Human Evolution :

Human Evolution : 

Human Evolution

Today’s Objectives : 

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?

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Classification Hierarchy Kingdom Animalia Phylum Chordate Class Mammal Order Primates Family Hominids Genus Homo Species Sapiens

Theories of Evolution : 

Theories of Evolution Origin Myths/Cosmologies Greek – Prometheus Genesis Left: Prometheus and Athena Top: God and Adam

Theories of Evolution : 

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 : 

Theories of Evolution - Corollaries Darwin’s principle of natural selection “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 : 

Theories of Evolution - Corollaries Random genetic drift is the loss of alleles from a population's gene pool through chance. Mutation introduces genetic variation into a breeding population. Gene flow 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.

Other Theories : 

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. Intelligent Design states 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 : 

Early Primates Prosimians (65mya) Monkeys (35mya) Apes (23mya) Hominids (5mya)

Early Primates - Traits : 

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 : 

Primate Family Tree

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Evolution of Primates The evolution of primates is characterized by trends towards: mobile limbs grasping hands (with opposable thumbs) a flattened face binocular vision a large, complex brain (for learned behavior) a reduced reproductive rate

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Mobile Limbs Most primates have flat nails as well as sensitive pads on the undersides of fingers and toes. Many also have both an opposable big toe and thumb. Mobile limbs and clawless opposable digits allow primates to freely grasp and release tree limbs.

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Primate Hands

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Evolution of Primates (cont..) Prosimians were the first type of primate to diverge from the ancestral primate line. Surviving anthropoids are classified into three superfamilies. New World monkeys Old World monkeys Hominoids

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Primate Bone structure

Evolution of Bipedalism : 

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)

Hominid Evolution : 

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?)

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Hominoid Evolution Proconsul is believed ancestral to hominids.

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Evolution of Hominids Phylogenetic tree indicates humans are most closely related to African apes. Last common ancestor appears to have lived about 5-7 million years ago (mya) Genetic changes used as a molecular clock to measure relatedness of different groups.

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Hominids To be a hominid, a fossil must have an anatomy suitable for standing erect and walking on two feet. Bipedalism Human anatomy differs from that of an ape largely because humans are bipedal while apes are quadrupedal.

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Australopithecines It is possible that one of the australopithecines that evolved and diversified in Africa 4 mya is a direct ancestor of humans. Southern Africa Australopithecus africanus Eastern Africa Australopithecus afarensis (Lucy)

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A reconstruction of Lucy’s skeleton Lucy is ~ 3.5-million-years-old Australopithecus afarensis adaptations in Lucy’s hip, leg and foot allowed a fully bipedal means of locomotion Lucy

Homo habilis : 

Homo habilis Artist’s representation of a Homo habilis band as it might have existed two million years ago. 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

H. habilis v. H. erectus : 

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 : 

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.

Homo erectus – 1.9mya to 27k yBP : 

Homo erectus – 1.9mya to 27k yBP 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) Distribution of H. erectus

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Homo erectus Homo erectus and like fossils are found in Africa, Asia, and Europe and are dated between 1.9 and 0.3 mya. Larger brain and flatter face than Homo habilis. Much taller than previous hominids. Believed to have first appeared in Africa and then migrated into Asia and Europe. First hominid to use fire.

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Homo erectus Using Tools Re-creation of a Pleistocene setting in which Homo erectus use fire & stone tools

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Homo erectus1.6 mya bipedal Homo habilis = handy human1.5 to 2 mya

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Evolution of Modern Humans Most researchers believe Homo sapiens evolved from Homo erectus. Multiregional Continuity Hypothesis Similar evolution occurred in many different places. Out-of-Africa Hypothesis H. sapiens evolved from H. erectus only in Africa, and thereafter migrated to Europe.

Homo neanderthalensis : 

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.

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Neanderthals Neanderthal (H. neanderthalensis) skeletons were first discovered in Germany’s Neander Valley. Skeletons date back 200,000 years. Massive brow ridges with protruding nose, jaws, and teeth. Heavily muscled. Culturally advanced. Manufactured variety of tools. Neanderthals 35,000 to 100,000 ya

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Reconstructed Neanderthal skull characterized by prominent heavy brow ridges and week chin

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Burial Ceremony in a Cave Neanderthals lived in caves and had ritual burials, such as this depiction from Shanidar Cave, Iraq

Neandertal Culture : 

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

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Flaked stones that fit in wood handles. Buried their dead with spices and bedding. Built sturdy huts. Made flutes! A flute formed from a femur & 4 remaining holes.

What happened to Neandertals? : 

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 : 

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 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

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Cro-Magnons – Homo sapiens Oldest fossils to be designated H. sapiens. Modern humans who entered Asia and Europe from Africa 100,000 years ago. Made advanced stone tools. Accomplished hunters. Hunted cooperatively. First to have complex language?

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Cro-Magnon 35,000 to 40,000 ya

Archaic H. sapiens Culture : 

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 : 

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

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Cro-Magnons were very skilled cave painters Painting of a horse from a cave in France Painting From a Cave in France

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Homo Floresiensis (hobbits) - one meter high - lived in Flores 12,000 yrs ago - Upright posture - 380 cc cranial size (like a chimp)

Upper Palaeolithic – Hotbed of Culture : 

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 : 

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 : 

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

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With the appearance of Cro-Magnons, human evolution has become almost entirely cultural rather than biological Humans have spread throughout the world by devising means to deal with a broad range of environmental conditions Cultural Evolution

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