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Flashcards in Evolution Deck (43):

-Biological anthropology

-Anthropology: The study of humankind
-Biological anthropology: The study of humans as biological organisms, considered in an evolutionary framework
-Primate: member of the mammalian order of Primates; includes prosimians, monkeys, apes & humans
-defined by a mix of anatomical and beh. traits/characteristics




-Evolution: a change in the frequency of a gene or a trait in a population over multiple generations
-Genotype: the genetic makeup of an individual (genetic traits that are within genome)
-Phenotype: the observable or measurable feature feature of an organism which is under genetic control
-can be anatomical, biochemical or behavioural


Evolution as a theory (4 reasons)

Is a theory because;
-it is a statement of well supported laws, principles or causes of something known or observed
-we can make predictions and testable hypothesis
-we can make direct observations or events or objects
-specific hypotheses are under constant modification, testing and re-evaluation


-Biological evolution
-2 important points in regards to evolution

-Biological evolution: change in population or species over time
-Important points;
1. Living things descended from a common ancestor and thus have common chemistry
2. Living things adapt to their environment
-Adaptation: a trait that increases the reproductive success of an organism, produced by natural selection in the context of a particular environment.
-humans are the product of adaption


3 vital elements for natural selection

1. Variation: there must be physical variations that can be passed from generation to generation
2. Competition: There must be competition for limited resources (food, shelter, mates) and those better adapted will survive and reproduce
3. Adaptation: subsequent generations will see an increase in individuals w/ same adaptations, as long as the enviromnet remains unchanged


Artificial selection

*carried out by humans for thousands of years
-desirable trait is bred for
-i.e. wolves into domesticated dogs
-Chinese cabbage,, brussel sprouts & kohlrabi all derived from single species (Brassica oleracea)


Evidence to support theory of evolution by common descent (4)

1. Fossil record
2. Biogeographical evidence
3. Anatomical evidence
4. Biochemical evidence


Evidence for evolution;

-what they are
-transitional fossil
-what the fossil record tells us

*are traces of past life (can be trails, footprints, burrows, worm casts, coprolites (fossilized poo), plant impressions, insects trapped in amber).
-Paleontology = method that allows us to trace the descent of a particular group
-Transitional fossil: fossils that have characteristics of 2 different groups
*fossil record tells us that life progressed from simple to more complex


Evidence for evolution;

Biogeographical evidence

*Is the study of the distribution of plants and animals throughout the world
-supports the hypothesis that organisms originate in one locale and then may spread out
-Diff. life forms expected whenever geography separates them
-Islands have many unique life forms because of geographic isolation


Evidence of Evolution;

-Anatomical Evidence

Homologous structures
-analogous structures
-Vestigial structures

*common descent hypothesis offers explanation for anatomical similarities among living organisms.
-Homologous structures: structures anatomically similar that are inherited by a common ancestor
-i.e. vertebrate forelimbs
-Analogous structures: structures that serve the same function but do not share common ancestry (therefore not constructed the same
-Vestigial Structures: anatomical features fully developed in one group that are reduced and may have no function in another group
e.g. humans have appendix and tail bone - coccyx


Pentadactyl limb

-Modified from the terrestrial vertebrate forelimb for various functions/use
-similar layout in alive and extinct tetrapods
-distal ends may be modified according to the environment they live in


Evidence from embryology

-Early in embryo development; many different species look very similar


Evidence of Evolution;

Biochemical evidence

-Almost all living things use same biochemicals (i.e. DNA and ATP)
-use same triplet genetic code and use same 20 a.a.
-living things also share many of the same genes



-What it is
-Common name

-Science of classification by hierarchy
-Scientific taxonomy is testable classification of life forms
*common name often different in different countries


Linnean Classification

*starting with Domain

*go from general to specific


Binomial Classification

-Each species receives double name in Latin
-Genus & species


The 3 domains of life




-5 kingdom system standard for some years -> largely based on nutrition
-monera and protista (single celled or simple cellular colonies)


Kingdom animalia - 4 features

-Eukaryotic: possess nuclei w/ DNA arranged in chromosomes; possess organelles
-multicellular (tissue specialization)
-Heterotrophic (digest food in internal chamber)
-Lack rigid cell walls


Phylum - Chordata


*Share certain taxonomic features
-Notochord: a rodlike body found in all embryos serving as longitudinal support
-Hollow dorsal nerve cord (runs in line w/ notochord)
*vertebrates are a subset of phylum Chordata


Subphylum: Vertebrata

-no of species
-what all of them have
-limb numbers

-Animal w/ spinal column (backbone) and a cranium (brain case)
-approx 40 000 species of vertebrates in 8 classes
-Most have a spinal column made of vertebrae (shark doesnt - has cartilage)
-are all bilaterally symmetrical
-body usu. divided into a head & a trunk
-more advanced land vertebrates have a neck
-In mammals: trunk divided into thorax & abdomen
*Vertebrates never have more than two pairs of limbs


Class - features of a class

-class human belong to

-4 features of this class

-Have more characteristics in common than members of a phylum - generally more easily recognized as similar
-Humans belong to class MAMMALIA
features (4):
-Mammary glands (modified sweat glands)
-Warm blooded (endothermic) w/ 4 chambered heart
-viviparous (gives birth to live young)


Order -> Primate

-Unique feature of primate (unusual in normal orders)
-what are they

-Uniquely among Mammalia, primates have no single anatomical trait that is the identifying mark of a primate and no trait that unites them
-Are generalist foragers w/ relatively large brains and intricate, complex social system


Characteristics of Primates (6)

-Opposable thumb
-steroscopic vision (depth perception)
-Well-developed brain
-Reduced number of offspring w/ an increased period of parental care
-Emphasis on learned behaviour and social interactions
-long lives


What is a Primate?

-general traits that primates generally have some or all of

-Primates (including fossil) have SOME or ALL of these traits;
-bony ring around eye socket or bony enclosed eye socket
-hands or feet that are constructed so they can grasp objects (exhibit prehension)
-opposable thumb
-external genitalia; 2 pectoral mammary glands
-nails on edges of digits (unguiculate)
-binocular vision
-long gestation
-slow-post natal growth compared to maternal body size
-emphasis on learned behaviour and social interactions
-large brain size relative to body size


Family Hominidae

-when appeared -> when human group appeared


-early hominids appeard in Miocene (approx. 20 MYA)
-4 genera w/in
-human group (Hominins) dates back to around 5 MYA
-still larger brain
-larger body size
-mostly terrestrial
-arms and pectoral girdle for suspension
-highly reduced or absent tails
-Y-5 shaped pattern on occlusal surface of molar teeth


Genus and Species - Homo sapiens

-name of modern humans

-'wise man' emerged approx. 200 000 years go
-modern humans classed as Homo sapiens sapiens
-various extinct subspecies such as Homo (sapiens) neanderthalensis, homo heidelbergensis


Genus and Species of Homo sapiens

-characteristics (6)

-upright posture and bipedal locomotion
-larger brains
-language capabilities and symbolic thought
-the manufacture and use of complex tools
-shortened jaw & shorter digestive tract (due to development of agriculture)


Evolutions of hominins
-what is a hominin?
-3 major characteristics

-when first hominins fossils appeared (can give detail about which region of african (3))

-when hominids split from ape line of descent

-Hominins: all species of genus Homo and their close relatives

3 features;
1. Bipedal
2. Flatter face with more pronounced chin
3. Brain size

*first hominin fossil approx 6-7 MYA
-central african fossil 7MYA (Sahelanthropus tchadensis)
-Eastern African fossil 6 MYA (Orrorin tugenensis)
-Eastern African Fossil 5.8-5.2 MYA (Ardipithecus kadabba)

*Hominins split from the ape line of descent 5-6 MYA



-when evolved & diversified
-famous skeleton

-Most likely ancestral candidate for early Homo

-Group of hominins that evolved and diversified in Africa approx 3MYA
-Various frames (some slight others robust) w/ massive jaws for feeding on plant material
*walked upright
-limb portions apelike
-small brain
-famous skeleton named Lucy (A. afarensis)

*Australopithecus africanus (w/ large brain) is most likely ancestral candidate for early Homo


Characteristics of Homo (3)

-2 representatives from early Homo and later Homo

-Brain size is 600cm^3 or greater
-evidence of tool use
-jaw and teeth resemble humans

-Early Homo representatives (Homo habilis & Homo erectus)
-Later Homo representatives (Neandertals & Cro-Magnons)


Homo habilis

-when lived
-4 features

-Lived 2.0-1.9MYA

-large brain w/ enlargd speech area (derived from skull)
-Omnivorous (hunters and gathers)
-Primitive tools
-May have had culture


Homo erectus

-when lived
-6 features
-where thought to have come from

-lived 1.9-0.3MYA

-Larger brain than H. habilis
-flat face with nose projected
-tall and stood erect
-striding gait
-Advanced tools and fire (systemic hunters)
-May have had language
-may have migrated from Africa to Europe and Asia


Modern Humans: Replacement model

-AKA out of Africa Hypothesis -> is most widely accepted hypothesis
-proposes that modern humans evolved from archaic humans only in Africa
-Then, modern humans migrated to Asian & Europe where they replaced the archaic species about 100000 years BP

-waves of species that came out of Homo ergaster and differentiated into different species in different continents



-when & where discovered

-3 features

-discovered in Germany 2000 years ago
-Homo sapiens have 1-4% similarity to their DNA -> suggests interbreeding

-massive brow ridges
-nose, jaws, and teeth protrude forward
-low and sloping forehead; no chin



-when lived

-Lived about 40 000 - 10 000 years ago
*oldest fossils designated to Homo sapiens
-modern appearance
-advanced culture including art, tools and maybe language
-Good cooperative hunters


Human Variation

-why variations exists between populations (e.g. of it)

-Bergmann's rule
-Allens rule

-Human variations b/w populations = ethnicities
-Variations evolved as adaptation to local environments
-i.e. skin colour and body shape
-Bergmann''s rule: colder regions mean bulkier build
-Allen's rule: colder regions mean shorter limbs, digits and ears


Requirements for Bipedalism (3)

-3 times it has occurred in mammals

1. Positioning of centre of mass over lower limbs
2. Efficient maintenance of this position
3. Reduction of protrusions away from centre of mass (to be more efficient)

Has only occurred 3 times in mammals; Kangaroo, Kangaroo mouse & humans


Human Engineering -> adaptations that make us suitable for bipedal life

*bone modifications

-gluteus maximum v. powerful hip extensor (prevents torso from falling over)
-bowl shape, short and broad pelvis bone -> enables us to support abdominal organs
-shorter ileum (decreases centre of gravity & makes childbirth easier as pelvis rotated)
-spine has lots of ligaments attached
-curvature of spine to distribute weight appropriately
-elongation of neck of femur (import. in balance)
-femur curves in to knee (centre of gravity)
-Menisci present in knee to help weight distribution


Human Engineering -> adaptations that make us suitable for bipedal life

*foot modifications

-big toe adducted to facilitate walking
-toes shorter so we don't trip
-thickening of plantar fascia provides platform that can absorb energy and return it by giving added thrust
-arches in foot = shock absorbers


Human Engineering -> adaptations that make us suitable for bipedal life

Cranial Modifications & Pectoral girdle

-Prognathism: Projection of lower jaw and facial skeleton
-Has been a decrease in the protrusion of the face (helps maintain the center of gravity
-foramen magnum more inferior to cranium
-pectoral girdle is wider laterally
-Scapula more medial (apes have lateral scapula)


Human skeleton vs. chimpanzee skeleton (human examples) (6)

1. Spine exits inferior to center of skull and this = midline of body
2. Longer, S-shaped spine -> places trunk's center of gravity squarely over feet
3. Broader pelvis & hip joints keeps humans from swaying when walk
4. Longer neck of femur in humans cause femur to angle inward at knee
5. Human knee joint modified to support body's weight (femur larger at bottom, tibia larger on top)
6. Human toe not opposable - foot has arch that enables humans to walk & run long distances


Classification of humans (domain to species)

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens