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 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 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 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.

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. 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 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.

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

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 from 20,000 years ago at Vallon-Pont-d’Arc in southern France (left) and from Lascaux, in southwest France 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

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 Migration 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).