Introduction
Physical anthropology is the study of human biology within the framework of evolution. In this essay we will investigate the biological basis of human life through the study of inheritance, and the principles of evolution. In the same category we will also be concerned with human adaptation and variation. Physical anthropologists also study non-human primates, thus we will become acquainted with the principal living primates and their social behavior, as well as fossil anthropoids and hominoids. We will then critically analyze the data, methods, theories, and debates surrounding the evolution of hominids, with special emphasis on biocultural evolution. By expanding our knowledge of millions of years of evolution, we will develop a deeper appreciation for the nature of humankind.
Background of Geologic Time Scale data including Eras Periods
and Epochs as well as the data on fossil primates
The Geologic Time, it is the time scales that covers Earth’s entire geologic history from its origin to the present. Before the growth of a geologic time scale in the 19th century natural historians recognized that Earth has a lengthy history, but the scale used today developed over the last 200 years and continues to evolve. A geologic time scale helps scientists think about the history of the planet in manageable sections of time. (Morgan, 2005)
Era Period
In geology an era is a major division of time. Eons, the longest division of time, are subdivided into eras and eras are subdivided into periods. The present, or Cenozoic Era, the shortest of all eras, has already covered a period of about 65 million years. In a historical sense, an era is a period of time computed from a specific moment or event. The present chronological era, the Christian Era, began on January 1 in the year 1 ad, conventionally fixed as the date of the birth of Christ.(Encarta,2006)
Epoch Period
Division of geologic time shorter than a geologic period and longer than a geologic age. Epochs cover ranges of time generally from about 5 million to 30 million years. The largest division of geologic time is called an eon. Eons are divided into eras, which are divided into periods, which are further divided into epochs. Scottish geologist Charles Lyell was the first to subdivide a period into epochs. (Morgan, 2005).
Fossil Primates
The earliest fossils of primates that have been discovered date from the end of the Cretaceous Period, about 65 million years ago. These early fossils include specimens of a species called Notharctus, which resembles today’s lemurs and had a long pointed snout.(Burnie, 2005)
1. Hominid Evolution
Human Evolution is a lengthy process of change by which people originated from apelike ancestors. Scientific evidence shows that the physical and behavioral traits shared by all people evolved over a period of at least 6 million years. Humans are primates. Physical and genetic similarities show that the modern human species, Homo sapiens, has a very close relationship to another group of primate species, the apes. Humans and the so-called great apes (large apes) of Africa—chimpanzees (including bonobos, or so-called pygmy chimpanzees) and gorillas—share a common ancestor that lived sometime between 8 million and 6 million years ago. The earliest humans evolved in Africa, and much of human evolution occurred on that continent. The fossils of early humans who lived between 6 million and 2 million years ago come entirely from Africa. (Potts, 2005)
i. Bipedal locomotion
Bipedal locomotion means walking on two legs in an upright position. Scientists identify whether a set of bones represents an animal who walked on two legs by examining the pelvis; bipedal locomotion is possible only with a specially adapted pelvis. Bipedal is one of the innovations of our hominid ancestors, the Australopithecus, and is one of the symptoms of being hominid. (Hirst,
ii. Biocultural evolution
The term biocultural evolution is a means of describing the influence of both biological makeup and cultural behaviors on human evolution. There are many examples of how environment surroundings have influenced cultural behaviors. Often times, evolutionary changes may take place as a result of both biological and cultural factors working together or occurring alongside one another, and this phenomenon is still happening to humans. (Petro, 2006)
2. Dating Methods
Geologists can determine the age of a rock layer in terms of absolute years, or in relation to the layers of rock around it. In order to determine the relative age of rock layers, scientists use three simple principles. The first is the law of superposition, which states that younger beds of rock occur on top of older beds of rock in an undisturbed sequence of layers. The second is the law of cross-cutting relationships, which states that any feature or structure that cuts through and disturbs a rock sequence must be younger than the disturbed beds. (Morgan, 2005)
The third principle is fossil succession, deals with fossils in sedimentary rock. Careful mapping around the world has revealed that rock of certain ages contains distinctive combinations of fossils—Paleozoic rocks contain trilobite and graptolite fossils, Mesozoic rocks contain dinosaur remains and ammonite fossils, Cenozoic rocks contain remnants of flowering plants and abundant mammal remains. By matching the fossil content of rock sequences, even across widespread geographic regions, paleontologists believe that certain sequences are probably about the same age. All of these methods facilitate the relative dating of rock sequences, but do not provide absolute ages for the rocks. (Morgan, 2005).
i. Australopithecines
The earliest humanlike primates, known from fossil remains found in Africa, australopithecines, or australopiths, represent the group from which the ancestors of modern humans emerged. As generally used, the term australopithecines covers all early human fossils dated from about 7 million to 2.5 million years ago, and some of those dated from 2.5 million to 1.4 million years ago. The group became extinct after that time. (Tattersall, 2005).
ii. Homo
Traditionally, paleo anthropologists classified as Homo sapiens any fossil human younger than 500,000 years old with a braincase larger than that of H. erectus. Thus, many scientists who believe that modern humans descend from a single line dating back to H. erectus use the name archaic Homo sapiens to refer to a wide variety of fossil humans that predate anatomically modern H. sapiens. (Potts, 2005)
3. Early Primate Evolution
i. Eocene
Two extinction pulses likely occur — the first at 37 mya, and the second at about 33 mya affecting both marine and land faunas. In marine communities, tiny single-celled organisms with shells called foraminifera suffer gradual but severe losses, as do gastropods, bivalves, and echinoids (sea urchins). On land, plants, rodents, primitive primates, and ungulates (hoofed mammals) are affected. While impact craters have been identified from this time period, evidence in rock layers suggests that meteors do not trigger the extinction. Instead, global cooling is a more likely cause. This hypothesis is supported on land by the appearance of open woodlands where densely forested habitats previously existed, and the extinction of many animal groups that lived in warm, higher latitudes. (WGBH, 2001)
ii. Direct Ancestor of Living Prosimians
The scientific classification of primates reflects evolutionary relationships among individual species and groups of species. Strepsirhine (meaning “turned-nosed”) primates—of which the living representatives include lemurs, lorises, and other groups of species all commonly known as prosimians—evolved earliest and are the most primitive forms of primates. The earliest monkeys and apes evolved from ancestral haplorhine (meaning “simple-nosed”) primates, of which the most primitive living representative is the tarsier. (Potts, 2005)
iii. Late Eocene: Early Anthropoids
a. Aegyptopithecus
A primate group known as Propliopithecus, one lineage of which is sometimes called Aegyptopithecus, had primitive catarrhine features—that is, it had many of the basic features that Old World monkeys, apes, and humans share today. Scientists believe, therefore, that Propliopithecus resembles the common ancestor of all later Old World monkeys and apes. Thus, Propliopithecus may also be considered an ancestor or a close relative of an ancestor of humans. (Potts, 2005)
b. Apidium
the first fossils were thought to be from a hoofed animal) is that of at least three extinct primates living in the early Oligocene, roughly 36 to 34 millions years ago. Apidium fossils are common in the Fayoum deposits of Egypt. Fossils of the earlier species, Apidium moustafai, are rare; fossils of the later species Apidium phiomense are fairly common.(Wikipedia Encyclopedia, 2006)
4. Miocene Fossil Hominoids
i. African Forms: Proconsul
Proconsul had features that suggest a close link to the common ancestor of apes and humans—for example, the lack of a tail. The species Proconsul heseloni lived in the trees of dense forests in eastern Africa about 20 million years ago. An agile climber, it had the flexible backbone and narrow chest characteristic of monkeys, but also a wide range of movement in the hip and thumb, traits characteristic of apes and humans.
ii. European Forms: Dryopithecus, Ouranopithecus
Dryopithecus in Western and Central Europe probably a descendant of Kenyapithecus in Africa. They became extinct about 9 mya. It may be ancestral to chimpanzee and ultimately hominids. Ouranopithecus (11-9 mya): northern Greece. Some have suggested it is ancestral to hominids; not common view. (Potts, 2005)
iii. Asian Forms: Sivapithecus
Sivapithecus (16-7 mya), Africa, Europe, and Asia esp. India and Pakistan 70-150 lbs. , dental arcade transitional between the U-shape of apes and parabolic form of humans,molars are large, with thick enamel (savanna diet?) large canines precludes efficient grinding , once considered great candidate for last common ancestor of humans and apes. Comparison of Sivapithecus skull (center) with modern orangutan (right) shows that this fossil genus was most likely direct ancestor to oranges. Thus, Sivapithecus shows derived facial features not found among other hominoids .Note that postcranial elements are unlike modern oranges.( Sassaman, 2004).
iv. Data suggest that the hominoid divergence occurred in the late Miocene.
Hominoids evolved during the Miocene Epoch (24 million to 5 million years ago).
v. Significance of Ardipithecus
Ardipithecus ramidus was discovered in December 1992.This discovery lead to modification of the current theories about why hominids became bipedal in the first place.(WGBH, 2001)
vi. Late Miocene/Early Pliocene Hominids
Comparative biomolecular studies suggest that the last common ancestor of humans and chimpanzees, our closest living relatives, lived during the Late Miocene–Early Pliocene. Fossil evidence of Late Miocene–Early Pliocene hominid evolution is rare and limited to a few sites in Ethiopia, Kenya and Chad. Here we report new Early Pliocene hominid discoveries and their palaeoenvironmental context from the fossiliferous deposits of As Duma, Gona Western Margin (GWM), Afar, Ethiopia. ( Simpson, 2005)
vii. Characteristics of these fossils
The hominid dental anatomy (occlusal enamel thickness, absolute and relative size of the first and second lower molar crowns, and premolar crown and radicular anatomy) indicates attribution to Ardipithecus ramidus.( Mcintosh, 2005) The combined radioisotopic and palaeomagnetic data suggest an age of between 4.51 and 4.32 million years for the hominid finds at As Duma. Diverse sources of data (sedimentology, faunal composition, ecomorphological variables and stable carbon isotopic evidence from the palaeosols and fossil tooth enamel) indicate that the Early Pliocene As Duma sediments sample a moderate rainfall woodland and woodland/grassland. ( Simpson, 2005)
viii.Comparison with modern hominids
The researcher of the fossil evidence for the diets of the earliest hominids reviewed and trace what has been inferred concerning the diets of the “gracile” australopithecines through time to put changes in Pliocene hominid diets into some temporal perspective. (Andrws ,1978). Such evidence has come in basically five categories: tooth size, tooth shape, enamel structure, dental microwear and jaw biomechanics. These lines of evidence suggest a dietary shift in the early australopithecines indicating an improved ability to consume hard, abrasive foods compared with their hominoid forebearers. Changes in diet-related adaptations from Australopithecus anamensis to A. afarensis to A. africanus suggest that hard, abrasive foods became increasingly important through the Pliocene.( Beynon and Wood,1986)
5. African Hominids: Data or Physical Characteristics, Geographic location, and evidence for culture
i. Africanus
The early history of South Africa dates nearly 3 million years to Australopithicus africanus, one of the earliest human ancestors. Archaeological evidence indicates that people resembling the San (bush people) and the Khoikhoi inhabited southern Africa thousands of years ago. (Lemon, O’Meara, and Winchester, N. Brian., 2005)
ii. Afarensis
A. afarensis, a gracile australopith that thrived in eastern Africa between about 3.9 million and 3 million years ago. The most celebrated fossil of this species, known as Lucy, is a partial skeleton of a female discovered by American paleoanthropologist Donald Johanson in 1974 at Hadar, Ethiopia. (Potts, 2005)
iii. Anamensis
Researchers have since found other A. anamensis fossils at nearby sites, dating between about 4.2 million and 3.9 million years old. The skull of this species appears apelike, while its enlarged tibia (lower leg bone) indicates that it supported its full body weight on one leg at a time, as in regular bipedal walking.(Potts, 2005)
iv. Robustus
The southern robust species, called Australopithecus robustus, lived between about 1.8 million and 1.3 million years ago in the Transvaal, the same region that was home to A. africanus. Later it was find out that it is different from africanus hey named it Paranthropus robustus (Paranthropus meaning “beside man”).(Potts, 2005).
v. Sahelanthropus
The oldest known australopith species is Sahelanthropus tchadensis. Fossils of this species were first discovered in 2001 in northern Chad, Central Africa, by a research team led by French paleontologist Michel Brunet. The researchers estimated the fossils to be between 7 million and 6 million years old. One of the fossils is a cracked yet nearly complete cranium that shows a combination of apelike and humanlike features.
It is Genus and hominid according to rsearcher it is about human origins, the discovery of Sahelanthropus in Chad significantly expanded the known geographic range of the earliest humans. The Great Rift Valley and South Africa, from which almost all other discoveries of early human fossils came, are apparently not the only regions of the continent that preserve the oldest clues of human evolution.(Potts, 2005)
vi. Habilis
H. habilis lived in eastern and possibly southern Africa between about 1.9 million and 1.6 million years ago, and maybe as early as 2.4 million years ago. Although the fossils of this species somewhat resemble those of australopiths, H. habilis had smaller and narrower molar teeth, premolar teeth, and jaws than did its predecessors and contemporary robust australopiths. (Potts, 2005).
Scientists began to notice a high degree of variability in body size as they discovered more early Homo fossils. This could have indicated that H. habilis had a large amount of sexual dimorphism. For instance, the Olduvai female skeleton was dwarfed in comparison with some other fossils—exemplified by a sizable early Homo cranium from East Turkana in northern Kenya. However, the differences in size actually exceeded those expected between males and females of the same species, and this finding later helped convince scientists that another species of early Homo had lived in eastern Africa. (Potts, 2005).
6. Homo erectus
i. Geographic distribution
Paleoanthropologists now know that humans first evolved in Africa and lived only on that continent for a few million years. The earliest human species known to have spread in large numbers beyond the African continent was first discovered in Southeast Asia. In 1891 Dutch physician Eugène Dubois found the cranium of an early human on the Indonesian island of Java. He named this early human Pithecanthropus erectus, or “erect ape-man.” Today paleoanthropologists refer to this species as Homo erectus.
ii. Differences between African, European, and Asian types
African have is large-bodied, with thick molar enamel, European have thin-enameled Y-5 molars while Asian have molars are large, with thick enamel large canines precludes efficient grinding. ( Sassaman, 2004)
iii. Tool technologies in Lower, Middle, and Upper Paleolithic and evidence for associated cultural behavior
Lower – Oldowan toolmaking involved hitting one palm-sized cobblestone against another. This process created large, sharp-edged core tools capable of breaking bones and slicing meat or vegetation, and smaller flakes that could scrape hides and sharpen wooden sticks. (Schick and Toth 2005)
Middle – Toolmakers in the Middle Paleolithic used a range of retouched flake tools, especially side-scrapers, serrated scrapers, backed knives (blade tools with the no blade side dulled to fit comfortably in the hand), and points. Experts believe these tools were used to work animal hides, to shape wood implements, and as projectile points. (Schick and Toth 2005)
Upper – During the Upper Paleolithic, tools of bone, antler, and ivory become common for the first time. These tools include points, barbed harpoons, spear throwers, awls, needles, and tools that have been interpreted as spear-shaft straightness. The presence of eyed needles indicates the use of sewn clothing (presumably of hide and possibly early textiles) or hide coverings for tents or shelters. (Schick and Toth 2005)
Cultural Behavior – In the Upper Paleolithic, evidence of human burial is much more common. In addition, burials tend to be more elaborate than in Neandertal times, often associated with rich grave goods. (Schick and Toth 2005)
7. Neandertals
i. Tool technology and associated cultural data
The Neandertals made stone tools quite skillfully and relied on them for their survival. Triangular spear points may have been hafted (attached to a wooden handle or shaft) to make hunting weapons. Scrapers, hand axes, and backed knives (sharp flakes with one side dulled to fit comfortably in the hand) would have been highly effective for butchering animals and scraping hides for clothing or shelter. Sharp-edged chopper stones were probably used for cracking open animal bones to get at marrow. (Tattersall, 2005
Neandertals were the first humans known to have buried their dead. Numerous burial pits have been discovered in the floors of caves and rock shelters, sometimes accompanied by stone tools or a few animal bones. To some authorities, these burials and grave items represent evidence that Neandertals practiced religious rituals, believed in the afterlife, and had the ability to think symbolically. (Tattersall, 2005)
8. Homo sapiens sapiens
` The 130,000 year-old reconstructed skull shown below at left represents the earliest known example of a modern human being, Homo sapiens sapiens. It was found at Omo in East Africa; skull size and shape are completely modern. Shown beside the skull are some characteristic tools of Homo sapiens sapiens, all from East or South Africa: a bola for throwing at small game, flake tools, and a long flake blade and the core from which such blades have been struck. (WSU, 2006)
The H. sapiens sapiens skull is smaller and more compact and the face is much less elongated than the Neanderthal; the modern human skull has a higher forehead, less prominent brow-ridges and smaller teeth. Modern humans are typically much less robust in body form and skeleton than Neanderthals. (Potts, 2005).
9. Technology and Art in the Upper Paleolithic
In the Upper Paleolithic, standardized blade industries appear and become much more widespread than in previous times. The first of these industries to appear in the Near East and Europe is known as Aurignacian. Later Upper Paleolithic industries include the Perigordian, Solutrean, and Magdalenian. The Upper Paleolithic is usually characterized by specially prepared cores from which blades (flakes at least twice as long as they are wide) were struck off with a bone or antler punch. Upper Paleolithic humans also developed new forms of scrapers, backed knives, burins, and points. Beautifully made, two-sided, leaf-shaped points are also common in some Upper Paleolithic industries. Toward the end of the Upper Paleolithic, microliths (small, geometric-shaped blade segments) became increasingly common in many areas. ( Schick and Toth Nicholas, 2005)
Europe are famous for their artwork, but prehistoric Stone Age art has also been richly documented in Africa, Australia, and other parts of the world. Animals are common subjects of Upper Paleolithic art, and human figures and abstract elements such as lines, dots, chevrons, and other geometric designs are also found. Animals such as bison, wild cattle, horses, deer, mammoths, and woolly rhinoceroses are represented in European Upper Paleolithic cave art, with human figures relatively uncommon. Later Stone Age paintings of animals have been found at sites such as in Apollo 11 Cave, in Namibia; and stylized engravings and paintings of circles, animal tracks, and meandering patterns have been found in Australia’s Koonalda Cave and Early Man Shelter. .( Schick and Toth Nicholas, 2005)
The earliest known musical instruments also come from the Upper Paleolithic. Flutes made from long bones and whistles made from deer foot bones have been found at a number of sites. Some experts believe that Upper Paleolithic people may have used large bones or drums with skin heads as percussion instruments. (Schick and Toth Nicholas, 2005).
Conclusion
Therefore I can say that the researchers of the fast are successful in tracing our ancestors where the human being evolved. The new generations today are very lucky having those people who are devoting their life tracing the missing link of our history. As new generation we must continue the work they had started and give importance to everything that surround us.
References
“Era.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
“South Africa.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
“Eocene.” WGBH Educational Foundation and Clear Blue Sky Productions, Inc. 2001. 19 December 2006, from ;http://www.pbs.org/wgbh/evolution/change/deeptime/eocene.html;.
“Homo sapiens sapiens: The Symbol User.” WSUEducation. P. 1. 19 December 2006, from ; http://www.wsu.edu:8001/vwsu/gened/learn-modules/top_longfor/timeline/h-sapiens-sapiens/h-sapiens-sapiens-a.html;.
Age of the Earth, U.S. Geological Survey (1999
Andrws P (1978) A revision of the Miocene Hominoidea of East Africa. Bull. Brit. Mus. (Nat. Hist.) 30: 85-224.
Beynon AD, and Wood, BA (1986) Variations in enamel thickness and structure in East African hominids. Am.J. Phys. Anthropol.70: 177-193.
Burnie, David. “Primate.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
Changing Views of the History of the Earth, Richard Harter (1998)
Hirst, Kris. “Bipedal Locomotion”. 19 December 2006, from ;C:Documents and SettingsPentium DDesktopBipedal Locomotion.htm;.
Mcintosh, William. Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro, New Mexico, 87801, USA
Morgan, Alan V. “Geologic Time.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
Petro, Barbara. Bioclutural Evolution still affecting Humanity. 19 December 2006, ;http://www.associatedcontent.com/article/21288/biocultural_evolution_still_affecting.html;.
Physical Anthropology, 8th edition, Philip Stein and Bruce Rowe 2003
Potts, Richard B. “Human Evolution.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
Schick, Kathy, and Toth, Nicholas. “Stone Age.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
Simpson, Scottw W. Laboratory of Physical Anthropology, Cleveland Museum of Natural History, Cleveland, Ohio, 44106, USA
Tattersall, Ian. “Australopithecines.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
Schick, Kathy, and Toth, Nicholas. “Stone Age.” Microsoft Encarta 2006 [CD]. Redmond, WA: Microsoft Corporation, 2005.
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