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  1. 1. Homo habilis and Homo erectus Early Tool Producing Hominims and Expansion in Africa
  2. 2. Australopithecus garhi The Earliest Tool Producing Hominim
  3. 3. Importance of the Species ● A species known as Australopithecus garhi was found in Ethiopia in 1996 ● This species dates between 2.6 million and 2.5 million years; a broader temporal determination for its persistence cannot be made at present because of the paucity of fossils ● It is particularly significant, though, because it is the earliest hominim species that can unequivocally be demonstrated to have made tools ● Most of the finds have been concentrated in Ethiopia, at a series of sites near Gona but also at Bouri ● Although clearly primitive and simple tools, they show affinities with the industry at Olduvai Gorge associated with Homo habilis
  4. 4. Dentition and Cranial Capacity ● The traits of A. garhi fossils such as BOU-VP-12/130 are somewhat distinctive from traits typically seen in Australopithecus afarensis and Australopithecus africanus ● An example of the distinction can be seen when comparing the Hadar maxilla (A. afarensis) to the Bouri specimen of A. gahri ● The cranial capacity of A. garhi measures 450cc, the same size as other australopithecines ● Studies made on the premolars and molar teeth have a few similarities with those of Paranthropus boisei since they are larger than any other gracile form of australopithecine ● It has been suggested that if A. garhi is ancestral to Homo (ie. Homo habilis) the maxillary morphology would have undergone a rapid evolutionary change in roughly 200,000 and 300,000 years
  5. 5. Gona, Ethiopia ● As there is so little skeletal evidence, it must be expected that the observations of differences between A. garhi and other hominims will be refined and expanded ● The main point of discussion concerning A. garhi is its status as the first hominim to produce tools ● Excavations at Gona in Ethiopia have resulted in the discovery of an handful of sites affording tools that have been dated between 2.6 million and 1.5 million years ● The earliest tools are associated with A. garhi, but it is not certain which hominim was responsible for the manufacture of the later tool assemblages ● Most of these are based on small cores and therefore conform to the 'chopper industry' seen at Olduvai Gorge and elsewhere in the earliest phases of the Lower Palaeolithic in Africa
  6. 6. Dating the Earliest Tools ● We have little occasion to doubt the early dates for these tools, nor for concern over the accuracy of the dates associated with the remains of A. garhi, for the stratigraphic succession affords several horizons of tephra that permit good dating opportunities ● The volcanic material also provided the raw material for the production of the tools—namely, small pebbles of trachyte ● It is possible to follow some of the tephra horizons elsewhere in the region, and numerous dating assays have confirmed the chronological succession ● In short, the tools here are certainly at least 500,000 years earlier than those at Olduvai Gorge
  7. 7. The Industrial Tradition ● The tools were fashioned from small pebbles of trachyte, being struck once or twice, and used as 'choppers' ● We nonetheless also see the use of small flakes detached from the pebbles ● Although relatively primitive, they differ little from the tools made at Olduvai Gorge by Homo habilis ● The raw material was also deliberately selected, as there are other rocks available in the vicinity ● This implies that a conscious decision was made to choose those rocks with the best flaking properties ● They were probably used to process vegetable food
  8. 8. Homo habilis and Homo rudolfensis Physical Characteristics, Sites and Behaviour
  9. 9. Significance of Homo habilis ● The importance of Homo habilis discoveries in the 1960s for the advancement of our knowledge of hominid evolution and the stimulation of excitement and controversy cannot be understated ● It was the finds of small bone fragments at Olduvai Gorge associated with stone tools that began the process of confirming that our genus arose in Africa and that there were fossil remains of considerable antiquity here ● Because this species was the first that could be unequivocally demonstrated to have produced stone tools, it was named Homo habilis, or the 'tool-maker' ● Finds from this species span the period of 2.4 million years and 1.5 million years and its distribution is restricted to East Africa and South Africa
  10. 10. Physical Characteristics ● This species shares many physical attributes with the gracile australopithecines, but also evinces important differences ● Because of differences in cranial capacity evident in the earlier and later specimens, some have restricted the term Homo habilis to refer to those with a smaller cranial capacity and those with a larger capacity to Homo rudolfensis ● It is intriguing that the earlier specimens, which some authorities do not believe to have led onward to other forms in the genus Homo, is that with the larger cranial capacity ● Nonetheless, this distinction may reflect temporal differences within the species rather than the evolutionary bifurcation of this hominim type
  11. 11. Homo rudolfensis ● Homo rudolfensis is a fossil hominin species discovered by Bernard Ngeneo Koobi Fora on the east side of Lake Rudolf (now Lake Turkana) in Kenya ● The scientific name Homo rudolfensis was proposed in 1986 by V. P. Alekseyev for the specimen ● Skull 1470 (KNM ER 1470), which has an estimated age of 1.9 million years ● Originally thought to be a member of the species Homo habilis, the fossil was the centre of much debate concerning its species ● Assigned initially to Homo habilis, the skull was at first incorrectly dated at nearly three million years old ● The continuing controversy about whether this is a distinct species explains some of the disagreements in the date range of Homo habilis
  12. 12. Another Species ? ● The differences in this skull, when compared to others of the Homo habilis species, are too pronounced, leading to the presumption of a Homo rudolfensis species, contemporary with Homo habilis ● In the Homo rudolfensis a strong supraorbital torus on 1813, whereas the supraorbital torus of 1470 is slight at best, and does not have the depression behind it that is seen in 1813 ● The face of 1470 is longer than 1813's and 1470's upper jaw is square instead of rounded-off ● There is a great discrepancy between the cranial capacities of the two individuals as well. ER 1470 has a cranial capacity of 775 cm3, where ER 1813 has a cranial capacity of only 510 cm3 (which is above the australopithecine average, but well below the accepted 600 cm3 cut-off for Homo)
  13. 13. The Principal Fossils ● KNM ER 1813 is a relatively complete cranium which dates to 1.9 million years old, discovered at Koobi Fora, Kenya by Kamoya Kimeu in 1973. The brain capacity is 510 cm3, not as impressive as other early specimen and forms of Homo habilis discovered. However, some scientists conclude that KNM-ER 1813 is a near perfect Homo erectus, except for its small brain and size, and that it could be an erectus that was small or even be a Homo ergaster. ● OH 7 dates to 1.75 million years old and was discovered by Jonathan Leakey on 4 November , 1960, at Olduvai Gorge, Tanzania. It is the type specimen. It has a lower jaw complete with a number of teeth and the left parietal is nearly completed. The brain size attributed to this specimen (assumed to be a young boy) ranges from 590-710 cm3
  14. 14. Principal Fossils, continued ● OH 24 (AKA 'Twiggy') is a deformed cranium dating 1.8 million years old, discovered in October 1968, at Olduvai Gorge, Tanzania by Peter Nzube. It was found in a very fractured state, cemented in limestone rock, and had to be reconstructed, but over 100 small fragments could not be assigned a location in the reconstruction. An estimate of 590 cm3 is given for the brain volume. A reduction in a protruding face is present compared to members of more primitive Australopithecines. ● KNM ER 1805 is a specimen of an adult Homo habilis made of 3 pieces of cranium dating 1.74 million years old from Koobi Fora, Kenya. Previous assumptions were that this specimen belonged to Homo erectus based on the degree of prognathism and overall cranial shape
  15. 15. Reconstructions ● The reconstructions of Homo habilis and Homo rudolfensis are based on the fossil evidence, but additionally, there are suppositions made concerning the thickness of skin and muscles and assumptions regarding the prevalence of body hair ● Ultimately, these reconstructions are unreliable, representing a series of postulates regarding their intermediate status between the higher primates and humans ● Some general postulates are, however, probably relatively accurate: the skin colour was likely dark, being well adapted to the high UV radiation of the regions in Africa which they occupied ● Less is known about body hair, given the lack of clothing evidence, but some possibly remained although this may have rapidly been lost as they expanded their ranges outwith Africa and into more temperate regions
  16. 16. Cranial Capacity and Dentition ● Homo habilis had a cranial capacity was (on average 50 percent larger than australopithecines), but considerably smaller than the 1350 cm to 1450 cm3 3 range of modern Homo sapiens ● Little is known about the teeth of Homo habilis, but the available evidence indicates that the teeth of Homo habilis are larger than those of modern humans ● In addition, the shape of the premolars of this species were more elongated than were those of their ancestors and, thus, much more similar in appearance to those of modern humans ● This implies that the dentition began to change from one largely suited to the processing of tough vegetable foods, to teeth well adapted to a more omnivorous diet ● Is this associated with hunting and the discovery of fire ?
  17. 17. Locomotion and Stature ● Hands and feet enable us to perform a variety of functions, such as digging soil, grasping objects, and even hanging from the stems of trees ● Unexpectedly, a fossil belonging to this species, dating from approximately 1.75 MYA, was found at Olduvai; this fossil was complete except that the back of the heel and terminal bones of the toes were missing ● It displays modern human characteristics: the stout basal bone of the big toe is aligned with the other toes, whereas in apes the big toe is larger and more robust ● Additionally, the hands show a capacity for gripping and precision permitting tool manipulation and production ● This species reached heights of 1.2 to 1.4 metres, but its bones and pelvic structure were quite robust and suggests an heavy musculature that indicates significant power in short running bursts
  18. 18. Subsistence and Social Structure ● The best evidence for the diet of Homo habilis is afforded by the dentition of the specimens found ● As the arrangement of teeth and chewing muscles does not necessarily reflect the actual diet, given the time-lag between evolution and behaviour, it is most apposite to consider the evidence of tooth wear ● The site of the fossils found at Olduvai Gorge indicates that this species inhabited open grasslands near the edge of a lake ● Other animals that also resided in this area include elephants, giraffes, wild pigs, various species of antelope, rabbits, baboons, hyenas, lizards, tortoises, and birds ● Among these animals, early members in the human lineage preyed on lizards, tortoises, pigs, rabbits, young antelope and fish from the nearby lake. In addition, they probably depended on carrion left by larger predators, like lions
  19. 19. Lithic Industry ● The tools characteristic of the earliest sites are called 'choppers' ● This term describes the existence of cores, produced mainly on pebbles, that have had flakes struck from them to produce primitive chopping or cutting implements ● In some instances, the flakes (those pieces detached from the cores) were also used as tools ● Sometimes this early chopper industry is term 'Oldowan' after the type-sites of the Oldowan Gorge, but it is also called the 'Omo' industry or 'Mode I' industries to distinguish them from the slightly more complex implements produced later ● The later complexity in production may, however, reflect access to better raw materials than an actual development in technique to produce implements
  20. 20. Distinguishing the Chopper Industries ● Although the chopper industries are primitive, in the sense that they represent the most simple form of lithic reduction, they are clearly produced by hominims ● Most important are the signs of flaking: this produced flakes (the material removed from a larger pebble or cobble) with the distinctive 'bulb of percussion' ● This rarely occurs naturally—only the most unusual conditions of pebbles striking one another would result in a flake being struck off ● The discovery of many of these flakes in a restricted area, along with the signs of multiple flakes being struck from the pebbles, confirms that they were produced by hominim agency ● All these criteria were met at the sites affording tools at Olduvai Gorge and elsewhere
  21. 21. Homo ergaster in Africa The First Colonists: Expansion of Hominim Range
  22. 22. Distribution and Nomenclature ● The designation of Homo ergaster is relatively recent, and is intended to distinguish the early forms of Homo erectus from the later forms ● This has met with some resistance from specialists, for those that are opposed to this distinction see no justification for positing a different species ● Irrespective of the controversies amongst the palaeoanthropologists, there is evidence of a change in the anatomy and behaviour in the species that is considered by some as Homo ergaster ● Our earliest finds derive from East Africa, sometimes at the sites where Homo habilis was found in older layers ● It is clear that Homo ergaster/Homo erectus was an extremely successful species and was the first to colonise regions outside of Africa
  23. 23. Affixing the Age of Homo ergaster ● Nevertheless, in this lecture we shall consider the evidence only from East Africa, where this species presumably diversified from Homo habilis and explore the later diffusion inside Africa and into Asia in the following lecture ● The paucity of sites affording remains of Homo ergaster renders it difficult to determine the age range of this species ● It is, however, commonly thought to have flourished between 2.0 million and 1.6 million years ago ● Some have suggested that it is significantly younger, emerging only at 1.7 million years ● The dates from the site of Dmanisi in Georgia have affixed the occupation by Homo ergaster here to 1.88 million years, so presumably it must be older in Africa
  24. 24. Physical Characteristics ● No agreement exists on which features distinguish Homo ergaster from Homo erectus ● This renders the determination of this species rather arbitrary; hence the controversy regarding its status ● An enlargement of cranial capacity and a slightly smaller set of teeth does, however, distinguish Homo ergaster and early forms of Homo erectus from Homo habilis ● It is widely accepted that this form of hominim evolved out of Homo habilis, although there are some that select Homo rudolfensis as a probable direct ancestor ● We are able to study the inter-relationship of cultural behaviour and evolution with this species (and Homo erectus) better than with any other preceding hominim form because of the larger data-set but also the expansion of the range of settlement which implies certain social and technological features of culture
  25. 25. Cranial Capacity ● Homo ergaster shows an increase in cranial capacity (700-900 cm3) from that of Homo habilis ● The skull bones are thinner and lack an obvious depression, or sulcus, on the surface, which may be the most- distinguishing characteristic between Homo ergaster and Homo erectus skulls ● Also, the face of Homo ergaster is less robust (more gracile) than is that of Homo erectus ● Homo ergaster skulls also display increased cranial breadth across the parietal bones, as well as an increase in the length of the occipital bone ● A broadening in the nasal bones and nasal openings also can be seen ● Homo ergaster skulls also show a shorter cranial base and greater development of the mandibular symphysis
  26. 26. Dentition and Diet ● The dentition of Homo ergaster is similar to that of Homo sapiens, but the teeth of the former were slightly larger to that of the latter ● However, Homo ergaster shows some dental reduction when compared to earlier Homo species ● The interesting feature of Homo ergaster teeth is located on the backside of the incisors ● These teeth are ‘scooped’ in appearance and referred to as ‘shovel-shaped' ● Some scholars have suggested that such teeth constitute an adaptation for hunter-gatherers to process food, and this is indeed a distinguishing characteristic of the Native American populations
  27. 27. Locomotion and Stature ● It is indisputable that Homo ergaster was fully bipedal—the pelvis, joints and vertebral column demonstrate this ● This species was slightly taller than Homo habilis, but the small fossil sample renders it difficult to make any statements regarding diversity in size ● Altogether, the species is more gracile and was probably faster than Homo habilis ● The long arms of Homo habilis have vanished, and there is more proportion in the body, possibly a result of evolutionary adaptations associated with full bipedalism and also a greater endurance for long- range movement ● Rather than having the ability to run quickly, Homo ergaster seems better suited for walking long distances
  28. 28. Social Structure and Behaviour ● We can be certain that Homo ergaster was capable of producing fire, for this was a necessity in their expansion within and beyond Africa ● This undoubtedly began to accelerate the transformation of dentition, the digestive tract, and the range of foods that could be consumed ● Moreover, it may have also permitted a more developed social structure focusing on the hearth and the communal sharing and preparation of food ● Expansion of range also suggests slightly larger population numbers, perhaps even an adaptive advantage over Homo habilis in that this species never appeared to have colonised new territories ● A question of climatic change, too, is also relevant to the triggers for Homo ergaster expansion, but it is probable that social structure, technological innovation, and dietary flexibility were essential for the expansion to have been successful
  29. 29. Lithic Industry ● After roughly 1.6 million years, a new lithic industry emerges in Africa known as the Acheulean ● This refers to a tool-kit based on the production of bifacially manufactured handaxes ● Although a relatively simple type of tool to produce, it was highly practical and was distributed throughout the Old World and persisted until at least the end of the Middle Palaeolithic (ca. 35,000 BP) ● Its production implies a good grasp of causality, but also a sense of symmetry that can possibly be explained with reference to the development of mechanisms coordinating the function of the two sides of the brain, namely, a change in the frontal cortex ● This industry completely supplants the chopper industry in Africa, but the chopper industry continues to flourish elsewhere— in East Asia, handaxes do not occur at all