Human Evolution Exam 3

Who do these earliest hominins include?

Sahelanthropus, Orrorin, and Ardipithecus

Derived characters of Au. anamensis include?

Somewhat smaller canine crown, thick enamel, and adaptations to bipedalism

Neandertal teeth

Their teeth indicate that they had delayed development similar but somewhat quicker than modern humans, and some parts of their skeleton may have matured more quickly.

Anatomical characteristics of the earliest hominins?

They all lack a functional CP3 honing complex and may not be fully bipedal.

How do East and South African sites differ?

They differ in their geology with radiometric dates being more feasible in East Africa.

The robust species show...

a suite of craniodental adaptations for producing high bite forces including postcanine megadontia.

what do Au. anamensis and Au. afarensis form?

an ancestor descendant lineage, and later australopithecines may have arisen from this.

When do the earliest hominins appear?

between 5 and 7 million years ago.

Derived characters of Au. africanus?

include a rounded vault (absence of cranial cresting), a somewhat flexed cranial base, and a more parabolic dental arcade.

Show your understanding of the implications of the Australopithecine radiation by discussing the evolutionary relationships among the species in the genus Australopithecus and begin to explain their evolutionary radiation in Africa.

look in textbook

The multiregional model

- hypothesizes that the origin of modern humans is the result of the diffusion of the genetic underpinnings of the modern human phenotype among multiple archaic hominins from multiple regions via gene flow. - Predicts the presence of intermediate fossil forms in each region. - Predicts continuity of behavior (as inferred from the tool types). - Predicts genetic contribution from archaic to modern populations in a region

Explain the role of molecular genetics and human origins, including the role of mitochondrial, Y-chromosome, nuclear, and ancient DNA in testing models for human origins.

- Ancient DNA suggests that fossil H. sapiens of Europe are more similar to living humans than they are to fossil Neandertals from Europe of the same geologic age. - The last common ancestor for all H. sapiens is reconstructed to be approximately 200,000 to 800,000 years ago based on various kinds of DNA comparisons.

What do these tools + fossils tell us about the early homos?

- Animal bones with cutmarks show that hominins were eating meat. - Broken and cutmarked bones found at butchering sites provide evidence that early hominins were sometimes eating meat and marrow. - We do not know whether those animal resources were hunted or scavenged, but we do know that they provide high-quality resources. - Studies of modern carnivores suggest that scavenging carcasses would have been a possible source of nutrition for early hominins.

Compare Neandertal behavior with earlier hominins

- Archaeological hearths indicate that Neandertals routinely used fire. - Animal skins and hides were probably also used for protective shelters and cloaks. - Neandertals migrated seasonally, and during long-lasting glacial events their range seems to extend further south and not so far north. - Most Neandertals are found with Middle Paleolithic tool industries, which are characterized by prepared-core technologies, in which multiple steps are required to release a flake with specific characteristics (e.g., Levallois technique, disk cores etc.). - A few later Neandertals are associated with an Upper Paleolithic industry, known as the Châtelperronian. - Neandertals possessed thrusting spears and may have had projectile technology. - Neandertals left relatively little evidence of symbolic behavior in the form of beads or artwork. - They are likely to have buried their dead either for ritual or practical purposes. Few if any grave goods have been found with these burials. - Neandertals were probably hunters rather than scavengers. - A few sites suggest that Neandertals practiced cannibalism, at least occasionally.

Describe the behavior of archaic Homo sapiens as inferred from the evidence preserved in the archaeological record.

- Archaic H. sapiens are usually associated with Middle Stone Age and Early Stone Age tools. - Bone tools are also known from these time periods. - These technologies suggest they may have hunted big game.

Scenarios proposed for the origin of hominids? & The link to bipedality

- Bipedality is more energy efficient than knuckle-walking, and bipeds dissipate heat faster so they might be favored, especially in a savanna environment. - Postural adaptations to particular food resources (from trees, or specialized grasses) might favor bipedalism. - Bipeds have freed hands that can be used to carry infants, weapons, or food; the latter may be important to provisioning by males.

Describe the archaeology of modern human origins including how the upper paleolithic or later stone age differs from middle and early stone age tool technologies and describe the behavioral differences and role of symbolism in the Upper Paleolithic

- Earliest AMH are found with Middle Stone Age technologies. - Upper Paleolithic technologies are more typical of most AMH-associated finds. - Symbolic behavior, as represented by personal ornaments, portable art, cave art, and burials, seems an increasingly important part of how H. sapiens organized the world, suggesting that symbolism had important survival value

Discuss the anatomy and distribution of early humans around the world.

- Earliest modern humans appear in Africa about 195,000 years ago. - The earliest modern humans outside Africa are in the Near East around 100,000 years ago. They may appear as early as 80,000 years ago in China. - Modern humans disperse into Island Southeast Asia and Australasia by 50,000 years ago. - Early modern humans are recognized by: a chin, reduced facial size, reduced brow size, and presence of a canine fossa large globular brain case with parallel sides and the greatest breadth high on the parietals, and a distinct mastoid process and a relatively gracile postcranial skeleton compared to Neandertals or archaic H. sapiens.

Early Homo tools

- Early Homo is associated with Oldowan stone tools. - The Oldowan industry consists of flakes struck from cores have sharp edges useful for cutting. - Hammerstones were used for flaking and to smash open animal bones to access marrow

Explain the transitions that took place during hominin evolution in the middle to late Pleistocene including the anatomical characteristics that distinguish modern H. sapiens from earlier hominins.

- From the Middle to Late Pleistocene a transition from H. erectusto Neandertal and recent human anatomy takes place. - Modern humans have larger, more globular crania and small faces. - However, middle Pleistocene Homo has a large face and large double arched supraorbital region

Discuss the settlement of the New World and the Pacific Islands.

- H. sapiens disperses into the New World by at least 13,000 and probably by 15,000- 16,000 years ago. - Genetic evidence suggests a single Asian origin of the dispersing peoples and ancient DNA shows ties to Beringia. - Early dispersal may have been along both coastal and inland routes. - H. sapiens disperses into the Pacific by 3,500 years ago. - These are the last of the initial dispersals by humans into "hominin-free" ecosystems

Explain who Homo erectus was, including the anatomical differences between H. erectus and H. habilis.

- Homo erectus has larger average brain and body size than early Homo; however, there is a great deal of size variation in H. erectus. - Members have long, low, and relatively angular cranial vaults, often with welldeveloped supraorbital and occipital tori and other superstructures. - H. erectus teeth suggest a different diet that Australopithecus and a slightly different diet than earlier Homo. - Homo erectus first appears about 1.8 to 1.9 million years ago and persists until perhaps 100,000 years ago. - Some H. erectus use Acheulean tools others use Oldowan tools. - Some scholars divide the species into two—H. ergaster in Africa and H. erectus in Asia—based on cranial anatomy.

Discuss the distribution and characteristics of Homo erectus around the world.

- Initially an African species, H. erectus disperses into Asia and Southeast Asia by about 1.7 million years ago. - There was a great deal of variation in body size, which may be related to sexual dimorphism, regional differences, or differences in nutrition or climate. - A web of interrelated factors, including a shift to greater animal resource use, larger ranging, and body size, may be related to this hominin's ability to disperse from Africa.

Discuss the arguments surrounding the earliest genus Homo, including those for recognizing one species of early Homo versus those for recognizing two.

- Many scholars divide the species into H. habilis and H. rudolfensis. - H. rudolfensis has a more derived face, but the species overlap in size. - Other scholars argue that only one species H. habilis encompasses all the variation and that some of it is attributable to sexual dimorphism. - So far, early Homo is restricted mostly to eastern Africa. - Homo may appear as early as 2.8 million years ago, with the H. rudolfensis group appearing about 2.1 million years ago. - The last early Homo not belonging to H. erectus is dated to 1.44 million years ago

anatomical characteristics used in defining the genus Homo?

- Members of Homo differ from Australopithecus by increases in brain and eventually body size, and decreases in tooth and jaw size. - Brain size ranges from 500 to 750 cc.

Describe the anatomy and distribution of archaic Homo sapiens

- Middle Pleistocene fossils, from about 800,000 to 200,000 show intermediate morphology between H. erectus and recent humans. - Some scholars classify all of these into archaic H. sapiens. - Other scholars use the species name H. heidelbergensis for the European fossils and H. rhodesiensis for the African fossils. - Archaic H. sapiens are likely ancestral to later hominins in their regions. Ancestral to Neandertals in Europe and modern humans in Africa.

Discuss the anatomical characteristics that identify the emergence of modern humans compared to earlier hominins.

- Modern humans have large, globular crania and small faces. - Modern humans have more gracile postcrania than Neandertals and archaic Homo sapiens

Discuss the phylogenetic and taxonomic issues related to understanding relationships among the many late-middle and late Pleistocene hominins

- Neandertals likely evolved from archaic H. sapiens (H. heidelbergensis), who preceded them in Europe. - Archaic H. sapiens may represent two species, H. heidelbergensis and H. rhodesiensis - Neandertals are either seen as a separate species, H. neanderthalensis, or sometimes as a subspecies of H. sapiens.

Who were oldowan tools used by?

- Oldowan tools are made by H. habilis, H. erectus, and possibly some Australopithecus species.

Compare and contrast adaptation and adaptability; discuss the ways human biology reflects adaptation to heat, cold, high altitude, and high/low sun exposure.

- Organisms must make adjustments to cope with long- and short-term changes in their environments. - Acclimatization, adaptability, and adaptation are terms used to describe the different physiological levels at which these adjustments may be made. - Studying human biology in extreme environments allows us to understand adaptation at both the individual and population levels. - The stresses associated with hot, cold, dry, and high-altitude environments contribute to population variability in body size, shape, and physiology. - Although it has been of critical importance in classic and popular concepts of race, skin color is best understood in the context of human adaptation and adaptability. - Clinal variation in skin color suggests an interaction between population history and sunlight exposure.

Neandertal bodies

- Postcranially, Neandertal bodies follow both Bergmann's and Allen's rules. - Neandertal newborns had large brains similar to those of modern humans.

Explain the different ways of categorizing human variation at the group level.

- Species are generally composed of different populations, which may vary genetically or phenotypically. - Subspecies or races are identified when population variation combined with geographic separation reaches a certain level, which is not formally defined.

Describe the anatomical features that define the hominins

- The canine is reduced in size and often lacks a CP3 honing complex. - Eventually the dental arcade is relatively parabolic in shape. - Brain size increases, but is small in the earliest hominins.

Using examples such as lactase persistence and sickle cell trait, describe the evolution of polymorphisms in human populations as a result of direct natural selection or of balancing selection.

- The evolution of lactose tolerance in some human populations demonstrates clearly how positive natural selection acts on human polymorphisms. - Balanced polymorphisms, such as that observed for sickle cell trait, demonstrate how polymorphisms are maintained via positive and negative selection.

Outline the anatomical changes necessary for becoming a biped.

- The foramen magnum is placed on the inferior of the cranium. -Vertebral bodies bear progressively more weight lower in the column and so are largest in the lumbar region. - The spinal column has two secondary curvatures (in the cervical and lumbosacral regions) that keep the center of gravity directly above, rather than in front of, the feet of the biped. - The arm is not weight-bearing and is relatively gracile and foreshortened with short straight fingers. - The femur is angled from hip to knee to bring the foot directly below the center of gravity. - The femoral condyles are enlarged to bear greater weight, and the groove for the patella is deep to prevent dislocation. - The foot has arches for shock absorbing and short, straight phalanges. - The pelvis is bowl-shaped, with the ilium shortened and rotated around the side of the biped, which reorients the gluteal muscles into a position in which they can provide support while standing on only one foot.

Summarize the history of the study of human variation, including the polygenism/monogenism debate, and discuss the biological basis of traditional "racial" features.

- The formal identification of "human races" began in the eighteenth century. - The race concept in anthropology was heavily critiqued during the twentieth century, when anthropologists responded to the need to combat racism at the political and cultural levels.

Recognize how population genetics can be used to identify microevolutionary patterns of human variation, including how that variation may relate to human health, and reconstruct the histories of human populations.

- The microevolutionary changes that can be observed within and between species can be measured using the tools of population genetics. - Specific genetic polymorphisms are often best understood in terms of their clinal variation across populations. - Understanding the evolution of human polymorphisms is a critical part of biological anthropology. - Polymorphisms provide important information that can be used for the phylogenetic reconstruction of population relationships.

Use these data to help in interpreting models of human origins.

- Two models for the origins of modern humans have been proposed: replacement and multiregional models. - Genetic, archaeological and anatomical data are combined to address each model - Anatomical and archaeological evidence of overlapping lineages support replacement. - Small amounts of genetic introgression from Neandertals to AMH rules out complete replacement.

The Out of Africa or Replacement model

- hypothesizes a single, probably African, origin of modern humans, with subsequent dispersal into the Old World and replacement of archaic hominins by H. sapiens. - Indicates little or no gene flow between modern humans and earlier hominins in the various regions of the Old World. - Predicts anatomically distinct, temporally overlapping lineages of hominins in each region of the world. - Predicts possible disjunction in the archeological and genetic records.

Earliest Neandertals appear in western Europe around?

150,000 years ago and disappear around 39,000 years ago, overlapping for a few thousand years with H. sapiens.

When was stone tool use ubiquitous?

2 million years ago

Primitive characters of Au. anamensis include?

A shallow, U-shaped palate and large anterior teeth

Au. afarensis is more derived than?

Au. Anamensis and may be ancestral to later Australopithecus

Au. anamensis is likely ancestral to ?

Au. afarensis

Au. africanus is more derived than?

Au. afarensis and may have a unique relationship to Au. robustus or Homo.

Less well known species between 2.5 and 3.5 MYA?

Au. bahrelghazali, Au. garhi, and K. platyops.

Climate during plio-pleistocene?

Climate fluctuates dramatically in the plio-pleistocene. (Look in textbook) The genus Homo may be adapted to climatic fluctuations.

Primitive cranial characters of Au. afarensis?

Cranial cresting (compound temporo-nuchal and sagittal); a prognathic face; a shallow, U-shaped palate; and large anterior teeth

Species of robust

East Africa Au. (P) aethiopicus, Au. (P) boisei, and South African Au. (P) robustus.

Many Neandertals lived around the...?

Mediterranean, with some found as far east as Uzbekistan and Siberia and as far south as the Near East.

Anatomical characteristics of genus Australopithecus

Members of the genus Australopithecus are small-bodied, small-brained, bipedal African apes with both primitive and derived characters

Neandertal DNA

Neandertal DNA is relatively distinct from modern humans, suggesting that they did not contribute much to the recent human gene pool.

Au. sediba characteristics

Small bodied and brained (around 420 cc), Au. sediba had long arms and derived face, and some changes to the pelvis are like homo.

Discuss the lifeways of Homo erectus

The archaeological record suggests that meat and marrow became a more consistent part of the diet of Homo and H. erectus providing a high-quality resource in addition to gathered plants. - Dental evidence suggests that H. erectus grew more quickly than we do but more slowly than do living African apes or Australopithecus. - Acheulean tools include bifacial handaxes and cleavers. - Acheulean tools retain their cutting edges longer and are easier to hold than simple flakes. - Homo erectus used both Oldowan and Acheulean tools. - The Acheulean industry may be an adaptation to carcass processing and is made by H. erectus and archaic H. sapiens. - Teeth suggest H. erectus grew more slowly than Austrlopithecus. This, along with larger brain sizes, suggests they must have had a high quality diet. - Many scenarios of the evolution of genus Homo consider these new animal resources important (but not necessarily exclusively responsible) for brain expansion and dispersal from Africa.

Neanderthal skull characteristics

The brain case is large, but long and low. From behind, the brain case is oval shaped, with the greatest breadth in the middle of the parietal. The mastoid processes are small and juxtamastoid eminences large. A suprainiac fossa and an occipital bun are present, but an occipital torus is lacking.

Neanderthal face

The midface is prognathic, with a swept back cheek region and large nasal aperture. Browridges are large and double-arched. A retromolar fossa is present on the mandible. Neandertals have no chin.

Most scholars agree that robust australopithecines did not...?

give rise to genus Homo because the robusts are so specialized.

Derived characters of Au. afarensis include?

somewhat smaller canine crown and root, somewhat sma

What happened to the australopithecines

the robust australopithecines appear to have been an evolutionary dead end