BioAntro Chapter 10

Later Gracile Australopithecines

(3 - 2 mya), South and East Africa, Cranial capacity estimated at 450 cc Species include: Australopithecus garhi -first evidence of tools through cutmarks on animal bone -shorter arms relative to legs -East Africa: Ethiopia Australopithecus africanus (famous fossils: Mrs. Ples and Taung Child) (South Africa) Australopithecus sediba (South Africa) -Possible link between Homo and Australopithecus -Open grassland habitat - but ate forest foods

Provisioning Hypothesis explaining the emergence of bipedalism

(Owen Lovejoy) -Freeing the hands allowed males to assist females -Provisioning as sexual competition -Birth spacing ↓ -Sexual dimorphism/paternal care and non-human primates -Hominin sexual dimorphism? (cf. Larsen) -Monogamous fathers? -Controversial

Australopithecus garhi

-(East Africa, Ethiopia): about 2.5mya, brain size 450cc, large teeth. Only one skull, and who or what it is related to is uncertain. -Ratio of upper arm length to upper leg length more humanlike than apelike -Curved foot phalanx (like Au. afarensis's) -Lived in grasslands, on lakeshore -Tool maker/user (animal butchering) -The best evidence for an association of stone tools with the genus Australopithecus

Australopithecus Boisei

-2.3-1.2mya -Olduvai, Tanzania and Lake Turkana, Kenya -Small brain (510 cc) -Massive posterior teeth -Robust skull with sagittal crest -Lived in open grasslands

Australopithecus aethiopicus

-2.5 mya -Lake Turkana, Kenya -Small brain (410 cc) -Massive posterior teeth -Robust skull with sagittal crest -Lived in open grasslands

Australopithecus Sediba

-2mya -South Africa -Small brain (420 cc) -Relatively small teeth -Equal-size cusps on third premolars -Gracile face and jaws -Phalanges not curved -Short finger, long thumbs for precision grip -Long arms -Small, australopithecine-like skeleton -Homo-like pelvis -Lived in open grasslands

Australopithecus africanus

-3-2mya -South Africa: Tuang -Skulls, teeth, endocast (impression of brain), postcrania, two partial adult skeletons found -Small brain (450 cc) -Moderate-size teeth -Equal-size cusps on third premolar -Phalanges not curved -Adult partial skeleton has apelike leg-to-arm ratio (short legs, long arms) -Lived in open grasslands

Laetoli

-3.6mya -Laetoli is a site in Tanzania, dated to the Plio-Pleistocene and famous for its hominin footprints, preserved in volcanic ash -The Laetoli footprints demonstrate that the foot of australopithecus afarensis was humanlike in having a rounded heel, non divergent big toe, and double arch

Evolutionary tradeoffs from bipedalism

-Exposure -Bad backs -Circulatory system works harder -Clearly beneficial

Australopithecus platyops

-Platyops comes from Greek for "flat face." -dates to 3.5 mya -a lesser-known hominin from about the same time as Au. afarensis -discovered by Meave Leakey and her colleagues at Lomekwi, on the western side of Kenya's Lake Turkana -habitat was mainly woodlands -face was unusually flat

Australopithecus anamensis

-The oldest species of australopithecine from East Africa and a likely ancestor to A. afarensis. -Large outer cusp (like apes') on third premolar -Large canines -Parallel tooth rows in upper jaw (like apes') -Curved hand phalanx -Less than 1 m (3.3 ft) tall -Lived in wooded setting

australopithecus robustus

-may have descended from Au. afarensis -large teeth and large face -prominent sagittal crest -South African -found at Swartkrans, Kromdraai, and Drimolen -Australopithecus robustus was a robust australopithecine found in Swartkrans, South Africa. -2-1.5mya -Small brain (530 cc) -Massive posterior teeth -Robust skull with sagittal crest -Lived in open grasslands

Robust Australopithecines

2.5-1 m.y.a (East and South Africa) ~500cc extinct by 1mya Australopithecus aethiopicus: East Africa-Ethiopia; 2.5 mya; 510cc Australopithecus boisei; -East Africa: Tanzania/Kenya; -2.3 - 1.2 mya; -510cc -Zinj Australopithecus robustus; South Africa; 2 - 1 mya; 530cc

Early Gracile Australopithecines

4-3 mya central and east africa cranial capacity 400-500 cc Includes Australopithecus anamensis -East Africa- Ethiopia and Kenya Australopithecus afarensis -East Africa- Ethiopia and Kenya Australopithecus/Kenyanthropus platyops -Eat Africa: Kenya: Lake Turkana

Age of Mammals

65 mya

Dinosaurs extinct

65 mya

Pre-Australopithecines

7-4mya Central and East Africa Cranial capacity 350cc Includes: Sahelanthropus tchadensis Orrorin tugenesis Ardipithecus kadabba/ ramidus

Famous Fossils

Ardi (Ardipithecus), Mrs. Ples (A. africanus), Taung Child (A. africanus), Zinj (P. boisei), Lucy (A. afarensis)

Ardipithecus kadabba/ramidus

Ardipithecus kadabba/ ramidus -East Africa: Ethiopia -5.5-4.5 mya -Variation in teeth (peri-honing early and then lost); enamel thickness between apes and later Hominins [Hominins have thicker enamel] -Lived in a forest - other faunal remains -Bipedal adaptations clear -Lovejoy: canines = paternal care and dependent women; less male-to-male competition & pair-bonding -Small - "Ardi" was ~4ft tall and 110lbs -Opposable big toe, rigid foot = "facultative bipedalism" -No evidence of large canines

______________ arose around 3.5 mya and gave rise to at least two branches of hominins—later australopithecines and the genus Homo.

Au Afarensis

The best-known australopithecine, represented by hundreds of fossils and dozens of individuals found mostly at Laetoli and Hadar, is a. Au. africanus. b. Au. garhi. c. Au. afarensis. d. Au. anamensis.

Au afarensis

What is a homin?

Bipedal locomotion and nonhoning chewing preceded speech and tool use by several million years

General Features of Pre-Australopithecines

General Features • Bipedal characteristics (base of skull, femur neck; but some dispute) • Some arboreal characteristics (divergent big toe, curved phalanges, long arms) • Dental features mixed (enamel thickness in between ape and hominin, variation from peri to non-honing complex, reduced canines with tip wear) • Forest environments! • "Facultative bipedalism" • "No evidence of large canines" - Lovejoy controversy

The Oldowan Complex is a part of the:

Lower Paleolithic

Australopithecus afarensis

Lucy, dubbed by some as the "Missing Link". The longest living hominin species. Shorter and more similar to chimpanzees. -Found in Hadar, ethiopia -lived in a great diversity of habitats -a biped, but retained considerable climbing/arboreal ability -animal bones found with cutmarks -3.6-3mya -Curved hand phalanges -Short legs -Footprints indicate bipedal foot pattern with no divergent big toe -Lived in wooded setting, but a more open one than associated with Ardipithecus or Au. anamensis

Orrorin tugenensis

Orrorin tugenesis -6mya -bipedal based on femur -arms and hands ape-like/arboreal- curves hand phalanx -only hominin with thin enamel -non-honing chewing complex -wear on tips of canines -lived in woodlands -East Africa: Tugen Hills, Kenya

Patchy Forest Hypothesis explaining the emergence of bipedalism

Resources fragmented (arboreal/terrestrial) Greater efficiency of bipedalism (running). Freed the hands for carrying food.

Sahelanthropus tchadensis

Sahelanthropus tchadensis -7-6mya -lived in forest -wear on canine tip -Central Africa: Chad -oldest known hominin -massive brow ridges -Cranial Capacity: 350 cc

`The only preaustralopithecine found outside the East African Rift Valley is:

Sahelanthropus tchadensis.

Savanna-based hypothesis explaining the emergence of bipedalism

Savanna: To See Predators/Follow Herds, Prevent Heat Stroke -To (be) see (n by) predators [on the savanna] -To follow herds [on the savanna] (diet?) -Prevent heat stroke [on the savanna]

Taxonomy/phylogeny

Taxonomy, the science of classifying organisms, is based on phylogeny (ancestor/descendant relationships in a species' or group's evolutionary history, usually represented as a tree diagram); roots = ancestral lineages; tips of the branches = descendants of the ancestors

You find a fossil that you are sure shows evidence of bipedalism. You know this because which of the following anatomical traits is present:

Thigh bones that angle towards the knees

Along with other distinct traits, robust australopithecines had large _______ adapted for grinding food. a. premolars and molars b. temporalis muscles and a sagittal crest c. front teeth and small back teeth d. both a. and b.

a and b

Robust australopithecines differ from earlier australopithecines in their a. larger back teeth. b. smaller front teeth. c. larger faces. d. All of the choices are correct.

all of the above

The Laetoli footprints demonstrate that the foot of Australopithecus afarensis was humanlike in having a: a. rounded heel. b. nondivergent big toe. c. double arch. d. all of the above

all of the above

The Oldowan Complex includes tools like: a. hand axes, flakes, and cores. b. cobbles, flakes, and side scrapers. c. choppers, cobbles, flakes, and bone tools. d. choppers, hand axes, and side scrapers.

choppers, cobbles, flakes, and bone tools.

Compared to the robust australopithecines, australopithecus africanus has

dental proportions similar to later Homo

Speech, advanced cognition, and complex material culture: a. define a hominin. b. do not define a hominin. c. did not evolve through the primate lineage. d. define a higher primate.

do not define a hominin

Australopithecus garhi has been proposed as an ancestor for Homo mainly because it: a. had smaller molar teeth than other australopithecines. b. had a bigger brain than other australopithecines. c. was bipedal. d. had longer legs relative to arm length than other australopithecines.

had longer legs relative to arm length than other australopithecines.

Beginning more than 3 mya, at least two lineages of hominin emerged, one that led to the genus Homo and one that: a. included the now extinct descendants of Au. afarensis. b. ended with Au. africanus. c. gave rise to the genus Ardipithecus. d. was an evolution of other australopithecine lineages.

included the now extinct descendants of Au. afarensis.

Australopithecus robustus was likely the longest-surviving species of australopithecine in South Africa. It had: a. a large body, large teeth, and a sagittal crest. b. large molars, a big face, and a sagittal crest. c. a big face, large teeth, and a large body. d. a big brain, big teeth, and a big face.

large molars, a big face, and a sagittal crest.

Which of the following is an adaptive characteristic of bipedalism? a. opposable thumb b. nails instead of claws c. convergent eyes d. longitudinal arch in the foot

longitudinal arch in the foot

According to the Larsen text (and based on the research of Philip Reno), some scholars argue that early hominins show reduced sexual dimorphism, which is evidence for cooperation and likely for:

pair bonding

Imagine you have found a skull with an ape-size brain, very large back teeth, and large cheekbones. Based on this information, this is most likely a specimen of

robust australopithecine

Compared to other hominid species, the robust australopithecines have relatively smaller front teeth and smaller back teeth. larger front teeth and larger back teeth. larger front teeth and smaller back teeth. smaller front teeth and larger back teeth.

smaller front teeth and larger back teeth.

General Features of Gracile Australopithecines

• Compared to us: smaller overall brain and body • Short/Small (Lucy estimated at 3 foot 3 inches, 60 lbs) but more robust, very strong • Cranial Capacity: 450-500 cc average (chimp-sized) • Ape-like face with a low forehead, a bony ridge over the eyes, flat nose, protruding (prognathic) jaws, and no chin • Teeth and jaws much larger than those of humans, but human-like in other ways (jaw parabolic [vs. rectangular], canine and diastema reduced) • Bipedal; human-like pelvis, intermediate knee (note from this and text what these would look like) • Some ape/arboreal (tree dwelling) characteristics (proportionally long arms and feet, curved fingers and toes, glenoid fossa oriented superiorly)—retained adaptation to trees or evolutionary baggage? • So brains ape-like but pelvis human like (imagine potential problems of interpretation if skull or pelvis found in isolation as usually are) • Australopithecus garhi: first evidence of tools through cutmarks on animal bone

bipedal locomotion

• Evolved before large brain size • Walking on two limbs (with associated skeletal changes) • Associated Structures of Foot, Legs, Thorax/Spine, Pelvis, Head/Neck [See notes from last section] -the foramen magnum is positioned on the bottom of the skull, the spine is S-shaped, the ilium is short from front to back, the legs are long relative to the body trunk and arms, the knees are angled inward, the foot has a longitudinal arch, and the big toe (hallux) is not opposable -An increased inability ability to see greater distances is one of the adaptions to bipedalism

Nonhoning chewing

• Grinding instead of slicing • Refers to the way the mouth processes food • Lack of projecting canine, diastema • More pressure on front portion of chewing muscles (i.e., molars)

Darwin Hypothesis explaining the emergence of bipedalism

• Hunting and Carrying Tools (Darwin) -freed hands for carrying weapons, increased intelligence, decreased size of canines -unlikely because tools found 2.6mya whereas bipedalism began 4-7mya • Savanna: To See Predators/Follow Herds, Prevent Heat Stroke -To (be) see (n by) predators [on the savanna] -To follow herds [on the savanna] (diet?) -Prevent heat stroke [on the savanna] • Efficient Travel (Rodman and McHenry) • Carrying (Food, Infants) and Male Provisioning (monogamous families) (Lovejoy) • Evolutionary Tradeoff: exposure, bad backs, circulatory system works harder, cut clearly beneficial

General Features of Robust Australopithecines

• Overall larger (4 - 5'4" tall (males ~100lbs, females ~75 lbs.)) • ~410 - 530 cc cranial capacity • Adaptation for chewing tough plant materials - heavy jaws, relatively large rugged attachments for chewing muscles, large back teeth, sagittal crest and zygomatic arch • Bones found with robustus may be digging tools • Likely offshoot from the direct human line. Lump or split?