Midterm #2 Flashcards
What are common primate traits
two bones in the lower leg and forearm
flexible prehensile (grasping) hands and feet
Bigger portion of the brain devoted to vision rather than smell (compared to other mammals)
Male’s with pendulous penis not attached to the abdomen by skin
Most females with 2 nipples
forward-facing eyes and stereoscopic
vision
large brain relative to body size
How do primates differ?
Body size
- Affected by the time of day the species is active, where it is active ,and the kinds of food it eats
Relative brain size
Group size
- Nocturnal = hunt in pairs or alone
- Density of food
Sexual dimorphism
What are the seven big categories of movement
Vertical clinging and leaping:
tarsier - tiny guys with huge eyes
lemurs → adapted to living on the ground - leap around to trees
Slow Climber:
Loris - tiny and adorable but not very fast because they don’t have to be
Branch Runner:
Capuchin - very fast
Ground running and walking:
Mandrill - hand the same as humans - flat on the ground
Brachiation → swing between trees:
Gibbon - little sexual dimorphism - territorial
Knuckle-walking
Mountain gorilla (Rwanda) → like a lineman playing football - on knuckles
Gorilla gorilla - huge
Bipedalism
Most curious one because a huge number of anatomical changes required to get here
What are the right names for prosimians and anthropoids
prosimians - strepsirhines (wet nose)
antrhopoids - haplorhines (dry nose)
Two main groups of anthropoids
Platyrrhine (new world) (Parapithecids): broad, flat-bridged noses with nostrils facing outward, three premolars, prehensile tail, arboreal
Catarrhines (old world) (Propliopithecoids): subdivided into cercopithecoids and hominoids , narrow noses, two premolars, more closely related to humans
3 groups of hominoids
the hylobates (lesser apes)
the pongids (great apes) (including orangutans, gorillas, and chimpanzees),
hominins (humans)
What’s the difference and similarity between cultural ecology and behavioural ecology?
Both have the idea that natural selection can operate on the behavioural or social characteristics and not just physical traits
Cultural = group selection + natural selection of group characteristics
Behavioural = individual selection + natural selection of individual characteristics
Describe the 3 ecological zones that non-human primates inhabited?
Tropical Rainforest:
Hot, humid
Cloudy
Rain most months
Year-round growing season
Advantage- you have a continuous growing season - things are constantly renewing
Primates living on the ground and in different sections of the trees (canopy)
Life is horizontal and vertical
Woodland:
Lower, less continuous canopy
Less rain - have distinct wet and dry seasons
Food more limited
Ground-dwelling primates
Savannah (grassland):
Unpredictable rain
Microhabitats
Explain and contrast two models for understanding hominin behaviour in the past
Non-human primate models: based on either experimental or natural observations of behaviours in living non-human primate groups
Ethnographic analogy: relies on what we know from small, non-Westernized foraging or hunting-and-gathering societies that may be similar to such prehistoric populations
Describe the major traits that are distinctive to hominins
Physical:
- bipedal
- largest and most complex brain of all the anthropoids, especially the cerebral cortex
- move their jaws both vertically and horizontally when chewing
- Relatively hairless
Behavioural:
- Hominin females are not limited to when they can engage in intercourse
- Offspring have a much longer dependency stage, and more hominin behaviour is learned and culturally patterned
- Hominins usually have a division of labour in food-getting and food-sharing in adulthood
- The use of tools to make other tools
spoken symbolic language unique to modern humans
What are the different kinds of communication?
Referential: refers to a specific event or thing
Symbolic : has meaning even though the referent isn’t present → the meaning we give to these things must be learned
Humans - complex symbolism:
Grammar: the different way we combine words can change the meaning completely
Describe Orangutan, Chimpanzee, and Gorilla social organization.
Orangutan
Males live alone and the females live with their children
Large sexual dimorphism
Heaviest of the arboreal primates
Chimpanzees
Females and children move to groups headed by dominant male and all males born in that area
Gorillas
Live in groups composed of a single male that heads a group of females
Male defends the females
Single females will move between groups
Young males will return to their natal group
What is Cladistics and Phylogenetics?
Cladistics = shared physical features
Phylogenetics = changes in physical features
Endocast
A preserved, fossilised relief of the hominin brain, created by the skull filling with minerals and taking on the morphology and structure of the brain
Endocasts are an important source of evidence for understanding the evolution of the brain and questions related to the origins of language, etc.
Describe the evidence that can be used to interpret the fossil record.
Dentition can provide clues about the size of the primate as well as its diet
Fragments of the skeleton can give paleoanthropologist clues about locomotion
Evidence from the cranium can provide insight into vision, smell, and memory in early primates
What are the two major groups of prosimians and what is a candidate for the common primate ancestor of these two groups?
Adapids → led to modern lemurs and lorises
Daytime herbivores, wide teeth for grinding
Omomyids → led to tarsiers and anthropoids
Big eyes, nocturnal insectivores
adapids and omomyids date from the early Eocene, about 55 mya. Both possess more forward facing eyes, nails and not claws, and an opposable toe
Candidate = carpolesters → Mouse-sized arboreal creature living about 56 million years ago → mix of primate and non-primate characteristics
What is the geological period order?
Late cretaceous (ends at 65 mya) → paleocene → eocene → oligocene → miocene → pliocene → pleistocene
Explain the process of continental drift:
225 mya → formation of pangaea (world much colder and no pronounced seasonality)
Early Cretaceous (135 mya) → two supercontinents :
- Laurasia → North America and Eurasia
- Gondwanaland → Africa, South America, India, Australia, and Antarctica
Beginning of the the paleocene (65 mya) → Gondwanaland had broken apart, with South America drifting west away from Africa, India drifted east/north and crashed into eurasia (himalayas), and Australia and Antarctica drifting south
Why is continental drift important?
Position of continents:
Oceans act as barriers and isolate species → important role in the evolution of all primates
Engine of climate change:
Mountain ranges - weathering patterns changing (climate)
Ocean circulation
What is the arboreal theory and what is a weakness of it?
The primates evolved from insectivores that took to the trees
Weakness → squirrels live in trees very well and they lack many primate characteristics like front-facing eyes, nails, opposable thumbs → also, other animals have primate traits but do not live in trees like cats
Describe the emergence of anthropoids. (when and where first anthropoid and two diff groups)
The earliest undisputed anthropoids have been found in Egypt dating from the early Oligocene, about 34 million years ago
Early anthropoids include monkey-like parapithecids and the ape-like propliopithecids.
The origins of anthropoids may be related to a tougher climate. Changing patterns of monkey and ape diversity in the Miocene reflect a drying climate and loss of forested areas
Platyrrhines appeared 25 to 30 million years ago when South America was an island. Their origin is uncertain: they may have originated from either African or Asian anthropoids, or from North American primates of the Eocene
Aegyptopithecus may be ancestral to all Old world monkeys and apes
There are few monkey during the early Miocene, but they are abundant by the late Miocene
How might anthropoid primates have travelled from Africa to South America?
In the eocene, Omomyoids could migrate along forest corridors at high latitudes
By the oligocene these corridors had vanished:
Parapithecids: ancestors of old world monkeys ‘rafted’ on storm debris from Africa to South America during the later Eocene (wouldn’t have been too far across continents at this time)
Differentiate between early anthropoids and hominoids (apes).
During the Miocene (24 - 5.2 million years ago), monkeys and apes diverged in appearance and various kinds of apes appeared in Europe, Asia, and Africa
From the middle to the end of the Miocene, apes diversified and spread rapidly; they were bigger than earlier anthropoids and lacked a tail
Early apes, like Proconsul, had the Y-5 dental pattern of apes, but their postcranial skeleton was much like that of monkeys. True apes also have wide, not deep chests and a shoulder reflecting a brachiating ancestor
Apes are abundant during the early Miocene, but there are very few by the late Miocene
Describe the climate during the Miocene and how monkeys and apes began to diverge. (miocene apes emerged)
Furthest away from the sun than we’ve been → cooling (northern and southern hemispheres starting to happen) → drove differences in the radiation of different organisms around the world
Miocene (24-5.2 mya) = monkeys and apes clearly diverged in appearance ,and numerous kinds of apes appeared in europe, asia, and africa
In AFRICA :
- Immense rainforest reducing → lowland (very hot) and highland - (rainforest now tiny in the present)
- Grasses and shrubs fill the void of the reducing rainforest
- Warm and wet environment → changes to cool and dry conditions
- Major adaptations necessary for organisms
PROCONSUL:
- Fossils from 20 mya - seen as a proto-ape
- Front-facing eyes, flat hands
- Bigger than the anthropoids
- Primarily arboreal, large brains
- No tail → important divergence from monkeys to apes
Proconsul LED TO THE…
Miocene apes ( hominoids) 15-10 mya
Miocene apes from Africa, Europe, and East Asia
Africa → kenyapithecus (terrestrial)
Europe → Oreopithecus & Dryopithecus (arboreal) → mostly these guys
East Asia → Sivapithecus (arboreal)
What were the possible first hominins?
Transitional species, and possible the first hominins, include Sahlenthropus (7mya), Orrorin (6 mya), and Ardipithecus (5.8-4.4mya)
What are the 3 key fossils to bipedalism?
Sahelanthropus tchadensis: mix of primitive and advanced ape features
- Experiment in head:
- Hole where the brain stem goes in → moving to the front of the brain (modern humans right in the middle + quadruped at the back)
Orrorin Tugenesis
- Experiment in hips and knees:
- Human-like femur
- Apes have straight femurs - modern humans’ femurs go together at our knees
has the externus groove
Ardipithecus kadabba (ramidus)
- Experiment in feet and toes
- Tone bone
- Bipedal with grasping big toe and feet able to push off
Identify the main trends in hominin evolution - physical changes that led to genus Homo.
Physical changes in early hominins that led to the evolution of our genus, Homo, include the expansion of the brain, the widening of the female pelvis to allow birth of bigger-brained babies, and the reduction of the face, teeth, and jaws
Increased brain size may be linked to the emergence of stone toolmaking and to life in complex social groups.
Describe the different kinds of comparative anatomy in terms of evolution and divergence.
Heads/brain size - impression of a brain fossilized on a brain case - more often just the skull is found
- Looking at how brain cases have changed to accommodate the development of the frontal lobe
- Frontal lobe → the “control panel” of our personality (who we are) and our ability to communicate
Teeth :
- early on = teeth for grinding food
- Present = teeth for chomping
- Big teeth to small teeth that are more adaptable to other things
Locomotion and posture:
- Bipedalism
- Abductor muscles
- Humans : wide hip and narrow knees
Hands:
- Opposable thumb
Explain what has been determined about Paranthropines diet and what that can say about tool use.
Paranthropines had big chewing muscles → maybe they aren’t just herbivores?
Looked at strontium and calcium ratios → see if protein was in the diet
Concluded that they were eating meat protein regularly
Does this mean they hunted? Not necessarily, maybe just scavenged
But… there were tools found at some sites → maybe our assumption that only our genus can make tools is wrong
What are the two hypotheses about the evolutionary relationships from hominoids to hominins?
Single species hypothesis - anagenesis (one species ancestral to another
Coexistence hypothesis - cladogenesis (some species are contemporary = overlap in time)
What are the two different types of bipedalism?
Facultative - ability to walk on two legs regularly (not very effective- can’t run) - walking is an option
Obligate (habitual) bipedalism - only effective means of locomotion (can jog around) - can’t do other forms of transformation
Describe the evidence for the early species of the genus Homo - two groups of early Homo
Members of Homo have larger brains and bodies and smaller teeth and jaws than Australopithecus and other early hominins
Early Homo are sometimes divided into smaller and larger-brained groups; the smaller is H.habilis; the larger, H.rudolfensis
Both groups are found in East and South africa from 1.9-1.4 million years ago
They scavenged for meat or possibly hunted small animals. The evolution of cultural behaviour also seems to have played a role in the physical changes seen in early Homo
Describe the early Habilines (two subspecies):
H.habilis
- 2.4-1.4 mya
- Smaller face, brain, and teeth
- Older features: long arms and projecting face
- “Twiggy”
- Assumed to use tools “handyman” - tools older than habilis though (Oldowan tools)
- Didn’t eat hard foods like nuts and seeds (set apart from paranthropines)
H. rudolfensis
- 2-1.5 mya
- Much brain size variation - overall larger than habilis
- Smaller face and teeth than Apith
- Arm to leg length shrinking
Describe the tools (when ealiest tools) and lifestyle of early hominins
The earliest identifiable stone tools found come from East Africa and date from about 2.5 mya
Among later tools from Olduvai beds in Tansania, flake tools predominate, but choppers are also common. These early stone tools are referred to as Oldowan
Sites found dating to about 2 mya with concentrations of stone tools and animal bones
- Oldowan tools can be used for cutting hides, dismembering animals, whittling wood, and cutting branches
Hominins were likely cutting up animal carcasses shortly after 2 mya. Most sites in Olduvai Gorge appear to have been home bases or food-processing places
The presence of patterned stone tools and possible home bases suggest that early hominins had culture - a dynamic, adaptive process of learned, shared, and integrated behaviours and ideas
The early Homo brain was almost one-third larger than the australopithecine brain. Brain expansion may have required reduced maturity at birth and prolonged infant dependency, likely influencing cultural evolution
What did Glynn Isaac suggest?
Suggested we talk to chimpanzees
Chimpanzees think humans are weird → we walk a lot, carry thing, and keep food to share/save it
What are some aspects/results of ground living?
Wider range of plant foods but limited animal foods
Need to think about defence
Stimulates social behaviour → large groups are better for defence - requires cooperative organization → creativity and industriousness comes in groups
- Can stimulate weapons and tool making
