The Human Story

1. The Human Story Where We Came From & How We Evolved

2. Identifying the first hominids • In L.C.A., look for anatomical features shared by humans and living great apes • Starting from there, 1st hominids must have evolved at least one feature that we see only in modern humans • Scientists focus on two major areas • Anatomy related to bipedalism • Size / shape of canine and 1st premolar teeth Large brain size, hard evidence for culture, language, etc., come much later.

3. Evidence of Bipedalism • Placement of foramen magnum • Shape of spine • Shape of pelvic girdle • Bicondylar angle (knock-kneed) • Parallel toes (no divergent big toe) • Two fixed arches in foot • Side to side / front to back

4. Placement of Foramen Magnum

5. Shape of Spine

6. Pelvic Girdle & Bicondylar Angle

7. Anatomical Adaptations for Habitual Upright Bipedalism A comparison of the chimp, human, and A. afarensis femurs demonstrates a rounder femoral head and longer femoral neck length in hominids.

8. Parallel Toes / Fixed Arches

9. ORIGINS OF BIPEDALISM Or WHYWE WALK ON TWO LEGS Download and read these articles: The Origins of Habitual Upright Bipedalism The Origins of Obligate Bipedalism in Hominins The Whats and Whys of Habitual Upright Bipedalism

10. If you asked a roomful of anthropologists why we walk on two legs - not get the same answer from any two of them.Specialists cite everything fromchanginglandscapesto needing tokeep cool to heightening sexual attraction- generally agreeing only on one point: that everyone else's hypothesis is wrong. Let’s take a look at some of these hypotheses.

11. Six Major Hypotheses Hauling Food Grabbing A Bite A New World Keeping Cool Attracting Mates Weapons and Tools

12. Bipedalism: Hauling Food • As African landscape shifted from forests toward large patches of open woodlands & savannahs, food supplies waned, wannabe hominids descended from trees / became ground-dwellers. • Because could no longer feed where lived, were forced to carry food over long distances back to home bases - tricky task if remained quadrupeds. • While some contend early hominids gathered fruits and nuts, a few argue that they were scavengers. • Upright stance enabled ancestors to lug carcasses to safer areas for consumption, also allowing them to see other food sources or potential danger at greater distances

13. Bipedalism: A New World • As early hominids left forest to explore woodlands / savannas, no longer needed body structure for climbing. • Those who could walk upon two feet better able to survive • expended less energy / could travel longer distances than knuckle-walkers • better able to see potential dangers lurking in the distance • Our ancestors developed an upright posture to • carry food over long distances • or find it.

14. Bipedalism: Attracting Mates • Sex — specifically males' desire to get more of it — a direct reason for why we walk upright. • Upright males better breadwinners • Those who could walk bipedally freed their arms to carry more food - made knuckle-walkers far less appealing to females. • Their ability to have more food for females (who remained at the home base to care for the offspring) ensured that they were able to reproduce, thus leading to future generations of adept bipeds who in turn were able to pass on their own genes.

15. Grabbing A Bite • Ability to walk upright was in part a serendipitous by-product of new feeding habits. • As our ancestors descended from trees to forage on the ground for low-hanging fruits and berries, they began to feed from a squatting position. • Over time, physiological changes occurred in upper bodies, backbones, pelvic areas, causing weight and centers of balance to shift to a lower point in the body.

16. Bipedalism: Keeping Cool • Protected early hominids from overheating • Exposes less of body to direct sunlight on savannahs than quadrupeds of the same size (60% less heat load) • Raised bodies above the ground, enabling skin to come in better contact with cooler / faster-moving breezes • Also meant hominids needed only 3 pints of water / day, whereas quadrupeds needed 5

17. Weapons & tools Bipedalism:ß • Some hypothesize bipedalism brought forth our ability to use weapons / tools - others believe the reverse: advent of tool / weapon use encouraged us to become bipedal.

18. Six Major Hypotheses Grabbing A Bite Hauling Food A New World Keeping Cool Attracting Mates Weapons and Tools ALL these models may have played a role in the emergence of habitual upright bipedalism

19. From Ape to Hominid • Proto-Hominids (Opportunistic bipeds) • Sahelanthropus tchandensis / Orrorin tugeninsis • Transitional Opportunistic-into-Habitual Bipeds • Ardipithecus ramidus / Australopithecus anamensis • First True Habitual Upright Bipeds • Australopithecus afarensis / A. africanus / A. garhi • Australopithecus robustus / A. boisei

20. There is no straight line in the greater than four million-year-old journey of the family called HOMINIDAE.

21. From Ape to Hominid • Proto-Hominids (Opportunistic bipeds) • Sahelanthropus techandensis / Orrorin tugeninsis • Transitional Opportunistic-into-Habitual Bipeds • Ardipithecus ramidus / Australopithecus anamensis • First True Habitual Bipeds • Australopithecus afarensis / A. africanus / A. garhi • Australopithecus robustus / A. boisei

22. Proto-Hominids • Molecular biology strongly suggests: • Last common ancestor of chimps & humans lived 5-8 m.y.a. • Two recent finds warrant our attention: • Sahelanthropus tchadensis • Orrorin tugenensis

23. Sahelanthropus tchadensis • 6 - 7 m.y.a. • Brain size: 1/4th of ours • No post-cranial bones • Don’t know if habitual biped • Lived in variety of habitats • Likely ate mainly fruit, with smaller amounts of other foods. Download and read: The Earliest Possible Hominids

24. Orrorin tugenensis • 6 m.y.a. • Remains fragmentary • Canines / premolars extremely ape-like BUT with thick tooth enamel (like hominids) • Maybe bipedal • Inferior side of femoral neck (#1 on picture) is thick (like hominids)

25. Ardipithecus ramidus A species of bipedal apes • 5.8 - 4.4 m.y.a. • Possibly bipedal (but not like us) • Small bodied (64-100 lbs); small brained (300-350 cc) • Combo of hominid-like & chimp-like traits • Diet: unknown (relatively thin tooth enamel) • Well-watered, forested environment • Discovery Channel Website About "Ardi"

26. Ardi Revealed • Ardi’s skeleton includes many important bones of the skull, hands, feet, limbs, and pelvis. These fossil bones offer key insights into how 'Ardi' was built, and how she moved. Her skeleton demonstrates that she was capable of both walking upright AND clambering through trees with a grasping big toe, in a way unlike any other creature known to science. Ardi shows an unexpected mix of advanced characteristics and of primitive traits seen in much older apes that were unlike chimps or gorillas. As such, the skeleton offers a window on what the last common ancestor of humans and living apes might have been like. Interactive webpage: Ardi's Key Skeletal Features Interactive webpage: Ardi's Key Skeletal Features

27. Australopithecus anamensis • 4.2 - 3.9 m.y.a. • Fragmentary remains • Teeth and jaws similar to fossil apes • May be earliest incontrovertible evidence of bipedalism • Strongly resembles Austr. afarensis • Streamside forests

28. Australopithecus afarensis Small-brained, bipedal human ancestors. They are the benchmark by which the anatomy of all other early hominids is interpreted. • 4 - 3 mya • East Africa • Fully bipedal • Mix of human-like & ape-like traits • Sexually dimorphic

29. Lucy: 1st afarensis foundHer discovery revolutionized ways of thinking about early hominids. • 1974 - Hadar, Ethiopia • About 3’8” tall; 55 lbs • Long arms / short legs • Mid-20s when died • Teeth: small & unspecialized, indicating a mixed, omnivorous diet of mostly soft foods (fruits) Left to right: Lucy’s bones, reconstructed Lucy, modern human

30. A. afarensis skull morphology Male Female (Lucy) • Cranial capacity: 350 -500 cc (2/3rds - 1 water bottle • Small sagittal crest in males • Slightly projecting upper canine teeth in males • Parallel rows of cheek teeth (like apes)

31. afarensis body morphologyGround or tree-dweller? • Slightly curved hand & foot bones • Relatively long and powerful arms • Bowl-shaped pelvis • Knock-kneed (knee joint angled inward) • Heel bone heavily built (like ours) • Foot may have had high, fixed arches (Laetoli?)

32. A. afarensis footprints • Laetoli, Tanzania: home to a footprint trail 3.5 m.y. old • Probably a trackway of A. afarensis

33. An afarensis 3 yr oldbaby girl • Ethiopia (Hadar) • Lived 3.3 m.y.ago • Ape-like scapula • Human-like knees • Finger bones partially curved • Heel bone well-developed • Endocast shows delayed brain growth (like us) • Chimp-like hyoid bone

34. Australopithecus africanus • 3.5 - 2.0 m.y.a. • Mainly S. Africa • Mixture of habitats • Fruit, salads, insects, small easily captured prey • Brain size: 1/3rd ours • Relationship to other hominids? Unknown This species slightly different from A. afarensis: slightly taller, less facial prognathism, slightly larger brain. Also lived in drier habitats (especially dry scrublands and perhaps open grasslands), and thus may have exploited different resources.

35. Australopithecus garhi:A stone tool using australopithecine? • Ethiopia • 2.5 million years old • Mostly fragments of skulls, some post-cranial remains • Most intriguing: cut-marked animal bones found near garhi’s remains. Such marks are signs of stone tools being used to carve up animal carcasses. Can’t say for sure IF garhi was maker, maker-user, user (or none of these) of tools.

36. The Robust AustralopithecinesDietary specialists? • One of most fascinating branches of human family tree • Reveal radically different way of being hominid • About 2.5 m.y.a they diverged from our own lineage • Came to be defined by an adaptation to eating hard foods like nuts, seeds, and roots

37. Robust Austraopithecine Morphology • 2.5 - 1 m.y.a. • South and East Africa • 3 species - united by suite of features related to eating tough foods: • Extremely large molars / premolars • Dished face • Extremely large chewing muscles • Wide-flaring cheekbones • Pronounced pinching-in behind the eye orbits • Prominent sagittal crest

38. Robust australopithecine behavior Digging sticks used by modern chimpanzees. While such tools have not been found with robust australopithecine fossils, it is possible they used such tools • Omnivores, but relied on hard to chew foods (nuts, roots, seeds) • Probably used tools (bones/horns showing polishing, maybe used for digging up roots) • Lived in (open) woodlands and savannas • Evolutionary dead end

39. Australopithecine Foraging Behavior Foraging (the systematic search for food and other provisions) was THE lifeway of all hominids from the earliest australopithecines until about 10,000 years ago (the start of agricultural modes of subsistence. Foraging by australopithecines and early species of Homo most likely consisted of collecting roots, berries, seeds, nuts, salad greens, insects, etc. Around 2 m.y.a meat, obtained by scavenging, became part of the foraging way of life. Eventually fish and shellfish would be added.

40. Major adaptive shifts in hominid evolution ca. 2 m.y.a. • Australopithecine lineage • Intensification of adaptation to hard object feeding • Emergence of Homo lineage • Several new species appear on African landscape • Physically / behaviorally different from earlier & contemporary australopithecines • Flatter faces • Brain reorganized (lateralization & language regions) • Unquestioned manufacture/use of stone tools (bone/horn/wood?) • Added meat to diet (scavenging) • Some species have brains as large as 750 cc

41. Earliest Homo species • Contentiousness regarding who belongs to early Homo (Question: If one of the gracile australopithecine species is ancestral to Homo, how does one tell a late gracile australopith from an early Homo?) • At least 3 (perhaps more) Homo species • Homo habilis = 2 - 1.5 m.y.a • Homo rudolfensis = 2 - 1.8 m.y.a • Homo erectus (aka H. ergaster) = 1.8 - 1.0 m.y.a.

42. Earliest Members of the Genus Homo

43. Early Homo Behavior • Stone tools 1st appear ca. 2.5 mya • Most often attributed to H. habilis ( maybe A. garhi) • Earliest tools (Oldowan tradition) • Flakes (cutting/scraping) • Chopper / chopping tools (“smashers / bashers”) • Hammerstones • Some bone/horn w/scratches (digging?) • Meat eating takes on increasing importance after 2.5 m.y.a. • Several types of sites: quarries, food processing locations

44. Making / Using Oldowan Tools Hominids often traveled up to 10 km to acquire right kind of stone from which to make tools.

45. Early Homo Scavenging Behavior Can a hominid eat meat obtained like this and not get sick? Perhaps if one gets there within a few hours of a predator’s kill.

46. Out of Africa, Part OneHomo erectus • Found first in Africa = 1.8 - 1.0 m.y.a. • Perhaps Rep. of Georgia = 1.7 m.y.a. (H. georgicus?) • Island SE Asia = 1.8 m.y.a. • Continental Asia = 1.4 m.y.a

47. Out of Africa, Part 2 • Homo erectus • By 1.5 m.y.a develops a more sophisticated tool technology (Acheulian) • African forms sometimes called H. ergaster • Georgian forms sometimes called H. georgicus • Asian and southeast Asian forms always called H. erectus

48. H. ergaster vs. H. erectus H. georgicus

49. Homo erectus(Prometheus Unbound) • Invented new tool: handaxe • Larger tools, required more preparation than Oldowan choppers • First hominids to make tools to a predetermined shape • First hominids to make task-specific tools • Some tools used for butchering animal carcasses; others for working with wood; still others for use with veggies • Probably the first hominids to use, perhaps even control, fire • Hints of use at South African site between 1.5 - 1.0 m.y.a. • Fire allows cooking foods (makes meat and veggie consumption easier) • Useful to lengthen the day into the night • Keeps predators away • Warmth

50. Homo erectusWhy are these hominids so important? • ?? FIRST TO LEAVE AFRICA ?? • COMPETENT TOOLMAKERS: Acheulean • 1st appeared 1.5 m.y.a. • Shaping entire stone to stereotyped form • Bifacial flaking • Butcher animal carcasses / digging tools / cutting & scraping • FIRST to USE/CONTROL FIRE (ca. 1 m.y.a.) • FIRST SYSTEMATIC HUNTING of medium-size game animals