Posts filed under ‘ANTH 201’

ANTHROPOLOGY 201 – April 6th – Homo

No class on BSD, test on tuesday 21st at 12, not cumulative only on the last section!!! from primate evolution to human evolution

Homo ergaster

  • Tall and long, which helps disipate heat (less exposure to sun)
  • Tool culture advances over Olduwan (but Olduwan tools still retained)
  • Acheuleantool industry (Mode 2) appears 1.6 MYA in Africa (and lasts 1 million years!)
  • Biface (hand axes, cleavers, picks)
    • Very standardized, flattened form w/sharp edge along entire circumference
    • Leaf shaped core, Flat, sharp edges, can be sharpened as needed
  • The tool maker had a design in mind
    • learning curve in producing the tool
  • Likely used tools to butcher large animals
    • Experimanetal anthroplogy can prove that these tools can butcher animals
  • Supported by experimental use & microscopic wear patterns on hand axes
  • But maybe also/instead for digging, stripping tree bark, hunting weapons, or just flake dispensers
  • Were probably hunters & scavengers (ate elephants, carnivores –sometimes to their peril)
  • Likely controlled fire
  • Campfires leave bowl-shaped ash deposit, burn at very high temperatures (not like natural grassfires or burnt trees). Burned bones.
    • Found evidence of “baked” earth
    • naturally occuring firing dont burn that hot, flash fires
    • Camp fires burn for a long time and are smaller, so the effect is much different

Control of fire

  • A significant innovation, as cooked food is easier to digest, heat kills parasites, provides light, scares predators….
  • Also can allow to live outside of the tropics, which H. ergaster did.
  • Expands geographical range, and allows for deeper caves.
  • Extremely important innovation
  • most important distinguishing element between apes and human is that we cook our food

Middle Pleistocene (900-300kya)

  • Marked by continued fluctuations of climate, general cooling; glaciers cover Northern Europe (Fig 13.12). Arctic conditions.
  • Cold periods alternated with warmer periods where glaciers receded andforests reappeared. Major changes in habitats
    • mdeiteranian dried up
  • Flow of species was possible between Africa and Eurasia during inter-glacial periods; fossil records show movement tends to be from Africa to Eurasia, not vice-versa.
    • homo egaster crossed into europe
    • likely becuase the animals they were hunting had the ranges expand and the humans followed the animals
    • new range of resources were available to them

Changing environment means new selection pressures

  • Homo ergaster radiates
  • During middle pleistocene, Homo is present in Africa and Eurasia.
  • Several morphologically distinct species
  • Homo erectusin Asia (small brains)
  • Several species in Africa and western Eurasia (larger brains); we will come back to them later.
  • Taxonomical debate!

Homo erectus

  • Asian species similar to H. ergaster; probably arose from populations of ergaster that migrated in Asia 1.8mya.
    • simple to think as asian version of H. ergaster
  • Original specimen found by DuBois at Trinil, Indonesia (“Java Man”) From 1.6-1.8 MYA to about 30 KYA (all of Middle Pleistocene –0.9-0.13 MYA)
    • KYA = thousands of years ago
    • Very recent times!
  • Differs from H. ergasterin cranium; v-shaped sagittalkeel; unknown function.
  • Does not show much change during its life span as a species
  • No increase in brain size, no improvement in tool industry.
  • Used only Mode 1 tools Mode 2 appeared in Africa 1.6mya, shortly after H. erectusappears in
    • Asia; no cultural transmission??
    • Lack cognitive abilities??
      • Eregaster had very similar cognitive ability to Erectus
  • Environmental factors: may not have needed them w/ bamboo around??
    • negated the need to invent type 2
    • no fossil record becuase its organic material
  • New Hominid:  Homo floresiensis Found on Flores Island, Indonesia
    • Lived as recently as 13,000 years ago
    • Amazing becuase humans only domesticated plants 10000 years ago
    • amazing becuase just some few thousand km there were pre humans
  • Only 1 m tall
    • “the hobbit”
  • Possibly derived from H. erectus
  • Small brains, but complex tools
  • Hunted pygmy elephant Stegodon
  • Possible phyletic dwarf
  • Some argue was not diminutive species, but individual(s) suffering from microencephaly

Archaic Homo Sapiens

  • H. heidelbergensis(formerly known as Archaic Homo sapiens)
  • During Middle Pleistocene (900-130 KYA), more modern
  • looking species appear in Africa & Eurasia (somewhere in 800-500 KYA range).
  • Grouped in H. heidelbergensis
  • Derived:  large brain (1200- 1300 cc), higher foreheads, more rounded cranium
  • Primitive:  low skull, more prognathic, browridges, no chin
  • H. heidelbergensis
  • Clear evidence of hunting
  • Drove large game off cliffs
  • Made throwing spears
  • Developed Mode 3 technology
    • Approx. 300 KYA
    • Levallois technique (more detailed flaking of core, then removing large flake as a tool)
    • Some hafted (w/ handle) for better leverage and control
  • Around this time, moved into E. Asia and may have co- existed with H. erectus

The Neanderthals

  • Highly variable European population derived from H. heidelbergensisin Middle Pleistocene (around 300 KYA, lived until 30 KYA)
    • Period of warm interglacial (130-75 KYA), then very cold
    • found in spain portugal ect.
  • Derived:  cranium bulges in middle, rounded back of skull (occipital bun), double-arched browridges, taurodont teeth, huge noses and faces, stocky & heavily built, large heavily worn incisors, large brains (1520 cc)pp
    • Huge nose!
    • Allows air to warm before reaching body?
    • Larger brain size than humans
    • Larger Body size
      • to handle cold
  • Levallois technique (more detailed flaking of core, then removing large flake as a tool)
  • Some hafted (The Neanderthals
  • Cold adapted
    • near arctic condition in europe
  • Body proportions more similar to arctic modern populations
  • Large noses may have warmed air
  • Used Mode 3 tools
  • Mousterian tool industry
  • Language?
    • very likely…
  • Likely hunted large game
  • Did not construct permanent camps
  • Buried dead in perhaps ritual graves (pollens of flowers present)
    • possible religion?
  • Lived hard, short lives (broken bones, worn teeth)
  • Modern Humans Appear?
  • African fossil record for time of Neanderthals is very patchy (300-130KYA range)
    • Few finds are not like Neanderthals inanatomy (more like H. heidelbergensis)
  • Approx. 130-90 KYA, specimens in Africa (Border Cave & Klasies River Mouth, S. Africa, Omo-Kibish, Ethiopia, Dar es Soltan, Morocco) appear to be modern humans (H. sapiens)
    • Small faces, small browridges, higher & rounded crania
    • More advanced tool industries present
    • But finds are fragmentary & dates are insecure
  • Who is Who in the Middle
  • Pleistocene?
  • Traditional taxonomy held that all archaics (H. heidelbergensis, Neanderthals) were H. sapiens
  • More recent views see populations splitting into distinct (& more primitive) species during waves of migration through Europe & Asia
  • H. heidelbergensis evolved in Africa then migrated to Europe (includes Neanderthals) & Asia
  • Some consider Neanderthals isolated from all others in Europe (H. neanderthalensis) –old & complete split from other Homopopulations supported by ancient DNA analysis

April 6, 2009 at 10:49 am 2 comments

ANTHROPOLOGY 201 – April 3rd – Material Culture and Homo

  • Tools & Life History
  • Reliance on tools for food acquisition signals fundamental shift in lifestyle & life history pattern
  • Modern hunter-gatherers rely on:
    • Collected foods (easiest to obtain)
    • Extracted foods (difficult to obtain)
      • Nuts with hard shells needed to crack open
    • Hunted foods (most difficult to obtain)
      • requires planning
  • Tools & Life History: what can we predict??
    • Foraging skills for collected and extracted foods in particular require long-term learning
      • Favours larger brains, longer juvenescence (longer dependence on mother) & life span
    • Hunting & extractive foraging favours food-sharing(not all hunts are successful) & division of labour (difficult to hunt when carrying children; chimpanzee hunting is done only by males)
      • Hunting was very likely a sexual division of labour becuase it would have been difficult for females carrying children
      • Other types of hunts where females can participate, collaborative hunting
      • Chimp hunting is only done by males
    • Reciprocity in social relationships
      • mode  1 technology is not diffucult to do, most of can do it
      • But when the techniques become more complicated, specialization begins to occur
      • Trading may becoming possible
    • If leads to higher paternal investment, then probably contributes to lower sexual dimorphism
      • if males specializes in activities than there may be more importance on the choice of male from female
    • Dont know when it happened, but it likely did..

Olduwan Toolmaker Foraging

  • Experimental techniques demonstrate tools can be used for butchery
    • Also some likely used to extract termites
  • Tools found in association w/ large accumulations of animals bones with cut marks.
    • Taphonomic analyses (study of formation of archaeological sites) at Olduvai indicate not from natural accumulation (e.g., water borne)
    • But some may be carnivore kill/processing sites
  • Olduvai sites where hominids processed kills likely temporary (w/ cached tools) – not home bases
    • Carnivores present, bones are weathered, not intensively processed
    • Often the sites exist becuase there are resources to make tools, not to live
    • But there are sites with a large circle of stones
      • believed to be home sites becuase alot of effort was put into making the site
      • But there is a belief that a patch of trees could have made a circle of rocks aswell
      • Very likely early hunters were nomadic, not home based
  • Olduwan toolmakers were probably both hunters and scavengers
    • Animals parts processed by tools consistent with those usually eaten first by hunters (fleshy long bones) andlater consumed by scavengers (difficult to process parts like skulls, spines)
    • Cut marks over carnivore tooth marks (and vice versa)

Early Hominin Lifestyle

  • More variable habitats & climate likely led to new feeding habits for australopithecines
    • Gracile forms may have relied more on meat, robust forms on nuts, seeds, etc. (but have meat at least in some periods?)
    • CHIMPS never SCAVENGE only hunt
    • Gracile had a higher quality diet than robust form
    • Gracile would have relied more on meat
    • but some robust had meat
  • May have used primitive, impermanent tools (like chimpanzees) both for meat eating and other activities (digging up roots)
  • Scavenging may have been as important as hunting (but keep in mind chimpanzees hunt but do not scavenge…)
  • Chimpanzee hunting is a coordinated and rather frequent activity which occurs in periods of high availability of other resources (fruits) -applicable to hunting australopithecines?
    • hunting occurs when there is a high availability of other food
    • not all hunts are successful, so there is a need for food resources aside from hunting
  • Food sharing of high quality resources (meat) is frequent in chimpanzees; like in early hominins.

Social & mating system

  • Terrestriality made early hominins vulnerable topredators -this is associated with large groupsinother primates
    • found in larger groups than other living apes
  • Pronounced sexual dimorphism; linked to male- male competition for access to females
    • more than arboreal
  • Social system may have been multi-male/multi-female or uni-male multi-females
  • Mating patterns: several possibilities can be imagined: polygynyandry, with or without some “friendships” like in baboons (almost a monogamous unit within a larger group…)
    • many systems

The emergence of Homo

  • One species of australopithecines gave  rise to the genus Homo around 2.5 mya
  • Other lineages of Australopithecines  went extinct
  • Australopithecines had been restricted to Africa. Homo will widen its geographical range to include Eurasia.
    • Begining of a doubt on austalopithecins making their way into asia

Key Homo Adaptations

  • Fully terrestrial life (long legs, short arms)
  • Complex foraging techniques (extractive as opposed to collected)
  • Slow maturation rate
    • Longer juvinile period, and infancy
  • Low sexual dimorphism
  • Increased parental investment

Homo ergaster

  • First unequivocal member of our genus
    • Appear in Lower Pleistocene(1.8 MYA) –period of sharp cooling in world climate
    • Present in fossil record 1.8mya to 0.6
    • Widespread in East & Southern Africa
    • At early date, crossed into Eurasia
      • Found at Dmanisi, Georgia 1.7 MYA
      • First hominid to migrate out of Africa
  • Cranial morphology
  • Primitive features: receding forehead, no chin
    • Still would not look human
  • Derived (like later Homo):  flatter face, higher skull, small teeth
  • Derived (unique):  supraorbital & occipital torus
  • Probably for tearing meat w/ canines & incisors
  • 800 cc cranial capacity (larger than australopithecines)
    • Much bigger nearly double astalopithecines
  • Very complete juvenile male specimen from Lake Turkana (KNM-WT 15000) shows details of postcranial anatomy (+ other specimens).
  • This young male would measure 1.9 m as adult
  • Same body proportions as humans who live in tropical savanna today. Low sexual dimorphism
  • Birth canal relative to skull size similar to modern humans
    • Gave birth to undeveloped young
      • needs to go through much more development than most primates
      • The human baby cant support its own weight
      • but in primates most babys can support themselves almost immediatly
    • Slow maturation & extended juvenile dependency
    • Enamel growth rate suggests maturation rate slower than australopithecines, but faster than humans.
  • Tool culture advances over Olduwan (but Olduwan tools still retained)
    Acheuleantool industry (Mode 2) appears 1.6 MYA in Africa (and lasts 1 million years!)
    Biface(hand axes, cleavers, picks)
  • Very standardized, flattened form w/ sharp edge along entire circumference
    The tool maker had a design in mind

April 3, 2009 at 10:48 am 1 comment

ANTHROPOLOGY – March 30th – Australopithicus

  • Australopithecus anamensis
  • Earliest in genus (4.2-3.8 MYA); oldest  australopithecus find. Specimen from Kenya and Ethiopia
  • Descendant from Ardipithecus??
  • Derived traits
  • Thick enamel
  • Knee & ankle for bipedalism
  • Primitive traits
  • U-shaped jaw like apes, larger canines than later
  • australopithecines, more receding chin
  • Upper limb features still adapted for arboreality
  • Probably lived in mixed habitats (riverine forests, savannah, woodlands)

Australopithecus afarensis

  • Most well-publicized discovery in history of paleoanthropology
  • Found in Hadar, Ethiopia, in 1974
  • by Don Johanson (other specimen  in Laetoli, Kenya)
  • AL 288-1 (“Lucy”)
    • 40% complete skeleton revealed details (& opened debates) regarding locomotion
    • Dated to 3.2 MYA (oldest at time)
    • There are older specimins found, that are hominids
  • Newer finds reveal wider range in space (Chad, S. Africa) & time (3.5-3.1 MYA)
  • Includes “Selam” (“Peace”): 3-yr old from 3.3 MYA, reported in Sept 2006
  • New finds from Hadar are 4-3.8
  • MYA, but not sure which species (maybe A. ramidus)
  • Habitat of A. afarensis
    • Lived in mix of forest, woodland & savannah habitats; clearly not as forested as earlier forms of hominins.
    • Tooth wear is more varied than earlier australopithecines, suggest a more diverse diet.
    • Species is more successful?? Inhabits wider range of habitats, uses a wider diet??
  • A. afarensis
    • Once again, see a mixture of primitive & derived traits
    • Face intermediate in flatness, medium canines, intermediate curve to jaw, more ape-like back of skull
    • Highly sexually dimorphic body size & canines, but canines smaller than earlier hominins
      • “modest” diastema on mandible
      • highly dimophic but still ONE species
    • Ape-like brain size or very slight increase (404 cc cranial capacity in Lucy); 430 cc in other specimen
      • pre australopithecines are about 350 cc
    • Shows clear evidence of habitual bipedalism
    • Short legs relative to body trunk would have produced shorter stride length than what we can do.
    • Upper limbs still show adaptations to arboreality
      • longer arms
  • Laetoli Footprints Found in in Tanzania in 1976 by Mary Leakey
    • Formed by A. afarensis walking in wet volcanic ash (carbonanite, which dries up very hard)
    • Analyses show pattern of foot falls similar to modern humans (round heel, non-divergent big toes).
    • But the differnt foot patterns show differing possiblities

Australopithecus africanus

  • A. africanusfirst discovered in 1924 by Dart (“Taung baby”)
    • Debate as to whether this was a homonid
    • But when bi pedalism became the defining feature of hominids…
  • Discredited ideas about Eurasian/big brain origins
  • Southern Africa, 3-2.2 MYA
  • Compared to A. afarensis:  slightly larger brain, larger body size.Still quite sexually dimorphic
  • Compared to humans:  larger molars for heavy chewing, rapid maturation
    • layers of enamal can tell you how fast the grew up
  • Probably not nearly as complex socially if infants were less dependent than in humans (ie developed faster).
  • Has implications for sexual division of labor, home base, food sharing…
  • Rate of development inferred from daily layers of enamel produced for teeth growth (Dean et al.) and pattern of teeth eruption
  • No tool industry as Dart proposed (“osteodontokeratic”) –more likely prey than predator
    • No evidence of tools, but does not mean they were not capable of making tools from organic material
    • For example the way orangitangs use tools, or chimps
    • But this cant be proved becuase the evidence did not fossilize

Australopithecus garhi – found 1996 etheiopia

  • Awash, Ethiopia, 2.5 MYA
  • Prognathic face; sagittal crest; brain at 450 cc
  • Larger teeth than A. afarensisand africanus
  • Derived feature is elongated femurs?
  • First stone tool producer??
    • Very important
    • aldeman? tradition. Stone being chopped away to make sharp edges.
  • In some ways, more Homo-like than other australopithecines, so was thought for a while to be directly ancestral to Homo. Now, believed to be a side-branch.

Robust Australopithecines

  • Separate line that diverged from early hominins
  • Share dietary adaptations
    • Massive molars (with molariform premolars)
    • Large sagittal crests & wide flaring zygomatic arches (leaves room for large temporalis muscle)
      • Big cheeks for big muscles
    • Diet likely of very hard, tough foods (seeds, nuts, roots) as reflected by dental wear… but some meat as well based on strontium to calcium ratio + stable isotope analyses.
    • Same bipedal adaptations as A. africanus
  • Paranthropus aethiopicus
    • “Black Skull”, Lake Turkana, Kenya, 2.5 MYA
  • P. robustus
    • South Africa (w/ A. africanus), 2-1 MYA
  • P. boisei
    • East Africa (w/ A. habilis), 2.2-1.3 MYA P. boisei

The First “Real” Humans?

A. or Homo (h)abilis

  • Gracile specimens from Olduvai Gorge, Tanzania, 1.9-1.6 MYA
  • Found in association w/ very basic flaked stone tools (Olduwan choppers)
  • Evidence of tool use led to classification as first species of Homo:  H. habilis (still dominant taxonomy)
    • 50% larger cranial capacity than australopithecines, small teeth, parabolic dental arcade, less prognathic face, reduced jaws & chewing muscles
  • But retentions (postcranial skeleton, developmental patterns) may mean still more similar to australopithecines (= A. habilis)
    • in particular the upper body shows arboreality
  • Jane goodall crushed this concept of tool making as the defining charecteristic of “Homo” becuase she observed tool use in chimps

The First “Real” Humans?

  • KNM-ER 1470 & friends (first letter refers to Kenya)
    • Population found in Kenya up to 2.4 MYA
    • Larger brain & body size than A. habilis from Olduvai (75% larger cranial capacity than A. africanus)
  • Together, these specimen may represent single highly variables pecies…
  • or Kenyan finds are second larger species (with larger brain; A. rudolfensis= H. rudolfensis) that coexisted in East Africa 2 mya (the specimen with smaller brain would be A. habilis)

Whether one or 2 species…

  • It seems that they should likely be Australopithecines based on post- cranial morphology and pattern of development which is more ape-like than Homo like.
  • If A. garhi produced stone tools 2.5 mya, the association with habilis becomes irrelevant in classfication
  • From Meave Leakey’s description of K. platyops
  • Question marks represent uncertain links -note they are nearly everywhere

Hominin Phylogeny

  • A. rudolfensisshown as K. rudolfensis
  • A. bahrelghazali specimen some consider A. afarensis
  • Shows how unclear lineages are
  • some even consider the whole groups as a side branch (with Orrorinor Sahelanthropusas human ancestor) Convergent evolution?
  • If the heavy-chewing complex of the robust australopithecines is considered a case of convergent evolution, then A. afarensis leads to africanus, which leads to Homo. Fig 11.33

March 30, 2009 at 10:40 am Leave a comment

ANTHROPOLOGY 201 – March 27th – Pre Australopithecines

Dentition

  • We saw that hominins tend to have an arc- shaped jaw (as opposed to chimpanzees,  who have pre-molars and molars parallel).
  • canines now appear to provide crucial information for identifying hominins (e.g. the  non-honing chewing, or “non-honing masticatory complex”) (Larsen 2008 in “Our Origins)
    • no lateral movement in chimps and apes
    • in hominins the masticatory complex allows for lateral movements
    • Early hominids can do this a little, help use identify early humans
  • Hominin canines
  • Non-projecting
  • Small in relation to other teeth
  • No diastema
    • (in apes, gap between canine  and third premolar on the lower jaw, and between canine and second incisor on the upper jaw)
  • Wear on tips of canines instead of the back:
    • When apes eat food, the upper canines and lower premolars (P3) rub against each other; this sharpens the edges on the canine and premolar, helping slicing up fruits and leaves.
    • Humans and apes will have much different wear on the teeth
    • Apes will have sharper sides of teeth

Human-Chimpanzee split

    • Most of the early humans are found in eastern Africa
    • about 1/3 is found outside east Africa
  • Genetic data (molecular clock) indicate that the last common ancestor of humans and chimpanzees lived 5 mya. Most paleoanthropologists suggest split was in fact a bit earlier probably 6-7 mya.
  • It is only recently that fossil hominins for that period have begun to surface… “Pre-australopithecines”
  • Finds in last 10 years include the “newest oldest” hominids

Hominin Traits:

  • Traditional view:  common ancestor of humans & chimpanzees probably more closely resembled a chimpanzee
  • But derived human features of the face (flat face) & teeth (thick enamel) are turning up in earliest hominin fossils –near time of split with chimpanzees.

What does it suggests?

  • Makes taxonomy difficult!! But this is not new!
  • Did common ancestor more closely resembled Homo than chimpanzee? Where do these early hominin fit? Ancestral to australopithecines or direct link to Homo? Debate is ongoing.
    • Some have traits that resembled more modern humans, so some believe that australopithesis is a side branch of humans
  • More likely, the hominin radiation included a wide range a species. Did not follow a simple path towards developing more “human traits”
    • adaptive radiation
    • Few species found, perhaps because there were only a few species, or lack of research
    • 2.5 – 5 mya, has much more species
      • one species may have given way to multiple species, but only a few survived, taxonomy is very difficult

Earliest Hominins

  • Sahelanthropus tchadensis
  • Near complete cranium & mandible from Chad (unusual location for early hominin; center of the continent; larger range for early homonins?)
    • Chad is a weird location for a find
    • Thus geographical range is much larger than expected
    • dated to 6-7 MYA
  • No post-cranium material
    • Primitive brain size (~350 cc like chimpanzee ;modern human is 1350 cc). massive browridge like gorilla
  • Shows several derived traits:
    • flat face like later
    • hominins, thick enamel, small canines and non-honing chewing,
    • foramen magnum seems to be under skull,
      • so would suggest bipedalism, but skull was crushed and has been modelled in 3D; position of the foramen magnum is debated Critics suggest is a gorilla ancestor
      • The debate is over the placement of the foramen magnum, the hole in the back of the skull that says weather they are bipedal or not
    • -which would still make it an interesting find.
    • Habitat was likely forest & grassland -some say forest setting.
  • Orrorin tugenensis
    • Found at Tugen Hills, Kenya (at least 5 individuals)
    • From ~6 MYA
    • Canines, incisors and premolar look like chimpanzee teeth for some scientists; but some argue that non-honing complex was present and that wear for canines was on top of tooth.
      • characteristic of homonins and not apes
    • Teeth have thick enamel like Homo
    • Femur has thicker bone at bottom, suggesting bipedalisÏm but arms and hands have features related to arboreality.
      • bipedals have thicker bones there
      • But upper body suggest arboreality, but thats cool because many homins have this as a derived trait
    • Debate in scientific circles as to whether it is directly ancestral to later Homo or whether it is ancestral to Australopithecines and Homo. It relates to how bipedal was Orrorin; some argue itwas better adapted to bipedalism than the later Australopithecines
    • This view is challenged in last issue of Science; suggest it was ancestral to Australopithecines.
    • Faunal assemblage suggest mosaic of savanna and woodland, although some suggest more of a closed forest.
  • Ardipithecus ramidus & A. kadabba
  • Found in Awash, Ethiopia
    • 4.4 MYA (recent finds older: 5.8-5.2 MYA)
    • Derived traits:
      • Position of Foramen magnum suggest bipedalism
      • Small canines like australopithecines and later Homo; non-honing although some polishing of the outside of 3rd premolar is called “peri-honing”…
        • Getting there
    • Primitive traits
      • A. ramidus had thin enamel
      • Still adapted to arboreality
      • But this does not challenge the definition, these elements are common on all early homonids
      • Bipedal, but seems to have lived in forested environment (not savanna).
    • Ancestral chimpanzee??

Features of pre-Australopithecines

  • Retained several primitive traits (arboreality, teeth in some cases: “peri-honing”)
  • Highly diverse in association of traits
  • Lived in wooded areas, sometimes forest, although probably spent time on the ground
  • If so, should lead us to revise trigger for bipedalism…Did bipedalism really evolve in a drier, more open environment???????
  • From Pre-Australopithecines to Australopithecines
  • Canines with “peri-honing” to clear non- honing
  • More pronounced apelike arboreal traits to gradual loss of these traits
  • Small apelike brain to slight increase in brain size

March 27, 2009 at 10:49 am Leave a comment

ANTHROPOLOGY 201 – MARCH 25 – Emergence of hominids

Emergence of Hominoids

  • Apes originated in the Oligocene (at least 27 MYA) & dominated in Miocene(23-5 MYA)
    • Miocene is age of apes
  • Began in Africa but spread through Eurasia
  • Morotopithecus bishopi (20 MYA)
    • Uganda
    • Suspensory ape-like locomotion (e.g., shape of the scapula -shoulder blade)
  • Proconsul (27-17 MYA)- recieved the most attention
    • Found in the site discussed in the previous class
    • E. Africa
    • Lacked a tail, larger brain, but mostly not suspensory like modern apes
    • Retains primitive Y-5 molars (like early catarrhines & modern apes)
    • Moslty frugivores, arboreal, forest-dwellers
    • Related to morphology of the shoulders
  • Middle Miocene (15-10 MYA) –apes diversify
    • Land bridge to Eurasia formed
  • Several major groups appeared:
    • Afropithecus &
    • Kenyapithecus (possibly basal great ape) in Africa
      • Early species that gave rise to vast number of species
    • Dryopithecus, Ouranopithecus, Oreopithecus, Pliopithecus (gibbon-like) in Europe
    • Sivapithecus,
      • Many related species were thought to be early hominids but this turned out to not be the case
    • Lufengpithecus in  Asia
    • Very hard to group this and relate these to great apes…
  • Ape adaptive radiation coincided w/ more variable climate
    • Key adaptation was probably thicker enamel on molars (w/ rounded, grinding cusps)
      • Allows for a diverse diet, can include tough fibrous materials
    • Allowed for more diverse diet, feeding on tough, fibrous foods during scarce seasons
  • Taxonomic relationships among Miocene apes unclear & under constant revision
  • No clear ancestors to modern African apes (?) or to gibbons
    • E.g., no knuckle-walkers found in miocene
    • But sivapithecines likely closely related to modern orangutans (ranged from Turkey through South Asia)

New Find…

  • Pierolapithecus catalaunicus
  • Reported in 2004
  • Hominoid found near Barcelona
  • Dates to 13 MYA
  • Shows similar locomotion adaptations to modern apes (wide & flat thorax, stiff lumbar region for climbing)
  • May be ancestral to great apes & humans (after split from gibbons)

Decline of Ape Diversity

  • By late Miocene (9-5 MYA), # of apes species was in decline
  • Climate became much drier
  • Apes were mostly out-competed by cercopithecoid monkeys
  • Only one ape lineage adapted successfully to drier, more mixed habitats (woodland & savannah)

Emergence of Hominins

  • Hominins evolved in Africa 5-7 mya, in this new environment
  • Key adaptations in diet, locomotion linked to surviving more severe, drier, more seasonal habitats

Hominin Traits:

  • What distinguishes us from apes?
  • Early evolutionary biologists thought our brain was the defining human adaptation.Under this scenario:
    • Increased cognition allowed us to descend from the trees to exploit open new habitats
    • Bipedal locomotion followed this increase in intelligence
    • Allowed us to free our hands for tools
      • carrying tools and weapons ect.
  • First fossils discovered in Asia (H. erectus) & Europe (Neanderthals) seemed to support this theory
  • But later finds of earlier species forced scientists to reconsider the why and where of early human evolution
  • Austalopithesis, discovered in south africa, small brain bi pedal apes
  • Piltown? man was found in the 40′s and was a valid hominid until the 50′s
    • very old hominid form, showed a big brain
    • turned out to he a hoax, artificial aging, and mis matched bones

First differences to appear were adaptations for bipedalism

  • Nearly all primates are “facultative” bipeds; postural vs. locomotory bipedalism
    • most primates can stand up and stay bi pedal for a little while
    • But only hominids can use this position as locomotion effectively
  • Dentition: parabolic dental arcade, thick enamel, reduced canines, larger molars
    • Apes have a U shape of teeth
    • But humans have a more parabolic shape
  • Later hominin traits are adaptations related to larger brains & increased cognitive abilities (including language & advanced tool use & other culture)
    • Brain size, smaller teeth, increased juvenile dependency

Bipedalism

  • Bipedalism involved a set of important morphological changes
  • Although our immediate “ape-ancestor” was a primate adapted for brachiation; so adaptations for arboreality have been retained (and were perhaps in use).
  • Let us review the anatomical changes necessary
  • for bipedalism to occur. Comparison Chimpanzee-Human.

Major morphological changes

  • Center of gravity of the body: lower & closer to the center of the body in a human.
  • posterior limbs have greater mass in humans
    • legs are heavier than our arms
  • lumbar curve brings the top of the body in line with the center of the pelvis.
    • Brings the body weight to the center, chimps dont have this
  • Iliac bone (pelvis): Long & narrow in chimpanzees vs wide & short in Humans.
  • foramen magnum: central in Human vs sideways in apes
    • hole where spinal cord connects to brain through skull
    • In by pedal it is parallel to the ground,
    • but in quadrupedal is will be the opposite
  • Full extension and locking of the knees in humans
    • No other mammals can do this?!? .
  • angle of femur: towards the interior in Humans, bringing leg and foot closer to center of body
  • Feet: heel, ball and big toe act as support. + big toe parallel with other toes (lacks prehensility). The feet are closer to each other in Humans (angle of femur). Minimizes displacement of center of gravity of the body.

Bipedal Adaptations

  • Foot
    • Enlarged heel to absorb forces at heel strike
    • Longitudinal arch for distributing forces
    • Big toe in line with the other toes for efficient toe off

Arboreal Retentions in early hominids

  • Relatively long arms
  • Slender, curved fingers & toes
  • Big toe relatively abducted (away from foot)
    • not parallel to the rest of the toes
    • some degree of prehensibility
  • May have spent a lot of time in the trees (safe from predators)
  • early hominid was probably not a habitual terrestrial biped
  • Ability to move arms about the shoulder is also a retained trait
  • Early hominids likely live in both trees and Savanah

Trigger for bipedalism?

  • End of Miocene, changes in climate lead to disappearance of most species of apes.
    • Dried up, forest thinned out, arbeoal apes died
    • End of Miocene, forest shrink
      • favors apes
  • Decrease in mean temperatures. Mediterranean sea dries up; faunic exchange between Europe and Africa
  • Cold Marine currents from Antarctica contribute to dry up the eastern coast of Africa.

Rift Valley in E Africa

  • Geological activity provoke the creation of the Rift Valley. Contributes to a drier climate in East Africa (mountains block the rains coming from west and center of the continent).
  • Provoke changes in flora:
    • tropical forest is replaced by flora more resistant to dry climate, more seasonnality in terms of rainfall.
    • Patches of forest surrounded by woodland savanna; “transition zone” between savanna and forest increases.
    • The transition zone was the key habitat for early hominids

Exaptation: bipedalism

  • Postural vs locomotory bipedalism in early hominids: bipedalism may have evolved as a mean to acquire food or to display, and only after as an efficient mode of locomotion.

Why bipedalism??

  • foraging posture?
    • allows much different access to trees and bushes than other animals
  • more efficient terrestrial locomotion than found in other apes (knuckle-walking, palm-walking) -but early hominins not “perfectly” bipedal…Also not more efficient than quadrupedal monkeys (about equal)
  • Reduces heat stress?
  • Other advantages:, frees hands (to carry things and use tools?)
  • Dentition gives information on:
    • 1-diet: shape and size of teeth, & by pattern of use on the surface of the enamel.
    • 2-Degree of sexual dimorphism: variation in size of canines gives indication about mating system and degree of male-male competition for females.

comparison dentition

  • Chimpanzee:
    • posterior teeth (back teeth) parallel (small), long canines + diastema (Space between first incisor and molar)
      • When chimp closes its mouth the canines interlock from top and bottom, the jaw no langer moves sideways
    • One functional result of long canine + diastema is that once the jaws are closed or semi-closed, the canines block any lateral movement.
    • Diet of chimp is largely frugivorous, incisives and canines are strong to cut and pierce fruits with toughskin, but relatively little stress on the molar and pre-molars.
  • Humans
    • Molar and premolars have an arc shape.
    • Canines not longer or bigger than other teeth
      • some variation in this, some people have canines longer than other teeth, but they still are not interlocking
      • Lack the diastema (space between incisor and molar)
    • No diastema (allows lateral movement of jaw) See diagram p. 278
  • Genetic data
    • Indicate that the last common ancestor of humans and chimpanzees lived 7-5 mya
      • based on genetic clock
    • It is only recently that fossil hominins for that period have begun to surface…
    • End of miocene the apes begin to disapear, and homonims begin to surface (5-7 mya)
      • pre austialopithesis

March 25, 2009 at 10:47 am 1 comment

ANTHROPOLOGY 201 – March 23rd – Primate Evoloution

Starts the class with info about the final exam for 201-01

Tues April 21st 12-2 gold gym, seating chart…

We are now gonna discuss human evolution

  • Human Evolutionary History:  From
  • the First Primates to Modern Humans
  • Earliest Primates
  • Primates are one of the older lineages of mammals
  • Evolved from mammalian ancestor 65-85 MYA (million years ago)
    • Earliest known unequivocal fossils date to ~55 MYA
  • Primates evolved at the end of the Cretaceous (65 MYA, when dinosaurs went extinct)
  • Remember the slide of geological timescale
    • We will focus on plioscene and pleistocene mostly

Continental Drift & Climate Change

  • Geological periods are not regular
    • Defined by major shifts in the history of life on Earth
    • Defined by geologist
    • not symmetrical, not regular
  • Most major upheavals in species makeup occur due to environmental change linked to climate change
  • Our evolutionary history is marked overall by progressively cooler & more variable climate
  • Continents have moved considerably over the last 200 MYA (plate tectonics)
  • Break-up of the continents created geographic barriers between groups of related species
    • Become isolated, separate lineages (ex: Madagascar)
    • Explains distribution of species or fossil finds; I.e. primate fossils in NA, no prosimians in SA
    • Size & orientation of continents affects climate; for instance influences oceanic currents, which heavily influences climate
    • Overall, climate has changed to drier and colder particularly in last 20 million years.
    • Pangea, super-continent
    • by 65 mya most of continents are defined north America is still connected to Europe, the beginning of the paleocene

Tracing History of Primates

  • Paleontology–study of fossilized remains of past animals & plants
    • Paleoanthropology–study of fossils from the human lineage
    • Fossils are mineralized–organic materials (usually bone) replaced by minerals
    • Body parts with higher mineral rates tend to fossilise better, thus muscles dont often fossilies while teeth and bones do
    • fossil brains have never been found, but sometimes mud leaks in and that will fossilize leaving and inprint of the brain
    • Copperlights are fossilized poo, can tell you about the diets of a species
  • Taphonomy – how a fossil site forms, why do some sites accumulate
    • Rivers? animals? Carnivores…
  • Study of fossil remains can help us reconstruct lines of descent, morphological adaptations, behaviour, past climates & environments
  • Dating is obviously important; techniques described p.  249-251 in your textbook
  • Huge amounts of disciplines dedicated to explaining human origins

Establishing Phylogenies

  • Having fossils and assigning them to a species is only the first step; the second step is to establish relationships between fossil species, and establish ancestor-descendants lines.
  • Result is very few unequivocal relationships, partly because of the “luck of the draw” in finding fossils. Not all species give rise to descendants.
  • Since palentology is dependent on finding sites, we only know a very limited amount of species
  • Thus there is lots of debate
  • A lrage number of species likely went extinct and did not give way to a new species
  • Primate Origin
  • Whether for insectivory or frugivory, rise of angiosperms 65 mya offered new environments to exploit.

Plesiadapiforms

  • Group of mammals closely related to primates that evolved 65-54 MYA (paleocene)
    • Arboreal nocturnals w/ diverse diets (insects, seeds)
    • Lacked derived primate features (do not have; nails, opposable toe or thumb, postorbital bar, forward-facing eyes); so not yet “primates”
    • But provide information about ancestral form that might have preceded primates
    • Grasping hands seem to have evolved in frugivorous forms prior to forward facing eyes, lending support to “foraging on terminal branches” as opposed to visual predation theory.
  • True Primates (Euprimates)
    • First appear in Eocene (54 MYA) but evolved up to 85 MYA. Period of expansion of the tropics.
      • Always a time lag between appearance of species in fossil record, from when they actually appeared
    • “Fossil prosimians”
    • Found in N. America & Europe (connected, then separated) so they continued to evolve separately
    • Later found in Africa, E. Asia, India but not in South America, which was isolated (see map p. 254)
    • Possess primate features: postorbital bar, nails, larger brains, stereoscopic vision, less olfaction
  • True Primates (Euprimates)
  • 40-50 genera in two families
  • Adapidae
    • lemur-like
    • arboreal quadrupeds
    • Slow arboreal climbers
    • Smaller orbits (diurnal)
    • Generalized dentition for omnivory (leaves & fruit)
  • Omomyidae
    • Smaller, galago and tarsier-like
    • Elongated tarsal bones for leaping
    • Nocturnal (large orbits)
    • Sharp shearing teeth –insectivores
  • Ancestors?
  • The primate radiation included a very large number of species -but it is not clear which species gave rise to modern groups of prosimians and anthropoids…
  • Anthropoids may have arisen at the end of the Eocene, but it is in the Oligocene that they greatly diversified.
  • Anthropoids
  • Eocene-Oligocene boundary (36-33 MYA) shows great increase in diversity
  • The Fayum, Egypt
    • One of most important primate fossil deposits anywhere
    • Up to 14 genera, including adapids, omomyids & anthropoids
    • Severe desert now, but tropical swamp during Oligocene (34-23 MYA)

New World Monkey Origins

  • Appear relatively early in “anthropoid” fossil record
    • Oligocene-Miocene boundary:  26-23 MYA
    • E.g., Branisella boliviana (oldest NWM fossil)
  • Platyrrhine
    • Share many derived traits w/ catarrhines(post-orbital closure, fused mandible, more forward-facing eyes)
    • But some features also shared w/ tarsiers(meaning omomyidancestor possible = North American origin?)
    • Also, some derived features shared w/ catarrhines would have evolved independently(fused mandible)
    • And… NWM’s lack a bony ear tube –a derived feature shared by tarsiers & catarrhines
  • Nevertheless, the consensus is that NWM split from a common ancestor to all NWM & OWM in Africa
    • Some fossils at Fayum might be related to NWM (2133 dental formula)
  • Must have reached South America by rafting
    • Group of rodents originally from Africa appears suddenly in S. American fossil record at the same time
    • A migration of an omomyid ancestor from N. America would have also had to cross water (C. America did not yet exist)
    • The rafting theory originated from the the possibilty of mangrove forests drifting across the ocean.

We will start with the emergence of homonoids on wednesday

March 23, 2009 at 10:48 am Leave a comment

ANTHROPOLOGY 201 – March 20th – Movie notes

Looks like another movie… I swear if we do another, I’m bringing popcorn…

  • APE MAN!!!
    • This does not look good
    • Ape and Man, Man and Ape, APE MAN!!!!
    • Why do we probe our past?
    • Primates are curious
    • This movie is pretty rough, sorry guys, I’m done

First off every one should go to Fuck you, Penguin it’s great!!

now im gonna google jokes with monkeys in them:

We’ve all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.

Q: How do monkeys get down the stairs?
A: They slide down the banana-ster!
Q. What’s black and white and has sixteen wheels?
A. A capuchin wearing roller skates!

Q. If you were in a jungle by yourself and a gorilla charged you, what would you do?
A. Pay him.

http://www.cracked.com/article_14990_what-monkeysphere.html

http://www.cracked.com/article_14827_monkeys-vs-toddlers-who-can-kick-whose-ass.html

March 20, 2009 at 10:15 am Leave a comment

ANTHROPOLOGY 201 – Chapter Summaries – Submitted by Steph

These are some great chapter summaries submitted by Steph, Thanks!

Chapter 6– Primate Ecology

  • The Distribution of Food
  • The total amount of energy that an animal requires depends on four components:
  • 1) Basal metabolism: Basal metabolic rate is the rate at which an animal expends energy to maintain life when at rest.
  • 2) Active metabolism – when animals become active, their energy needs rise above baseline levels.  The number of additional calories required depends on how much energy the animal expends.
  • 3) Growth rate – Growth imposes further energetic demands on organisms.  Infants and juveniles who are gaining weight require more energy than would be expected.
  • 4) Reproductive effort – Female primates the energetic costs of reproduction are substantial.   Example. During lactation females requires 50% more calories than usual.
  • Primates cannot synthesize amino acids from simpler molecules therefore must consume them from foods.
  • Many plants produce toxins called secondary compounds to protect themselves from being eaten.
  • Primates get most of there protein from insects and young leaves.
  • Prosimian obtain protein generally from insects and carbohydrates from gum and fruit.
  • Activity Pattern
  • Fact that many prosimians are nocturnal suggests they evolved from a nocturnal ancestor.
  • Common daily cycle is wake up, eat, nap when sun gets hot, resume eating in later afternoon, find sleeping site in evening and sleep
  • Ranging Behaviour
  • All primates have home ranges but only some are territorial.
  • Some species like gibbons maintain exclusive access to a fixed area = territories
  • Nonterritorial species such as squirrel monkeys and long-tailed macaques may fight if they encounter or mingle peacefully.
  • Two main reasons for territoriality is resources and mate defence.
  • Predation
  • Primate Sociality
  • Most primates except for oragutans and some prosimians spend most of their lives in stable groups of familiar individuals.
  • Grouping provides safety from predators because of the 3 D`s: detection, deterrence and dilution.
  • Distribution of Females
  • Scramble competition – resources are distributed evenly across the landscape. Ex. Scrambling for candy when a piñata breaks, but nobody fights over candy.
  • Contest competition – occurs when resources are limited and can be monopolized profitably, generating direct confrontation over access of them.
  • Resource competition is expected to generate dominance relationships
  • When a dominance encounter had a predictable outcome we say that a dominant relationship has been established.
  • When contest competition within groups is stronger than between groups, females will remain in their natal group and cooperate with kin in contest with unrelated females in their group over resources.
  • Philopatry – the tendency to remain in their natal group throughout their lives. Common in Old World Monkeys.
  • When between group competition is greater than within group, competition dominance will be less important but female philopatry will still be favoured.
  • When both are strong females must compete for both.
  • Distribution of Males
  • Ecological factors shape the distribution of females and males go where the females are.
  • Found that groups facing the highest risk of predators lived in the largest groups and had the most males.
  • Resource competition also influences male dispersal strategies because inbreeding is a disadvantage.
  • Terms to know in Chapter 6
  • Basal Metabolic Rate – the amount of energy use required to maintain life when an animal is at rest.
  • Secondary Compounds – toxins produced in plants as a defence mechanism so animals will not eat them.
  • Frugivore – an animal who diets mostly on fruit
  • Folivore – an animal who diets mostly on leaves.
  • Insectivore – an animal who diets mostly on insects.
  • Gummivore – an animal who diets mostly on gum.
  • Cathemeral – Active both during the day and at night.
  • Socioecology – the study of how social structure is influenced by ecological conditions.
  • Scramble Competition – a form of competition that occurs when resources are distributed evenly through space and not worth defending.
  • Contest Competition – a form of competition that occurs when resources are clumped in space and worth defending.
  • Dominance- The ability of one individual to intimidate or defeat another individual in a pair wise encounter.
  • Dominance hierarchies – a ranking of individuals in a group that reflects their relative dominance.
  • Philopatry – the tendency to remain in their natal group throughout their lives. Common in Old World Monkeys
  • Inbreeding – mating between closely related individuals.

Chapter 7– Primate Mating Systems

  • Darwin’s theory – complex adaptation exists because they evolve step by step by natural selection
  • Mating Systems play a crucial role in our understanding of primate societies.
  • Reproductive strategies are influenced by their phylogentic heritage as mammals.
  • The Language of Adaptive Explanations
  • In evolutionary biology the term strategy is used to refer to behavioural mechanisms that lead to particular courses of behaviour in particular functional contexts, such as foraging or reproducing.
  • Strategy implies a conscious plan and a goal-directed course of action.
  • Biologist believe there is an underlying mechanism in monkeys that allow them to just know how much and what to eat.  They do not have any conscious knowledge of it.
  • The terms cost and benefit refer to the effect of particular behavioural strategies on reproductive success.
  • The Evolution of Reproductive Strategies
  • Males do not care for their offspring when

    • (a) they can easily use their resources to acquire many additional matings, or
    • (b) when caring for their offspring would not appreciably increase the offspring’s fitness.
  • Investing vs. Noninvesting males
  • Reproduction Strategies of Females
  • Often invest more to their offspring than males do.
  • Pregnancy and lactation are tiring time consuming activities for females.
  • Because primates brains are larger for their body size it takes extra time for them to grow.
  • High ranking females tend to reproduce more successfully than low ranking.
  • Group size is shown to effect reproductive success..ideal is small group with a high ranking.
  • Reproductive Trade-offs
  • Must balance the quality and quantity
  • Parent-offspring conflict – conflict between mother and infants over the amount and extent of maternal investment.
  • Some animals perform altruistic acts that increase other individuals fitness and reduce their own fitness. à Kin selection provides one mechanism for evolution of altruism.
  • Altuism will be favoured when the benefits to the recipient (b) multiplied by the degree of relatedness between the actor and the recipient (r) is greater than the cost to the actor(c). Rb>c
  • Sexual Selection and Male Mating Strategies
  • Sexual Selection is a special category of natural selection that favors traits that increase success in competition for mates.
  • Two types of sexual selection
  • 1) Intrasexual selection results from competition among males.
  • 2) Intersexual selection results from female choice.
  • 1)Intrasexual Selection
  • Competition among males for access to females favors large body size, large canine teeth and other weapons that enhance male competitive ability.
  • Most intense among males
  • Leads to the evolution of sexual dimorphism.
  • The fact that sexual dimorphism is greater in primates species forming one-male or multimale groups tan in monogamous species indicates that intrasexual selection is the likely cause of sexual dimorphism in primates.
  • In species that form one-male groups there are many bachelor males which are males that don’t belong to social groups. They exert constant pressure on resident males.
  • the species where the sexual dimorphism is more similar they are commonly in monogamous relationships.
  • Estrus – period of time where a female is able to reproduce.
  • 2) Intersexual Selection
  • Favours 3 kinds of traits in males:

    • a) traits that increase fitness of their mates,
    • b) traits that indicate good genes and thus increase the fitness of the offspring, and
    • c) nonadaptive traits that make males more conspicuous to females.
  • Only a few morphological traits among primates have evolved because they help males attract females.
  • Is possible that these traits evolved in response to female preference.
  • Male Reproductive Tactics
  • Investing Males
  • Monogamous pair-bonding is generally associated with high levels of paternal investment.
  • Males do no compete over females, more so over the territory, finding mates and having viable offspring.
  • Mate guarding may be an important component of pair-bonded males. Seen in titi monkeys and gibbons
  • In cooperatively breeding species, males invest heavily in offspring, but the reproductive benefits to males are not clear.
  • Male-Male Competition in Nonmonogamous Groups
  • In nonmonogamous groups the reproductive success of males depends on their ability to gain access to groups of unrelated females and mating with receptive females.
  • Infanticides
  • Shortens interbrith intervals
  • Is linked to change in male membership and status
  • Do not kill their own infants
  • Gain reproductive benefits
  • Can sometimes be a substantial source of mortality
  • Females have evolved a battery of responses to infanticidal threats.
  • Paternal care in Nonmonogamous Groups
  • The existence of male care of offspring varies in nonmonogamous species.
  • Female Mate Choice
  • Female preferences include male competitive tactics.
  • Little idea of what traits are more preferred. We just know that they have preferences.
  • Terms for Chapter 7
  • Mating System – the form of courtship, mating and parenting behaviour that characterizes a species.
  • Strategy – a complex of behaviours deployed in a specific functional context such as mating, parenting or foraging.
  • Parent-Offspring Conflict – conflict that arises between parents and their offspring over how much the parent will invest in their offspring.
  • Sexual Selection – a form of natural selection that results from differential mating success in one gender.
  • Intrasexual Selection – a form of sexual selection in which males compete with other males for access to females.
  • Intersexual Selection – A form of sexual selection in which females choose who they mate with.  The results is that traits making males more attractive to females are selected for.
  • Sexual Selection Infanticide Hypothesis – A hypothesis postulating that infanticide has been favoured by sexual selection because males who kill unweaned infants are able to enhance their own reproductive prospects if they 1)kill infants whose deaths hasten their mothers resumption of cycling, 2)do not kill their own infants, and 3)are able to mate with the mothers of the infants that they kill.
  • Infanticide – practise of intentionally killing an infant.
  • Mating Effort – efforts made to secure access to a mate.
  • Parenting effort – efforts made to secure the survival of offspring

Chapter 8 – The Evolution of Social Behaviour

  • Kinds of Social Interactions
  • Interactions that involve two individuals is called dyadic or pairwise interactions.
  • 4 types of pairwise interaction that are based on the effects of the actor and the recipient
  • (Actor/Recipient) Selfish=+/- , Mutualistic = +/+ , Altruistic -/+ and Spiteful -/-
  • Altruism:  A Conundrum
  • Altruistic behaviour cannot evolve by ordinary natural selection.
  • May arise by accident
  • Kin Selection
  • Natural Selection can favour altruistic behaviour if altruistic individuals are more likely to interact with each other than chance alone would dictate.
  • Hamilton’s Rule
  • Theory of Kin selection predicts that altruistic behaviours will be favoured by selection if the cost of performing the behaviour are less than the benefits discounted by the coefficient of relatedness between actor and recipient.
  • Rb>c
  • 2 important insights:

    • 1) altruism is limited to kin
    • 2) closer kinship facilitates more costly altruism.
  • Food Sharing occurs among chimpanzees, tamarins and marmosets.
  • Evidence of Kin Selection in Primates
  • Kin-based support in conflicts has far-reaching effects on the social structure of many primate groups.  Evidence of these effects come from studies of macaque, vervets and baboon groups
  • Maternal rank is transferred with great fidelity to offspring, esp. Daughters
  • Maternal kin occupy adjacent ranks in the dominance hierarchy and all the members of one matrilineage rank above or below all members of other matrilineages.
  • Ranking this way is often predictable.
  • Kinship influences howler males in important ways:  Red howlers 2-4 females 1-2 males
  • Reciporcal Altruism
  • Altruism can evolve if altruistic acts are reciprocated.
  • 3 conditions together favour the development
    • 1)individuals must have an opportunity to interact often
    • 2) have the ability to keep track of support given and received
    • 3) Provide support only to those who help them.
  • Term for Chapter 8
  • Dyalic- describing an interaction that involves two individuals.
  • Pairwise – describing an interaction that involves two individuals a.k.a dyadic
  • Actor – the individual performing a given behaviour.
  • Recipient – the individual whom a particular behaviour is directed.
  • Selfish – a behaviour that increases the fitness of the actor and decreases the fitness of the recipient.
  • Altruistic – behaviour that reduces the fitness of the individual performing the behaviour
  • Spite – costly to both individuals.
  • Mutualistic -  beneficial to both individuals.

March 17, 2009 at 11:41 am Leave a comment

ANTHROPOLOGY 201 – Notes from textbook – Chapter 5

  • Primate order is defined by 9 characteristic, where all primates share some of these characteristics
  • Prosimians have a a stronger reliance on olfactory sense (smell) than anthropoids
    • Prosimians are Lorises and Lemurs ect.
  • Primates are restricted to tropical regions of the world
    • fossil records show that some primates lived in southern Europe, America, South west Asia, and the southern tip of south America
    • Vast majority of primates live in forested areas
  • Two sub orders are Prosimii and Anthropoidea
  • Prosimii
    • Can live in darkness
    • developed sense of smell
    • Large Eyes
    • independently movable ears
  • Anthropoidea
    • Diurnal
    • More complex behavioural traits
    • Generally larger
    • more dependent on vision
    • live in bigger more complex social groups
  • Basal metabolic rate is the rate at which an animal expends energy to maintain life when at rest
  • Diet
    • All primates rely on at least one type of food high in protein
    • Another that is high in carbohydrates
    • Prosimians generally get protein from insects, and carbs from gum and fruit
    • Monkeys and Apes generally get protein from insects or young leaves and carbs from fruits
    • In general insectivores are smaller than frugivores
    • Larger animals are less constrained by the quality of food than by the quantity because they afford to process lower quality foods more slowly
    • Folivores can generally find more food than frugivores and insectivores
    • Because of the consistency of a folivores food supply its home range is smaller than others
  • Activity
    • Most time spent foraging, feeding and resting
    • Least time spent grooming, playing, fighting and mating
    • Difference in activity patterns is based largely on ecological differences
  • Ranging Behaviour
    • Interactions with other species, and groups of the same species are dependent on how the borders of a given species are defined
    • Both resource defence and mate defense have influenced the evolution of territoriality
  • Predation
    • A very significant amount of smaller and more immature primates are killed from predators
    • Hard to research because mores predators work at night
    • Rather the data is inferred for example if a member of the group disappears over night
    • or by studying the nests of predators, for example if there are monkey bones…
    • Many defense have evolved
      • Vervet monkeys have different calls to alert their group
      • Smaller primates generally flee and hide
      • Larger primates sometimes confront the predator
      • Sometimes species work together to protect each other from predators
        • Inter-specific associations
  • Primate Sociality
    • Likely evolved because of predation
      • Predator who strikes a pair of primates, there is only a 50% chance of survival
      • same situation in a group of ten yields a 90% chance of survival
    • Many benefits as well as costs
      • More competition over access to food and mates
  • Primate conservation
    • Reasons for endangered species;
      • Habitat destruction
      • Hunting
      • Live capture for trade and export
    • 100 species considered endangered

March 16, 2009 at 12:05 pm 1 comment

ANTHROPOLOGY 201 – March 16th – Field Research

Stuff being covered is on the outline. Primates through to field work. Chapters 5-8 + 2 examples of field work.Wont be asking us to memorize scientific names, she’ll give us both often. Its good to know determining characteristics about the primates. For example knuckle walking, pre hensile tail, wet nose, cheek pouches. Know who has em! She wont ask us to name and recreate taxonomies, much more important to know characteristics that compare and contrast the different species.

Colobusvellerosusat Boabeng-Fiema
Monkey Sanctuary: An example of egalitarian species

  • Colobus vellerosusis a member of the subfamily “colobines”, so has a complex stomach allowing for a high proportion of leaves in the diet.
  • C. vellerosus is one of the 5 species of black and white colobus. One of the 3 clusters of African colobines (B&W, red and olive colobus).

The social system and dispersal pattern of B&W colobus show variation between species

  • Infants are pure white
  • Colobus guereza, best known B&W, has egalitarian female relationships.
  • However, presence orabsence of female hierarchies depending on species; C. polykomos shows female dominance hierarchy.
  • female philopatry and dispersal depending on species (“facilitative philopatry” Steenbeek 1999)

Goal of our research program

  • Chose Ghana because, the great lake areas become too unstable
  • Ghana was rather stable and there were strong ties to the U of C
  • Better understand social dynamics of Colobus vellerosus, which was the least known of the 5 species of B&W colobus at the beginning of our
  • Study of diet, habitat use, social behavior to describe C. vellerosus‘ social system, social dynamics and dispersal patterns.
  • Colobus vellerosus
  • C. vellerosusmost closely related to guereza, so we suspected that C. vellerosus showed egalitarian female relationships, but needed confirmation.
  • Also, there is an east-west variation in diet of black and white colobus(more seeds in West-Africa / more mature leaves in East); so more competition in WA?

RE or DE?

  • We also wanted to establish C. vellerosus’ dispersal pattern; do females show residency or dispersal?

The Study Site I

  • Boabeng-Fiema Monkey Sanctuary
  • Ghana, West africa
  • The Study Site II
  • Small forest (1.9Km2) in forest-savanna transition zone, associated with two villages.
    • Community based ecotourism project
    • Local taboos & national laws prohibit hunting of monkeys at BFMS
  • The areas on western Africa, south africa, Madagascar are called Guinean Forrest’s
    • These are hot spots for unique wildlife, a high priority for conservation efforts
  • Monas : offspring of the female god Daworoh from Boabeng
  • B&W:  offspring of the male god Abodwo from Fiema

The Study Subjects

  • 15 groups of B&W in the sanctuary: population at 250 and increasing
  • Mean group size at 14 individuals
  • age/sex class categories
  • Individual recognition is now possible thanks to the hard work of J. Teichroeb and E. Wickberg.
    • Found that males and females have different fur in crotch region
    • Girls taint is not white
    • guys taint is white
  • Observations from a distance
  • Diet of C. vellerosus
  • Highly folivorous:
  • Annual diet:
    • Young and mature leaves (78%),
    • Seeds and seedpods (8% and up to
    • 57% for a single month in the dry season
    • Unripe fruits (8%)
    • Flowers and buds (5%)
  • Effect of diet on social relationshisp?
    • If leaves are low quality and rather evenly distributed, should lead to egalitarian female relationships.
    • Do not plan to do plant nutritional analysis in near future because very time consuming. So look at behavioral outcome of feeding.
  • Time budget
    • Feeding: 23.7%
    • Resting: 59.1%
      • very common in folivores, folivourous primates need this time to digest
    • Moving: 14.6%
    • Social behavior: 2.6%
    • Typical folivore: high
    • resting, low social behavior.
  • Feeding competition?
    • No contest competition within group for access to food resources. No displacements over food, so no dominance hierarchy apparent.
    • We have scramble competition for food. Large groups have longer Day Journey Length, spend more time feeding, have a larger Home Range, etc.
    • This supports female egalitarian relationships.
  • Grooming & affiliate events
  • In study of affiliation, S. Marteinson conducted 102 hrs of focal observations (adults only):
    • 56 grooming boutsin the 2 groups (45 in WW, 11 in B2). Median duration = 46 s.
    • Affiliate events: Gentle hand touch, present for grooming, open mouth and tail/leg hold. 58 events (WW:39, B2 :19).
    • Low Frequency vs. cercopithecines
      • in comparison to macaques, or other cercopithecines

What does it tell us?

  • C. vellerosus does not show high F-F affiliation
  • Low affiliation suggests that maintenance of alliances (within and between group) is not of great importance
  • Variation between groups; Group size & composition influence distribution of affiliation

How about between groups?

  • In majority of cases, males are aggressors and targets during IGE.
  • We have documented the occurrence of male incursions, where males encounter a reproductive unit.
  • Last much less than inter-group encounters (9 min. vs 43 min. median duration).

Takeovers and attacks on immatures

  • We know that male takeovers regularly take place (at least 2 incidences well documented since 2000).
  • We have several male attacks on immatures during these
  • takeovers, + one several cases of male infanticide.
  • Male incursions
    • Test for takeover??
    • See what type of resistance he faces, and what type of reception he gets from females
  • Females…
  • Relatively few cases of female participation in inter-group encounters;
  • However, in some groups, seems to be more frequent than others. Variation in relatedness between females??
    • Evidence of some female transfer at BF (during male incursion) ; consistent with other colobines. Resident / dispersal not a simple dichotomy?
  • Female aggression could then be related to resistance to immigration, or to defense of food resources. Study ongoing…

Sorry I wasnt really taking many notes, sorry!

March 16, 2009 at 10:44 am Leave a comment

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