ORIGIN OF MODERN HUMANS

modern human technology: composite tools

Atlatl is a spear-thrower that uses leverage to achieve greater velocity in dart-throwing

out of africa model

"Out of Africa model" suggests that modern human anatomy first appeared in Africa, then spread across the Old World. While modern humans were appearing in Africa, other more archaic humans were still living elsewhere in the world. When modern humans migrated, they encountered these archaic humans.

the origins of modern humans: fossil evidence

"anatomically modern human" refers to fossils that are the same as we are today. Anatomically modern humans (homo sapiens) first appeared approx. 200,000 years ago in Africa. the Omo fossils are the earliest representatives of Homo sapiens. In 1960s-70s, the Omo fossils were recovered by Richard Leakey near the Omo River in Ethiopia.

craniofacial features: homo sapiens

- high, round cranium - smaller nose - chin -face does not project : homo sapiens

craniofacial features: homo neanderthalensis

-long, low cranium - occipital bun - no chin -bigger brow ridge - no chin - gap behind 3rd molar

temporal lobe is important in...

-organizing sensory input -auditory perception -language and speech production -memory association and formation

human genetic variation

Across the human genome...83% to 97% of human variation is found within populations. 3% and 17% is found between populations. These results have been confirmed with studies of DNA markers, blood groups, and craniometric traits. In humans, there is more variation within populations than between populations!

more genetic support for out of africa: comparing genetic diversity

Africa tends to be more genetically diverse than other regions. Higher levels of Africa diversity is consistent with the Out of Africa model. The older a population, the more time it has to accumulate mutations. More genetic variation found in people living outside Africa is a subset of that found among Africans.

modern human technology: shelter

Archeological evidence shows evidence of manufactured shelter. Huts made of wood, animal bone and animal hides. 18,000 year old site in south-central Russia. 15,000 year old site from the Ukraine.

modern human technology: bone tools and burins

Bone tools appeared relatively recently, between 90,000 - 40,000 years ago. Bone was used to make needles, awls, points, knifes, and harpoons. burin = stone tool with sharp edge to cut and engrave bone

emergence of symbolism: cave art

Cave art dates back to more than 30,000 years ago in Europe, Africa, and Australia. Painting has no function for day to day survival, so why did early humans paint images on cave walls? Cultural symbolism, communication of ideas,...?

selection for cognitive abilities

Changes in the cranium of anatomically modern humans resulted from increase in the size of the temporal lobe of the brain.

craniofacial anatomy

Control of fire led to cooked diet. Cooked food items resulted in changing selection on chewing mechanisms. Reduction in the size of dentition and muscles for chewing.

importance of social relationships

Did not find the same relationship of group size and brain size in other organisms, with the exception of horses. Brain size in other organisms related to long term cooperative relationships. Examination of brain size compared to social and mating systems of 480 bird species, larger brain found in small groups with cooperative mating systems.

emergence of adornment: jewelry

Earliest evidence adornment appears between 100,000 to 135,000 years ago. These 82,000 year old shell beads were discovered more than 25 miles from the Med Sea, where they originated. Indicating that humans were transporting decorative shells.

modern human technology: clothing

Evidence of the manufacture of clothing appears 80,000 to 70,000 years ago. Clothing is a cultural adaptation that allowed humans to survive in different environments. Within cold environments, clothes prevent loss of heat. Within hot environments, can provide protection from ultraviolet radiation.

why did modern humans evolve?

Explanations for the origin of modern human craniofacial anatomy...-changes associated with cooked diet -need for head stabilization during endurance running -associated with shortened pharynx -selection for improved vocal linage skills -selection for cognitive abilities. Likely to have been a combination of these forces which produced an advantage for modern humans.

anatomically modern humans: homo sapiens

FIRST DESCRIBED: 1758 WHERE: First Africa, and then everywhere HOW OLD?: 200 Ka- present KEY FEATURES -brain size: 1350 cc -postcrania: like you! -tool traditions: upper paleolithic tools, composite tools -language -shelter -art and symbolism

modern human origins debate

General trend in the fossil record shows that modern humans evolved from Homo heidelbergensis. Debate revolves around: location of the transition, nature of the transition.

isolation by distance

Genetic distance between populations increases with geographic distance, but differences are very small!

behavioral reflections of the brain

Greater size and complexity of the primate brain is reflected in behaviors: social cognition, learning. Strong relationship between reproduction, care of offspring, and learning. Primates spend a longer time growing up, both biologically and socially...they have much to learn about their environment and society!

the origin of modern humans

Homo sapiens evolved from earlier populations of middle Pleistocene hominid. What are the differences between archaic humans and modern humans? Was the change widespread or did it occur in one place? Emergence of homo sapiens involves both biological and cultural adaptations.

mixing it up

In the 1980s, Svante Paabo succeeded extracting DNA from an ancient corpse. He discovered genetic evidence of some interbreeding between Neandertals and modern humans. Out of Africa with some genetic contribution from Neanertals, supporting assimilation.

modern human technology: blades

In the upper Paleolithic, we see development of blade technology and diversity of other tools materials (bone, wood, etc.). Blade = stone tool that is twice as long as it is wide

modern human society: social learning

Increased tolerance and sociality enables us to transmit information between individuals. For example, improved tool technology can be passed through generations. Culture allows humans to exploit a wide range of environments. Humans can not be understood without the complex interplay of biology and culture.

human modern technology: shelter

Interior was framed with large animal bones and wood, which was covered by animal hides

selection for improved vocal language skills

Language is important for communication of social and technical information. What were hominids talking about? Recent research has shown that 2/3 of modern human conversations focus on social relationships or gossip.

type of specimen for H. sapiens?

Linneaus described humans just as he did any other plant or animal. Scientific name of a species usually based on a partiular type specimen. PPhysical specimen kept in a museum research collection or herbarium. Did not designate a type specimen fror humans. We still do not have a type specimen for humans. we still do not have a type specimen because it must be examined by the original author who names a species.

hominin distribution: 30,000 years ago

Modern human populations flourish, while other hominins dwindle. Modern humans reach Australia, presumably by rafting. Homo floresiensis in Indonesia from 94,000 to 12,000 years ago.

review of genetic insights on history of human populations

Modern humans evolved in Africa between 200 and 90 kya. Modern humans outside of Africa all descended from a small population that left Africa 60,000 years ago. Small amount of interbreeding between expanding modern human populations and the hominids already living in Eurasia (including Neandertals and Denisovans).

hominin distribution: 100,000 years ago

Morphologically heterogeneous collection on hominids: -neandertals in Europe, survived until 28,000 years ago-homo erectus may have survived until 27,000 years ago -humans had spread to extents of AFrica

multiregional evolution moel

Multiregional evolution model proposes that modern humans emerged more or less simultaneously in major regions of the Old World from local archaic humans. Supporters believed that the common ancestor of all modern people was an early Homo erectus in Africa who lived ~ 1 mya. There was sufficient gene flow between regions to prevent reproductive isolation.This model emphasizes the role of migration: HYPOTHESIS TESTED AND REJECTED!

origin of modern human craniofacial anatomy

Need for better stabilization of the head during endurance running. Dan Lieberman's lab conducts experimental research projects on the biomechanics and evolution of running, walking, throwing, chewing, food processing, and sweating. Also, morphometric and developmental studies of craniofacial growth in humans, hominids, and other mammals.

What happened after they expanded out of Arica--reeplacement or assimilation?

One scenario is the african replacement model which suggests that when modern humans begin migrating around the world, they replaced preexisting human populations . These other populations are not of the ancestry of living humans : HYPOTHESIS TESTED AND REJECTED.

our social brains

Research has suggested that primate brain sizes scaled with social group size.

emergence of symbolism: statues

Several different forms of statues, most of animals. Venus figurines found throughout Europe. Pregnant females with exaggerated features. Could be fertility symbols, but we are not certain of their meaning or function.

why are our brains so big?

Social brain hypothesis = brain size (particularly the size of the neocortex) shows a relationship with the size of a species' social group. Keeping track of who is doing what to whom requires considerable processing power...and so bigger groups, demand bigger. Numerous studies have found correlations between size of social networks and that of specific areas of the brain linked to sociality. One study found a positive relationship between gray matter and number of Facebook friends.

evolution of culture

Some scientists have suggested there was a "cultural explosion"- 55,000 years ago. Other argue that culture developed gradually with the emergence of modern humans.

chins?! What is there function?

There is still debate about the function of the human chin: -masticatory stress hypothesis: safeguard jaw against forces generated by chewing food teeth, jaws and chewing muscles got smaller -result of our unique form of speech: protect jaw against stresses produced by contraction of tongue muscles -sexual selection: may be a physical signal of mate quality

integration and modularity

Unclear whether the derived cranial traits of modern humans: -evolved independently in response to separate selection pressures -resulted from the inherent morphological integration throughout the skull. Morphological integration coordinates variation among interacting parts of organisms, and thus ensures organismal function. Study of 390 human skulls in Austria. Genetic and phenotypic shape variation were not consistent with the hypothesis that the face, cranial base, and cranial vault were completely independent modules, but rather were relatively strongly integrated structures. CONCLUSION: PERVASIVE INTEGRATION IN THE HUMAN SKULL

global expansion of modern humans: genetic evidence and climatic factors

Used genetic variation in modern populations to develop spatially explicit model of the expansion of anatomically modern humans. Past climate change dictated pattern and timing of the out of Africa expansion validates fossil and archeological evidence.

modern human brain size

What factors are correlated with this large brain? - australoptihecines, early homo, homo erectus

human cognition

What makes human cognition different is not more individual brain power but rather: -the ability to learn through other persons and their artifacts - the ability to collaborate with others in collective activities

human social networks

Within human societies, close relationships have been extended to other group members besides mates in the form of friendships. Human social networks are characterized by a number of social relationships.

human distribution: 10,000 years ago

World inhabited by modern humans with similar morphology. Modern humans extend distribution to North and South America.

testing hypothesis of human origins

collect genetic samples from around the world and examine the degree of variation between populations

homo spaiens: lifestyle

composite tools, shelter & clothing, social networks, language, art, rituals

genetic data support out of africa

genetic data reveal...recent, African origin for all humans. SMALL differences between groups!

genetic differences reflect migration

genetic differences reflect migration...distance = difference

The origin of modern humans: genetic evidence

mtDNA in every living person can be traces back to "Mitochondrial EVE" . Genetic studies estimate that this most recent common ancestor lived around 200,000 years ago, most likely in East Africa. This date and location corroborate the fossil evidence for the origin of our species.

neocrotex

outer layer of the cerebral hemisphere, involved in higher functions (conscious thought, language, etc. )

changes that accompany a shortened pharynx

shortened pharynx would make breathing more efficient in hot and arid climate

assimilation model

suggest that the transition to modern anatomy took place in Africa, and these changes spread to other populations through gene flow. Genes of non-AFrican populations were assimilated into the gene pool of expanding human populations, rather than being replaced.

cooperation

the key to establishing and maintaining a strong affilitative relationship of which the pair bond is the archetypal example