Lecture 6

Question 1

Hominoid Taxonomy

Answer 1

○ Hominidae (Great apes = chimps, gorillas, bonobos, organutangs humans)
○ Homininae (Hominidae minus orangutans
○ Hominini (Sahelanthropus tchadensis (hominin status highly disputed), Orrorin, Panina (chimps and bonobo) and Hominina
○ Hominia (Ardipithecus, kenyanthropus, australopithecus, paranthropus and homo
○ Homo = immediate ancestors of modern humans
○ Hominoids (Hominids and Gibbons)
○ Hominids (family of great apes)
○ Hominins ( humans and their ancestors)

Question 2

R-selected

Answer 2

(quick, monkeys)

Question 3

K-selected

Answer 3

(slower, apes)

Question 4

Phylogeny

Answer 4

Refers to actual evolutionary relationships between organisms

Question 5

Molecular Phylogeny

Answer 5

Tree of relatedness among taxonomic group based on a gene or protein

Question 6

Molecular Clock

Answer 6

• Calibrated with a date that corresponds to a node on the tree
• Rate consistency
• -relative rate test
• -comparison of amount of genetic difference between each species

Question 7

Molecular Phylogeny and Primate Origins

Answer 7

○ Morris Goodman
○ Beta- globin
■ Polypeptide chain that makes hemoglobin
○ Last common ancestor of all primates 63 million years ago

Question 8

Molecular Phylogeny and Human Origins

Answer 8

○ Sarich and Wilson
■ First molecular phylogeny
■ Caused re-evaluation of fossil evidence that considered 15 myo earliest hominin
○ Maryellen Ruvolo
■ Goodman phylogeny
■ Modern humans and chimps more closely related than humans and gorillas

Question 9

Plesiomorphic Trait

Answer 9

○ A primitive trait inherited by species from their ancestor

○ - Example prehensile feet in living apes

Question 10

Apomorphic Traits

Answer 10

○ New or derived traits. they first appear in species in question
○ No tail in primitive apes
○ Non- prehensile feet in hominins

Question 11

Chimpanzees post- crania

Answer 11

○	Long arms
○	Short legs
○	Long, narrow pelvis
○	Legs widely spaced
○	Long narrow fingers/toes
○	Prehensile hands and feet
○	Narrow, deep rib cage

Question 12

Chimpanzee cranium

Answer 12

○	Brian size: 300-400 cc
○	Robust brow ridge
○	Alveolar prognathism
○	Canine pillar
○	U-shaped tooth row
○	Small molars and premolars
○	Large incisors
○	Very large canines w/ honing complex
○	Thin enamel

Question 13

Sahelanthropus tchadensis

Answer 13

○	The earliest pre-australopithecine species found in central Africa with possible evidence of bipedalism.
○	6-7 Mya
○	Nuchal line
○	Foramen magnum
○	Features:
■	Less prognathic face
■	Large brow ridge
■	Smaller canines
■	Anterior foramen magnum
■	Small brain (320-380 cc)
■	U-shaped arcade
■	Thin enamel (btw chimps and australopithecus)

Question 14

Orrorin tugenesis

Answer 14

○ A pre-australopithecine species found in East Africa that displayed some of the earliest evidence of bipedalism.
○ Arms and femoral fragments may suggest bipedalism
○ Features
■ Thick enamel
■ Large upper canines

Question 15

Becoming Biped

Answer 15

○ - Walking upright is extremely rare in world of the mammals
○ - Only humans are habitual striding bipeds
○ - There are morphological adaptations to bipedality

Question 16

Anatomical Changes: Vertebrae

Answer 16

● S-shaped spine, rather than C-shaped spine of quadrupeds

Question 17

Anatomical Changes: Foramen magnum

Answer 17

● Hole in the occipital bone

Question 18

Anatomical Changes: Nuchal plane

Answer 18

● Horizontally flat region on the bottom of the skull

● Face forward in quadrupeds

Question 19

● Comparison of Human/Great Ape: foramen magnum and nuchal plane

Answer 19

○ Spine meets the skull from below in biped, so the foramen magnum, in blue, is directly beneath the skill and neck muscles run down the skull
○ In apes spin meets the skull from the back so the foramen magnum is positioned posteriorly and neck muscles also run posteriorly from the skull

Question 20

Anatomical Changes II: Innominate bones

Answer 20

● Ischium, ilium, and pubis bones

Question 21

Anatomical Changes II: Gluteal muscles

Answer 21

● Aid with balance

Question 22

Anatomical Changes II: Hip joint closer to the joint between sacrum and ilium

Answer 22

● Good for balance, but narrows birth canal

Question 23

Anatomical Changes III: The Leg

Answer 23

■ Angled femurs
● Problems at the knee; enlarged groove for patella
■ Femoral condyles
● To keep the foot under the center of gravity, the biped’s femur is angles from hip to knee. The quadruped femur is not

Question 24

Anatomical Changes IV: The Arm

Answer 24

■ Released from locomotor activities

Question 25

Anatomical Changes IV: Foot

Answer 25

``` ■ Tarsals ■ Metatarsals ■ Phalanges ■ Main propulsive force at toe-off ■ Arches act as shock absorbers ```

Question 26

Anatomical Changes V: Teeth structure of modern humans

Answer 26

``` ■ Very small canines ■ Non diastema ■ Deeper palates ■ Parabolic dental arcade ■ Smaller teeth ■ Increased enamel ```

Question 27

Canine/premolar (CP3) Plus honing complex

Answer 27

○ A canine/premolar or CP3 honing complex consists of a large, projecting upper canine passing across the bladelike edge of the lower premolar. ○ Hominins lose this complex as the anterior teeth decrease in size

Question 28

Mosaic Evolution

Answer 28

○ Each small change was beneficial. | ○ Emerging bipeds changed to survive and reproduce

Question 29

Ardipithecus ramidus

Answer 29

■ Smaller canine ■ Anterior foramen magnum ■ Apelike molars

Question 30

Ardipithecus kadabba

Answer 30

■ More apelike dentition | ■ Originally considered a variant of ramidus

Question 31

Great Rift Valley of East Africa

Answer 31

■ Creation and disappearance of lakes and streams during hominin evolution

Question 32

What might have led to the origin of habitual bipedalism

Answer 32

○ Carrying tools, food, or infants ○ Ecological influences: Traveling between trees or seeing over tall grass ○ Preadaptation from a change in feeding postures ○ Provisioning family ○ Energy efficiency

Question 33

Australopithecus and Kin

Answer 33

○ Nebulous category ■ Difficult to differentiate early hominin from ape ○ Features ■ Moderately prognathic faces ■ Primitive and derived cranio-dental anatomy

Question 34

Australopithecus anamensis

Answer 34

○ Thickened tibia (was probably bipedal) ○ Primitive dentition, e.g. CP3 honing complex (more ape-like), shorter molars ○ Lumped with Au. afarensis, but Au.anamensis is more primitive. ○ Fossils of fish and aquatic animals found with Au. anamensis indicate streamside forests in the early Pliocene.

Question 35

Australopithecus afarensis

Answer 35

``` ○ "Type Specimen" ○ East African Species ○ Lucy ■ Partial skeleton ■ Mosaic of human/ape- like features ■ Big differences in dimorphic size between males and females (as in ape populations) ○ General Features ■ Short, broad pelvis ■ Tilted femurs ■ In-line big toe ■ Sagittal crest ■ Small brain ■ Mosaic postcranial anatomy ○ Environment ■ Perhaps had vegetal diet ■ Likely lived in groups ■ Probably not monogamous (sexually dimorphic) ■ Lived in lush arboreal environment ○ Features ■ (a) a small cranial capacity and cranial crests. ■ (b) a shallow, U-shaped palate with reduced canines. ■ (c) (and d) features of the postcranial skeleton that indicate habitual bipedality ```

Question 36

Australopithecus Bahrelghazali

Answer 36

○ First hominin found in Western Africa ○ Single fossil has mandible fragment with seven teeth. ○ Slightly different mandibular symphysis

Question 37

Australopithecus Deyiremeda

Answer 37

○ Recent naming of fossils discovered in Woranso-Mille, Ethiopia ○ Thicker enamel than Ardipithecus ○ Smaller postcanine teeth than Au. anamensis/afarensis

Question 38

Kenyanthropus Platyops

Answer 38

○ Very flat face ○ Small molar teeth ○ Kenya ○ Lived at the same time as Au. afarensis ■ One of these taxa is not a direct ancestor of modern people.

Question 39

Australopithecus Garhi

Answer 39

``` ○ Found in Ethiopia ○ Small brain ○ Prognathic face ○ Large canines and robust cheek teeth ○ Sagittal crest ○ More human- like postcranial proportions ○ slightly younger than Au. afarensis ○ Possible tool use (found in the same beds as early stone tools) ```

Question 40

Australopithecus Africanus

Answer 40

○ Dating techniques: South African fossils cannot be dated with the same techniques as East African fossils (where they use 40K/40Ar or 40Ar/39Ar techniques), but these dolinas/sinkholes pose a complex stratigraphy. ○ Main features ■ Slight brain increase from 415 cc (in Au. afarensis) to 440 cc in Au. Africanus ■ Rounded vault ■ No crests ■ Less projecting face ■ Bipedal postcranial anatomy

Question 41

Australopithecus Sediba

Answer 41

``` ○ Slight brain increase (420-435 cc) ○ Characteristics similar to Homo ■ Dental anatomy ■ Derived face ■ Features of the pelvis ```

Question 42

Robust Australopithecines

Answer 42

``` ○ Main features ■ Sagittal crest ■ Large cheek teeth ■ Flared zygomatic arch ■ Dished face ■ Extreme postorbital construction ```

Question 43

Tools and Intelligence

Answer 43

○ No nonhuman primates make stone tools, but they do use materials as tools ○ Osteodontokeratic culture ■ Dart's interpretation of animal bones, teeth, and horns as tools ○ Butchered remains of animals about 2.5 million years ago indicates evidence that australopithecines were smarter than we may have estimated ○ - Hand anatomy indicates capabilities of production

Question 44

Three possible phylogenies for the australopithecines with Au

Answer 44

○ 1. Au. robustus and Au. Boisei ○ 2. a larger number of species and only distant relationship between Au. robustus and Au. boisei, or ○ 3. a large number of species and a close relationship between Au. robustus and Au. boisei.