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Ecology & Evolution Final Exam > Unit IV: Hominidae > Flashcards

Unit IV: Hominidae Flashcards

1
Q

Hominidae

A

(great apes)
- Pan: chimpanzee & bonobo
- Homo: humans
- Gorilla: gorillas
- Pongo: orangutans

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2
Q

Hylobatidae

A

(lesser apes)
sister to Hominidae

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3
Q

Hylobatidae characteristics

A
  • Extend: 4 genera & 18 species
  • Tropical Asia
  • Low sexual dimorphism
  • Highly arboreal (tree mobility)
  • Very long arms and experts at brachiation locomotion
  • Omnivorous diet, but >50% fruit
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4
Q

Brachiation Locomotion

A

using arms to swing from tree to tree, common among hylobatidae

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5
Q

Hominidae general characteristics

A
  • Long arms, short legs, no tail
  • Large body size
  • Sexual dimorphism (degree varies, typically larger in males)
  • Omnivorous, most have preference for fruit
  • Large brains for body size
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6
Q

Genus Pongo characteristics

A
  • 2 species in southeast Asia rainforests (endangered)
  • Most arboreal and solitary of great apes
  • Sexually dimorphic (males are larger)
  • Quadruped fist walking (rarely bipedal)
  • Omnivorous, preference for fruit
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7
Q

Genus Gorilla

A
  • 2 species in sub-Sahara Africa rainforests (endangered)
  • Live in group called troops
  • Arboreal and ground dwelling
  • Strong sexual dimorphism, males 2x the size
  • Quadruped knuckle walking, bipedal for short distances
  • Omnivorous, high percentage of diet is foliage (males have prominent sagittal crest)
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8
Q

Sagittal Crest

A

bone ridges in the skull, provides surface area for jaw muscle attack, common among male gorillas

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9
Q

Genus Pan characteristics

A
  • 2 species in sub-Sahara rainforests (endangered)
  • Arboreal and ground dwelling
  • Quadruped knuckle walking, bipedal for short distances
  • Omnivorous
  • (Equally) closest relatives to humans
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10
Q

Chimpanzee specific characteristics

A
  • Larger
  • Male-dominated
  • More aggressive
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11
Q

Bonobo specific characteristics

A
  • Smaller
  • Female dominated
  • Less aggressive
  • Frequent sexual behavior helps resolve conflicts
  • Great preference for fruit
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12
Q

Did humans evolve from chimps?

A

Humans did not evolve from chimps, but rather from this common ancestor

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13
Q

What are the 3 extinct genera of the intermediate taxa between Humans/Chimps and their common ancestor?

A
  • Ardipithecus (~5-4 mya)
  • Australopithecus (~4-2 mya)
  • Paranthropus (~3-1 mya)
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14
Q

What is the 1 extant genus from Human’s ancestral line?

A
  • Homo (~3 mya-present)
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15
Q

Genus Ardipithecus characteristics

A
  • 2 extinct species (~4-5 mya)
  • Fossils from Ethiopia
  • Grasping hallux (adaption for locomotion in trees)
  • Hands more similar to modern humans than chimps
  • Pelvis shape for walking upright
  • Brain slightly smaller than modern chimps
  • Reduced canines (less aggression?)
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16
Q

Genus Australopithecus

A
  • 7 to 9 species (~4-2 mya)
  • Fossils from eastern Africa
  • Thought to be most closely related genus to Homo
  • Brain sizes ~35% the size of humans
  • High degree of sexual dimorphism (larger males)
  • Teeth wear suggest mainly fruit diet, but also veggies and tubers (also meat consumption theory)
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17
Q

Australopithecus Afarensis (“Lucy”)

A
  • oldest member of genus; lived 3-4 mya
  • fossils from Ethiopia
  • Dentition and jaw traits intermediate between humans and more distantly related apes
  • Strong evidence of bipedalism:
    (shape of pelvis, angle of femur, attachment of muscles around knee)
  • Arboreal or terrestrial?
    (Curvature of fingers/toes adapted for grasping = arboreal
    Loss of grasping hallux = terrestrial)
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18
Q

Grasping Hallux

A

the adaptation of the big toe for easier locomotion in trees

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19
Q

Genus Paranthropus

A
  • Lived 1.5 to 2 mya
  • “Robust” body type:
    (strong upper body, large skull with flat face and no forehead, large brow ridges, large grinding teeth for diet)
  • Most specimens have sagittal crest
  • Evolutionary “dead end”
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20
Q

Genus Homo

A
  • 7 or more species (1 extant species = Homo sapiens)
  • Genus is about 2.5-3 mya
  • Long lower legs (walking, running)
  • Smaller teeth
  • Larger brains
  • Bulge of Broca’s area (essential for speech) becomes visible
  • Evidence of tool, fire use, and burial of dead
21
Q

Broca’s area

A

part of the brain that controls the ability to produce language; becomes prominent in the Homo genus

22
Q

What are the defining traits of human lineage?

A
  1. Adaptations for bipedalism
  2. Evolution of big brains
23
Q

List of adaptation for bipedalism:

A
  1. Foramen magnum more anterior (where the spine connects to skull)
  2. Trunk
    - S-curve of spine
    - Larger surfaces for muscles supporting upright posture
    - Expanded lumbar area
  3. Shortened forearms
  4. Pelvis and legs
    - Narrow pelvis
    - Femur angles towards midline
    - Long legs
  5. Feet
    - All toes point forward
    - Enlarged heal and arch (to take impact of walking)
24
Q

Advantages of Bipedalism

A
  • frees hands for caring items, tool use
  • may be particularly beneficial in open habitats (travel greater distances for food)
25
Q

What is the reason for an increase in brain size/evolution of big brains?

A
  • Increase in brain size is due to increase in body size, or may be linked to increased meat intake (energy)
  • Positive feedback between cultural/linguistic complexity, technology advances, and diet
26
Q

What are the 4 benefits of evolution of BIG BRAIN?

A

– Store information
– Quickly process information
– Problem solving
– Abstract ideas

27
Q

What are the 2 costs of evolution of BIG BRAIN?

A

– Lots of energy
* Your brain is ~2% of your body size but uses ~20% of your energy
– More difficult childbirth (we have narrow hips, but babies have a big brain)

28
Q

What is the history of Homo?

A
  • oldest Homo species were in Africa
  • Some species migrated out of Africa before the first H. sapiens (eg. H. erectus, H. neanderthalensis, and Denisovans in Eurasia)
  • Before Homo sapiens, there were Homo species in Africa, Europe, and Asia
29
Q

Where did Homo sapiens originate?

A
  • Oldest H. sapiens fossils are all from Africa
  • First H. sapiens fossils in other continents are 30-60,00 years old
30
Q

Why do populations outside of Africa have less diversity?

A

Consistent with:
- Younger populations
- Bottleneck during founder event

31
Q

What are the Pros & Cons of UVB:

A

Pros:
- causes synthesis of vitamin D, which is needed for absorption of calcium

Cons:
- damages skin surface, causes sunburns and some skin cancer

32
Q

What are the 2 Ultraviolet Lights besides visible light?

A

UVA & UVB

33
Q

What are the Pros & Cons of UVA?

A

Pros:
- Less intense than UVB (but still causes skin damage)

Cons:
- Breaks down folate
- Deficiency of folate can lead to birth defects and decreased sperm production

34
Q

How is UV radiation distribution?

A
  • Near equator: high levels of UV radiation (both types, due to more direct sunlight)
  • Near poles: less UV light
35
Q

What are determinate of Skin Pigmentation?

A
  1. Human ancestors in Africa (moved from forest to Savanna)
    - with less shade, more exposure to UV light
  2. Selection for cooling mechanisms
    - more sweat glands and less hair from chimps
  3. More skin exposure = selection for more melanin pigmentation
    - melanin protects from UVA, preventing too much breakdown of folate
    - since UVB levels are so high, vitamin D synthesis persists despite melanin
  4. Migration to Europe = lower UV radiation (as move up latitude)
    - this movement protected from loss of folate, but loss of vitamin D
    - alleles that results in less pigmentation have high fitness due to increased ability to make essential vitamin D
36
Q

What is the hypothesis of skin pigmentation?

A

Hypothesis that skin pigmentation is a balance between the pros (vitamin D production) and cons (folate breakdown) of UV radiation

  • natural selection favors less/more melanin depending where you live
37
Q

What are recent evolution in Homo sapiens?

A
  1. Selection at high altitude
  2. Lactose Intolerance
38
Q

What occurs in Homo sapiens at high altitudes?

A

Lower concentration of oxygen in the air, leads to Hypoxia:

  • deficiency of oxygen
  • lots of complications (including fatigue, dizziness, headaches, insomnia, nausea, vomiting, and dilated veins)
39
Q

What is Homo sapiens’ Plastic response to high altitude?

A

increased red blood cell production (uptake of oxygen) when you move to high altitudes

40
Q

Phenotype plasticity

A

same genotype can produce different phenotypes
(change depending on environment, but not over generations)

41
Q

What are examples of some populations experiencing evolution across generations?

A

Selection for allele that increase fitness at high elevations:

  1. Andes Mountains:
    - variants of hemoglobin that carry more oxygen
    - allows greater uptake/delivery of oxygen
  2. Tibetan Plateau:
    - naturally higher production of red blood cells, rates of breathing, and lung capacity
    - expanded blood vessels = increased blood flow and delivery of oxygen
42
Q

EPAS1

A

gene linked to red blood cell production

43
Q

LCT

A

lactase gene

44
Q

MCH

A

major histocompatibility complex (immune system)

45
Q

Explain why some people may be Lactose Intolerance.

A
  • Most mammals only drink milk early in develop while nursing, which means lactase expression is reduced after wearing
  • It is costly to produce when not needed (not drinking milk)
  • In most mammals, lactase is not produced after drinking milk (in nursing)
46
Q

What is the Enzyme lactase for?

A

to break down lactose (sugar) in milk

47
Q

Human Niche construction

A

the ability to change the environment and resources we receive

48
Q

Explain the Evolution of lactase persistence.

A

Alleles that keep lactase gene turned on past weaning were “selected for” because they provided higher fitness

Ecology & Evolution Final Exam (15 decks)

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