Modern Humans

1. Modern Humans Early Homo, Out of Africa, Archaic Homo sapiens, Neandertals, Advances in technology, cave art and more.

2. Skulls linked early humans to Africa • Without a doubt, the origins of all humans can be traced to Africa. • From last chapter we learned that at 2 m.y.a there is African evidence for 2 distinct hominind groups: Homo and A. boisei. • A. boisei became more specialized: living on savanna vegitation. Dental, facial and cranial robustness continued with this species. • These structures (above) were reduced when early forms of Homo evolved into H. erectus.

3. Early Homo (habilis) • Earliest members of our genus. First discovered at Olduvai Gorge in Tanzania. Cranial capacity between 600 and 700cm cubed. • Oldest layer of earth there is 1.8 million years. • Skull was small, and had ape-like limb bones. • Scientist thought it would be taller than Lucy and have less apelike appearences. • Limbs suggested greater tree-climbing ability than later hominids. • Homo erectus cranial capacity of 900cm cubed, with a modern body shape and height.

4. Contrasting H.habils and H. erectus • The differences in H.habilis (1.8 m.y.a) and H.erectus (1.7 to 1.6 m.y.a) suggests an acceleration in hominid evolution during that 100,000 to 200,000 year period=punctuated equilibrium. • Punctuated equilibrium: here you have long periods of equilibrium, where species change little, are then interrupted by (punctuated) sudden changes. • H. erectus looks much more human than H. habilis does.

5. Gradual and Rapid Change • One reason for punctuated jumps or sudden changes in fossil record may be extinction followed by invasion by a closely related species. • Another is that when barriers are removed, a group may replace, rather than succeed, a related one because it has a trait that makes it adaptively fitter in the environment they share. • There is no doubt that the pace of hominid evolution sped up around 1.8 m.y.a, which resulted in the emergence of H. erectus.

6. Reasons for the rapidly evolved H. erectus • 1) A dramatic change in adaptive strategies: greater reliance on hunting through larger body sizes, along with improved tools and other cultural means of adaptation. • Significant changes in technology occurred during the 200,000 year evolutionary spurt. Tool making got more sophisticated after H. erectus evolved. • Tools were being made and used for different jobs, which means Homo could obtain food more efficiently and on a regular basis.

7. Better Tools Changes Anatomy • With changing tools, lots of chewing ceased. • Chewing muscles and jaws were reduced • Smaller teeth were now more adapt to surviving. • Homo erectus dentition: smaller back teeth, larger front teeth to pull, twist, and grip objects. • Larger skulls were more beneficial to fight larger prey. If you had a larger skull, you were more likely to survive and protect your brain. • Cranial capacity of H. erectus increases to 1000cm cubed.

8. Traveling H. erectus • With new tools and technology, H. erectus started hunting and gathering. • This enabled them to become more mobile. They gradually spread and changed.

9. Paleolithic Era • Also called Old Stone Age • 3 Divisions: Lower (early), Middle and Upper (Late). • Lower is associated with H. erectus • Middle is associated with archaic H. sapiens (including Neandertals) • Upper is associated with early members of our own subspecies H. sapiens sapiens (US)

10. Tools of the Paleolithic Era • Stone-tool making lasted until about 15,000 y.a. • Made from rocks that fracture sharply and in predictable ways when hammered. Ex: Flint, Quartz and chert. • Acheulian tools (Lower): Ex: the hand ax was just a modified core of rock. Made by chipping the core all over rather than at one end only. Greater efficiency and increasing complexity.

11. Adaptive Strategies of H. erectus • Biological changes also increased hunting efficiency. • Body much larger and longer-legged, permitting longer-distance hunting of large prey. • Go to page 200 “Understanding Ourselves” Read together. • Skeleton and chewing apparatus show a fuller commitment to hunting and gathering which was their only adaptive strategy until domestication (12,00o y.a.) • Archaeological evidence shows they made temporary huts and built hearths. • Fire provided protection against animals, cooking (which killed parasites and make meat more digestable) and warmth to last through winter. • Must have had some kind of language to have cooperative hunting.

12. Archaic Homo sapiens • Evidence suggests that physical changes and cultural advances were proceeding in in Asia and Africa. • Archaic H. sapiens (300,000 to 30,000BP) and H.sapiens neanderthalensis (130,000-30,000) fill in the gap between H. erectus and H. sapiens. • Brain size within modern human range (1,350 cm cubed). Evolution was pumping in more brain. • Lived during the last part of the Middle Pleistocene. • Evidence suggest that their tolerance of environmental diversity had increased. Managed to survive extreme cold.

13. The Neandertals • First discovered in W. Europe, in a German valley called Neander Valley in 1856. • Very confusing. Darwin’s Theory of Evolution had not yet been published. • By 75,000 BP the Wurm glacial period began. They wore clothes, made elaborate tools, hunted reindeer, mammoths and woolly rhinos. • They were stocky, with large trunks, a phenotype that minimizes surface area and conserves heat.

14. Neandertal adaptations • Face pulled forward by the nose, which increased the distance between outside air and arteries that carry blood to the brain. Brain is sensitive to changes and must be kept warm. • Huge front teeth, broad faces and large brow ridges, and ruggedness of the skeleton and musculature. • Front teeth=very heavy wear, suggesting that they were used for varied purposes, including chewing animal hides to make soft winter clothing.

15. Early and later Neandertals • Trend toward reduction of their robust features. • Technology called Mousterian, improved during the Wurm glacial. Tools took over jobs done by front teeth. • Facial muscles and supporting structures developed less. Projecting face reduced, along with brow ridge.

16. Neandertals and Modern People • Scientists disagree about whether Neandertals were ancestral to modern Western Europeans. • Prevailing view: proposes that H. erectus split into separate groups, one ancestral to H. sapiens sapiens (anatomically modern humans AMHs) who appeared in W. Europe after 40,000 BP. Often called Cro-Magnon. • Another version: Modern humans evolved in Africa, C. Europe, or the Middle East. Eventually colonized W. Europe, displacing Neandertals, who were to anatomically specialized to evolve into modern humans.

17. Contrasts between Neandertals and AMHs • Neandertals: heavy brows, and slanting foreheads, with larger cranial capacity than modern humans. Large jaws and massive faces. • Skulls more rugged and greater sexual dimorphism than AMHs. • There is also evidence that suggest modern humans evolved from Neandertals. Many fossils have been discovered that shows mixed Neandertal and modern features. • AMH’s brain cases are higher, shorter, and rounder than Neandertal skulls.

18. continued • AMHs have a more filled out forehead region, rises more vertically above the brows. • A marked chin is another modern feature. • Evidence shows that H. sapiens evolved directly into AMHs in the Middle East more than 50,000 years before the demise of the Western European Neandertals. • Neandertals and AMHs overlapped in time rather than being ancestor and descendant.

19. Proof in mitochondrial DNA • Support for the idea that H. sapiens sapeins arose in Africa, then spread out and colonized the world. • Analyzed genetic markers in placentas donated by women whose ancestors came from Africa, Europe, Middle East, Asia, N. Guinea, and Australia. • Research focused on mtDNA, which is only contributed by the mother. Usually an exact replica of mother’s DNA, except with mutations. • After estimating the number of mutations, researchers drew an evolutionary tree, which started in Africa and then branched into 2.

20. mtDNA cont. • One group remained in Africa, while the other split off, carrying its mtDNA to the rest of the world. • The greatest variation in mtDNA occurred in Africa, which means they have been evolving the longest. • Concluded that everyone alive today has mtDNA that descend for a woman (dubbed “Eve”) who lived in sub-Saharan Africa around 200,000 years ago. • mtDNA descent lines will disappear when a woman has no children or has only sons. • This evidence suggests that “Eve’s” decendants left Africa no more than 135,000 y.a. and they eventually displaced the Neandertal’s in W. Europe and went on to colonize the rest of the world.

21. Recent DNA evidence • To support views that Neandertals and AMH’s were distinct groups. • DNA extracted from a Neandertal bone found in Neander Valley in 1856 was compared to DNA of modern humans. • 27 DNA differences were found • There are 2 competing theories about the origin of AMH’s. One is the Eve theory mention earlier and the other is Multiregional evolution theory.

22. Multiregional Evolution • States: A small group of modern people arose recently in one place (Africa) then spread out and occupied the rest of the world. They replaced all other more archaic species. • This theory proposes that evolution was more inclusive. • Human bands have always maintained relations with their neighbors, including interbreeding. • If a genetic change had a substantial selective advantage, it would spread rapidly from one group to all the others. • As regional populations evolved, gene flow always connected them, so that beneficial mutations would spread rapidly from one group to another.

23. Advances in Technology • During Upper Paleolithic by H.sapiens sapiens • Neandertals had an evolutionary technique of flake-tool manufacure. • H. sapiens sapiens emphasized blade tools.Blades were hammered off a prepared core, but is longer than a flake and more than 2X its width. • Blades were later modified to produce a variety of special-purpose tools. • Blade faster and produced 15X as much cutting edge.

24. Glacial Retreat • After the Wurm glacial ended between 17,000 and 12,000 y.a. the tundra and steepe vegetation grazed by large herbivores gradually moved north, along with their prey (people). • With most of the big game gone, Western Europeans were forced to use a greater variety of foods. • More water flowed as a result of melting ice. • Sea level rose, better conditions to support marine life were available in shallower and warmer offshore waters. • Edible marine species increased tremendously. • More birds, more saltwater and freshwater fish

25. Broad-spectrum Revolution • A wider range and broader spectrum of plant and animal life was being hunted and gathered. • Revolutionary because it led to food production-human control over the reproduction of plants and animals. • Plant cultivation and domestication replaced hunting and gathering in most areas.

26. Cave Art Art made the Upper Paleolithic people most familiar to us. Earliest cave paintings date back 30,000 years. Over time paintings have been absorbed by limestone walls and preserved. Prehistoric big game hunters painted their prey: mammoths, wild cattle, horses, deer and reindeer. Most interpretations associate cave painting with magic and ritual surrounding the hunt. (the painting could influence their hunt) Another interpretation is that it was a magical human attempt to control animal reproduction

27. Cave art cont. • Paintings often occurred in clusters. • May have been a kind of pictorial history, a reenactment after the hunt. • During late Upper Paleolithic-most spectacular multi-colored cave paintings.