The origin of modern humans and the fate of the Neanderthals are two of the most hotly debated topics in paleoanthropologist
Recent fossil finds new information from the field of molecular genetics that led to a re-evaluation of the question of the origin of the modern human beings. Where, when and how did modern human beings first appear? These critical questions have engaged anthropologists since the birth of their science. In last several decades paleoanthropologists have concentrated in solving the problems of Plea- Pleistocene origins of our genus, Homo. Interest in this issue remains passionate, but we have grown to understand that the origin of our species, Homo sapiens, is the outcome of an equally interesting and complete set of evolutionary factors.
Origin of Homo Sapiens and the Fate of Neanderthals
Neanderthal refers to a group of morphologically distinct human fossils. It is found throughout Western Eurasia way back ca. 130,000-30,000 BP. They evolved in Europe from Homo heidelbergensis populations, such as those from Sima de los Huesos in Atapuerca, Spain, Steinheim in Germany and Petralona in Greece. The primary Neanderthal fossils of the Levant come from the cave sites of Tabun, Amud, Kebara, and Dederiyeh, as well as Shanidar Cave in northern Iraq. Neanderthals physically were ruggedly built, with thick chests and relatively short limbs, a body shape today found among arctic populations.
The modern humans evolved from archaic Homo sapiens primarily in East Africa. A 195,000 year old fossil from the site in Ethiopia shows the beginnings of the skull changes that we associate with modern people, including a rounded skull case and possibly a projecting chin.
A 160,000 year old skull from the Herto site in the Middle Awash area of Ethiopia also seems to be at the early stages of this evolution. It had the rounded skull case but retained the large brow ridges of archaic Homo sapiens. Somewhat more advanced intermediary forms have been found at Laetoli in Tanzania dating to about 120,000 years ago. By 115,000 years ago, early modern humans had expanded their range to South Africa and into Southwest Asia shortly after 100,000 years ago. Evidently, they did not appear elsewhere in the Old World until 60,000-40,000 years ago. This was during a short temperate period in the midst of the last ice age.
The Fossil and Genetic study of Homo Sapiens and Fate of Neanderthal
At present the only way of studying ancient ancestors was through old fossils and stone tools. As we go back further in time fossils become rarer. Of the billions of people who lived before the invention of agriculture only the fossilized remains of a few hundred have been found. In the absence of fossils, human DNA that transmits genetic information from one generation to the next has proved to be a valuable tool in recording the evolution of the human species.
Two pieces of the human genome are particularly useful in discovering human history. One is the Mitochondrial DNA and the other is the Y chromosome. These are the only two parts of the genome that are not interchanged about by the evolutionary mechanisms designed to generate diversity with each generation. Hence the Mitochondrial DNA and the Y chromosome are passed down generation to generation intact. Studies of modern DNA, especially mitochondrial DNA (mtDNA) which occurs only in the cellular organelles called mitochondria, reveal that humans are amazingly homogeneous, with rather little genetic variation.
In fact, there is significantly more genetic variation between two individual chimpanzees drawn from the same population than there is between two humans drawn randomly from a single population. Until recently, the Levant was seen as furnishing the strongest evidence for a biocultural transition between the Neanderthals and early modern human populations. In the mid-1980s, geophysicists had developed several methods, thermoluminescence, electron-spin resonance, and uranium-series, for dating sites older than 40,000 BP that provided revolutionary results.
While estimated ages for the Levantine Neanderthals were broadly comparable to those from Europe, between 65,000-47,000 BP, the new dating methods showed that the early modern humans from Skhul and Qafzeh date to 130,000-80,000 BP, older than the Neanderthals who were supposedly their ancestors (Valladas et al. 1998). Minimally, these new dates call for a reinterpretation of Neanderthal vs. early modern human biological and behavioral contrasts.
Overview from the revolution of Homo sapiens and the Fate of Neanderthal
The evolution of these two hotly debated topics in paleoanthropologists was basically about to, when and where they lived, their physical appearance, their way of living and to whom they originated. According to paleoanthropologists and some people who showed interest in studying those ancient people is that Neanderthals lived in Europe while the coming of modern man or the Homo sapiens was essentially compared to Asian people. There are many similarities in the Neanderthals and early modern humans according to archaeological records. Both lived in similar Mediterranean woodland habitats and occupied Kars tic caves.
Both hunted and gathered the same range of animal species. Such similarities are to be expected between closely related hominids, but they do not necessarily imply a close social or cultural relationship. Instead, evidence for evolutionarily significant behavioral differences between Neanderthals and early modern humans is likely to be delicate, reflected in the different strategies these humans used to realize their settlement, survival, and social goals. The specific topic they end up of arguments was about their physical appearance in which each of them was distinguish by a unique set of anatomical features. The Neanderthals are characterized with a large, long, low cranial vault with a well-developed double-arched brow ridge.
a massive facial skeleton with a very projecting mid-face, backward sloping cheeks, and large nasal aperture, with large nasal sinuses
an oddly shaped occipital region of the skull with a bulge or bun
molars with enlarged pulp chambers, and large, often very heavily worn incisors
a mandible lacking a chin and possessing a large gap behind the last molar . While the Homo sapiens were a cranial vault with a vertical forehead, rounded occipital and reduced brow ridge, a reduced facial skeleton lacking a projecting mid-face a lower jaw sporting a chin, a more modern, less robustly built skeleton. These two descriptions gave much idea on how they differ each other.
Are we genetically different from our Homo sapiens ancestors who lived 10-20,000 years ago? The answer is almost certainly yes. In fact, it is very likely that the rate of evolutionary change for our species has continuously accelerated since the end of the last ice age, roughly 10,000 years ago. The evidence for a biocultural transition between the Neanderthals and early modern human populations they creatively construct social and cultural identities that transcend actual biological kinship (Wobst 1977). The best-documented early examples of symbolic artifacts are bone, ivory and stone beads from Aurignacian.
This is mostly due to the fact that our human population has deliberately grown and moved into new kinds of environments, including cities. This has exerted strong selection for individuals who were fortunate to have immune systems that allowed them to survive. We have been exposed to new kinds of environmental pollution that can cause increased mutation rates.
There has been a marked change in diet for most people around the globe to one that is less varied and now predominantly vegetarian with a heavy dependence on foods made from cereal grains. It is not entirely clear what all of the consequences of these environmental and behavioral changes have been. However, it does appear that the average human body size has become somewhat shorter over the last 10,000 years.
Finally, can we say what direction human evolution will take in the future? This is a captivating question to consider but impossible to answer because of innumerable unknown factors. Though, it is certain that we will continue to evolve until we reach the point of realizing factored that could possibly affect our lives.
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