Natural History of Homo Erectus - Case Study Example

 The EVOLUTION of HOMO ERECTUS ( UPRIGHT MAN ) This essay considers various pieces of evidence with regard to the appearance, evolution and final disappearance of H. erectus. It considers how the species developed, its spread, habits and diet, and why there were physiological changes towards the end of its span. This is done by looking at the results of various pieces of research and discussion and consideration of the opinions which resulted. About 1.9 million years ago some early transitional humans in Africa evolved into a new, fully human species, it is thought evolving from H. habilis according to the Columbia Encyclopedia ( 2008). However, although it resembles modern man, the bone structures of this species are rather heavier on average. The size of its brain comes close to that of 21st century man , but the bones of the cranium are more robust than those of either its predecessor H. habilis, or of H. sapiens. Walker and Shipman (1996) puts the date of its earliest beginnings as far back as 2 million years ago. Most paleoanthropologists refer to this group as Homo erectus. According to Dennis O’Neill, as accessed November 2010, just a few researchers split the group into two distinct sections – Homo ergaster ( Working man) and the more common appellation of Homo erectus. The species H. erectus , originally called Pithecanthropus erectus was named by Eugène Dubois in 1894, three years after his 1891discoveries in Trinil, Java. The group were very successful in that they were able to adapt to various environments, and so were able to move out from Africa in order to populate other areas, both tropical and sub-tropical, in various parts of the Old World. Bower(1985) claims that the species was an example of ‘puncuated equilibrium’ that is a theory which states that species have definate starting points and ends. Anton ( 2003 ) argued that Homo erectus was notable for its enlarged body size and had its origins in the late Pliocene/early Pleistocene periods in Africa, but soon dispersed widely across Asia. This migration seems to have occurred at a time of general global cooling. There was little anatomical change until as recently as 800-700,000 years ago. O’Neill points out the various characteristics of this mammalian group such as binocular vision, a relatively large brain, hands that can grasp, flat finger nails instead of claws., fingerprints, a flattish face, a low birth rate of infants who receive a large amount of parental care. Three groups share these characteristics - lemurs, tarsiers and anthropoids. The apes who belong to the last group, have fully opposable thumbs as do hominids, but hominids also have true bipedalism. Chart 1 taken from Human Anthropology. How did our ancestors become human? D.O’Neill Aim. To consider how it was that homo erectus developed and evolved over time Method. A literature search using terms such as homo erectus, becoming human, bipedal hominids. Journals searched included the American Journal of Human Biology, the Yearbook of Human Anthropology, the Journal of Human Evolution and Quaternary International Literature Search and Discussion After about 700,000 years ago there were anatomical changes to the heads of H. erectus. Bower ( 1985) claims that this change occurred because a new species was about to walk the earth, in this case H. sapiens, By 500,000 years ago Homo erectus had evolved enough to make further moves into areas with seasons of cold in Asia and Europe. O’Neill puts his success in doing so down greater intelligence, coupled with the use of new technologies both with regard to obtaining food and in creating and using fire. There is evidence of hut building and the use of tools, both those made from stone and from other more perishable substances. The Columbia Encyclopedia ( 2008) also cites evidence of cooperative behavior both in areas of habitation and in hunting sites. The material culture of H. erectus was significantly more complex than that of its predecessors, including Achuelian stone tools (see Paleolithic ), a variety of tools fashioned from wood and other perishable materials, the use of fire, and seasonally occupied, oval-shaped huts. Evidence of extensive cooperative behavior is abundant in a number of European habitation and hunting sites, including Terra Amata,On the other hand Kreger points out that some researchers see H. erectus merely as an evolutionary cul de sac and stress instead the importance of H. ergaster. In his 1987 book Oxnard considers sexual dimorphism. This is a trait common in many species of both apes and hominids, but Oxnard ( page 33) asks whether H.erectus had this trait in a way that was more like humans or like species such as gorillas, chimpanzees or orangutans. However ( page 65) the author explains that it is teeth which are the most common fossil found,’ and these do not bear recognizable gonads.’ Rightmire in 2000 points out that the group disappeared from the west long before it did so in the east. Others take a rather different view placing the three species as sub species, with ergaster, heidelbergensis, and erectus all belonging to Homo sapiens. Oxnard ( page 69) asks if in species so far discovered it is possible to see the regional variations we find among modern man. He also asks whether the fossil remains supply evidence of the kind of adaptations, social and cultural, which are like, or unlike, those of modern man, concluding that such evidence is very sparse. O’Connell et al (1998) believe that H.erectus acted in ways that were different from the way in which modern man, and also the apes behaved, but are unable to be specific, which leads us to the opening remarks of O’Neill who asks two important questions. ‘How did we become upright bipedal hominids?’ and ‘How did we attain humanity and what does this mean?’ It is indeed true that in order to obtain any real understanding the evolutionary pattern of humanity knowledge is needed of both the behavior and cranial faculties of our earlier ancestors. According to Aiello and Key ( 2002) body size is of immense importance. They wrote about the various implications of being larger bodied for female Homo erectus females, who, according to estimates were on average half as heavy again as australopithecine females. There studies investigated upon inferred energy used in reproduction for Homo erectus females as compared with chimpanzee and human reproduction. The amounts of energy required daily during the periods of gestation and lactation would have been much higher for Homo erectus females, than those of australopithecines as would sum total of energy required to bring each child to maturity if the two species had reproductive systesm that were similar. The researchers suggest that by shortening the interval between births the female Homo erectus could reduce her energy costs per child, while at the same time she would increase her reproductive output. On the other hand there would be more dependent offspring requiring care at the same time. This would mean huge changes including cooperation in the division of work , as well as changes in organ size and to the menopause as mechanisms to reduce undue labour and therefore the amount of energy required. O’Connell et al ( 1998) also concentrate on the female contribution to the evolutionary process. They point out that success of this group is often attributed to male activiites such as hunting skills and scavenging, discussing how some scholars believe that this led to such things as the nuclear family, work divided according to sex and long periods of juvenile dependence upon adults. This was based upon the behavior of modern hunter gatherers who may kill at one place, but tend to drag corpses a distance before processing and cooking at a home base. O’Connell however puts forward a different picture, one in which it was female foraging and food sharing practices which positively influenced the spread and persistance of H.erectus as opposed to male dominated philopatry. O’Connell et al point out ( page 462) that there has been a major rethink about hunting, which has been discovered to be far more prevalent among non-humans than had been thought earlier, yet this has no effect upon paternal input. It is food gathering and sharing by females that has the biggest impact upon the nutrition of their offspring. Longer life spans would also have been a benefit. It is this nutritional impact that would have led to larger size and brain development, just as it can be proved to do so in modern times when a child is removed from a nutritional poor background to a better one. The gathering of tubers, which tend to occur in large numbers in one place, would favor larger group size. Then, with both a larger group size and a larger group, there would have been more success as scavengers, even when this needed to involve aggressive behavior to scare off the original killer while the meat was still relatively intact. The larger sizes would also have been a deterrent to others who might attack. However the researchers point out that large animal kill need not necessarily play the largest part in nutrition, although of course the various skills required are important ones. To throw a spear successfully requires practice, coordination and the ability to change strategies according to alterations in situations e.g. if the animal turns on them. These acquired skills could then be used in other circumstances. The better nutrition, because it led to longer life spans, also led to delays in maturity and mid life menopause. This grandmother time distinguishes them from other hominids, who may well be grandmothers, but who at the same time still have dependent offspring. . O’Neill ( page 5) stresses the changes required for true bipedalism. These are that the foramen magnum must be at the base of the skull, the spine becomes S shaped, the pelvis bowl rather than box shaped, the femurs need to slant towards the knees and the feet had to develop arches. Such changes were necessary before hominids could move away from heavily forested areas and move pout on the long march across the savannah. O’Neill describes australopithecine afarensis, ( page 7) a creature which walked upright and lived in groups about 3 to 3.5 million years ago, but whose skull was still apelike in its various characteristics. Australopithecine africanus had a larger brain , but its skeleton had many ape like qualiites. Preceding homo ergaster came homo habils, the first creature known definitely to have made use of tools. It is homo ergaster who is the common ancestor to all humanity. According to O’Neill ( page 11) homo erectus lived over a wide area from China to the west of Europe. He gives the date of his appearance on earth as 1.6 million years ago, but O’Neill states that he may have been living in Java as recently as 50,000 years ago. In 1996 Swisher et al produced evidence that H.erectus was living at the same time as H. sapiens was elsewhere in Asia. This would mean survival in Asia for one million years longer than the species lasted on mainland Africa. Anton ( 2003) places him only in Asia , but also says that H. erctus was ‘an increasingly derived hominin with several regional morphs sustained by intermittent isolation, particularly in Southeast Asia’. She refers to to large differences in size between different specimens, this phenomenom being yet unexplained. Karen Baaab ( 2006) has analyzed these size differences by undertaking skull measurements using the techniques of dimensional geometric morphometricy. Other scholars Anton admits only recognise one hominin species as having lived in the Pleistocene, that being H. sapiens. Baab was trying to see if the variations found among specimens of H. erectus clearly resembled the differences discovered in other species. She concluded that , although there was variation, but given the species wide ranging habitats this was within expected limits, and only one species should be recognised , not two as some scholars suppose. She concludes :- Variation in cranial shape uncovered in this study should be interpreted within the framework of intraspecific variation, rather than species distinctions. Yet Kreger ( accessed November 2010) points out how various anthropologists have put forward not one or two, but many names for species from this period, and some claim that because proposed dates for erectus have gradually become earlier and earlier, while for the remains of habilis, deposits have been dated later and later. This makes it difficult to prove a continuous lineage involving habilis as being ancestral to erectus. On the other hand Rightmire ( 2000) mentions the specimens discovered at Broken Hill in Zambia as long ago as 1921. These and other fossils, found both in Africa and Europe, do have some H.erectus features, but have larger craniums as well as other changes, in such bones as the occiput, the temporal bones, the nose and palate. This type is usually referred to as Homo heidelbergensis. Rightmire points out how important it is to distinguish between Homo heidelbergensis, Neanderthals and modern humans and to discover their more exact relationships. Peter Brown points out on the other hand how difficult it is to trace real links between H. erectus and H. Sapiens when looking at samples from Java and Australia, because of the usual larger total body mass of erectus. Dates of his first appearance, as given by various researchers, vary by as much as half a million years, a difference which Swisher et al ( 1996) put down to ‘doubts about uranium migration’. The same group of researchers claim that the latest specimens are 20,000 to 400,000 years younger in age than was previously thought for this species It is clear that matters are not simple and that there are a variety of facts and of opinions still to be considered. H.erectus may long ago have disappeared, but his story continues to fascinate. Conclusion There are still very many questions to be answered despite the fact that Kaifu et al published a report as long ago as 1972 claiming new evidence for continuous evolution. Current knowledge remains incomplete about the evolution of hominids in the period from the early to middle Pleistocene periods. This is because there are not only relatively few specimens available, but also because reliable standardized datasets are rare. Did for instance the changed angle of the femur which allowed true bipedalism come about as a mutation or was it gradual? Did it occur in one place or several? Bipedalism would of course mean better success at food gathering as it enabled better long distnce sight across the savannah. However it does seem clear that more than one mechanism was involved References Cited Aiello, Leslie,C.. and Key ,Cathy., 21st August 2002, Energetic consequences of being a Homo erectus female, American Journal of Human Biology , , http://onlinelibrary.wiley.com/doi/10.1002/ajhb.10069/abstract accessed 27th November 2010, Anton, Susan C., 3rd December 2003, Natural history of Homo erectus, , http://onlinelibrary.wiley.com/doi/10.1002/ajpa.10399/abstract accessed 28th November 2010 Baab, Karen L., October 2006, The taxonomic implications of cranial shape variation in Homo erectus, , Journal of Human Evolution 54 ( 2008) 827-847, http://www.karenbaab.com/uploads/1/5/6/4/1564155/baab2008_taxonomy_cranial_shape_variation_erectus.pdf accessed 28th November 2010 Bower,Bruce.,May 4th 1985,Article: Human ancestors make evolutionary changes. (Homo erectus), Science News, , http://www.highbeam.com/doc/1G1-3762051.html accessed 30th November 2010 Brown,Peter., August 2010, Nacurrie 1: Mark of ancient Java, or a caring mother’s hands, in terminal Pleistocene Australia?, Journal of Human Evolution, Volume 59, Issue 2, pages 168 – 187, http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJS-50J3D17-1&_user=10&_coverDate=08%2F31%2F2010&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1560359041&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=9bced45792949d44b36be0085a02676d&searchtype=a accessed 28th November 2010 Homo Erectus, Columbia Encyclopedia, 6th Edition (2008) http://www.encyclopedia.com/topic/Homo_erectus.aspx accessed 30th November 2010 Kaifu, Y., Aziz, F., Indriatti, E., Jacob, T., Kumiawan, I. and Babas,H., 1972 Cranial morphology of Javanese Homo erectus : New evidence for continuous evolution, specialization, and terminal extinction, Elsevier, Kidlington, United Kingdom, , Refdoc.fr , http://cat.inist.fr/?aModele=afficheN&cpsidt=20775271 accessed 29th November 2010 Kreger, C.David, Homo erectus, Archeology Info., http://www.archaeologyinfo.com/homoerectus.htm accessed 28th November 2010, O’Connell, J.F., Hawkes,K., Blurton Jones, N.G., 1999, Grandmothers and the evolution of Homo erectus, April 1998 , Journal of Human Evolution, 36, 461-485, http://www.anthro.utah.edu/PDFs/Papers/homo.pdf accessed 29th November 2010 O’Neill, D., Human Anthropology, How did our ancestors become human ?, http://www.chesapeake.edu/faculty/farley/Bio101slides/human%20anthropology.pdf accessed 28th November 2010 Oxnard, C., 1987, Fossils, Teeth and Sex: New Perspectives on Human Evolution, , Hong Kong, Hong Kong University Press. Rightmire, G. Phillip, January 2001, Patterns of hominid evolution and dispersal in the Middle Pleistocene, Quartenery International, Volume 75, Issue 1, , pages 77-84 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VGS-41V33N2-9&_user=10&_coverDate=01%2F31%2F2001&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=7f4b3b9b2fad1b01f7f007086402559c&searchtype=a accessed 29th November 2010 Swisher, C., Rink,W. , Anton, S., Schwarcz, H., Curtis,G., Spurijo Widiasmoro, A., 13th December 1996, Latest Homo erectus of Java: Potential Contemporaneity with Homo sapiens in Southeast Asia, Science, , http://www.sciencemag.org/content/274/5294/1870.abstract accessed 30th November 2010 Walker, A. and Shipman, P., 1996, The wisdom of the bones. New York: Alfred E. Knopf Figures Figure 1. Chart taken from ‘Human Anthropology. How did our ancestors become human?’ D.O’Neill Read More