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ANTH 300 Final Exam Pangea - - a hypothetical landmass in which all the continents were joined, approximately 300-200 mya
- at beginning of time frame (within Mesozoic and Cenozoic eras; or within the last 200 million years), Pangaea began a process of separation, still ongoing. absolute dating techniques - absolute (numerical) age is determined through methods that result in a numerical time scale.
- Dendrochronology
- Radiocarbon dating
- Radio potassium dating -fission track dating
- amino acid dating
- paleomagnetic dating
- electron spin resonance
- thermo-luminescence dating Dendrochronology - A chronometric dating method that uses a tree-ring count to determine numerical age.
- A.E. Douglass developed it (noticed there tree growth stopped in winter and reactivated in spring - in temperate/very cold regions; this intermittence resulted in layers of growth, with each ring representing one year of growth)
- mostly used in American Southwest (where trees are excellently preserved) Radio potassium dating - measures the potassium radioisotope in volcanic rock associated with fossils (Potassium has a long half-life, and can be used to date fossils older than 200,000 years old). fission track dating - based on the radioactive decay of naturally occuring uranium-238. It is based on changes in uranium-238 and is used to date volcanic ash and glass millions of years old.
radio carbon dating - measures the half-life of carbon isotopes. This method is the most accurate for only the last 50,000 - 70,000 yBP. -Willard Libby discovered it following WWII -advantage: precise baseline for start of clock -- death of organism -disadvantage: c-14 has fairly short half-life (5,730 years) so its dates most accurate are between 50, and 70,000 yBP. radiocarbon dating (continued) - 1) C-14 is produced in the atmosphere
- C-14 is oxidized and forms Carbon Dioxide
- 14-CO2 is used by plants in photosynthesis. C-14 is incorporated in plant tissues
- Most C-14 is absorbed by the oceans.
- animals consume plants, and the plant c-14 is incorporated in animal bone and other tissues through metabolic processes
- when animals die, their metabolism ceases, and their tissues stop incorporating c-14. c-14 begins decaying to N-14. The proportion of c-14 begins to decrease. half-life - the time it takes for half of the radioisotopes in a substance to decay; used in various radiometric dating methods. -example: C-14 to N-14 = 5,730 (isotopes used in radiometric dating) amino acid dating - an absolute dating method for organic remains such as bone or shell, in which the amount of change in the amino acid structure is measured. -it is based on the decay of protein molecules, is useful for fossils up to 200,000 years old, and in some settings 1 mya. paleomagnetic dating - uses changes in the earth's magnetic field to date rock.
Cultural dating - - uses changes in material culture (such as stone tools, ceramics, etc.) to establish chronology When the hominid lineage diverged from chimps - the lineage leading to modern humans diverged from the chimpanzee lineage much more recently, somewhere between 5 and 7 mya. fossilization - increases the likelihood of fossilization:
- fossilization requires anoxic environment, where decomposition is limited -quickly buried or preserved
- swampy or riverine environments -volcanoes -tar pits decreases likelihood of fossilization: -scavengers
- ground water or acidic soils can dissolve teeth and bone -ground pressure/geologic activity can distort the appearance of any fossil how to reconstruct ancient environments - - past climates and habitat in general can be reconstructed via two of the three stable isotopes of oxygen. -ancient animals' diets and their habitats can be reconstructed through two of the stable isotopes of carbon. -researchers can look at bones of extinct animals and determine how they functioned during life and in what kinds of habitats they functioned past climates and habitat in general can be reconstructed via two of the three stable isotopes of oxygen (EXAMPLE) - - foraminifera (ancient ocean dwelling organisms) are preserved in sediments on the ocean floor worldwide.
- while they are living, they ingest the two stable oxygen isotopes from ocean water (O-18 and O-16)
- when temp decline: O-18 increases -when temp increase:O-18 decreases -we can learn about what ancient environments were like based on the changes in the temperature ancient animals' diets and their habitats can be reconstructed through two of the stable isotopes of carbon. (EXAMPLE) - -chemical analysis of the bones and teeth in fossils provides important information about past animals' diets and habitats
- animals ingest ratios of plants that are then transmitted to their bones and teeth.
- animals that ingest C-3 plants: include trees, bushes, and shrubs associated with relatively wet and wooded environment (animals that ingest C-3 have lower ratio of C-13 to C-12) -animals that ingest C-4 plants: open grasslands typical of the tropical savannas (animals that ingest C- have a higher ratio of C-13 to C-12) environments that brought about the 1st bipedal hominids - End of Miocene (around 6 mya) - cooling period that reduced forests and increased grasslands, which may have led to the selection of bipedalism typical primate traits - foward-facing eyes, a post-orbital bar or fully enclosed eye orbit, a large cranial vault, a reduced snout, and a versatile dentition. -primates usually have divergent big toes and divergent thumbs, grasping hands and grasping feet, and nails instead of claws on their fingers and their toes. hominid traits - bipedal locomotion and nonhoning chewing bipedal: s-shaped spine, foramen magnum placed directly beneath skull to balance the head and hold it upright, pelvis is short from front to back, legs are long relative to the body trunk and arms, foot has double arch, and the big toes (hallux) is not opposable. nonhoning chewing: blunt/nonprojecting canine, small canine relative to size of other teeth, no diastema, wear on tips of canines and of third premolars.
Bipedalism Evolution Hypotheses - rodman and mchenry's patchy forest hypothesis, owen lovejoy's provisioning hypothesis Charles Darwin's Hunting Hypothesis - - Bipedalism had freed the hands for carrying weapons -intelligence increased; size of canines diminished -tool production and use essential for development of human intelligence
- new evidence shows this not to be the case Rodman and McHenry's Patchy Forest Hypothesis - -toward the end of the Miocene the forests were becoming patchy, then food became more dispersed. -walking on two legs in this sort of habitat would have been more energy-efficient in comparison to quadrapedalism. -as forests fragmented, bipedalism freed the hands to pick up food allowing for both tree and ground resources to be exploited Owen Lovejoy's Provisioning Hypothesis - -freeing the hands allowed males to assist females more efficiently in procuring food. -a monogamous father enhanced the survival of the mother and her offspring by providing both food and protection from predators. -Lovejoy's evidence of monogamy: low sexual dimorphism in early hominids and reduced canines, and masked signs of ovulation in modern humans. -wrong with this hypothesis: think of bonobos (not monogamous, largely peaceful social life, inexact signs of ovulation, small canines relative to common chimps (less sexual dimorphism does not necessarily equate to monogamy) Laetoli site in Tanzania - -fossils representing Australopithecus afarensis found many sites including Laetoli, Tanzania
- Laetoli is especially extraordinary becuase of its assemblage of fossil hominids and because of its spectacular preservation of thousands of footprints left by numerous species of animals (ranging from tiny insects to giant elephants).
- geologic evidence indicates the eruption of nearby volcano, which spewed thin layer of ash across landscape. -after eruption, light rain fell, turning ash into gooey layer of mud. -animals then traversed the landscape, among them three hominids that left tracks indicating they had simultaneously walked across the muddy terrain around 3.6 mya.
- footprints are remarkable because they demonstrate the existence of human-like creatures with bipedal characteristics: round heels, double arches, and non-divergent big toes. Out-of-Africa Hypothesis - this hypothesis states that modern Homo Sapiens first evolved in Africa and then spread to Asia and Europe (50,000 yBP), replacing the indigenous archaic Homo Sapiens populations living on these two continents. -explains the single species of living humans by emphasizing a single origin of modern people and eventual replacement of archaic H. sapiens throughout Africa, Asia, and Europe. -no gene flow Multiregional Continuity Hypothesis - hypothesis regards the transition to modernity as having taken place regionally and without involving replacement (from this point of view, African archaic H. Sapiens gave rise to African modern H. Sapiens, Asian archaic H. sapiens gave rise to Asian modern H. Sapiens, and European archaic H. Sapiens gave rise to European modern H. Sapiens. -emphasizes the importance of gene flow across population boundaries; there is continuity of morphology in all regions of the globe. Assimilation/Partial Replacement Hypothesis - modern H. Sapiens evolved first in Africa, then spread to Europe and Asia. -once they arrive in Europe and Asia, modern H. Sapiens underwent gene flow with the Neandertals. Genetic diversity in modern H. sapiens - Two explanations exist for Africa's greater genetic diversity:
-at least two factors probably brought about agricultural revolution:
- environmental change to cooler conditions
- increase in human populations -why it came agricultural revolution came about - -at least two factors probably brought about agricultural revolution:
- environmental change to cooler conditions
- increase in human populations population pressure - human population increased at the time, and this increased the need for larger and more stable food resources agricultural advantages - support for larger numbers of people, creation of surplus food, long-term food storage, especially for grains agricultural disadvantages - increased demands on the environment (land degradation), pollution, conflict between populations competing for the same lands, loss of wild species through over-hunting, decline of biodiversity, health costs and quality of life implications. what are the consequences of the agricultural revolution - - population growth - domestication fueled population growth and formed the basis for complex societies and technologies; shift from foraging to farming lead to the increase in population size and the demands that the increases placed on the environment
- environmental degradation (began 10,000 yBP) - competition for resources strains the global environment; processes of domesticating and raising plants and animals affected ecology, including world biodiversity. biological changes with the agricultural revolution - diet influences human physical appearance, changes in food relate to changes in facial structure, face and jaw size are smaller than those of early hominids
Importance of Ceramics for our biology - the invention of pottery for storing food or cooking it was revolutionary. -cooking foods until they became soft mushes, meant people could easily chew their food -this would have required less powerful muscles while chewing; light use of muscle produces limited bone growth, so Nubians eating soft foods had reduced faces first animal to be domesticated during the Neolithic - Neolithic - the late Pleistocene/early Holocene culture, during which humans domesticated plants and animals -the first animal to be domesticated during this time was the dog at about 15,000 yBP Global Warming - increase in average earth temperature; has occurred during other times in the earth's history; current warming trend due at least in part to human activity; also due to technological changes like use of fossil fuels, emission of gases from manufacturing -if it is left unchecked, it potentially will threaten food production and continue to negatively affect health, and lead to rising sea levels from melting glaciers which threatens coastal areas anthropogenic (human) causes of global warming - population growth, lack of vegetation/heat from roads, fossil fuels, emission of gases from manufacturing Life expectancy in the US - - technology has increased human longevity through improvements in sanitation, medical care, and quality of life.
- costs of longer life include loss of bone mass, heart disease, and so on, as well as negative effects on Earth's biodiversity nutrition transition - the shift in diet to one that is high in saturated fat and sugar; a cause of the global obesity epidemic hygiene hypothesis - the proposition that increasing allergies among children are the result of decreased exposure to microbes, such as those found in dirt. -it argues that cleanliness decreases endotoxins, which help decrease allergies
-after eruption, light rain fell, turning ash into gooey layer of mud. -animals then traversed the landscape, among them three hominids that left tracks indicating they had simultaneously walked across the muddy terrain around 3.6 mya.
- footprints are remarkable because they demonstrate the existence of human-like creatures with bipedal characteristics: round heels, double arches, and non-divergent big toes. Kebara, Israel site - -Kebara Neandertals date to about 60,000 yBP -represented by complete mandible and body skeleton; the legs and cranium are missing (one of the most complete Neandertal skeletons found to date) -the Kebara Neandertal skeleton includes the hyoid bone, a part of the neck that can survive from ancient settings-identical to modern human hyoid (suggests that Neandertals were able to speak). Shanidar, Iraq site - -in northern Iraq's Kurdistan region -Seven adults and three young children Neandertals found here
- their skeletons provide important insight into the lives, lifestyles, and cultural practices of late archaic H. Sapiens -evidence found with the Neandertal skeletons suggests that they intentionally buried their dead and possibly performed some type of burial ceremony -Shanidar 1 - older adult male dating to at least 45,000 yBP (one of the most complete skeletons); has wide nasal aperture and projecting face; fracture on upper face-may cause blindness; severe arthritis in feet from stress of mountainous terrain -his upper incisors are severely worn (teeth as part of "tool kit"
- when he was excavated, his lower right arm was missing (may have been amputated or accidentally severed right above the elbow); the humerus was severely atrophied, probably owing to disuse of the arm during life
- the loss of the use of his arm meant that Shanidar 1 had to use his teeth to perform some simple functions like eating or making tools (his survival likely depended on the use of his front teeth) Krapina, Croatia site - -the Croatian paleontologist Dragutin Gorganovic Kramberger applied fluorine dating to human and animal remains found here.
-the significance of this dating method was demonstrated by his results, which suggested that extinct animals and Neandertals had coexisted.
- the Neandertal record begins in eastern Europe at the Krapina, Croatia site dating to 130,000 yBP.
- the Krapina fossils were excavated more than a century ago -Kramberger was careful in recording the stratigraphic locations of the several hundred bones and teeth found at the site
- the Krapina remains were recovered from a seriers of strata inside a rock shelter -Krapina 3 -most complete cranium and has the typical Neandertal features (round eye orbits, wide space between the eye orbits, wide nasal aperture, and protruding midfacial region) -the Krapina front teeth are the largest of any known fossil hominid (some of the biggest in human evolution) -the Krapina bones are mostly in fragments (some displaying distinctive cutmarks in places where ligaments were severed with stone tools - the cuts are similar to those on animal bones, suggesting that these people at animal and human tissue (practiced cannibalism) La Chapelle-aux-Saint, France site - -skeleton from this site has the characteristic Neandertal cranial morphology, including a wide nasal aperture, a projecting midface, an occipital bun, and a low/long skull
- this skeleton is also one of the most complete Neandertals
- Boule concluded that the individual must have walked with a bent-kneed gait (as in chimpanzees that walk bipedally), and could not have been able to speak
- his interpretations led to view at the time that Neandertals were evolutionary dead ends, replaced by the emerging modern humans and representing distant cousins of humanity that were not able to survive. REJECTIONS OF THIS VIEW:
- skeleton has enormous nasal aperture (huge nose); more likely an adaptive complex rejecting life in cold climates during Upper Pleistocene -nose's important function: to transfer ambient air into warm/humid air -the projecting nose typical of Neandertals placed more distance between the cold external environment and the brain, which is temperature sensitive -skeletons found in burial pits-suggesting that the Neandertals intentionally buried their dead and possible partook in burial ceremony/ritual
-skull sent to Dart and he spent months removing bones and teeth from the stone matrix
- found the skull to not be that of a baboon; found that the position of the foramen magnum was directly underneath the skull (bipedalism) and teeth were like human's (canines were very tiny) -skull had primitve small brain like an apes (creature was not human, but it was a human ancestor) -he named it Australopithecus africanus -Dart discovered other australopithecines in South African (partial skeleton of A. africanus) -A. africanus dates to around 3-2 may -after Piltdown fossils had been exposed as fraud, Raymond Dart was finally validated (A. africanus was the human ancestor, not Piltdown) Cranial capacities for all hominids - Ardipithecus kadabba - Ardipithecus ramidus - Sahelanthropus tchadensis -350cc Orrorin tugenensis - australopithecus anamensis - Australopithecus afarensis- 430 cc Australopithecus garhi-450 cc Australopithecus aethiopicus- 410 cc Australopithecus boisei - 510 cc Australopithecus robustus - 530 cc Australopithecus africanus -450cc Australopithecus platyops -400-500cc Australopithecus sediba -420cc Homo habilis -650cc Homo erectus-950cc Homo floresiensis- 400cc
Early archaic H. sapiens - 1,1000-1,3000cc Late archaic H. sapiens (Neandertals)-1,740cc Early Modern Homo Sapiens-1,500 cc FOSSIL Species: - Carpolestes - a plesiadapiform genus from the Paleocene, probably ancestral to the Eocene euprimates -has grasping foot (made possible by opposable big toe), long grasping fingers, nail on the end of the first foot digit. -link between Plesiadapiforms and Eurprimates Euprimates - the first true primates from the Eocene; the tarsierlike omomyids and the lemurlike adapids Eosimias - - a genus of very small basal anthropoids from the Eocene.
- ancient anthropoid (42 mya) that suggests anthropoids have 1st evolved in Asia Aegyptopithecus - a propliopithecid genus from the Oligocene, probably ancestral to catarrhines; the largest primate found in the Fayum, Egypt. Proconsul - a genus of early Miocene proconsulids from Africa, ancestral to catarrhines FOSSIL Species cont.: - Sivapithecus - a genus of Miocene sivapithecids, proposed as ancestral to orangutans Gigantopithecus - a genus of Miocene pongids from Asia; the largest primate that ever lived
-located in Ethiopia (East Africa)
- Dated to 2.5 mya
- cranial capacity of 450 cc -beneath the nose, the face has a primitive projection
- larger teeth than earlier austrolopithecines
- more human-like humerus (arm)-to-femur(leg) ratio -these features and the date suggest garhi is ancestral to Homo Homo habilis - (2.5-1.8 mya) -earliest member of our genus
- possible descendant of A. garhi -possibly ancestral to Homo erectus
- first substantial increase in brain size (650 cc) -reduction in teeth and face size
- definitely associated with production and use of stone tools Homo erectus - an early Homo species and the likely descendant of Homo habilis; the first hominid species to move out of Africa into Asia and Europe
- fossils date from 1.8 to 0.3 mya -Nariokotome (Turkana) Boy - -Homo erectus fossil is one of the most complete early hominid skeletons ever found
- discovered in East Africa (Nariokotome near Lake Turkana) in 1984
- dates to about 1.6 mya, placing it on the boundary between the Pliocene and Pleistocene epochs
- has short arms and legs (similar arm to leg ratio as humans); signals beginning of major shift to ground life (bipedal locomotion)
- enormous body size increase in taxon
- cranial capacity - 900cc (expansion in brain size is large compared with similar changes in earlier hominids) Homo naledi - tiny brain, and apelike shoulders for climbing (primitive) but has modern feature of face, skull and teeth that place it in Homo. Neandertals (locations/where were they) - -Asia (60,000-40,000 yBP) -Europe (130,000-30,000 yBP) Homo floresiensis - nicknamed "Hobbit" for its diminutive size, a possible new species of Homo found in Liang Bua Cave, on the Indonesian island of Flores
- some researchers believe the species represents a group of early hominids, evolving in isolation in the far western Pacific region. -others believe this species belonged to a modern human that had some developmental or genetic abnormality. difference between early archaic homo sapiens and modern homo sapiens - early archaic: big brow ridges, skeletal robusticity, wider/larger nasal aperture, smaller brain size, pronounced facial projection, reduced tooth size in premolars and molars, but front teeth increase in size, more projecting occipital bone (occipital bun) modern homo sapiens: small face, small jaws, vertical/high forehead, narrow nasal aperture, narrow body trunk, long legs, more gracile Archaic Homo sapiens - -1st of our species -from 350,000 yBP globally and evolving locally from earlier Homo erectus populations. After 150, yBP, regional patterns of diversity emerge, followed later by simultaneous occupation of Europe by late archaic (Neandertals) and early modern H. sapiens by 40,000 yBP -from 350,000 to 30,000 yBP -mixture of H. erectus and H. sapiens characteristics
