Find raises doubts on key theory of human evolution.

[snyper]

A 40,000-YEAR-OLD skeleton found in China has raised questions about the "out of Africa" hypothesis on how early modern humans populated the planet.

The fossil bones are the oldest from an adult "modern" human to be found in eastern Asia.

They contain features that call into question the widely held view that our direct ancestors completed their evolution in Africa before spreading out into Europe and the Far East.

The "out of Africa" hypothesis proposes that all humans alive today are descended from a small group of sub- Saharan Africans who made their way out of the continent about 60,000 years ago.

A rival theory suggests that modern humans evolved into their current form in a number of different locations around the world, not just Africa.

Some experts think people today are the result of interbreeding between the later emigrating humans and the older inhabitants they encountered.

The new discovery came after workers stumbled across the bones in Tianyuan Cave, in Zhoukoudian, near Beijing.

Experts writing in the journal Proceedings of the National Academy of Sciences dated the skeleton to between 38,500 and 42,000 years ago.

As well as having "modern" human traits, the skeleton also had physical characteristics normally seen in Neanderthals and other more ancient humans such as Homo erectus

http://news.scotsman.com/scitech.cfm?id=511592007

[Fresh]

A 40,000-YEAR-OLD skeleton found in China has raised questions about the "out of Africa" hypothesis on how early modern humans populated the planet.

The fossil bones are the oldest from an adult "modern" human to be found in eastern Asia.

They contain features that call into question the widely held view that our direct ancestors completed their evolution in Africa before spreading out into Europe and the Far East.

The "out of Africa" hypothesis proposes that all humans alive today are descended from a small group of sub- Saharan Africans who made their way out of the continent about 60,000 years ago.

A rival theory suggests that modern humans evolved into their current form in a number of different locations around the world, not just Africa.

Some experts think people today are the result of interbreeding between the later emigrating humans and the older inhabitants they encountered.

The new discovery came after workers stumbled across the bones in Tianyuan Cave, in Zhoukoudian, near Beijing.

Experts writing in the journal Proceedings of the National Academy of Sciences dated the skeleton to between 38,500 and 42,000 years ago.

As well as having "modern" human traits, the skeleton also had physical characteristics normally seen in Neanderthals and other more ancient humans such as Homo erectus

http://news.scotsman.com/scitech.cfm?id=511592007

Very Interesting; I beileve we are a long way off ever knowing...if we ever will.

[Sethos]

"Homo erectus" :laugh:

Yes, I'm immature.

[vincent]

It's like the "no electricity theory"

Suppose you get home one day and the lights are off, now the first thing that comes to mind instinctively is to flip the nearest switch. Suppose that the light doesn't work, so without further thinking you flick the switch a few more times you're forming and testing a hypothesis. After the light still fails to turn on you reject the bad switch hypothesis, and opt for a bad bulb hypothesis. So you replace the bulb and go back to the switch, after it fails to still turn on you reject that hypothesis in favor of a bad fuse.

Jsut like evolution, there being no electricity is a fact, No scientists doubt the fact that it occured amongst humans, they're just arguing certain mechanisms behind it. This is how discoveries are made, science builds on doubt, unlike the bible, or the book of Zeus, we don't take it in without questioning, we test the snot out of theories. It's a simple methodology, but creationists will take this story and run away with it, proclaiming that it's false.

[dreamz Veteran]

moved here

[TheElite]

It's like the "no electricity theory"

Suppose you get home one day and the lights are off, now the first thing that comes to mind instinctively is to flip the nearest switch. Suppose that the light doesn't work, so without further thinking you flick the switch a few more times you're forming and testing a hypothesis. After the light still fails to turn on you reject the bad switch hypothesis, and opt for a bad bulb hypothesis. So you replace the bulb and go back to the switch, after it fails to still turn on you reject that hypothesis in favor of a bad fuse.

Jsut like evolution, there being no electricity is a fact, No scientists doubt the fact that it occured amongst humans, they're just arguing certain mechanisms behind it. This is how discoveries are made, science builds on doubt, unlike the bible, or the book of Zeus, we don't take it in without questioning, we test the snot out of theories. It's a simple methodology, but creationists will take this story and run away with it, proclaiming that it's false.

Not even I argue against humans evolving throughout the ages. But, only to the extent that humans WERE humans, and only the size of the body/limbs changed.

Apart from that, I don't see any reason to believe anything else, including the monkey ancestors arguement.

[Boffa Jones Veteran]

So a group of early humans couldn't make their way from Africa to china in 20,000 years? I am a bit removed from anthro class though, so after exams I will have to pay more attention to this. I just don't see how this raises doubts on any key theories of evolution. I personally think that neanderthals interbred btw.

[Jason S. Global Moderator]

Jsut like evolution, there being no electricity is a fact, No scientists doubt the fact that it occured amongst humans, they're just arguing certain mechanisms behind it. This is how discoveries are made, science builds on doubt, unlike the bible, or the book of Zeus, we don't take it in without questioning, we test the snot out of theories. It's a simple methodology, but creationists will take this story and run away with it, proclaiming that it's false.

keep in mind though Ripgut that it's the Theory of Evolution. Like the Theory of Global Warming. Too many people take theories as fact.

[The_Decryptor Veteran]

Just like the Theory of Gravity :D

[Captain_Wang]

keep in mind though Ripgut that it's the Theory of Evolution. Like the Theory of Global Warming. Too many people take theories as fact.

And too many people misunderstand the term theory.

[Boffa Jones Veteran]

And too many people misunderstand the term theory.

Apparently. It is actually kind of depressing, but when you see what passes for entertainment on tv and in movies it really isn't all that surprising.

[TheElite]

And too many people misunderstand the term theory.

It doesn't matter what the term theory means, until it is not FACT or LAW of evolution, it is still a THEORY. There is nothing which dictates that a better theory cannot be brought forward. If it does, it will either alter all the tests currently done, or throw out the current theory completely.

[vincent]

It doesn't matter what the term theory means, until it is not FACT or LAW of evolution, it is still a THEORY. There is nothing which dictates that a better theory cannot be brought forward. If it does, it will either alter all the tests currently done, or throw out the current theory completely.

:rolleyes:

Yes still a theory, tell that to the doctor next time you're prescribed antibiotics...

[TheElite]

:rolleyes:

Yes still a theory, tell that to the doctor next time you're prescribed antibiotics...

Thanks to God, I go to a doctor once in a blue moon.

[ramesees]

Can I assume from your statement ZAnwar that people who dont believe in God get ill more often?

Or that they need to visit a doctor more often?

You see where I'm going with this .......

I havent been really ill that I need the doctor for it in years, and I have no belief in a creator God, (and I'm sure the same goes for a lot of others).

[TheElite]

Can I assume from your statement ZAnwar that people who dont believe in God get ill more often?

Or that they need to visit a doctor more often?

You see where I'm going with this .......

I havent been really ill that I need the doctor for it in years, and I have no belief in a creator God, (and I'm sure the same goes for a lot of others).

No, my statement didn't mean anything more than I don't go to the doctor too often. If you dont believe in God, so be it, you dont need to thank him.

[Fred Derf Veteran]

No matter how sure scientists get about evolution it will always remain a theory. In order to make it an scientific law we would need a duplicate earth and 5 billion years of waiting around. That's not likely to happen.

There are lots of theories that are accepted as defacto law. Electromagnetic theory, the theory of gravity, etc, etc... Evolution is accepted in much the same way. There is scientific consensus.

[Captain_Wang]

Exactly. Now it does raise a philosophical question on why we intrinsically seem to have a common sense in knowing whether a theory is plausible or ludicrous but that's not a quesiton for scientists, it's for philosophers. Semantics and connotations are the enemy here.

[TheElite]

No matter how sure scientists get about evolution it will always remain a theory. In order to make it an scientific law we would need a duplicate earth and 5 billion years of waiting around. That's not likely to happen.

There are lots of theories that are accepted as defacto law. Electromagnetic theory, the theory of gravity, etc, etc... Evolution is accepted in much the same way. There is scientific consensus.

Why exactly are the theories of gravity and electromagnetic not proven as fact and therefore true law? Surely nothing else can be added?

[Boffa Jones Veteran]

Why exactly are the theories of gravity and electromagnetic not proven as fact and therefore true law? Surely nothing else can be added?

Its the same thing with Evolution, they will always be theories.

[TheElite]

Its the same thing with Evolution, they will always be theories.

Yes, but the evolution theory is a tedious task to demonstrate, these 2 are not.

[Fred Derf Veteran]

Yes, but the evolution theory is a tedious task to demonstrate, these 2 are not.

There is scientific consensus on all three of them. Don't get hung up on the fact they are referred to as theories. Some of those ideas cannot be established as laws without a duplicate earth or some other impossibility.

[davemania]

The notion that whether the earliest human linage out of Africa is not challenged but rather if modern humans were direct descedant without interbreeding is (http://en.wikipedia.org/wiki/Recent_single-origin_hypothesis). The new finding seems to supports the multi-region hypothesis (http://en.wikipedia.org/wiki/Multiregional_hypothesis), (Note how they are referred to as hypothesis)

Origins of Modern Humans:

Multiregional or Out of Africa?

By Donald Johanson

Around 30,000 years ago humans were anatomically and behaviorally similar throughout the world.

One of the most hotly debated issues in paleoanthropology (the study of human origins) focuses on the origins of modern humans, Homo sapiens.9,10,3,6,13,15,14 Roughly 100,000 years ago, the Old World was occupied by a morphologically diverse group of hominids. In Africa and the Middle East there was Homo sapiens; in Asia, Homo erectus; and in Europe, Homo neanderthalensis. However, by 30,000 years ago this taxonomic diversity vanished and humans everywhere had evolved into the anatomically and behaviorally modern form. The nature of this transformation is the focus of great deliberation between two schools of thought: one that stresses multiregional continuity and the other that suggests a single origin for modern humans.

Multiregional theory: homo erectus left Africa 2 mya to become homo sapiens in different parts of the world.

Understanding the issue

The Multiregional Continuity Model15 contends that after Homo erectus left Africa and dispersed into other portions of the Old World, regional populations slowly evolved into modern humans. This model contains the following components:

* some level of gene flow between geographically separated populations prevented speciation, after the dispersal

* all living humans derive from the species Homo erectus that left Africa nearly two million-years-ago

* natural selection in regional populations, ever since their original dispersal, is responsible for the regional variants (sometimes called races) we see today

* the emergence of Homo sapiens was not restricted to any one area, but was a phenomenon that occurred throughout the entire geographic range where humans lived

Out of Africa theory: homo sapiens arose in Africa and migrated to other parts of the world to replace other hominid species, including homo erectus. In contrast, the Out of Africa Model13 asserts that modern humans evolved relatively recently in Africa, migrated into Eurasia and replaced all populations which had descended from Homo erectus. Critical to this model are the following tenets:

* after Homo erectus migrated out of Africa the different populations became reproductively isolated, evolving independently, and in some cases like the Neanderthals, into separate species

* Homo sapiens arose in one place, probably Africa (geographically this includes the Middle East)

* Homo sapiens ultimately migrated out of Africa and replaced all other human populations, without interbreeding

* modern human variation is a relatively recent phenomenon

The multiregional view posits that genes from all human populations of the Old World flowed between different regions and by mixing together, contributed to what we see today as fully modern humans. The replacement hypothesis suggests that the genes in fully modern humans all came out of Africa. As these peoples migrated they replaced all other human populations with little or no interbreeding.

To understand this controversy, the anatomical, archaeological, and genetic evidence needs to be evaluated.

Anatomical evidence

Sometime prior to 1 million years ago early hominids, sometimes referred to as Homo ergaster, exited Africa and dispersed into other parts of the Old World. Living in disparate geographical areas their morphology became diversified through the processes of genetic drift and natural selection.

* In Asia these hominids evolved into Peking Man and Java Man, collectively referred to as Homo erectus.

* In Europe and western Asia they evolved into the Neanderthals.

Neanderthals lived in quasi isolation in Europe during a long, relatively cool period that even included glaciations. Neanderthals are distinguished by a unique set of anatomical features, including:

* a large, long, low cranial vault with a well-developed double-arched browridge

* 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

* a massive thorax, and relatively short forearms and lower legs

* although short in stature they possessed robustly built skeletons with thick walled limb bones

* long clavicles and very wide scapulas

Homo sapiens is a separate species from Neanderthals and other hominids.

By 130,000 years ago, following a prolonged period of independent evolution in Europe, Neanderthals were so anatomically distinct that they are best classified as a separate species -- Homo neanderthalensis. This is a classic example of geographic isolation leading to a speciation event.

In contrast, at roughly the same time, in Africa, a body plan essentially like our own had appeared. While these early Homo sapiens were anatomically modern they were not behaviorally modern. It is significant that modern anatomy evolved prior to modern behavior. These early sapiens were characterized by:

* 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

Hence, the anatomical and paleogeographic evidence suggests that Neanderthals and early modern humans had been isolated from one another and were evolving separately into two distinct species.

Archaeological evidence

Very interestingly, while Neanderthals and early Homo sapiens were distinguished from one another by a suite of obvious anatomical features, archaeologically they were very similar. Hominids of the Middle Stone Age of Africa (H. sapiens) and their contemporary Middle Paleolithic Neanderthals of Europe had artifact assemblages characterized as follows:

* little variation in stone tool types, with a preponderance of flake tools that are difficult to sort into discrete categories

* over long periods of time and wide geographical distances there was general similarity in tool kits

* a virtual lack of tools fashioned out of bone, antler or ivory

* burials lacked grave goods and signs of ritual or ceremony

* hunting was usually limited to less dangerous species and evidence for fishing is absent

* population densities were apparently low

* no evidence of living structures exist and fireplaces are rudimentary

* evidence for art or decoration is also lacking

The archaeological picture changed dramatically around 40-50,000 years ago with the appearance of behaviorally modern humans. This was an abrupt and dramatic change in subsistence patterns, tools and symbolic expression. The stunning change in cultural adaptation was not merely a quantitative one, but one that represented a significant departure from all earlier human behavior, reflecting a major qualitative transformation. It was literally a "creative explosion" which exhibited the "technological ingenuity, social formations, and ideological complexity of historic hunter-gatherers."7 This human revolution is precisely what made us who we are today.

The appearance of fully modern behavior apparently occurred in Africa earlier than anywhere else in the Old World, but spread very quickly, due to population movements into other geographical regions. The Upper Paleolithic lifestyle, as it was called, was based essentially on hunting and gathering. So successful was this cultural adaptation that until roughly 11,000 years ago, hominids worldwide were subsisting essentially as hunter-gatherers.

In the Upper Paleolithic of Eurasia, or the Late Stone Age as it is called in Africa, the archaeological signature stands in strong contrast to that of the Middle Paleolithic/Middle Stone Age. It was characterized by significant innovation:

* a remarkable diversity in stone tool types

* tool types showed significant change over time and space

* artifacts were regularly fashioned out of bone, antler and ivory, in addition to stone

* stone artifacts were made primarily on blades and were easily classified into discrete categories, presumably reflecting specialized use

* burials were accompanied by ritual or ceremony and contained a rich diversity of grave goods

* living structures and well-designed fireplaces were constructed

* hunting of dangerous animal species and fishing occurred regularly

higher population densities

* abundant and elaborate art as well as items of personal adornment were widespread

* raw materials such as flint and shells were traded over some distances

Homo sapiens of the Upper Paleolithic/Late Stone Age was quintessentially modern in appearance and behavior. Precisely how this transformation occurred is not well understood, but it apparently was restricted to Homo sapiens and did not occur in Neanderthals. Some archaeologists invoke a behavioral explanation for the change. For example, Soffer11 suggests that changes in social relations, such as development of the nuclear family, played a key role in bringing about the transformation.

Social or biological changes may account for "smarter" hominids.

Klein7, on the other hand, proffers the notion that it was probably a biological change brought about by mutations that played the key role in the emergence of behaviorally modern humans. His biologically based explanation implies that a major neural reorganization of the brain resulted in a significant enhancement in the manner in which the brain processed information. This is a difficult hypothesis to test since brains do not fossilize. But it is significant that no changes are seen in the shape of the skulls between earlier and later Homo sapiens. It can only be surmised from the archaeological record, which contains abundant evidence for ritual and art, that these Upper Paleolithic/Late Stone Age peoples possessed language abilities equivalent to our own. For many anthropologists this represents the final evolutionary leap to full modernity.

Shortly after fully modern humans entered Europe, roughly 40,000 years ago, the Neanderthals began a fairly rapid decline, culminating in their disappearance roughly 30,000 years ago. Neanderthals were apparently no match for the technologically advanced fully modern humans who invaded Europe and evidence for interbreeding of these two types of hominids is equivocal.

Africans display higher genetic variation than other populations, supporting the idea that they were the first modern humans.

Genetic evidence

Investigation of the patterns of genetic variation in modern human populations supports the view that the origin of Homo sapiens is the result of a recent event that is consistent with the Out of Africa Model.

* Studies of contemporary DNA, especially mitochondrial DNA (mtDNA) which occurs only in the cellular organelles called mitochondria, reveal that humans are astonishingly homogeneous, with relatively little genetic variation.1,5

* The high degree of similarity between human populations stands in strong contrast to the condition seen in our closest living relatives, the chimpanzees.2 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. Furthermore, genetic variation between populations of chimpanzees is enormously greater than differences between European, Asian and African human populations.

* In support of an African origin for Homo sapiens the work of Cann and Wilson1 has demonstrated that the highest level of genetic variation in mtDNA occurs in African populations. This implies that Homo sapiens arose first in Africa and has therefore had a longer period of time to accumulate genetic diversity. Using the genetic distance between African populations and others as a measure of time, they furthermore suggested that Homo sapiens arose between 100,000 and 400,000 years ago in Africa.

* The low amount of genetic variation in modern human populations suggests that our origins may reflect a relatively small founding population for Homo sapiens. Analysis of mtDNA by Rogers and Harpending12 supports the view that a small population of Homo sapiens, numbering perhaps only 10,000 to 50,000 people, left Africa somewhere between 50,000 and 100,000 years ago.

* Scientists recently succeeded in extracting DNA from several Neanderthal skeletons.8 After careful analysis of particularly the mtDNA, but now also some nuclear DNA, it is apparent that Neanderthal DNA is very distinct from our own. In assessing the degree of difference between DNA in Neanderthals and modern humans, the authors suggest that these two lineages have been separated for more than 400,000 years.

Although in its infancy, such genetic studies support the view that Neanderthals did not interbreed with Homo sapiens who migrated into Europe. It is, therefore, highly likely that modern humans do not carry Neanderthal genes in their DNA.

Neanderthals and modern humans coexisted in some parts of the world for thousands of years.

Additional considerations

The chronology in the Middle East does not support the Multiregional Model where Neanderthals and anatomically modern humans overlapped for a long period of time.

* Cave sites in Israel, most notably Qafzeh and Skhul date to nearly 100,000 years and contain skeletons of anatomically modern humans. Furthermore, Neanderthal remains are known from sites such as the 110,000-year-old Tabun cave, which predates the earliest Homo sapiens by about 10,000 years in the region.

* The presence of Neanderthals at two other caves in Israel, Amud and Kebara, dated to roughly 55,000 years means that Neanderthals and Homo sapiens overlapped in this region for at least 55,000 years. Therefore, if Homo sapiens were in this region for some 55,000 years prior to the disappearance of the Neanderthals, there is no reason to assume that Neanderthals evolved into modern humans.

* Archaeological evidence from Europe suggests that Neanderthals may have survived in the Iberian Peninsula until perhaps as recently as 30,000 to 35,000 years ago. Fully modern humans first appear in Europe at around 35,000-40,000 years ago, bringing with them an Upper Paleolithic tool tradition referred to as the Aurignacian. Hence, Neanderthals and fully modern humans may have overlapped for as much as 10,000 years in Europe. Again, with fully modern humans on the scene, it is not necessary to have Neanderthals evolve into modern humans, further bolstering the view that humans replaced Neanderthals.

* The situation in southern France is, however, not quite as clear. Here, at several sites, dating to roughly 40,000 years there is evidence of an archaeological industry called the Ch?telperronian that contains elements of Middle and Upper Paleolithic artifacts. Hominids from these sites are clearly Neanderthals, sparking speculation that the Ch?telperronian is an example of Neanderthals mimicking the culture of modern humans. The lack of anatomical intermediates at these sites, suggests that if Neanderthals did encounter and borrow some technology from Homo sapiens, they did not interbreed.

* A potential 24,500-year-old Neanderthal/sapiens hybrid was announced from the site of Lagar Velho, Portugal.4 This 4-year-old has a short, squat body like a Neanderthal, but possesses an anatomically modern skull. There are a number of problems with interpreting this find as a Neanderthal/sapiens hybrid.14 First of all, as a hybrid it should have a mixture of traits throughout its body and not possess the body of a Neanderthal and skull of a modern human. For example, if we look at hybrids of lions and tigers they do not possess the head of one species and the body of the other, but exhibit a morphological mixture of the two species. Secondly, and more importantly, acceptance of this specimen as a hybrid would suggest that Neanderthal traits had been retained for some 6,000 to 10,000 years after Neanderthals went extinct, which is highly unlikely. This is theoretically unlikely since Neanderthal traits would have been genetically swamped by the Homo sapiens genes over such a protracted period of time.

* Proponents of the Multiregional Model, such as Milford Wolpoff, cite evidence in Asia of regional continuity. They see an evolutionary link between ancient Homo erectus in Java right through to Australian aborigines. A possible problem with this view is that recent dating of late surviving Homo erectus in Indonesia suggests that they survived here until 50,000 years ago, which is potentially when fully modern humans may have arrived in the region from Africa.

* China may contain the best evidence for supporting the Multiregional Model. Here there are discoveries of a couple of skulls dated to roughly 100,000 years ago that seem to possess a mixture of classic Homo erectus and Homo sapiens traits. Better geological dating and more complete specimens are needed to more fully assess this possibility.

Conclusion

For the moment, the majority of anatomical, archaeological and genetic evidence gives credence to the view that fully modern humans are a relatively recent evolutionary phenomenon. The current best explanation for the beginning of modern humans is the Out of Africa Model that postulates a single, African origin for Homo sapiens. The major neurological and cultural innovations that characterized the appearance of fully modern humans has proven to be remarkably successful, culminating in our dominance of the planet at the expense of all earlier hominid populations.

http://www.actionbioscience.org/evolution/johanson.html

These fossils in no way questions the idea of evolution either.

[The_Decryptor Veteran]

scientific laws and scientific theories and similar, but different, for one a law is a very limited thing (e=mc2 is a law for example, general theory of relativity is not)

Basically, laws make predictions about how reality behaves, theories explain the laws and reality.

laws are classified as fact (as much as you can get in science), and theories describe reality, Gravity will always be a theory, same with Evolution, that's as high as they can get.

I find it funny that there is so much argumentation about Evolution, while people seemingly ignore Gravity (e.g. there are two incompatible but valid theories explaining it).

[takecare]

Why exactly are the theories of gravity and electromagnetic not proven as fact and therefore true law? Surely nothing else can be added?

because you always have alternatives that are just as valid as the one before, let me try to explain myself with an example about gravity:

when Newton first thought of "gravity", he imagined it as a force that pulls objects towards ones with more mass, later on Einstein claimed that this "object pulling" happened because greater objects (object with lots of mass) distort the time and space around them thus making nearby objects "falling" towards them (you can think it as a funnel which center is occupied by that object with a great mass), despite this, we still think of gravity as a some kind of thing we call "force" (and i'm not saying that its wrong), Einstein's theory didn't "destroy" Newton's, in my point of view it worked as some sort of patch, bringing new functions and a bigger and more detailed manual :)

anyway, hope i made myself clear.

about the theory of evolution, well the one thing that i find really hard to understand is how can anyone not accept it?