1
Q
What is paleoanthropology?
A
The study of human fossils
2
Q
a. Two main concepts in biological anthropology
A
1) All humans are a product of their evolutionary history
2) all humans are a product of their individual life history
3
Q
What’s evolution?
A
“Evolution is a change in the frequency of alleles within a population from one generation to the next”
4
Q
John Ray
A
Identified the existence of biological species “natural theology: the creation of life”
5
Q
Carl Linnaeus
A
Created binomial nomenclature and taxonomy
6
Q
James Hutton
A
- Father of modern geology
- Understand Earth’s history through natural forces
-Uniformitarianism: The formation of the Earth is a long slow process
7
Q
iv. George Cuvier
A
Established extinction was a fact
8
Q
v. Jean-Baptiste Lamarck
A
- Recognized that evolution could occur in contrast to Cuvier
- Believed species change over time in response to the environment and changes are inherited by offspring
9
Q
Charles Lyell
A
- Principles of geology
- Uniformitarianism: the belief that geological processes shaped our world
- Deep time: geological processes are very slow, so the earth must be very old
10
Q
Thomas Malthus
A
-Highly influential to Darwin
- Wrote “An Essay on the Principle of Population”
1) food is necessary for human existence
2) humans populations can grow geometrically while resources grow (next additively
3) since humans don’t voluntarily choose not to reproduce famines, diseases, poverty, and war will result
11
Q
Charles Darwin
A
- Voyage of the Beagle (1831-1836): intended 3-year trip to chart S. American waters for the UK
- He returned from the voyage with the idea of evolution!
- He understood that species can diversify in descendent species
- Species can change and adapt to their environment, but he initially lacked a mechanism for this
12
Q
Importance of Galapagos Islands
A
- The islands were very isolated, so there were animals that had some resemblance to mainland species
- Lacked whole groups of animals, so the island animals filled these open niches (adaptive radiation)
- Different environments make certain features more advantageous; the animals were oddly approachable, making them easy to study
13
Q
Adaptive Radiation
A
New species evolve to fill voids left by other animals’ absences
14
Q
What were Darwin’s observations?
A
1) organisms vary in several traits (ex. Color, shape, and size)
2) much of this variation is heritable
3) more individuals are produced than can be supported by available resources. Therefore, there must be a fierce struggle for existence among individuals of a population
15
Q
What is Natural selection?
A
The gradual process by which heritable biological traits become either more or less common in a population because of the effect of inherited traits on the reproductive success of different organisms interacting within their environment.
16
Q
What are the 3 principles of Natural selection?
A
1) physical characteristics inherited from parents
2) individuals within a species vary
3) great fertility or organisms relative to support from the environment results in competition
17
Q
Darwin and Wallace’s Significance
A
- They independently came up with the idea of Natural Selection
- Darwin had been sitting on the idea for 25 years
- Wallace’s 1858 letter prompted Darwin to publish
- They presented the idea to the Linnean Society together in 1858 (although Wallace wasn’t there)
18
Q
a. Survival of the Fittest?
A
- Herbert Spencer
- It’s actually “Survival of the Fitter”: heritable traits of the more successful reproducers passed on at higher frequency
-Organisms with higher reproductive success pass on their genes (survival will help produce viable offspring) - Natural selection produces fit but not necessarily optimal phenotypes
19
Q
Gregor Mendel
A
- Father of genetics
- Cross pollinated true-bred strains of pea plants
20
Q
Phenotype
A
The observable appearance of an organism
21
Q
Genotype
A
The genetic components (alleles or variants) that an individual has for a particular gene
22
Q
Homozygous Alleles
A
Alleles are the same
- Homozygous dominant: AA
- Homozygous recessive: aa
23
Q
Heterozygous Alleles
A
Alleles are different (Aa)
24
Q
Dominant allele (A)
A
Only one copy of allele needed to produce phenotype
25
Recessive allele (a)
Both copies of allele needed to produce phenotype
26
Natural selection acts on _________
individuals
27
Evolution acts on __________
populations
28
Modern Evolutionary Synthesis
Combination of natural selection (mechanism of evolution) and genetics (mechanism of inheritance)
29
4 Forces of Evolution
(1) mutation: the spontaneous generation of new alleles
(2) migration: movement between two reproductively isolated populations
(3) genetic drift: random change in allele frequency (4) natural selection: differential reproduction based on adaptation
30
Mutation
Spontaneous error that occurs during the replication of DNA; the only source of new genetic variation or alleles
31
Basic DNA structure
Phosphate, diribose sugar, nucleotide
32
SNPs
Single nucleotide polymorphism, basically a point mutation
33
d. Point mutations
alteration of a single base pair in the DNA sequence
34
Missense
A single nucleotide change that results in a different amio acid being coded
35
Nonsense
A single nucleotide change that results in a stop condon. This causes that protein to stop translating early
36
Frameshift
Insertion or deletion of nucleotide bases in numbers other than 3
37
Silent mutations and codons
Silent mutations occur when a base is switched with another nucleotide, but the codon (3 nucleotides) still codes for the same amino acid
38
Large Scale mutations
Rearrangements that occur in lager sections of the chromosome
39
Examples of large scale mutations
- Melanocortin 1 receptor: redheads
- Sickle Cell Mutation: homozygous SS can lead to sickle-cell disease
- Sickle-Cell Anemia and malaria
40
Balanced polymorphism
Situation where selection maintains two or more alleles for a specific gene in a population
41
Migration/gene flow
Immigration from other populations can introduce new alleles; alleles can be selected for in one population and migrate into another
42
Genetic Drift
Drift changes in allele frequencies resulting from random chance (ex. Bottleneck)
43
Natural Selection simplified
Differential survival of individuals due to differences in phenotype
44
What are the types of natural selection?
- Directional selection
- Stabilizing selection
- Disruptive selection (know the graphs)
- Positive selection: fixes beneficial variation
-Purifying selection: removes deleterious variation
45
List out the taxonomy order
Life > Kingdom > phylum > class > order > family > genus > species
46
Ancestral traits
Old traits shared with a distant ancestor (primitive)
47
Derived traits
Newer more recently evolved traits inherited from a more recent common ancestor
48
Cladogram
Depicts the evolutionary relationships of species; each node is a speciation event, indicates a last common ancestor for a group of descendent species; more closely related species are linked by shared derived or more recently evolved character
49
What is a primate?
A very diverse group of mammals (~230-270 species)
50
General characteristics
Well adapted for a variety of ecological niches; anatomy more similar to earlier forms; well suited for changing environments (ex. Primates and black bears)
51
Specialist characteristics
Well adapted for stable environments with specific traits for that environment (ex. Pandas are well adapted for bamboo forests)
52
Postcranial traits in primates
- Grasping hands and feet; nails instead of claws
- Forearm mobility
- Clavicle: forelimb flexibility
- Unique quadrupedal gait
- Upright postures
53
Locomotion in primates
- Quadrupedalism
- Vertical clinging and leaping
- Slow or cautious climbing
- Brachiation
- Knuckle-walking
- Bipedalism
54
Cranial traits in primates
- Decreased reliance on olfaction
-Orbital frontation and convergence
- Postorbital bar
- Generalized dentition
- Encephalization
55
Behavior and life history in primates
- Life history
- Complex social systems
- Behavioral complexity and flexibility
56
Persymines
lemurs and tarsiers
57
Haplorhines
lemurs, lorries, galagoes
58
Strepsirrhines
anthropoids and tarsiers
59
Anthropoids
all haplorhines, except for tarsiers
60
Catarrhines
old world monkeys
61
Platyrrhines
new-world monkeys
62
Cercopithecoids
Old-world monkeys
63
Hominoids
apes and humans
64
Hominins
human lineage (genus Homo)
65
How unique are humans? What makes them so unique?
Very.
- Encephalization
- Life history
- Behavioral and dietary flexibility
- Phenotypically plastic/adaptable
- Tool use/culture, language
- Prosociality
- Socially transmitted knowledge -- teaching
66
How can we reconstruct human behavior?
Questions of hominin origins and evolution must be posed within the context of primate biology (body size, diet, life history; dental morphology; canine size and social structure; brain size and complex behavior; limb proportions and locomotion)
67
William “Strata” Smith
- He discovered the Principle of Faunal Succession: more ancient fossils tend to reside in the lower strata.
- He created the first large-scale geological map
68
James Hutton and Charles Lyell
- The Fathers of modern geology
- Helped us understand Earth’s history through natural forces
- Erosion from wind and rain provides material for new geological layers or strata
69
What are the different kinds of fossils?
Coprolite (poop); burrows; footprints
70
Fossilization process
1) Die
2) Buried quickly (not too acidic to dissolve bone (Few micro-organisms; dry good, damp bad; sedimentation)
3) Mineralized into rock (groundwater replacement; leeching of minerals)
4) Be found!
71
Geologic Time
- Precambrian (4.6 billion – 540 mya)
- Paleozoic – Early Life (570 mya – 230 mya)
- Mesozoic – middle life (230 mya – 66 mya) Age of dinosaurs
- Cenozoic – new life (66 mya -present) age of mammals
72
Epochs of the Cenozoic and major radiations that occurred
- Paleocene (66 mya) Origin of primates; radiation of primate-like mammals
- Eocene (56 mya) Adaptive radiation of true primates and prosimians
- Oligocene (34 mya) adaptive radiation of anthropoids
- Miocene (23 mya) adaptive radiation of apes
- Pliocene (5 mya) adaptive radiation of biped hominids
- Pleistocene (2.6 mya) evolution of genus Homo
- Holocene (10 ka) development of agriculture
73
What was the K-T boundary?
marks the extinction of dinosaurs. The rise of primate-like mammals
74
Plesiomorphy
Primitive trait
75
Symplesiomorphy
Shared primitive trait
76
Apomorphy
Derived traits
77
Synapomorphy
Shared derived trait
78
Homoplasy
Non-homologous similarity
79
Autapomorphy
Derived trait unique to a single taxonomy
80
Parsimony
The idea that the slimiest explanation is most likely to be true
81
Monophyletic
82
Paraphyletic
Group that shares apomorphy (derived traits)
83
Clade
A grouping that includes a common ancestor and all the descendants, living and dead
83
Polyphyletic
Taxa have different ancestors
84
Grades
A group of organisms that are united by a level of physiological or morphological complexity
85
Crown
All living representatives together with their ancestors back to common ancestor
86
Stem
Taxa closely related to crown group but lacking derived characters of crown group. Extinct.
87
What is a model of primate origins? What evidence if there? What is the problem with it?
The Arboreal Model
- Adapted to climbing and foraging in the trees because of their...
- Grasping hands and feet
- Tactile finger and toe pads
- Increase reliance on binocular vision and reduced olfaction
- Increased intelligence for mapping complex 3D environment
Problem: It doesn't explain generalized anatomy and care dedicated to single young
88
Proconsul
- Early Miocene of east Africa (22-17 mya)
- 4 species recognized, ranging from 17-50kg
- Dental characteristics linking to earlier
- Larger brain, no tail, longer limbs, some increased forelimb mobility
- Some old money-like features: IMI of 100, long flexible spine, deep chest, scapula on the side of the thorax
- Above branch quadruped
89
Ape demographic dilemma
- Apes have very low reproductive rates
- Typically 5-7 year interbirth intervals
- Monkeys have 2-3 year interbirth intervals
- You would think that monkeys would over take the apes from the Miocene to present time
90
Transition from apes to humans
- There is a break in the late Miocene fossil record in Africa form 13-15 mya
- Can't directly trace Proconsul to modern apes or the human lineage
- Apes in Eurasia are more "modern" since they showed signs of partial suspension
91
Hominin phylogeny (oldest to newest)
P. aethiopicus > P. boisei >
92
Challenges in paleoanthropology
- Only have bones and teeth
- Don't know the taxomomy
- Difficult to know whether a fossil should be assigned to a new species
- Limits to analyses and what we can know
- Confirmation bias
93
Major adaptive suites
1) Brain and behavior
- Ape: Small brain (<400 cc)
- Human: Large brain (~1300 cc)
2) Skeleton and bipedalism
- Ape: arboreal, suspensory
- Human: terrestrial, bipedal
3) Diet
- Ape: thin enamel, large canine dimorphism
- Human: thick enamel, small canine
4) Reproduction
- Ape: range in body size
-Human: moderate size
94
What makes a hominin?
- Reduced canine size and dimorphism
- Bipedalism
- Brain size
- Tool use
95
Late Miocene climatic change
- Increased seasonality
- Contraction of forest habitats
- Messinian Salinity Crisis
- Development of Asian monsoons
- Desertification of North Africa
96
Hominid vs. hominin
- Hominid: includes all apes and humans
- Hominin: includes the genus Homo and all bipedal, upright walkers
97
Sahelanthropus tchadensis
- Chad
- 6-7 mya
- Robust brow
- Intermediately thick enamel
- Small canine
Forwardly placed foramen magnum
- 360-370 cc
98
Orrorin tugenensis
- Kenya
- 6 mya
- Intermediately thick enamel
- Small canines
- Bipedal adaptations
99
Ardipithecus kadabba
- Ethiopia
- 5.8-5.2 mya
- Possibly some C/P3 honing (rubbing of canine on other teeth to sharpen them)
100
Ardipithecus ramidus
- "Ardi"
- Ethiopia
- 4.4 mya
- "Best known early hominin"
- ~300 cc
- Reduced canine dimorphism
- Intermediate enamel thickness
- Relatively low body size dimorphism
- Primative skeleton had... grasping toe, quadruped like limb proportions, hand adapted for palmigrady
- Not habitually bipedal
101
The Ardipithecines
- Lineage dating back to near 7 mya
- Canine reduction and bipedalosm are earliest hominin traits (they still had small brains)
- Wide geographic range from Central to Eastern Africa
- Lived in forested and woodland environments (not open grasslands)
- May be a common lineage
102
African hominin sites (generally)
- South Africa
- East Africa
- Chad
103
Lumpers vs. splitters
- Lumpers: lump fossils together into larger more diverse species
- Splitters: decided that fewer specimens get assigned to each species resulting in a more speciose phylogeny
104
Bipedalism in Au. afarensis
- Forelimb more primitive and ape-like
- Retained functional climbing features?
- Retained ancestral features because of the lack of selection to change them?
- Hind limb more derived and human-like
- Pelvis
- Bicondylar (pelvic angle)
- Non-grasping foot
- Clear evidence of adaptation to bipedal walking and running
- Legs intermediate between Ardi and humans: getting longer
- 5-6 lumbar vertebrae: similar to humans: can produce lorosis
105
Laetoli footprints
- Tanzania, 3.6 ma
- 3 individuals' footprints
- Big toe in line with rest of the foot
- Rounded heel
- Arch of the foot
- Fully bipedal
106
The Burtele foot
- 3.4 ma
- Ethiopia
- Retained Ardipithecus like divergent hallux
- Indicates locomotor diversity was around for longer than previously thought
- Not currently assigned to a specific species
- There isn't one way to walk bipedally
107
Au. afarensis
- Hadar, Ethiopia and Laetoli, Tanzania
- 3.6-3 ma
- "Lucy"
- "First Family": one site had more than 200 fossils, at least 13 individuals, infants to adults
108
Robust Australopiths (Paranthropus)
109
Au. garhi and stone tools
110
Australopithecine patterns
111
The oldest stone tools
- 3.3 mya, found in Kenya at Lomekwi
- Not associated with a particular hominin
- Date suggests stone tools were being used before the evolution of the genus Homo
112
Australopithecus anamensis
- 4.2-3.8 ma
- Kenya
- Mosaic of primitive and derived traits
- Parallel dentral rows
- Sexually dimorphic canines
- thick enamel, like afarensis
- Tibia indicates bipedalism, but some primitive features in upper limb
- ~50kg
113
Australopithecus afarensis environments
- Hadar, Ethiopia: open woodland
- Laetoli, Tanzania: grassland
- Invading new habitats
114
Little Foot
- 3.3 ma
- Australopithecus unidentified
- Prominent nuchal crest
- Posterior saggital crest
- Hand proportions like humans
- Curved phalanges
- Slightly divergent large toe
- Arm length = leg length
115
Australopithecus africanus
- "Taung Child" and "Mrs. Ples"
- 3.3-2.1 mya
- South Africa
- Fully bipedal
- Large molars
- Rounder slightly larger skull than afarensis (400-500 cc)
116
E. African Robusts (Australopithecus aethiopicus)
- "The Black Skull"
- 2.6-2.3 mya, Kenya and Ethiopia
- Prognathic face like Au. aferensis
- Enormous molar teeth (postcanine megadontia)
117
E. African Robusts (Australopithecus boisei)
- "Nutcracker Man"
- 2.3-1.2 mya
- Ethiopia, Kenya, Tanzania, Malawi
- Ginormous premolars and postcanine megadontia
- Flatter face
- Brain ~ 500 cc
118
Australopithecus garhi
- 2.5 mya, Ethiopia
- Brain 450 cc
- Larger molars than Au. afarensis
- Large incisors too
- Human like leg length
- Found with oldest stone tools at 2.6 ma
- Animal bones showing evidence of butchery
119
Australopithecus sediba
- 1.97 mya
- Malapa (cave), South Africa
- Distinct from E. Africa australopiths
- Biped, but retained primitive traits in the upper limb and torso
- Quite a few fossils, but 2 main partial skeletons
120
Australopithecus robustus
- 2-1.5 mya
- Kramdraai and Swaethkrans
- 530 cc
- Large molars and premolars
- Sagittal crest and zygomatic arch for chewing muscles
- Associated with more open habitats
- Ate more C4 plants
- Bulbs and tubers a possibility
121
Australopithecines
1) Obligate bipedalism: very human, maybe better
2) Enlarged molars and premolars: thick enamel
3) Multiple lineages
4) Initial use of stone tools
5) Expanding habitats and territory: continent-wide distribution
122
Bipedal stance
- Must place base of support under your COM
- Human COM in pelvis anterior to sacral vertebrae
- Feet form a supporting quadrangle
- Quadrupeds have a large supporting quadrangle and a relatively low COM
- Bipeds have a small supporting quadrangle and a relatively high COM
- Bipedalism is generally less stable than quadrupedal stance
123
Human gait
- Gait refers to a particular sequence of lifting and placing feet during legged locomotion
- Affected by speed, number of legs, terrain
- Human bipedal walking and running are two types of gait
- Gait cycle is the repetition of the sequence of leg movement
- In one gait cycle each leg goes through one complete step cycle
124
How does walking require little muscular work?
- Humans walk with extended limbs so relatively little muscular activity is needed support COM and resist ground reaction force
125
How is walking similar to an inverted pendulum?
- The COM oscillates up and down during gait
- Much of the energy for forward motion results from converting potential energy into kinetic energy
- Each stride relocates the pivot point anteriorly
- Most work goes into pushing the COM upward
126
Quadruped vs. biped
Quadrapeds:
- Wide base of support
- Low center of mass
- Forelimbs: shock absorbers
- Hind limbs: engine
Bipeds:
- Narrow base of support
- High center of mass
- Hind limbs: shock absorbers and engine
127
Foramen magnum position in quadrupedal and bipeds
- Quadrupedal posture places head in front of spinal chord
- Foramen magnum faces backward in quadrupeds
- For bipeds, their upright posture places the head on top of the spinal chord
- Foramen magnum points down
128
The curvature of the spine/lumbar lordosis
- Lordosis: the backward curvature of the spine
- Need longer back and lordosis to place trunk over pelvis and legs
129
Bent hip bent knee gait in chimps and monkeys
- Chimps must bend at the hip to place their center of mass over their feet
- Longer backs of monkeys enable them to become competent bipeds
130
Pelvis shape from ape to human pelvis
- Shorter and wider
- Shorter iliac blades
- Iliac blades flared to side
- Shorter ischium with curved attachment for hamstring muscles
131
Difference in lesser gluteal muscles
- In apes, they pull the top of the thigh forward which pushes the leg backward (propulsion)
- In humans they keep the pelvis from dipping toward the swinging leg with each step (stabilization)
132
Body proportions of apes and humans
- Apes have Long arms and short legs , with an IMI of >100
- Humans have short arms and long legs, with an IMI of <100
133
Lateral lip of the patellar surface
- Helps keep the patella from dislocating during bipedal movement
- Sexually dimorphic: females have more pronounced lateral lips than males
134
Loss of grasping feet
- Humans are the only primates to lose their grasping big toe
- It permits the formation of an arch
- The big toe (hallux) is now aligned with the rest of our foot and toes, which helps with fluid bipedal walking, rather than grasping for branches
135
Arch of the foot
Arch supported by ligaments and muscles; body weight placed on the foot stretches the muscles which absorb energy (like a rubber band); keeps shocks from going into bones and joints, reducing injuries
136
Calcaneal Tuberosity
Tuberosity the heel is mostly trabecular bone and less cortical bone, which helps with absorbing force when we heel strike
137
Femoral angle or Bicondylar Angle
- Human thigh bone (femur) slants inward from the hip joint to knee joint
- This only forms when an individual walks bipedally during their lifetime
- Allows foot and knee to be placed under the center of mass while walking
138
Australopithecus deyirmeda
- 3.3 -3.5 ma
- Ethiopia
- Found very close in time and space to Au. afarensis, indicates potential diversity of species living at the same time
139
Kenyanthropus platyops
- 3.5-3.2 ma
- Very flat face and unique dentition indicates morphological diversity at the time afarensis was alive
140
Australopithecus bahrelghazali
- 3-3.5 ma
- Evidence of Australopiths in central Africa (wide home range)
141
Au. afarensis dentition
- Small canines, but with small retained diastema
- Larger molars with thick enamel
- Low rounded cusps
- Likely a forest omnivore: tubers, fruit, vegetation., invertebrates, small animals
- Resist wear --> longevity
ANT-Human Evolution
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