Chapter 2 – Human Evolution. Today’s Objectives. How do humans differ from apes? Skeleton, organs, culture Why was Homo erectus so successful as an early hominid? What happened to Neandertals? Be able to briefly trace the cultural development of: tools, fire, clothing, shelter, art
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Today’s Objectives • How do humans differ from apes? • Skeleton, organs, culture • Why was Homo erectus so successful as an early hominid? • What happened to Neandertals? • Be able to briefly trace the cultural development of: • tools, fire, clothing, shelter, art • What is so important about the Upper Palaeolithic?
Theories of Evolution • Origin Myths/Cosmologies • Greek – Prometheus • Genesis Western examples Left: Prometheus and Athena Top: God and Adam
Carl Sagan’s Universe Calendar • 24 days = 1 billion years • 1 second = 475 years • “Big Bang” January 1 • Milky Way May 1 • Solar System September 9 • Life on Earth September 25 • Humanlike Primates December 31, 10:30pm Milky Way
Theories of Evolution • Darwin and Wallace, 1850s • Evolution theory holds that existing species of plants and animals have emerged over millions of years from simple organisms. • Darwin, On the origin of species, 1859 • Influenced by the principle of uniformitarianism Charles Darwin
Theories of Evolution - Corollaries • Darwin’s principle of naturalselection • “Natural selection is the gradual process by which nature selects the forms most fit to survive and reproduce in a given environment.” • For natural selection to work on a given population, there must be variety within that population and competition for strategic resources. • The concept of natural selection argues that organisms which have a better fit within their environmental niche will reproduce more frequently than those organisms that fit less well.
Theories of Evolution - Corollaries • Randomgeneticdrift is the loss of alleles from a population's gene pool through chance. • Mutation introduces genetic variation into a breeding population. • Geneflow occurs through interbreeding: the transmission of genetic material from one population to another. Gene flow decreases differences and inhibits speciation, the formation of new species.
Theories of Evolution - Corollaries • Mendel’s principle of inheritance, 1856 • The science of genetics explains the origin of the variety upon which natural selection operates. • By experimenting with successive generations of pea plants, Mendel came to the conclusion that heredity is determined by discrete particles, the effects of which may disappear in one generation, and reappear in the next.
Other Theories • Creationism accounts for biological diversity by referring to the divine act of Creation as described in Genesis. • Catastrophism is a modified version of Creationism, which accounts for the fossil record by positing divinely authored worldwide disasters that wiped out the creatures represented in the fossil record, who were then supplanted by newer, created species. • IntelligentDesignstates that modern physics and cosmology have uncovered evidence for intelligence in the structure of the universe and this intelligence seems to act with us in mind and that the universe as a whole shows evidence of design.
Early Primates • Prosimians (65mya) • Monkeys (35mya) • Apes (23mya) • Hominids (5mya)
Early Primates - Traits • Common physical primate traits: • Dense hair or fur covering • Warm-blooded • Live young • Suckle • Infant dependence • Common social primate traits: • Social life • Play • Observation and imitation • Pecking order Common Primate Traits
Primate Family Tree Orangutan Crown lemur
Evolution of Bipedalism • Anatomical changes • Neck (1), chest (2), lower back (3), hips and pelvis (4), thighs (5), knees (6), feet (7) • Theories • Tool use and bipedalism (Darwin/Washburn) • Energy efficiency and bipedalism (Isbell/Young) • Radiator theory (Falk) • Body temperature and bipedalism (Wheeler) • Habitat variability and bipedalism (Potts) • Reproduction and bipedalism (Lovejoy) • Canine reduction and bipedalism (Jolly) (Click for interactive skeleton)
Pre-hominid Evolution • Ardipithecus ramidus 4.4 - ? mya • A. anamensis 4.2 - 3.9 • A. afarensis 4.2 - 2.5 • A. bahrelghazali 3.5 - 3.0 • A. africanus 3.5 - 2.5 • P. aethiopicus 2.7 - 2.3 • A. garhi 2.5 - ? • P. boisei 2.3 - 1.3 • P. robustus 2.0 - 1.0 • Bipedalism • Tools • Language Reconstruction of Australopithecine
Hominid Evolution • Homo habilis (2.0 – 1.6mya) • H. rudolfensis (2.4-1.6mya) • H. erectus (1.9-27kyBP) • H. heidelbergensis (800-100kyBP) • H. neanderthalensis (300-30kyBP) • H. sapiens (130kyBP – present) Scale: Millions of Years BP
Hominid Evolution • Major Homo advances: • Brain size • Better bipedalism • Hunting • Fire (H. erectus) • Tools • Oldowon (H. habilis) • Acheulean (H. erectus) • Mousterian (H. heidelbergensis) • Solutrean (H. sapiens) • Built shelters (H. heidelbergensis) • Clothing (H. neandertalensis) • Language (Neandertals?)
Homo habilis • 612 cc brain • 2.3 - 1.6 mya • first toolmaker • prognathic face, brow ridge • probable meat-eater • possibly arboreal • discovered in 1960 by Leakeys • no speech Artist’s representation of a Homo habilis band as it might have existed two million years ago.
H. habilis v. H. erectus • Finds in east Africa indicate that Homo habilis was not very different from the australopithecines in terms of body size and shape. • The earliest Homo erectus remains indicate rapid biological change. • The fossil record for the transition from H. habilis to H. erectus supports the punctuated equilibrium model of evolution. • H. erectus was considerably taller and had a larger brain than H. habilis.
Homo erectus • 1891 - Eugene Dubois discovers H. erectus in Java • Dubois calls it Pithecanthropus erectus initially, also dubbed “Java Man” • finds in China called Sinanthropus • dates from 1.9 mya to 27,000 years B.P. • 994 cc brain size (compare to 612 for H. habilis) • Acheulean tool industry Photograph of Nariokotome boy, an early Homo erectus found near Lake Turkana, Kenya.
Why was H. erectus so successful? Less sexual dimorphism = possible pair bonds, marriage Less hair on body = wearing of furs, other clothing Wearing of furs = ability to live further north Quick adaptation to environment without physical changes Culture is main reason H. erectus was so successful organization for hunting ability to protect against predators control of fire? possible campsites tools (Acheulean industry) Homo erectus – 1.9mya to 27k yBP Distribution of H. erectus
Homo neanderthalensis • discovered in the Neander Valley (Tal) near Dusseldorf, 1856 • massive brain--about 1,400cc on average • large torso, short limbs, broad nasal passages • later remains show decrease in robustness of the front teeth and face, suggesting use of tools replaced teeth • retained occipital torus, some mid-facial prognathism The skull of the classic Neandertal found in 1908 at La Chapelle-aux-Saints.
Neandertal Culture • Homesites – In caves, also in the open (near rivers, framed with wood and covered with skins) • Burial – Is there evidence of purposeful burial and ritual? • Language – Could Neandertals talk or not? • Tools – Mousterian tradition Top: Reconstruction of Neandertal burial from Shanidar cave Bottom: Mousterian tools
What happened to Neandertals? • H. neanderthalensis coexisted with H. sapiens for at least 20,000 years, perhaps as long as 60,000 years • What happened? • Neandertals interbred with H. sapiens • Neandertals were killed off by H. sapiens • H. sapiens drove Neandertals into extinction by competition
Homo sapiens • Archaic – 100,000 to 35,000 years BP • Sometimes called Homo sapiens and Homo sapiens neanderthalensis • Modern – 35,000 years BP to present • Anatomically modern • Sometimes called Homo sapiens sapiens
Cro-Magnon Man • Cro-Magnon humans • 35,000 years B.P. in western Europe to 17,000 years B.P. • 1,600 cc cranial capacity • Name comes from a hotel in France • Not a different species, just old Homo sapiens from Europe Artist’s reconstruction of a Cro-Magnon man
Archaic H. sapiens Culture • Art • Traces of art found in beads, carvings, and paintings • Cave paintings in Spain and southern France showed a marked degree of skill • Female figurines • 27,000 to 22,000 years B.P. • Called “venuses,” these figurines depicted women with large breasts and broad hips • Perhaps it was an example of an ideal type, or perhaps an expression of a desire for fertility
Archaic H. sapiens Culture • Cave paintings • Mostly animals on bare walls • Subjects were animals favored for their meat and skins • Human figures were rarely drawn due to taboos and fears that it would somehow harm others Cave paintings from 20,000 years ago at Vallon-Pont-d’Arc in southern France (left) and from Lascaux, in southwest France
Upper Palaeolithic – Hotbed of Culture • 40 – 10k yBP • Shelters • 15,000 yBP Ukraine • Some made with mammoth bones • Wood, leather working; carpentry • Tools • From cores to blades • Specialization • Composite tools • Bow and arrow • Domestication of dogs • Gathering rather than hunting became the mainstay of human economies. Top: Straw Hut Left: Mammoth bone hut Bottom: Tool progression
Modern Homo Sapiens • Regional-Continuity Model (Milford Wolpoff, UMich) • Humans evolved more or less simultaneously across the entire Old World from several ancestral populations. • Rapid-Replacement Model (Chris Stringer, NHM London) • Humans evolved only once--in Africa from H. heidelbergensis ancestors--and then migrated throughout the Old World, • replacing their archaic predecessors. Also called the “Out of Africa” and “Killer Ape” hypothesis.
Social Organization • Hunter-gatherer analogy • Small group, low population density, nomadism, kinship groups • Migration • North America was the last colonized by hominids. • Beringia (land bridge) between Russia and Alaska • Asian origin of Native Americans • 30,000 to 12,000 years B.P. was first migration
Human Variation • Modern humans vary in skin color, hair color, and eye color. • Will talk about anthropological conceptions of race and ethnicity later in the semester (April 23).