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علوم گیاهی - Early Modern Homo sapiens
 

All people today are classified as Homo sapiens. Our species of humans first began to evolve nearly 200,000 years ago in association with technologies not unlike those of the early Neandertals. It is now clear that early Homo sapiens, or modern humans, did not come after the Neandertals but were their contemporaries. However, it is likely that both modern humans and Neandertals descended fromHomo heidelbergensis.

Compared to the Neandertals and other late archaic humans, modern humans generally have more delicate skeletons. Their skulls are more rounded and their brow ridges generally protrudemuch less. They rarely have the occipital buns found on the back of Neandertal skulls. They also have relatively high foreheads and pointed chins.
Neandertalmodern Homo sapiens
The first fossils of early modern humans to be identified were found in 1868 at the 27,000-23,000 year old Cro-Magnon rock shelter site near the village of Les Eyzies  in southwestern France. They were subsequently named the Cro-Magnon  people. They were very similar in appearance to modern Europeans. Males were 5 feet 4 inches to 6 feet tall (1.6-1.8 m.) That was 4-12 inches (10-31 cm.) taller than Neandertals. Their skeletons and musculature generally were less massive than the Neandertals. The Cro-Magnon had broad, small faces with pointed chins and high foreheads. Their cranial capacities were up to 1590 cm3, which is relatively large even for people today. 

Origins of Modern Humans
Current data suggest that modern humans evolved from archaic humans primarily in East Africa. A 195,000 year old fossil from the Omo 1 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 transition. It had the rounded skull case but retained the large brow ridges of archaic humans. Somewhat more advanced transitional 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 (Israel)
shortly after 100,000 years ago. There is no reliable evidence of modern humans elsewhere in the Old World until 60,000-40,000 years ago, during a short temperate period in the midst of the last ice age.
Important Early Modern Homo sapiens Sites
Date of Fossil
(years ago)

East Africa:
Herto, Middle Awash160,000-154,000
Omo 1195,000
Laetoli120,000
South Africa:
Border Cave115,000-90,000
Klasies River Mouth90,000
Israel:
Skhul and Qafzeh92,000-90,000
Australia:
Lake Mungo60,000-46,000
Asia:
Ordos (Mongolia)40,000-20,000 ?
Liujiang (China)139,000-111,000 ?
Zhirendong (China)100,000
Zhoukoudian upper cave
(China)
27,000
Europe:
Peştera cu Oase (Romania)36,000-34,000
Combe Capelle (France)35,000-30,000
Mladeč and Předmostí
(Czech Republic)
35,000-25,000
Cro-Magnon (France)27,000-23,000
Note: Artifactual evidence indicates that modernhumanswere in Europe by at least 40,000 and possibly as
early as 46,000 years ago. Dating of the earliest modern human fossils in Asia is less secure, but it is likely
that they were present there by at least 60,000 years ago and possibly 100,000 years ago.
It would seem from these dates that the location of initial modern Homo sapiens evolution and the direction of their dispersion from that area is obvious. That is not the case. Since the early 1980's, there have been two leading contradictory models that attempt to explain modern humanevolution--the replacement model and the regional continuity model.
The replacement model of Christopher Stringer and Peter Andrews proposes that modern humans evolved from archaic humans 200,000-150,000 years ago only in Africa and then some of them migrated into the rest of the Old World replacing all of the Neandertals and other late archaic humans beginning around 60,000-40,000 years ago. If this interpretation of the fossil record is correct, all people today share a relatively modern African ancestry. All other lines of humans that had descended from Homo erectus presumably became extinct. From this view, the regional anatomical differences that we now see among humans are recent developments--evolving mostly in the last 40,000 years. This hypothesis is also referred to as the "out of Africa", "Noah's ark", and "African replacement" model. 
The regional continuity model (or multiregional evolution model) advocated by Milford Wolpoff proposes that modern humans evolved more or less simultaneously in all major regions of the Old World from local archaic humans. For example, modern Chinese are seen as having evolved from Chinese archaic humans and ultimately from Chinese Homo erectus. This would mean that the Chinese and some other peoples in the Old World have great antiquity in place. Supporters of this model believe that the ultimate common ancestor of all modern people was an earlyHomo erectus in Africa who lived at least 1.8 million years ago. It is further suggested that since then there was sufficient gene flow between Europe, Africa, and Asia to prevent long-term reproductive isolation and the subsequent evolution of distinct regional species. It is argued that intermittent contact between people of these distant areas would have kept the human line a single species at any one time. However, regional varieties, or subspecies, of humans are expected to have existed.