ANTH 1 
Introduction to Physical Anthropology 
Study Guide #3

Last Updated: May 16, 2000

• 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
• Two 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 and anthropoids, found in N. America and Europe
• Oligocene (35-25 mya):
• 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 Faym, 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
• Hominids characterized by suite of features related to bipedalism & incisor-like canines
• Pleistocene (1.5 mya – 10,000 ya)
• Homo spreads
• Characterized by larger brain and capacity for culture

• Structure of Earth: Core, Mantle, Crust
• Convection currents in mantle, in part, drive movements of crustal 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.

• 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 (K/Ar)
• 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 K to Ar
• Carbon 14 (14C)
• half-life = 5730 years
• date fossils, not rocks
• a) 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 things up to 50 kya
• examine the ratio of 14C to 12C
• Relative methods
• Assumptions:
• Principle of Superposition
• strata higher in a column are younger than those lower in the sequence
• Principle of Uniformitarianism
• can infer what the paleo-landscapes were by the typeof rock left; e.g., limestone represents deep water; shale represents coastal shelf; sandstone represents ancient beach, etc.
• 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
• 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

• relationship of height of center of gravity (CG) of body relative to width/size of base of support
1. High CG and small Base = unstable (e.g., ballerina, some floor lamps)
2. 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)

• The distinctive difference between hominids and apes relates to locomotion: hominids are bipedal, whereas apes are quadrupedal
• modifications of skeleton for bipedal walking
• 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 hominids 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
• concealed ovulation/continued sexual receptivity
• related to bipedalism, loss of sexual swellings
• related to incisiform canines; loss of 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

• Gathering hypothesis - based on ethnographic data of hunters-gatherers that females provide the vast majority of food (i.e., veggies) for families, because hunting for meat is not always a successful endeavor. Suggests that previous hypotheses ignored the role of females.
• Scavenging hypothesis - based on fact that hominids had no known tools when bipedalism evolved; supporting evidence provided by later archaelogoical record, when tools were known, by superposition of tool cut marks over animal tooth marks on bones.
• Reproductive hypothesis - based on fact that apes have an interbirth interval of approximately 6 years, whereas humans can have an interbirth interval of approximately one year, IF the males provision the females. Suggests that monogamy and male-male bonding were important in the origin of bipedalism.
• problem: what if one male cheated and did not engage with other males in hunting but instead inseminated females. Monogamy would lead to cuckoldry!
• relationship of relative testes size and sexual dimorphism to social organization:
• orangs solitary, females come into heat once every 6 years, great deal of sexual dimorphism and male-male competition for access to females; very small testes.
• chimps gregarious and promiscuous, females come into heat once every 6 years, all males copulate with female in heat; strong male-male bonding, little sexual dimorphism, very large testes due to sperm competition
• humans; male-male bonding strong; minor sexual dimorphism; female choice for mates; testes similar to those of monogamous gibbons in relative size; females may have selected for large penis in males (maybe related to female orgasm, which is unique in primates, we think)

• genera Ardipithecus & Australopithecus:
• cranial capacity 450-500 cc
• Primitive group
• Ardipithecus ramidus, Australopithecus afarensis, A. anamensis
• trail of footprints at Laetolil, Tanzania
• some curvature of phalanges, suggesting some climbing activity
• 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
• Age: 4.5 mya - 3.0 mya
• Sites: E. Africa (Ethiopia, Kenya, Tanzania)
• Gracile group
• Australopithecus  africanus
• Dentally similar to us
• incisors and canines large relative to cheek teeth
• premolars narrow relative to molars: stepped condition
• Age: 3 - 2 mya
• Sites: S. Africa (Sterkfontein, Makapansgat, Taung [Taung child])
• 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; 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)
• Age: 2.5 - 1 mya
• 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
• Homo habilis/rudolfensis
• East Africa (Olduvai Gorge, Lake Turkana) and S. Africa (Swartkrans) at 2.5 - 1.7 mya
• Cranial capacity: 800 cc
• strictly bipedal
• hand capable of precision grip and making tools.
• Culture
• Oldowan Industry
• Chopper-Chopping tools
• core tools, with a few flakes taken off
• scavengers
• Homo ergaster/erectus
• East Africa (Olduvai Gorge, Lake Turkana) at 1.7 mya
• Asia at 700 kya: China (Zhoudoukian Cave); Java
• Morphology
• Thick bones
• cranial capacity approx 1000 cc
• occipital and sagittal keels
• 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
• Homo heidelbergensis (transitional forms)
• Time Range: 700 - 135 kya; Africa, Europe, Asia
• cranial capacity approx 1250 cc
• Intermediate in all senses between Homo erectus, H. neanderthalensis and H. sapiens
• Tools: Acheulean
• H.  neanderthalensis
• Time Range: 135 - 35 kya
• Geographical Range: peri-Mediterranean
• Morphology
• Cranial capacity: approx 1550 cc
• Mid-facial prognathism
• very wide, large nasal aperture
• sloping cheekbones
• incisors worn labially
• occipital bun
• Stocky body build (related to cold)
• Hollow brow ridges; round orbits
• Culture
• Buried dead (graves with pollen)
• Tools
• Mousterian Industry
• flake tools, not cores
• LeVallois Technique - mass production of tool types
• Homo sapiens
• Time Range: 100 kya - present
• Geographical Range: World wide
• Morphology
• cranial capacity: approx 1400 cc
• vertical forehead
• chin
• Culture
• art
• tools
• blades, complex compound tools (bow & arrow etc.)

• Multiregional Model
• Out of Africa Model (Population Replacement Model)

• 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