BIO105 Exam 2

Orrorin tungenesis

• one of the earliest known hominins (6 mya)

• displayed earliest evidence of bipedalism

• femur suggests bipedalism evolved before the loss of C/P3 honing complex

• relatively long arms and adaptations for climbing

Ardipithecus ramidus

• 4 mya

• maybe bipedal?; still had grasping big toe to climb trees

• small brain size, no facial flatness, no canine reduction

• pelvis badly crushed and distorted

• displays both ape-like and human-like features

• hominin status uncertain; shows bipedalism is the defining feature

Australopithecus afarensis (Lucy)

• 3 mya

• lower-limb = bipedalism (human-like pelvis and legs adapted)

• upper-limb = arboreal (long arms and curved fingers)

• unique sexual dimorphism — high in body size, low in canine size

• certain hominin status; fossils found in Ethiopia

Neandertals

• short, stocky, muscular bodies adapted to cold climates

• separate evolutionary lineages from modern humans

• larger brains than earlier hominins

• Midfacial projection, large nasal opening, thick & arched brow ridges

• sophisticated stone tools — hunted animals and cared for group members

• inbred with modern humans, but separate evolutionary lineages

Homo sapiens

• modern-day humans with large brains and rounded skulls

• relatively high foreheads, non-projecting face, small canines, bipedal

• complex langauge, symbolic thinking, cultural traditions

Jane Goodall

British primatologist that was the first to document primate tool use in wild chimps, but did not report on stone tool use

• studied wild chimpanzees in Gombe, Tanzania, beginning in 1960

• studies helped scientists understand.our evolutionary relationships

what was the name of jane goodall’s toy chimp

JUBILEE

what was the name of jane goodall’s prized chimp who loved to termite fish

DAVID GREYBEARD

Gombe Stream (Tanzania)

location where Jane Goodall conduced her chimpanzee research

Laetoli (Tanzania)

where hominin footprints of australopithecus afarensis species were found

• provides physical evidence for bipedalism

• Lucy found in Ethiopia — shows movement

Sima de los Huesos (Atapuerca)

important paleoanthropological site famous for contianing a large collection of ancient human fossils (very neandertal-like species)

• tiny ear bones found suggest a modern human auditory pattern

• 17 crania recovered

• ~ 430kya

Jebel Irhoud (Morocco)

site containing some of the oldest known fossils considered to be close to the origin of homo sapiens, but had reduced face and brow ridges & incipient chin

• approx. 300kya early homo sapien fossil

• found in 1960s during recent excavation

Omo Kibish (Ethiopia)

2 skulls with postcrania found in 1960s, very modern-looking humans (200kya)

• Omo 1 — early homo sapien fossil with rounded skull, reduced brow ridge, and chin

• tall & lean, build similar to marathon runners/jumpers

Herto (Ethiopia)

early homo sapien fossils recently rediscovered from 160kya

• adult cranium show derived homo sapien features: globular cranium, reduced brow ridge, facial flattening

Noulo

• archeologists discovered stones believed to be used by chimps to crack nuts due to found starch residue

• chimp tools vs. oldowan (early hominin) tools — chimp tools not systematically producing sharp stone flakes, only oldowan tools

• Pattern of tool breakage is consistent with thrusting percussion (hammerstone smashing on an anvil) produced experimentally

Kanzi experiment

chimp taught to strike stone, but still could not produce flakes like how they were on an Oldowan tool

primate features

placental mammals, clavicles, 3 classes of teeth, posterior brain lobe, calcarine fissue, well-developed caecum, pendulous penis, external testes, 2 mammary chest glands

• innermost digit of at least one pair of extremities is opposable (thumb/big toe)

• nails or claws on digit

• eye sockets encircled by bone

• strong positive relationship between body weight and brain weight

• k-selected (take longer to reproduce)

primate features problem

not all primate species show all of the features — a combination of them is considered characteristic

ape features

no tail, shoulder circumlocation, Y5 lower molar cusp pattern, forelimb dominated, tall and narrow pelvis

human features

bipedalism, increase brain size, facial flatness, canine reduction, S-shaped spine, non-divergent big toe, forward position of foramen magnum, short and wide pelvis, equal length arm and legs, angle in knee, upper femur projects to side

primitive feature

feature that was inherited from an earlier common ancestor, and has not changed through time

• 5 fingers/toes, grasping hands, opposable thumbs

derived feature

feature that evolved more recently compared to ancestors; newly evolved

• bipedalism, external ape tails, Y5 molars

arboreal features

physical, anatomical, and behavioral traits/adaptations that help primates live and move in trees

• quadrupedalism, long arms and short legs (forelimb dominated), curved fingers and hand phalanx, grasping hands and feet, opposable thumbs, flexible shoulders/superiorly-oriented glenoid fossa

bipedalism features

foward position/opening at bottom of skull for foramen magnum, S-shaped spine, short and broad pelvis, valgus knee/angled femur, longer legs, arched feet, non-opposable big toe, knee joints/locking knees

primate tool use

the ability of primates to use objects in their environment to accomplish different tasks

• chimp termite fishing and nut cracking

• capuchin monkey stone tools

primate archaeology

the study of material objects and evidence left behind nonhuman primates

• tool use, archaeological evidence, social learning, cultural transmission, material culture

savanna hypothesis

theory for human origin that may explain why early humans came down from trees and started to walk on two feet

• environmental changes and forest shrinkage led to transitional zones and more grasslands

• thought that life on the savanna brought out human characteristics:

  • terrestrial bipedalism, tool manufacture, brain expansion, increase sociality, meat eating/hunting/foraging

savanna hypothesis problems

1. forests still widesoread until ~3.5mya, when bipedalism was already developing

2. earliest human ancestors (orrorin, ardipithecus) lived in more forested environments, but both show evidence of adaptations with bipedalism, challenging idea that grasslands were needed for bipedalism

3. savanna expansion occurred ~1.8mya, when bipedalism already existed for millions of years

evolution of langauge

likely developed gradually as human ancestors evolved

• larger and more complex brains

• improved speech production abilities

• netter hearing abilities to recognize speech sounds

• more complex social interactions and symbolic thinking

language

a more complex, symbolic system used to communicate ideas. culturally specific, symbolic, and non-instincitive

communication

sharing information through sounds, gestures, and facial expressions

archaeological inferences of language

rely on identifying some expression of symbolic behavior in the archaeological record as evidence for the presence of language

• burials (symbolic/cultural practices)

• personal adornments (assigning meaning to objects)

• parietal art (abstract/symbolic thinking)

all cultural practices. assumes language as a recent origin of 50-75kya, and is associated exclusively with homo sapiens

biological inferences of language

rely on attempting to identify in our fossil human ancestors the anatomical correlation of language capacity seen in modern humans

• brain development, vocal tract, hyoid bone, evolution of hearing, FOXP2 gene

suggests language-related ability existed over 500kya

brain development and cerebral language areas

• broca’s area - associated with speech production

• wenicke’s area - associated with language production

• these brain areas found in endocasts of homo habilis by Philip Tobias — assumed language around 2mya???

problem: endocasts cannot show precise brain structure, so this evidence cannot conclusively prove that homo habilis had language

supralaryngeal vocal tract (SVT)

the part of the vocal tract above the larynx that changes shape to produce different speech sounds

• humans = 1:1 horizontal-to-vertical ratio, flatter face, low-placed vocal folds

• chimps = >1:1 ratio, projecting face, high-placed vocal folds

• a low-positioned larynx indicates the capacity for human speech

Neandertal vocal folds

there have been many attempts to reconstruct the vocal tract, but it is composed almost entirely of soft tissue, which does not fossilate

• they did not have 1:1 ratio, but if they had a low larynx placement in the throat, it might be consistent with the presence of speech capacity

• longer SVTh, similar SVTv, low-positioned larynx(?)

hyoid bone

the small bone located in the neck above the larynx

• provides attachment points for muscles involved in mouth and throat

• discovery of fossil human hyoid bone may shed light on SVT anatomy in fossil hominins

• fossil hyoid bones found in Neandertals

• suggests neandertals may have had anatomy compatible with human speech, but hyoid bone does not tell us the exact position of the larynx, so cannot prove language

evolution of hearing

scientists studied if early humans could hear the frequencies used in human speech

• modern human = 1-6kHz (overlaps with speech frequencies)

• chimps = >3Hz

• Sima de los Huesos discovery — suggests hominins had a modern human-like auditory pattern

• consonant importance

• implication of language >500kya

consonant importance (evolution of hearing)

the overlap between human hearing sensitivity and speech frequencies is related to consonant production

• human spoken language relies heavily on consonants

• nonhuman primate vocal communication is more vowel based

• increase emphasis on consonants may have been important in evolution of human language

FOXP2 gene

associated with the development of speech and language abilities

• modern humans have 2 specific derived mutations of FOXP2 compared to chimps

• same 2 mutations found in neandertals

• suggests neandertals and modern humans inherited these mutations from their last common ancestor (>500kya)

• suggests some biological foundations associated with speech and language existed before modern humans and neandertals became separate groups