1aa3 4 human origins.pdf

2023-09-28 INTRO TO ANTHRO: SEX, FOOD & DEATH Week 4: Human Origins Dr. Siek ANTHROP 1AA3, Fall 2023 McMaster University 1 Palaeoanthropology ■ Human ancestry ■ Fossil record ■ Identify early human and human-like species ■ Define chronological sequence of their relationships ■ Human origins and mi...

2023-09-28 INTRO TO ANTHRO: SEX, FOOD & DEATH Week 4: Human Origins Dr. Siek ANTHROP 1AA3, Fall 2023 McMaster University 1 Palaeoanthropology ■ Human ancestry ■ Fossil record ■ Identify early human and human-like species ■ Define chronological sequence of their relationships ■ Human origins and migration ■ Human evolution 2 1 2023-09-28 What Evolution Is Not: ■ Does not occur in lifetime of one individual ■ Does not have an end goal or final stage 3 Common Misconceptions ■ “It’s only a theory…” ■ “If humans evolved from monkeys… why are there still monkeys?” ■ Notion of linear progression 4 2 2023-09-28 “It’s only a theory…” ■ Explanatory statement or argument related to particular set of phenomena ■ Supported by observation and evidence ■ May be modified with new evidence over time 5 “Humans evolved from monkeys…” ■ Just, no. – Giant oversimplification ■ Humans and other nonhuman primates share a common ancestor that diverged millions of years ago 6 3 2023-09-28 7 What Evolution Is: ■ Change in genetic structure of a species over the course of multiple generations ■ Facilitated by natural selection 8 4 2023-09-28 Natural Selection ■ Biological characteristics are inherited and become more common over multiple generations ■ Typically they are advantageous or neutral to an individual possessing them to their offspring ■ Usually a response to environmental pressure 9 Taxon Human Kingdom Animalia Phylum Chordata Class Mammalia Order Primates Family Hominidae Genus Homo Species Sapiens 10 5 2023-09-28 Hominin ■ Humans and Human-like fossil ancestors ■ Divergence from common primate ancestor 11 What Separates Hominins From The Other Primates? 1. Bipedalism – 6 MYA 2. Non-Honing Chewing – 5.5 MYA 3. Material Culture & Tools – 2.6 MYA 4. Speech – 2.5 MYA 5. Hunting – 1 MYA 6. Domestication – 11 TYA 12 6 2023-09-28 Bipedalism ■ Foundational behaviour of hominins ■ Skull, spine, pelvis, legs, feet all adapted to obligate bipedal locomotion 13 How Do You Know It’s Bipedal? 14 7 2023-09-28 Spinal Curve Development In Humans C-Shape à à à S-Shape 15 Position of Foramen Magnum Human Foramen magnum is inferior in bipeds and posterior in quadrupeds Chimp 16 8 2023-09-28 The Pelvis iliac blades Human Chimp sacrum 17 ■ Long legs = longer strides ■ Knee posture (locked) ■ All result in energy efficiency 18 9 2023-09-28 Architecture of Foot Human Non-Human Primate 19 Bipedalism – Advantages ■ Surveillance ■ Free hands for tool use – Greater ease of transporting food, offspring, tools ■ Energy advantage – Ability to move/run long distances – Not faster, but further ■ Thermoregulation 20 10 2023-09-28 Bipedalism – Disadvantages ■ Standing upright = exposure to predators ■ If one foot injured, ability to walk is severely reduced ■ Carrying loads and walking for long periods = back pain 21 What Separates Hominins From The Other Primates? 1. Bipedalism – 6 MYA 2. Non-Honing Chewing – 5.5 MYA 3. Material Culture & Tools – 2.6 MYA 4. Speech – 2.5 MYA 5. Hunting – 1 MYA 6. Domestication – 11 TYA 22 11 2023-09-28 Non-Honing Chewing ■ Reduced canine size ■ No diastema 23 Hominin Teeth 24 12 2023-09-28 LET’S MEET (SOME OF) THE HOMININS 25 Sahelanthropus tchadensis ■ 7–6 MYA ■ Djurab Desert, Chad ■ Brain similar to modern apes (350 cc) ■ Massive browridge ■ Likely bidpedal (based on FM) ■ Non-honing dentition 26 13 2023-09-28 Ardipithecus ramidus ■ 5.8–4.4 MYA ■ Middle Awash Valley, Ethiopia ■ Large assemblage of fossils ■ Bipedal (based on pelvis, femur, foot) ■ Adapted for arboreal and terrestrial ■ Non-honing canines 27 Genus – Australopithecus ■ 4–1 MYA ■ Lots of fossils ■ ~10 species identified ■ Some are ancestor/descendant, others overlap ■ Small brains, small canines, large premolars and molars ■ Vary in size and robustiously 28 14 2023-09-28 Australopithecus afarensis ■ 3.9–3.0 MYA ■ “Lucy” – adult female, 40% complete ■ Skeleton similar to humans in some respects, but also similar to chimps ■ Bipedal (some climbing?) ■ Non-honing, small canine ■ Large molars ■ Walking with Lucy (1:58) 29 2016: Lucy Fell Out Of A Tree? ■ Evidence suggests she may have died by falling out of a tree ■ CT scans show bone injuries similar to modern humans in similar falls ■ Read the 2016 paper here ■ I think she was pushed… #justiceforLucy 30 15 2023-09-28 Recent study: 3D Muscle Reconstruction of A. afarensis (Wiseman 2023) ■ Reconstructed muscles of leg and pelvis of Lucy ■ Used modern human muscle data as analog ■ Wiseman 2023 Image from Wiseman 2023 31 Laetoli Footprints ■ Laetoli, Tanzania ■ Fossilized hominin footprints ■ Discovered 1976 ■ Attributed to A. afarensis ■ Three sets (two adults, one nonadult) ■ The Laetoli Footprints (7:13) 32 16 2023-09-28 Genus – Homo 33 Homo habilis ■ 2.4–1.4 MYA ■ Postcranial similar to Australopithecus – Larger brain (50%) ■ Rounded skull, flatter face ■ Smaller teeth ■ Tool use – Oldowan 34 17 2023-09-28 Key sites of Homo habilis Key Site Date Ledi-Gararu, Ethiopia 2.8 MYA Olduvai Gorge, Tanzania 1.7-1.8 MYA Lake Turkana, Kenya 1.9 MYA Sterkfontein, South Africa 1.7 MYA 35 Stone Tools (Oldowan) ■ Oldest stone tool industry ■ 2.5-1.6 MYA ■ ‘Flake and chopper’ tools ■ Butchering animals ■ How to Make Stone Tools: Oldowan (12:02) 36 18 2023-09-28 Homo erectus ■ 1.8 MYA – 30 TYA ■ Smaller molars ■ Thick cranial bones ■ Larger brains than Homo habilis ■ Modern body size and proportions ■ New food strategies ■ Emigration ■ Use of fire 37 Stone Tools (Acheulean) ■ 1.5 MYA ■ Africa, Asia, Europe ■ Multi-use tools ■ Symmetrical, bifacial flaking ■ Planning and skill 38 19 2023-09-28 Use of Fire ■ Probably accidental ‘discovery’ ■ Wood ashes where trees don’t naturally grow (i.e. inside caves) ■ Ash deposits lined with stones, burned bones, seeds ■ Possible reason for smaller teeth – easier to masticate cooked foods ■ Benefits: cooking, warmth, light, scaring larger animals ■ Social benefits of a campfire 39 Homo naledi ■ Newly discovered hominin in 2013 ■ 226–335 TYA ■ Rising Star Cave, South Africa ■ Lage cache of fossils – varying ages, both sexes ■ Nat Geo: Homo naledi (3:30) 40 20 2023-09-28 New Evidence: H. naledi May Have Buried Their Dead? ■ Intentional disposing of dead thought of as unique to Homo sapiens ■ If correct, burial practice is much older than we initially thought ■ Not everyone agrees… ■ Berger et al. 2023 - Original Paper ■ Petragila et al 2023 - Rebuttal 41 Homo sapiens neanderthalensis ■ 300–30 TYA ■ Body adapted to colder climates ■ Short, stocky build ■ Large nasal aperture ■ Occipital bun ■ Lived in cold climates ■ Evidence of culture – Burial practices – Mousterian tool kit 42 21 2023-09-28 Stone Tools (Mousterian) ■ 600–400 TYA ■ Quickly creating flakes from a single core – Less time consuming, more productive ■ Scrapers, hand axes, points 43 Homo sapiens neanderthalensis ■ Lumpers vs Splitters ■ Not direct ancestors of Homo sapiens ■ Overlapped with H. sapiens for 10,000 years ■ DNA evidence shows interbreeding ■ European and Asian populations share 1-4% Neanderthal DNA 44 22 2023-09-28 Homo sapiens – Archaic Human ■ 300,000 YA ■ Morphological differences between archaic and modern H. sapiens 45 7 MILLION YEARS OF HUMAN EVOLUTION 6:22 46 23