Hominin Evoluttion

Grasping hands and feet

A key primate trait characterized by opposable thumbs and toes for gripping objects or branches.

Stereoscopic vision

Depth perception provided by forward-facing eyes, a characteristic trait of primates.

Plesiadapiforms

The first primate-like mammals from the Paleocene epoch; they had small brains, prognathic faces, and lacked a postorbital bar.

Purgatorious

A plesiadapiform with a $3.1.4.3$ tooth formula and claws, lacking a postorbital bar.

Plesiadapis

A plesiadapiform with a $2.1.3.3$ tooth formula, rodent-like incisors, and no postorbital bar.

Adapoids

Lemur-like, strepsirrhine-like ancestors from the Eocene epoch.

Omomyoids

Tarsier-like, haplorhine-like ancestors from the Eocene epoch.

Foramen magnum

The hole in the occipital bone where the spine meets the skull; positioned directly beneath it in bipeds and posteriorly in quadrupeds.

Nuchal plane

A horizontally flat region on the bottom of the skull which is more vertical in bipeds and faces forward in quadrupeds.

Valgus angle

The angle of the femur from hip to knee in bipeds that keeps the foot under the center of gravity.

CP3 honing complex

A dental complex where a large, projecting upper canine passes across the bladelike edge of the lower premolar; this is lost in hominins as anterior teeth size decreases.

Diastema

A gap between the teeth, typically found in chimpanzees and other great apes but absent in modern humans.

Sahelanthropus tchadensis

The earliest potential hominin, dated to $7-6$ million years ago in North Central Africa, featuring an anterior foramen magnum and a small brain.

Orrorin tugenensis

An early hominin from Eastern Africa dated to $6.2-5.8$ million years ago with a femur suggesting bipedalism.

Ardipithecus ramidus

A $4.4$ million-year-old hominin with a short and curved ilium, facultative bipedalism, and a highly abducted hallux for climbing.

Abducted hallux

A grasping big toe that is set away from the other toes, found in Ardipithecus ramidus and adapted for climbing.

Australopithecus afarensis

A species dated to $4-3$ million years ago in East Africa, including the specimen Lucy, characterized by a bipedal pelvis and relatively short legs.

Taung child

A specimen of Australopithecus africanus that established early fossil humans occurred in Africa; possibly killed by a predatory bird.

Breccia

A matrix that builds up in limestone caves where South African fossils are often discovered.

Killer ape hypothesis

An incorrect interpretation by Raymond Dart suggesting australopiths were big game hunters due to the presence of bones near fossils (Osteodontokeratic culture).

Paranthropus

A genus of robust australopiths characterized by heavy chewing complexes, including sagittal crests, huge molars, and massive mandibles.

Zinj

The nickname for Paranthropus boisei, the most robust species of its genus.

Homo habilis

Known as the handy man, this species lived $2.4-1.4$ million years ago and is associated with Oldowan stone tool use.

Homo rudolfensis

The large morph of early Homo with a larger brain ($~775$ cc) and a flatter face compared to Homo habilis.

Homo erectus

A species characterized by a long, low skull, sagittal keel, and thick skull bones, and the first to exhibit modern human-like body proportions.

Homo floresiensis

Small-bodied hominins from Flores Island often cited as examples of island dwarfism.

Occipital bun

A prominent bulge or projection on the back of the skull, diagnostic of Neanderthals and absent in modern humans.

Intermembral index (IMI)

A formula used to compare limb proportions: $rac{ ext{humerus} + ext{radius}}{ ext{femur} + ext{tibia}} imes 100$.

Bergmann’s Rule

The principle that warm-blooded animals from colder climates usually have larger body masses than equivalent animals from warmer climates.

Allen’s Rule

The principle that animals in colder climates have shorter appendages to conserve heat, while those in warmer climates have longer appendages for heat dissipation.

Acclimatization

Short-term physiological changes that occur in response to changes in environmental conditions.

Oldowan

A tool tradition characterized by simple stone flakes, typically associated with Homo habilis.

Acheulean

A tool tradition characterized by handaxes, typically associated with Homo erectus.

Mousterian

A Middle Paleolithic tool tradition associated with Neanderthals.

Basal metabolic rate (BMR)

The rate at which the body uses energy while at rest to keep vital functions going.

Lactose tolerance

A genetic mutation producing the lactase enzyme in adulthood, allowing for the digestion of milk, common in agricultural populations.

Heterozygote advantage

A phenomenon where carriers of a single mutation (like sickle-cell trait) have higher fitness, such as resistance to malaria.

Ardipithecus traits

Earliest hominins, small brain, anterior foramen magnum, ape-like limbs, reduced canines, large brow ridge, facultative bipeds

Australopithecus traits

walking upright but still climbed trees, short, long arms and short legs, broad and funnel shaped torso, small brains and large jaws, first stone tool maker

Paranthropus traits

Robust Australopiths, sagittal crest, wide face, huge molars, small incisors, post-orbital constriction

Homo traits

Larger, more rounded brain case, less projecting face, smaller teeth, more efficient bipedalism, longer legs, shorter arms, more human-like body proportions, tool use

Archaic humans

Homo heidelbergensis, homo neanderthalensis, Denisovans

Modern human traits

Small face, chin, round globular skull, cranium widest at the top, tall forehead

Sahelanthropus

Ardipithecus, Chad, ape-like limbs, facultative bipedalism, large brown ridge

Orrorin

Ardipithecus, Kenya, climbing hands

Australopithecus afarensis location

Ethiopia, Kenya, Tanzania

Lucy

Australopithecus afarensis, pelvis of a biped, relatively short legs, short but curved phalanges

Dikika baby

Australopithecus afarensis, legs and ankles for walking but shoulders for climbing

Kadanuumuu “big Man”

Australopithecus afarensis

First family

Australopithecus afarensis, 13+ individuals, Ethiopia, evidence of group living

Laetoli footprints

Australopithecus afarensis, striding bipeds with arches, toe-off, and adducted hallux

Australopithecus afarensis traits

Apelike face proportions, strongly projecting lower jaw, small brain, long arms for climbing, bipedal, large anterior teeth, no CP3 honing complex, strong body size sexual dimorphism

Australopithecus africanus traits

Rounder cranium and larger brain than A. afarensis, Ape-like features relatively long arms, strongly sloping face that juts out from underneath the braincase, pelvis, femur, and foot bones indicate bipedalism, shoulder and hand bones indicate climbing

Taung Child

Australopithecus africanus, first to establish early fossil humans in Africa

Little Foot

Australopoithecus africanus

Mrs. Ples

Australopithecus africanus

Paranthropus traits

Sagittal crest, wide face, huge molars, small incisors, post-orbital constriction

Paranthropus aethiopicus location

Eastern Africa, 2.7-2.3 ma

Black skull

Paranthropus aethiopicus

Paranthropus aethiopicus traits

Primite traits: relatively large anterior teeth, small face, very prognathic

Derived traits: Large posterior teeth, wide zygomatics, huge posteriorly-placed sagittal crest

Paranthropus boisei location

Tanzania, Kenya, Ethiopia, 2.3-1.2 ma

Paranthropus boisei traits

Massive jaws and molars, most robust of the robusts

zinj (Nutcracker Man)

Paranthropus boisei

Paranthropus robustus location

South Africa, 2.0-1.5 ma

Paranthropus robustus traits

Somewhat less robust than E. African forms

Homo traits

Larger, more rounded brain case, less projecting face, smaller teeth, more efficient bipedalism, longer legs, shorter arms, more human-like body proportions, tool use

Earliest homo location

Ethiopia, 2.5 ma

Homo habilis location

Tanzania, 2.4-1.4 ma

small morph

homo habilis

Handy man

homo habilis

Homo Habilis traits

Reduced facial size, parabolic dental arcade, some brain enlargement, large browridges, small posterior teeth

Homo rudolfensis location

Eastern Africa, 1.9-1.8 ma

Large morph

Homo rudolfensis

Homo rudolfensis traits

Larger brain, flatter face, smaller relative browridges, large posterior teeth

Homo erectus location

Africa, Asia, 2-0.1 ma

Homo erectus traits

First out of Africa, long low skull, robust body, subnasal prognathism, large browridge, sagittal keel, larger brain, smaller and narrower posterior teeth

Nariokotome Boy

homo erectus, most complete early hominin skeleton

Java Man

Homo erectus, first h. erectus discovered

Peking man

Homo erectus

Homo floresiensis location

Flores island, 700-60 ka

Homo floresiensis traits

Small bodied, island dwarfism

Homo naledi location

South Africa, 300-230 ka, rising star cave

Homo heidelbergensis location

Africa, Europe, Asia

Homo neanderthalensis locations

double-arched brow ridges, large face, long and low skull, cranium widest in the middle, midfacial prognathism, occipital bun, no chin, large joints, stocky

Homo neanderthalensis behaviors

Burials, care for injured, hunting, tools

Modern human traits

Small face, chin, round globular skull, cranium widest at the top

Location of oldest Homo sapiens

Jebel Irhoud, Morocco, 300 ka

Omo & Herto

H. sapiens, Ethiopia, 150-200 ka

Qafzeh & Skhul

H. sapiens, Israel, 100 ka

Cro-Magnon

H. sapiens, France, 40 ka

Epochs of the Cenoizoic Era

Eocene, Oligocene, Miocene, Pliocene, Pleistocene

Paleocene

55-34 ma, True primates, earliest anthropoids

Oligocene

34-25 ma, anthropoids evolve,

Miocene

23-5 ma, apes diverge, hominins appear

Pliocene

5-2.5 ma, Australopiths evolve

Pleistocene

2.5 ma-10 ka, homo evolves

Advantages of bipedalism

Vigilance to see over tall grass, frees hands for tools and carrying, energy efficient for long-distance walking, thermoregulation for less sun exposure, dominance

Adaptations to bipedalism

Skull: Anterior foramen magnum

Spine: S-shape

Pelvis: short, broad, curved

Femur: Valgus angle

Foot: arched and adducted hallux

Limbs: shorter arms, longer legs, short and straight phalanges

Intermembral index

Humerus + radius / femur + tibia x 100

Fossil preservation in South Africa

Breccia in limestone caves