Modern HumansModern Humans

Homo sapiensHomo sapiens

Origin TheoriesOrigin Theories

Time LineTime Line

Homo sapiensHomo sapiens(ca. 200 kya…)(ca. 200 kya…)

Fully modern humansFully modern humans Upper Paleolithic tool technologyUpper Paleolithic tool technology Elaborate Cave ArtElaborate Cave Art

Homo sapiensHomo sapiens sites in Europe sites in Europe

TransformationTransformation

Reduced robusticity-everything gets Reduced robusticity-everything gets smallersmaller

Back teeth continue to reduce, so do front Back teeth continue to reduce, so do front teethteeth

Cranial buttresses much less in evidenceCranial buttresses much less in evidence• loss of brow ridgeloss of brow ridge• development of chindevelopment of chin

Sexual dimorphism reduces to modern Sexual dimorphism reduces to modern levelslevels

Homo sapiensHomo sapiens

What causes this overall reduction?What causes this overall reduction? Teeth and cranial Teeth and cranial

buttresses: food buttresses: food processingprocessing• Especially cooking Especially cooking

technologytechnology• Earth ovensEarth ovens• Reduced selection for big Reduced selection for big

molarsmolars

What causes this overall reduction?What causes this overall reduction?

Skel. robust. & sex. dimorph.: projectiles & Skel. robust. & sex. dimorph.: projectiles & stringstring• With modern humans, first projectile weaponsWith modern humans, first projectile weapons• Atlatl (spear-thrower)Atlatl (spear-thrower)• No close quarter killing of big-gameNo close quarter killing of big-game

Selection reduced for maintaining big Selection reduced for maintaining big bonesbones

Sex. dimorph: males get relatively smallerSex. dimorph: males get relatively smaller

AtlatlAtlatl

http://www.crt.state.la.us/archaeology/POVERPOI/food.htm

Cro MagnonCro Magnon

Species: Homo sapiens

Age: ~30,000 years

Date of Discovery:

March 1868

Location:Les Eyzies, Dordongne,

France

Discovered by:

Louis Lartet

 

Skuhl 5Skuhl 5

Species: Homo sapiens

Age: ~ 90,000 years

Date of Discovery:

May 2, 1932

Location:Mount Carmel,

Israel

Discovered by:T. McCown and

H. Moivus, Jr.

Upper Paleolithic ToolsUpper Paleolithic Tools

Upper Paleolithic ToolsUpper Paleolithic Tools

Multiregional TheoryMultiregional Theory H. erectusH. erectus left Africa, spread to other left Africa, spread to other

areas of the world, and evolved into areas of the world, and evolved into modern humans.modern humans.

Human populations linked throughout the Human populations linked throughout the world were linked by gene flow.world were linked by gene flow.• Caused modern humans to evolve as a single Caused modern humans to evolve as a single

species from species from H. erectusH. erectus to to H. sapiensH. sapiens all over all over the world. the world.

• Also separated by distance and environment so Also separated by distance and environment so had considerable regional variation in had considerable regional variation in morphology.morphology.

All genes arose in many parts of the world All genes arose in many parts of the world and were mingled together as people from and were mingled together as people from different regions mated.different regions mated.

Replacement Theory Replacement Theory (Eve Hypothesis)(Eve Hypothesis)

Hominid populations genetically separated Hominid populations genetically separated during the Middle Pleistocene (before during the Middle Pleistocene (before 200,000 B.P.), evolving independently.200,000 B.P.), evolving independently.• Between 100,000 and 200,000 years ago Between 100,000 and 200,000 years ago

modern humans evolved in Africa and spread modern humans evolved in Africa and spread out, replacing archaic H. sapiens.out, replacing archaic H. sapiens.

Little or no gene flow as modern humans Little or no gene flow as modern humans replaced local populations, all genes replaced local populations, all genes necessary for moderns assembled in Africa.necessary for moderns assembled in Africa.

““Mostly” Out of AfricaMostly” Out of Africa

Modern Humans evolved in Africa around Modern Humans evolved in Africa around 150,000 years ago.150,000 years ago.

Spread to Asia, Middle East and Europe Spread to Asia, Middle East and Europe and replaced earlier settlers.and replaced earlier settlers.

In Europe, with Neanderthals, this may In Europe, with Neanderthals, this may have been complicated by absorption of have been complicated by absorption of Neanderthals into the Modern gene pool.Neanderthals into the Modern gene pool.• This allowed a very few Neanderthal traits to This allowed a very few Neanderthal traits to

persist in living populations in very small persist in living populations in very small percentages.percentages.

Lagar Velho 1 Skeleton Lagar Velho 1 Skeleton

Neanderthal/Human Hybrid??Neanderthal/Human Hybrid??•Analysis of the skeletal remains of this four-year-old boy has revealed that he may be a Neandertal-Cro-Magnon hybrid.

•Found in a Portuguese rock-shelter and dating to 25,000 to 24,500 years ago has yielded startling evidence that early modern humans and Neandertals may have interbred.

•While the boy's prominent chin, tooth size, and pelvic measurements marked him as a Cro-Magnon, or fully modern human, his stocky body and short legs indicate Neandertal heritage, according to Erik Trinkaus, a paleoanthropologist at Washington University in St. Louis.

Lagar Velho 1 Skeleton Lagar Velho 1 Skeleton

Presence of artifacts in burial also a modern trait.

Chin-on Lagar Velho Specimen, not Chin-on Lagar Velho Specimen, not on Neanderthalson Neanderthals

Lagar Velho 1Lagar Velho 1

Evidence: FossilsEvidence: Fossils

Evidence from Europe and Middle Evidence from Europe and Middle East is inconsistent with Multiregional East is inconsistent with Multiregional model.model.• long period of overlap between long period of overlap between

Neanderthal and moderns in this area. Neanderthal and moderns in this area. • anatomically modern people appeared anatomically modern people appeared

60,000 years before Neanderthals 60,000 years before Neanderthals disappeared. disappeared.

Evidence: ArchaeologicalEvidence: Archaeological Cave sites in Israel, most notably Qafzeh Cave sites in Israel, most notably Qafzeh

and Skhul date to nearly 100,000 years and Skhul date to nearly 100,000 years and contain skeletons of anatomically and contain skeletons of anatomically modern humans.modern humans.

Qafzeh Cave

Amud and KebaraAmud and Kebara

The presence of Neanderthals at two other The presence of Neanderthals at two other caves in Israel, Amud and Kebara, dated to caves in Israel, Amud and Kebara, dated to roughly 55,000 years means that roughly 55,000 years means that Neanderthals and Neanderthals and Homo sapiensHomo sapiens overlapped in this region for at least overlapped in this region for at least 45,000 years.45,000 years.

Therefore, if Therefore, if Homo sapiensHomo sapiens were in this were in this region for some 45,000 years prior to the region for some 45,000 years prior to the disappearance of the Neanderthals, there disappearance of the Neanderthals, there is no reason to assume that Neanderthals is no reason to assume that Neanderthals evolved into modern humans. evolved into modern humans.

Amud Cave, IsraelAmud Cave, Israel

Evidence: Tools/CultureEvidence: Tools/Culture

Tools associated with moderns are not found Tools associated with moderns are not found with Neanderthals.with Neanderthals.

A remarkable diversity in stone tool types for A remarkable diversity in stone tool types for moderns.moderns.• tool types showed significant change over time and tool types showed significant change over time and

space  space  • artifacts were regularly fashioned out of bone, artifacts were regularly fashioned out of bone,

antler and ivory, in addition to stone  antler and ivory, in addition to stone  • stone artifacts were made primarily on blades and stone artifacts were made primarily on blades and

were easily classified into discrete categories, were easily classified into discrete categories, presumably reflecting specialized use  presumably reflecting specialized use 

Bone Bone ToolsTools

Upper Paleolithic toolsUpper Paleolithic tools

Aurignacian blades

Dufour bladelet Bone point

Tools/Culture con’dTools/Culture con’d Burials were accompanied by ritual Burials were accompanied by ritual

or ceremony and contained a rich or ceremony and contained a rich diversity of grave goods  diversity of grave goods 

Living structures and well-designed Living structures and well-designed fireplaces were constructed fireplaces were constructed

Raw materials such as flint and shells Raw materials such as flint and shells were traded over some distances  were traded over some distances 

Double Burial from Skuhl (adult Double Burial from Skuhl (adult female and young child)female and young child)

Genetic EvidenceGenetic Evidence

Contemporary patterns of genetic Contemporary patterns of genetic variation provide clues to origins of variation provide clues to origins of modern humansmodern humans

Mitochondrial DNA (mtDNA) passed Mitochondrial DNA (mtDNA) passed from mother to her children, an exact from mother to her children, an exact copy of genetic material.copy of genetic material.

Humans are less genetically variable Humans are less genetically variable than other populations-suggests than other populations-suggests population explosion.population explosion.

Genetic Evidence, con’dGenetic Evidence, con’d The high degree of similarity The high degree of similarity

between human populations stands between human populations stands in strong contrast to the condition in strong contrast to the condition seen in our closest living relatives, seen in our closest living relatives, the chimpanzees.the chimpanzees.

In fact, there is significantly more In fact, there is significantly more genetic variation between two genetic variation between two individual chimpanzees drawn from individual chimpanzees drawn from the same population than there is the same population than there is between two humans drawn between two humans drawn randomly from a single population. randomly from a single population.

Genetic EvidenceGenetic Evidence In support of an African origin for In support of an African origin for Homo sapiensHomo sapiens

the work of Cann and Wilson has demonstrated the work of Cann and Wilson has demonstrated that the highest level of genetic variation in that the highest level of genetic variation in mtDNA occurs in African populations. mtDNA occurs in African populations.

This implies that This implies that Homo sapiensHomo sapiens arose first in arose first in Africa and has therefore had a longer period of Africa and has therefore had a longer period of time to accumulate genetic diversity. time to accumulate genetic diversity.

Using the genetic distance between African Using the genetic distance between African populations and others as a measure of time, populations and others as a measure of time, Homo sapiensHomo sapiens arose between 100,000 and arose between 100,000 and 200,000 years ago in Africa.  200,000 years ago in Africa. 

Genetic EvidenceGenetic Evidence The low amount of genetic variation The low amount of genetic variation

in modern human populations in modern human populations suggests that our origins may reflect suggests that our origins may reflect a relatively small founding a relatively small founding population for population for Homo sapiensHomo sapiens..

Analysis of mtDNA by Rogers and Analysis of mtDNA by Rogers and Harpending supports the view that a Harpending supports the view that a small population of small population of Homo sapiensHomo sapiens, , numbering perhaps only 10,000 to numbering perhaps only 10,000 to 50,000 people, left Africa somewhere 50,000 people, left Africa somewhere between 100,000 and 200,000 years between 100,000 and 200,000 years ago.  ago. 

Neanderthal mtDNANeanderthal mtDNA

Scientists recently succeeded in extracting Scientists recently succeeded in extracting DNA from several Neanderthal skeletons. DNA from several Neanderthal skeletons. • After careful analysis of particularly the After careful analysis of particularly the

mtDNA, but now also some nuclear DNA, it is mtDNA, but now also some nuclear DNA, it is apparent that Neanderthal DNA is very distinct apparent that Neanderthal DNA is very distinct from our own. from our own.

• In assessing the degree of difference between In assessing the degree of difference between DNA in Neanderthals and modern humans, the DNA in Neanderthals and modern humans, the authors suggest that these two lineages have authors suggest that these two lineages have been separated for more than 400,000 years.  been separated for more than 400,000 years. 

ImplicationsImplications

Suggestions from mtDNASuggestions from mtDNA• Human populations spread out across Human populations spread out across

the globe well before any major the globe well before any major population expansion took place.population expansion took place.

• Size of pop before expansion was Size of pop before expansion was between 10 and 50,000 people.between 10 and 50,000 people.

• Major expansion of people beginning Major expansion of people beginning around 100,000-200,000 years ago in around 100,000-200,000 years ago in Africa and 50,000 years ago in the rest Africa and 50,000 years ago in the rest of the world.of the world.

Why important?Why important?

Resolution of this controversy because it affects Resolution of this controversy because it affects our view of contemporary human variation.our view of contemporary human variation.

Affects our perspective about the significance of Affects our perspective about the significance of genetic differences and modern human genetic differences and modern human populations.populations.

If replacement model correct, then all humans If replacement model correct, then all humans descended from a lineage that arose around descended from a lineage that arose around 100,000-200,000 years ago.100,000-200,000 years ago.

If multiregional correct then humans related as If multiregional correct then humans related as long as 1 million years ago and arose separately long as 1 million years ago and arose separately from there.from there.