Midterm 2

Question 1

The main levels of taxonomic hierarchy?

Answer 1

Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 1

*The full classification of our species

Answer 1

• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Primates
• Family: Hominidae
• Superfamily: Hominoidea
• Tribe: Hominini
• Genus: Homo
• Species: sapiens

Question 2

*the taxonomic classification of the primates

Answer 2

SEE picture on phone

Question 3

Explain the trade-off between number of offspring and investment in offspring

Answer 3

The trade-off between number of offspring and the investment in offspring is a key concept in evolutionary biology, as it involves a balance between quantity and quality of offspring. Species that produce more offspring (r-selected) may have lower individual investment in each one, while species with fewer offspring (k-selected) tend to invest more resources into ensuring their survival and success

Question 4

Concept of life history

Answer 4

How different stages of growth and development are typically distributed across the lifetime of an animal
- How much time is spent as an infant?
- How much time is spent growing?
~ When do teeth erupt (weaning; independence from mother)
~ When do bones fuse (adult size)
- When does reproduction start!?

*Generally thought about as a trade-off

Question 5

What does it mean to say a primate species has a slower life history vs. a faster life history?

Answer 5

Life history theory predicts that certain strategies are optimal in certain situations
-Grow quickly, reproduce early, be small
- Grow slowly, reproduce late, be big

Primates have a slower life history compared to other mammals, which allows for increased opportunities for learning and social interactions. This prolonged development period likely contributed to the development of complex social structures and behaviors in hominid populations.

Question 6

What biological features do primates share?

Answer 6

• Grasping hands and feet (5 fingers and toes; thumb and “big” toe position)
• Nails instead of claws (distal phalanx)
• Pronation and supination ability (radius and ulna; tibia and fibula)
• Binocular and stereoscopic vision (eye orbits facing forward)
• Color vision in cones (ability to see red; for fruit? for sex?)
• Reduced reliance on smell (reduced snout)

Question 7

Why are social groups and social behavior so important for most primates?

Answer 7

• Safety and defense (strength in numbers)
• Other individuals around to do stuff; potential for cooperation; potential for exploitation
• Food gathering
• Pool of potential reproductive partners
• Decreasing predation risk
• Easy to defend good food sources

Question 8

In what ecological niche do we think the earliest primates evolve?

Answer 8

Tropical rainforests

Question 9

What biological features are present in the strepsirrhines that are more primitive than the haplorhines?

Answer 9

means “wet nose”
- lacks color vision
- rely on smell (large snout)
- nocturnal
- grooming claw
- partially open orbits
- mandible with suture at midline

Question 10

What biological features are more derived in monkeys and apes than in strepsirrhines?

Answer 10

means “dry nose”
- color vision
- small snout
- diurnal
- no grooming claw
- closed orbits
- no mandible with suture at midline

Question 11

Platyrrhines dental formula

Answer 11

2.1.3.2-3/2.1.3.2-3

Question 12

Catarrhines dental formula

Answer 12

2.1.2.3/2.1.2.3

Question 13

What is the difference between an ape (a hominoid that is not a hominin) and a monkey (a catarrhine this is not a hominoid)?

Answer 13

The main distinction between apes and monkeys lies in their anatomical features, with apes having no tails and larger bodies compared to monkeys

Question 14

Pronograde vs. orthograde

Answer 14

A pronograde body plan means that an animal moves with its body parallel to the ground, with limbs extending out to the sides. This type of body plan is common in quadrupeds like dogs and cats, allowing for greater stability and agility while moving on all fours.
- in quadrupedal locomotion, the body is this

An orthograde body plan , on the other hand, involves an animal moving with its body perpendicular to the ground, with limbs extending vertically underneath. This body plan is often seen in primates like humans and apes, allowing for more efficient bipedal locomotion.
- in forelimb-dominated, below-branch suspension, the body is this

Question 15

Below-branch suspension vs. over-branch quadrupedalism

Answer 15

Below-branch suspension involves hanging from branches using the arms, while over-branch quadrupedalism involves moving along branches using all four limbs. Both forms of locomotion are adaptations to life in the trees, with below-branch suspension allowing for greater stability and over-branch quadrupedalism providing more speed and agility

Question 16

Why do apes tend to move around the trees by climbing or hanging below branches, whereas monkeys walk around on all fours above branches?

Answer 16

Apes are larger bodied and have longer arms than monkeys, which allows them to swing and hang from branches more easily without breaking the branches. Monkeys, on the other hand, have shorter arms and smaller bodies, making it more efficient for them to walk on all fours across branches

Question 17

Example of an adaptation that helps apes move around by swinging below branches

Answer 17

• long arms relative to legs
• short, stiff back
• very mobile wrist
• wide shallow crest with shoulder blades on back
• long, curved fingers

Question 18

Identify the Y-5 pattern vs. bilophodont patterns in lower molars

Answer 18

The Y-5 pattern is characterized by five main cusps arranged in a Y-shape, while bilophodont patterns have two main transverse ridges

Y-5 pattern is on lower molars on: “bifurcation is buccal”

In monkeys, mesial and distal cusp pairs are separated (bilophodonty)

Question 19

Ecology

Answer 19

The study of how an organism’s biology relates to the environment– especially extracting resources from the environment

Question 20

Niche

Answer 20

The ecological “space” an organism takes up

Question 21

Generalist/specialist

Answer 21

Generalists are species that can thrive in a wide range of environmental conditions and feed on a variety of resources, while specialists are adapted to specific habitats and diets.

Generalist=broad
Specialist=very narrow

Question 22

Frugivory/folivory

Answer 22

Frugivory
- fruits

Folivory
- leaves

Question 23

Arboreal terrestrial

Answer 23

Arboreal
- live primarily in trees

Terrestrial
- live primarily on the ground

Question 24

Cooperative breeding

Answer 24

Allomaternal care - care of offspring by nonparents Paternity is certain so there is less male-male competition (one breeding male and female)

Question 25

Which primates are cooperative breeders?

Answer 25

Humans, marmosets, and tamarins

Question 26

How does cooperative breeding affect the number of offspring that can be produced?

Answer 26

Increases net reproductive output - can have more and more closely spaced offspring, despite longer periods of dependence because not only ones using energy to care for young

Question 27

Principle of competitive exclusion

Answer 27

Principle of competitive exclusion states that two species competing for the same limited resource cannot coexist in the same ecological niche for an extended period of time. This leads to one species outcompeting the other, resulting in either the extinction of one species or a shift in their ecological roles

Question 28

Example of niche partitioning in primates

Answer 28

- change physical space occupying - change diet - Nocturnal vs. diurnal (temporal change) Ex. different species of monkeys will occupy different levels of the forest canopy, with some species specializing in the upper canopy while others stick to the lower levels. This allows each species to access different food sources and avoid direct competition with one another. By utilizing different parts of the same habitat, these primates are able to coexist and thrive in the same environment without overlapping too much in their resource use

Question 29

Describe an example of a primate adaptation that allows that group/species to occupy a specific dietary niche

Answer 29

- physiological and soft-tissue anatomy changes - behavioral changes - skeletal changes One example of a primate adaptation for occupying a specific dietary niche is the specialized dental morphology of leaf-eating primates like colobus monkeys, which have sharp ridges on their molar teeth to efficiently process tough, fibrous leaves. This adaptation allows them to extract maximum nutrients from their primary food source and thrive in their forest habitats

Question 30

Describe how canine size, canine dimorphism, and the canine-P3 honing complex relate to social structures in living primates

Answer 30

Canine size in primates is often correlated with social behavior, with larger canines typically seen in species where males compete for dominance and access to females. Canine dimorphism, or differences in canine size between males and females, can also reflect social hierarchies and mating strategies within primate groups. For example, in baboon societies, males with larger canines are often seen as more dominant and have greater access to mating opportunities. Additionally, the presence of a canine-P3 honing complex, which sharpens the canine teeth through repeated contact with the lower third premolar, can indicate aggressive behaviors and social interactions within primate societies. This honing complex is more commonly found in species where males use their canines for display and intimidation, such as in gorillas and some species of monkeys. Overall, canine dimorphism and the presence of a honing complex can provide valuable insights into the social dynamics and reproductive strategies of primates

Question 31

Explain how fossilization occurs from burial to discovery

Answer 31

1.) Burial under specific conditions - quickly covered is good - certain kinds of sediments are better than others 2.) Mineral replacement - biological minerals are replaced by rock minerals (diagenesis) 3.) Exposure

Question 32

Mineral replacement is in the middle of burial and discovery, but what is that?

Answer 32

Biological molecules and minerals replaced by rock materials

Question 33

Stratigraphy

Answer 33

The sequence of layering of the various rock formations

Question 34

Principle of original horizontally

Answer 34

Everything starts out roughly horizontal; disruption of horizontality is caused by later factors

Question 35

Principle of superposition

Answer 35

Younger layers are deposited on top of older layers (superposition) - a layer that cuts across others is younger than those it cuts

Question 36

Relative vs. absolute dating

Answer 36

Relative dating involves determining the age of a rock or fossil based on its position in relation to other rocks or fossils, while absolute dating provides a specific age in years. Relative dating is often used when the exact age of an object cannot be determined through absolute dating methods, which are the more preferred methods

Question 37

Example of relative dating

Answer 37

Biochronology - relies on the law of superposition: *The sediment layers at the bottom are the oldest, those on the top are progressively younger *Establishes a sequence within the site *Fossils that appear in the bottom strata are older than fossils in the top strata

Question 38

Example of absolute dating

Answer 38

Radioisotopic dating: based on radioactive decay of elements

Question 39

Radiometric dating

Answer 39

using the decay of radioactive isotopes to determine the age of fossils and artifacts

Question 40

Parent element

Answer 40

Element before decay

Question 41

Daughter element

Answer 41

Element after decay

Question 42

What starts the radiometric clock?

Answer 42

Some event related to death or burial of an organism starts the radiometric clock and the daughter element begins accumulating

Question 43

Is radiometric decay constant or variable?

Answer 43

Constant on average

Question 44

What is half-life?

Answer 44

the average length of time it takes for half of a sample of parent to decay to daughter

Question 45

What can age be calculated based on?

Answer 45

Knowledge of the half-life and the observed ratio of the parent to daughter

Question 46

How is volcanic activity involved in Argon-based dating methods?

Answer 46

Rocks heated to high temperatures (volcanic temps) release all argon and start the clock of argon accumulation - the volcanic rock layers above and below a fossil are dated by using the half-life of Potassium isotope to decay to Argon isotope - slower decay rate means it can be used to date much older things

Question 47

What is the molecular clock?

Answer 47

The molecular clock in paleoanthropology is a method used to estimate the timing of evolutionary events based on changes in DNA sequences over time. By comparing genetic differences between species, researchers can determine when these species diverged from a common ancestor - combines phylogenetic and genomic analyses, calibrated by fossils to estimate when living animals last shared a common ancestor

Question 48

What is a divergence date?

Answer 48

refers to the estimated time when two species or populations of hominins split from a common ancestor

Question 49

When does molecular evidence suggest the human and chimpanzee lineages diverged?

Answer 49

4.5 Ma

Question 50

How are fossils involved in the molecular clock (calibration)?

Answer 50

Fossils are used to provide a minimum age for specific branches on the tree of life based on morphology, allowing researchers to estimate when certain genetic changes occurred. *By combining fossil data with genetic data, scientists can calibrate the rate at which mutations accumulate over time, providing a timeline for evolutionary events

Question 51

Cenozoic Epochs and boundary dates

Answer 51

(from bottom/oldest and up) Paleocene 65.5 Eocene 56.5 Oligocene 34 Miocene 23.3 Pliocene 5.2 Pleistocene 2.6 Holocene 0.01

Question 52

"Put Eggs On My Plate, Please Honey"

Answer 52

Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Holocene

Question 53

What epoch did the earliest primate-like mammals originate?

Answer 53

Paleocene Epoch

Question 54

Know which epoch primates originated in Ex. Euprimates --> Eocene

Answer 54

Euprimates --> Eocene

Question 55

Which epoch hominoids originated in

Answer 55

Hominoids originated in the Miocene epoch, approximately 23 to 5 million years ago

Question 56

What epoch hominins originated in

Answer 56

Pliocene epoch

Question 57

What epoch did Homo originate in?

Answer 57

Pleistocene epoch

Question 58

How can we reconstruct the temperature of the earth in the distant past?

Answer 58

Global temperature curves are built from oxygen isotope data - The more 18 Oxygen found in the sediment, the colder the climate, the more 16 Oxygen, the warmer the climate

Question 59

Oxygen isotopes are helpful for reconstructing how____

Answer 59

1.) cool and dry vs. 2.) warm and wet An environment is

Question 60

Carbon isotopes from paleo-sites are helpful for understanding whether the plants growing in an area were_________ vs. __________.

Answer 60

trees and bushes (closed environment) vs. tropical grasses and sedges (more open environments) "You are what you eat"

Question 61

What is a hominin?

Answer 61

- any species on our side of the split - a member of the taxonomic Tribe Hominini

Question 62

When do we think human evolution started (about how many million years ago)?

Answer 62

6-7 Ma

Question 63

How old are the oldest hominin fossils?

Answer 63

4.2 Ma

Question 64

What are the characteristics of hominins?

Answer 64

- distribution - population size and density - reliance on material culture - genetic uniformity - cognition - bipedalism - sex & social organization - relatively large brain - diet - longer gestation, later age at maturity - unique body proportions

Question 65

How can we identify a hominin in the fossil record?

Answer 65

1.) Skeletal evidence of bipedalism 2.) Skeletal evidence of reduced, non-honing canines and low canine dimorphism

Question 66

Skeletal evidence of bipedalism

Answer 66

Indicators can be found in: - skull - spine - pelvis - legs - feet

Question 67

What is the canine-P3 honing complex?

Answer 67

functions to keep canines sharp - large dagger-like upper canine, diastema, and asymmetric third premolar (P3) - the back side of upper canine wears against the front side of the lower P3, keeping canine tips sharp

Question 68

What do the reduced, non-honing canines of hominins imply, with regard to social structure and reproductive biology?

Answer 68

The reduced, non-honing canines of hominins suggest a shift towards a more cooperative and less aggressive social structure rather than intense male-male competition for females. Additionally, this change may reflect a shift towards pair bonding and monogamous relationships in hominin reproductive biology Reduced canine dimorphism means that there is less sexual selection pressure on males to have large, sharp canines for competition, indicating a shift towards a more peaceful and cooperative social structure. This may also suggest that females choose mates based on other factors besides physical aggression and dominance

Question 69

Australopiths

Answer 69

group of Plio-Pleistocene hominins characterized by a combination of ape-like and human-like features

Question 70

Where were australopiths found and when did they exist?

Answer 70

They originated sometime before 4.2 Ma and lasted until about 2.0 Ma (gracile) and 1.2 Ma (robust)

Question 71

What are the characteristic features of Australopiths?

Answer 71

- Ape-sized brains - subnasal prognathism (jaws that stick out in front of the face) - Smaller than living humans (- long arms, short legs) Derived - bipedal

Question 72

How big are australopiths?

Answer 72

Ranged in stature from 3'6'' - 5'6''

Question 73

Were australopiths dimorphic in body size?

Answer 73

Yes, australopiths were dimorphic in body size, with males typically being larger than females, however, there were no signs of the canine size dimorphism we see in gorillas and orangutans HIGHLY dimorphic in body size BUT NOT in canine size!!!

Question 74

Upper limb morphology of australopiths

Answer 74

Australopiths have primitive limb proportions, compared to living humans - long forearms - long, curved fingers - upward facing shoulder joint

Question 75

Was there evidence to support australopiths being bipedal?

Answer 75

Yes! - There is behavioral evidence from Laetoli footprints are indisputable evidence that a bipedal hominin walked across this layer of volcanic ash in 3.6 Ma - There is behavioral evidence from the knee - There is evidence from the pelvis Yes, there is evidence to support the theory that australopiths were bipedal, including the structure of their pelvis and foot bones which suggest adaptations for walking upright. Additionally, studies of their fossilized footprints have shown characteristics consistent with bipedalism

Question 76

Australopiths had non-dimorphic canines. What does that imply about structure and reproductive biology?

Answer 76

Non-dimorphic canines in Australopiths suggest that there was likely less competition among males for mates, as they did not need to rely on physical displays of dominance. This may indicate a more cooperative social structure and potentially a more monogamous reproductive system compared to species with dimorphic canines

Question 77

What function does the Australopithecus sagittal crest serve?

Answer 77

An extension of bone on the cranium that provides attachment surface for extra large chewing muscles

Question 78

What did robust australopiths eat and how do we know that?

Answer 78

Robust australopiths show major anatomical adaptations and isotopic evidence of eating some (or a LOT) of foods derived from grasses since extreme chewing adaptations to aid in digestion of such tough food items

Question 79

Carbon isotopes can help us know if an extinct animal was eating foods derived from___________ vs. ___________.

Answer 79

grassy-style plants vs. foods derived from tree/bush style plants