during the Cenozoic:

Paleocene (65-55 mya):
Possible (archaic) primates appear; now considered by many to be non-primates; found in N. America and Europe
Eocene (55-35 mya):
True primates appear, characterized by nails and grasping ability, postorbital bar, stereoscopic vision, large brain
Three groups recognized:
adapids, which are ancestral to living lemurs and lorises, found in N. America, Europe, N. Africa and China
omomyids, which are ancestral to living tarsiers, found in N. America and Europe
possible primitive anthropoids from E. Asia
Oligocene (35-25 mya):
Definitive anthropoids appear, characterized by postorbital closure, closed metopic suture and closed mandibular symphysis, color vision, diurnal life style, sexual dimorphism
Found primarily in Jebel el Qatrani Formation of Fayum, Egypt
New World monkeys appear in South America later in Oligocene
Miocene (25-5 mya):
Old World Monkeys (OWM) and apes appear in E. Africa; apes dominate
Living apes characterized by lack of tail, suspensory abilities
Pliocene (5-1.5 mya):
OWM spread, apes decline, hominids appear
Hominins characterized by suite of features related to bipedalism & incisor-like canines
Pleistocene (1.5 mya - 10,000 ya)
Homo spreads

Hominin species:

Mio-Pliocene Hominins (Sahelanthropus, Orrorin, Ardipithecus)

cranial capacity ~350 cc
evidence of bipedalism
Age:7- 4.5 mya
Sites: E. Africa (Kenya, Ethiopia), Central Africa (Chad)

Australopiths

Primitive Group (Australopithecus anamensis, Kenyanthropus platyops, A. afarensis)
Primitive dental features related to honing triad:
diastema between upper incisors and canine
canine worn on apex and posterior surface (intermediate between apes and other hominids)
first premolar not fully bicuspid
cranial capacity on avg 450 cc
trail of footprints showing they were bipedal
Age: ~4 - 3 mya
Sites: E. Africa (Kenya, Ethiopia, Tanzania)
Gracile group (Australopithecus africanus, A. bahrelghazalia, A. garhi)
Dentally similar to us
incisors and canines large relative to cheek teeth
premolars narrow relative to molars: stepped condition
cranial capacity on average 450 cc
Age: 4 – 2 mya
Sites: S. Africa (Sterkfontein, Makapansgat, Taung [Taung child]), Central Africa (Chad), E. Africa (Ethiopia)
Robust group (Paranthropus P. robustus, P. boisei, P. aethiopicus)
Dental condition
incisors and canines relatively tiny compared to cheek teeth
premolars relatively wide compared to molars: continuous condition; megadontia of cheek teeth serves to increase surface area for chewing seeds etc.
large chewing muscles; so large cheek bones (for masseter muscles) and a sagittal crest (for temporalis muscles)
cranial capacity on average ~500 cc
Age: 3 - 1 mya
Sites: P. boisei & P. aethiopicus are from E. Africa (Olduvai Gorge, Lake Turkana); P. robustus is from S. Africa (Swartkrans, Kromdraai)

Leapord Hypothesis to explain origin of S. African cave sites

Genus Homo

Characterized by
larger brain size, expanded cranial vault
smaller, straighter face
less massive mandible
rounded dental arcade
narrow cheek teeth and reduced third molar
Homo rudolfensis
Cranial capacity: 750 cc
Maximum breadth of skull: low
Age: 2.3 – 1.9 mya
Sites: E. Africa (Lake Turkana)
Homo habilis
hand capable of precision grip and making tools.
Cranial capacity: on average 600 cc
Maximum breadth of skull: low
Culture
Oldowan Industry
Chopper-Chopping tools
core tools, with a few flakes taken off
scavengers
Age: 1.9 - 1.6 mya
Sites: E. Africa (Olduvai Gorge, Lake Turkana)
Homo ergaster
Thin cranial bones
Cranial capacity on average 800 cc
Maximum breadth of skull: low
Sites/Age:
Europe: Georgia at 1.8 mya
E. Africa (Kenya: Olduvai Gorge, Lake Turkana) at 1.7 mya
Homo erectus
Morphology
Thick bones
cranial capacity approx 1000 cc
low, long skull with occipital and sagittal keels
Maximum breadth of skull: low
strong brow ridges
Culture
controlled fire
Tools: Acheulian Industry
hand-axes typical tool
bifacial core tools
Big-game hunting
clothes likely
skin color? probably becoming lighter (UV etc) as moved out of Africa
Age: 1.8 mya – 400,000 ya
Sites:
S. Africa (Swartkrans)
E. Africa ( Ethiopia: Middle Awash; Kenya: Olduvai Gorge, Olorgesailie)
N. Africa (Algeria: Ternifine)
Asia: (China: ZhoukoudianCave; Java)
Homo floresiensis (the Hobbits)
Age: 40,000 – 18,000 ya
SE Asia: FloresIsland
Homo antecessor
Maximum breadth of skull: low
Age: 900,000 – 700,000 ya
Europe (Spain,Italy)
Homo heidelbergensis
Cranial capacity approx 1250 cc
Maximum breadth of skull: low
Intermediate in all senses between Homo erectus, H. neanderthalensis and H. sapiens
Tools: Acheulean
TimeRange: 800,000 – 25,000 ya
Sites
E., S. & N. Africa
Europe (England, Germany, France, Hungary, Greece)
Asia (China)
Homo neanderthalensis
Morphology
Long, low skull with cranial capacity: approx 1575 cc
Maximum breadth of skull: intermediate, resulting in barrel shape
occipital bun
Hollow brow ridges; round orbits Mid-facial prognathism
very wide, large nasal aperture
sloping cheekbones
incisors worn labially and shovel-shaped
Stocky body build (related to cold)
Culture
Buried dead (graves with pollen)
Tools
Mousterian Industry
flake tools, not cores
LeVallois Technique - mass production of tool types
TimeRange: 300,00 – 30,000 ya
GeographicalRange: peri-Mediterranean
Homo sapiens
TimeRange: 200,000 ya - present
GeographicalRange: World wide
Morphology
cranial capacity: approx 1500 cc
vertical forehead
Maximum breadth of skull: high
chin
Culture
art
tools: blades, complex compound tools (bow & arrow etc.)
Models for Origin of Homo sapiens:
Multiregional Model
Out of Africa Model (Population Replacement Model)
Out of Africa Again and Again Model
Anatomy of Human Speech.
Chimps:
have long, thin tongue & short pharynx (supralaryngeal space);
can drink and breathe at same time
Humans:
as adults have short, thick tongue & long pharynx
as babies have short, thick tongue, but a short pharynx