1. Primate Origins & Evolution
1.1. Fossilization: much of our discovery of primate origins comes from finding fossils formed in Sedimentary rock. Sedimentary rock cover 3/4 of the Earth's land
1.1.1. Sediment protects remains + minerals leach into bone
1.1.2. Variety of Fossil Dating Techniques:
1.1.2.1. Relative Dating: Looking at Stratigraphic layers to determine age of fossil.
1.1.2.2. Absolute Dating: Radiometric techniques - produce approximate absolute dates through use of radioactive decay such as Carbon-14. Non-radiometric techniques - produce chronological ages but do not involve the use of radioactive decay.
1.1.2.2.1. One Non-radioactive technique is paleomagnetic dating. This is based on the random reversals of Earth's magnetic field. Earth reflects these random reversals of N/S polarity through sedimentary rock.
1.1.2.2.2. Another Non-radioactive technique is genetic dating. Species that are more closely related share more similar DNA sequences.
1.2. 3 Hypothesises:
1.2.1. Angiosperm radiation hypothesis: Increased availability of fruit due to angiosperm radiation
1.2.2. Visual Predation Hypothesis: adaptations to hunting insects and other small prey
1.2.3. Arboreal Hypothesis: primate traits are due to arboreal adaptations. Grasping hands + feet, stereoscopic vision, and greater intelligence
1.3. Evolution over time
1.3.1. Paleocene Epoch (65-55 mya)
1.3.1.1. Plesiadapiforms: lived in NA, Western Europe, Asia, and probably Africa. Had a small brain, lacked opposable digits, had claws instead of nails
1.3.2. Eocene Epoch (55-34 mya)
1.3.2.1. Euprimates: first true primates, contain 2 closely related groups
1.3.2.1.1. Adapids
1.3.2.1.2. Omonzids
1.3.2.1.3. Had postorbital bar + convergent eye orbits, long possible digits
1.3.3. Late Eocene - Early Oligocene (37-29 mya)
1.3.3.1. Higher Primates of the Fayum, global cooling brought many extinctions but also introduced many new species
1.3.3.2. Platyrrhines
1.3.3.2.1. Where did they come from and how did they reach South America? 4 Possibilities
1.3.4. Miocene Epoch (23 - 5 mya)
1.3.4.1. Proconsulidae might have been the earliest apes. 10 genera and 15 species
1.3.4.1.1. Combination of Hominoid and Catarrhine traits. Skull and teeth had ape-like characteristics such as Y-5 molar pattern.
1.3.4.2. We find the first hominoid fossils in Europe and Asia about 17 mya
1.3.4.2.1. Dryopithecids were in modern France + Spain, about size of modern chimp. Large brains, long forelimbs, grasping hands and feet
1.3.4.2.2. Sivapithecids lived in modern Pakistan, India, China, and Thailand. Skull similar to orangutans.
1.3.5. Late Miocene
1.3.5.1. Drastic shift in climate. Climate became dryer and cooler. Many apes went extinct and some possibly went back to Africa. IN early miocene there were 100s of apes. Now there are only 4
2. Beginnings of Genus Homo
2.1. Characterized by increased brain size, body size, prognathic face, prolonged life, expanded geographical range, reduced size of cheek teeth
2.2. Origin Possibilities
2.2.1. 1.) Killer Ape hypothesis: savage hunters that led us to adapt
2.2.2. 2.) "Man the Hunter" hypothesis: Tools to hunt animals led us to adapt
2.2.3. 3.) Scavenging hypothesis: Hominin ancestors were not hunting but rather scavenging meat from carcasses
2.3. Brain Growth
2.3.1. More behavioral flexibility, higher problem solving skills, improved communication, improved social networking
2.3.2. Higher energetic cost, difficult birth, slower development
2.3.3. increased brain size, larger forehead, reduced robusticiity
2.4. Dental Features
2.4.1. Derived Traits: larger relative size of anterior teeth, reduced size of cheek teeth
2.5. Post-cranial
2.5.1. short stature, short leg length relative to arm length
2.5.1.1. shorter stride, inefficient bipedalism
2.6. Oldowan tool complex carried down from A. garhi to H. Habilis
2.6.1. increased tool use includes stone blades, hammer stones. Tool use tied to brain size
2.7. Homo Habilis and Homo rudolfensis
2.7.1. Homo Habilis is referred to as "Handy Man", 2.5-1.8 mya, used Oldowan tools with similar morphology to A. garhi
2.7.2. Homo rudolfensis is very similar in structure to Homo Habilis
2.8. Homo Erectus
2.8.1. Intermediate stage between Homo Habilis and anatomically modern humans.
2.8.2. receding forehead, no chin, larger brain, less prognathic face, sagittal keel, large bones, robust, large
2.8.3. First Homo to leave Africa, found in Asia and Europe too
2.8.4. Homo Ergaster: possibly new species but very similar to Homo Erectus, found across Africa
2.8.5. Acheulean Complex: intro to hand axe!
2.8.6. Fire use became common. Buried animal bones, stone tools, burned plants. Heat allowed expansion into more regions of the world. Fire allowed Homo Erectus to protect itself at night
3. Archaic Humans
3.1. Archaic homo sapiens: earliest appearance -350,000 years ago
3.1.1. combo of homo Erectus and anatomically modern human traits, reduction in skeletal complexity, smaller teeth, longer skull with more projecting occipital bone, more robust post-cranial bones, wider nasal aperture
3.1.2. Everywhere across the Globe!
3.1.2.1. Africa: found in Zambia with large brow-ridges, large face.
3.1.2.2. Asia: found in Java with long, low skulls
3.1.2.3. Europe: 32 individuals found in Spain, "Pit of Bones"
3.1.3. Used very nice Archelean tools
3.2. Later Archaic Homo Sapiens
3.2.1. These included Neanderthals, Denisovans, Homo Sapien Sapiens
3.2.1.1. Neanderthals: 130,000-24,000 years ago, Increased brain size, reduced teeth size, decreased skeletal robusticiity, large nasal aperture, heavy muscle markings, short and stocky, cold adapted body
3.2.1.1.1. Found mainly in Europe and Asia
3.2.1.1.2. Neanderthals have been damaged by wrongful depictions over the years from pop culture. HG Wells called Neanderthals "wolf-like monsters"
3.2.1.1.3. Neanderthals buried the dead. Some dead have been found with flowers on them. This could mean the Neanderthals believed in symbolism. Shell jewelry has also been found.
3.2.1.2. Very little fossil evidence on Denisovans, but we know they interbred with humans and Neanderthals.
3.3. Later Archaic Homo Sapien Tool Complex
3.3.1. Mousterian tools complex: Middle Paleolithic, replaced Acheulian complex, Mousterian flake tools helped greatly in making spears to hunt
3.4. Admixture between AMH and Neanderthals
3.4.1. 350 kya, Neanderthals and Denisovan ancestors leave Africa + migrate throughout Eurasia. 60-70 kya human ancestors leave Africa. Neanderthals and human ancestors interbred, and then interbred with Denisovans
4. Exciting fact: Neanderthals accumulated a variety of artifacts. These included tools and animal bones
5. Exciting Fact: 40-50 Homo Erectus individuals were found in a cave in Zhoukoudian, China. One individual, "Peking Man" was found in this cave. The cave served as shelter and there is evidence of controlled use of fire.
6. Lab 8: I observed hominin species from between 2.5 to 1 million years ago. I observed the Homo Erectus species an it's spread across the entire world. I saw the complex tools these creatures used, alongside the foods they ate.
7. In Lab 9, I observed the many characteristics behind Neanderthals. Neanderthals lived complex lives similar to the ones we live. They buried their dead, developed social relationships, and even lived in little huts. Neanderthals were cared for by one another, especially when they were injured.
8. Overarching theme: Over thousands of years, we can observe how hominin brains got larger, how skeletal structures slowly changed, and how they became more like us! All of this was due to the vast environmental changes that were occurring. There were constant cycles of the Earth warming and cooling
9. Early Hominins before the rise of Homo
9.1. Hominin characteristics
9.1.1. Bipedal locomotion
9.1.1.1. One of the earliest anatomical adaptations
9.1.1.2. hominin feet are wider to support weight
9.1.1.3. smaller toes
9.1.1.4. shorter tarsals
9.1.1.5. issues: weak exposed abdomen, weak knees, fallen arches
9.1.2. Non-honing chewing complex
9.1.2.1. Humans do vertical and horizontal crushing and grinding, not slicing like non-humans
9.1.2.2. Thick enamel, human teeth strong
9.1.3. Large brain size and advanced cognition
9.1.3.1. forâmen magnum located inferiorly
9.1.3.2. flatter face helps with weight distribution
9.1.4. Basin-shaped pelvis
9.1.4.1. Supports organs and larger birth canal.
9.1.4.2. Muscle attachments in better mechanical position
9.1.5. Knee
9.1.5.1. Enlarges surface area to support greater weight, knees angled inwards
9.1.6. Vertebral collumn
9.1.6.1. S-shaped rather than C-shaped, allows for up-right posture
9.2. Why did we emerge?
9.2.1. Hunting Hypothesis: free hands to carry tools and weapons
9.2.2. Patchy Forest: Savannah-like environments at end of Miocene era made it more difficult to find food. Hands could be used for food collecting.
9.2.3. Male Providing Hypothesis: males provide food to females and offspring
9.3. First Hominins:
9.3.1. Pre-Australopithecines: Early hominins that bridge the previous gap between hominid and hominin
9.3.1.1. Sahelanthropus: found in Central Africa in 2001, small brain, massive brow ridge, sagittal crest, less prognathic, foramen magnum more anteriorly placed, non-honing chewing complex
9.3.1.2. Orrorin tugenesis: found in east Africa, long femoral neck, Curved hand phalanges,
9.3.1.3. Ardipithecus: found in Awash River Valley, several species including Artdipithecus kadabba and Ardipithecus ramidus
9.3.1.3.1. Ardipithecus ramidus als
9.3.1.4. Highly diverse, lived in forest setting throughout Africa, spent a lot of time on the ground, but also spent some time in trees
9.4. The Australopithecines
9.4.1. Confirmed bipeds who lived in southern and Eastern Africa. 4-1mya. Small anterior teeth and large posterior teeth. Small braided and small bodied
9.4.2. Compared to pre-Austrlopithecines, the Australopithecines lost many arboreal traits. Asutralopithecines also have an increase in brain size
9.4.3. Gracile Australopithecines
9.4.3.1. Australopithecus anamnesis: found in east Africa, large canines, u shaped mouth, thick enamel, flexible elbow joint
9.4.3.2. Australopithecus Afarensis: found in east Africa, Lucy is the most famous one found, prognathic face, parabolic tooth rows, bipedalism with thick femur, short legs relative to arms
9.4.3.3. Australopithecus platyops: combination of primitive and derived traits, small brain size, flat face
9.4.3.4. Australopithecine garhi: likely ancestral to early Homo. Primitive traits including large teeth compared to earlier Australopithecines, prognathic face, small brain. Arm/Leg ratio is more human-like
9.4.3.4.1. Used Oldowan tool complex: lower Paleolithic stone tool culture, earliest tool industry, used for butchering, woodworking, and cutting soft plants
9.4.4. Early hominin trends include a reduction in size of teeth + muscle attachments. Mouth went from u shaped slowly to v shaped
9.4.5. Robust Australopithecines: big mandibles and high cheek bones
9.4.5.1. Australopithecus Africanus: found in South Africa, anteriorly-placed foramen magnum, rounded cranial vault, small brain, moderate-size teeth
9.4.5.2. Australopithecus Robustus: small brain, massive flat face, large molars, small incisors, thick enamel
9.4.5.3. Australopithecus sediba: small size/longer arms, small brain
9.4.5.4. Australopithecus aethiopicus: Ancestor of A. boisei, small brain, hyper-robust, prognathic face, huge molars
9.4.5.5. Australopithecus boisei: Descendant of A. aethiopicus, small brain, hyper robust, sagittal crest, very specialized diet
9.4.5.6. Only difference between Robust and Gracile is in skull. Not body size. All differences derive from muscles of mastication