What evidence supported the hypothesis of ..
In developing plate tectonics, continental drift helped form hypothesis of a shifting landmass and sea floor....
of evidence that support the continental drift ..
The book that made Milankovitch famous (Croll’s work is still obscure, even though Milankovitch gave full credit to Croll in his work) was co-authored by Alfred Wegener, who a decade earlier first published his hypothesis that . As is often the case with radical new hypotheses, , but Wegener was the first to propose a comprehensive hypothesis to explain an array of detailed evidence. Wegener was a meteorologist working outside of his specialty when he proposed his “continental drift” hypothesis. His hypothesis was , and . His continental drift hypothesis quickly sank into obscurity. It was not until my lifetime, when , that Wegener’s work returned from exile and became a cornerstone of geological theory. Ice age data and theory does not pose an immediate threat to the or "," so the history of developing the data and theories has been publicly available.
Were the dramatic changes in a result of cooked food, or was Turkana Boy as his species became hunters instead of hunted, and the stone tools softened up the meat and plant foods so that he did not need to chew as much? Wrangham co-authored a that began with . It concluded that food processing, cooking in particular, accounted for the effect. Cooked food versus raw food and the number of neurons that can be supported in a brain has been . The primary reason why Wrangham’s hypothesis was initially dismissed was that archeological evidence for fires that long ago is almost nonexistent. When was published, the earliest evidence with wide acceptance only supported fires , where Israel is today, which is more than a million years after Wrangham’s estimated timeframe. Wrangham did what all bold scientists do: he made falsifiable predictions. If it turned out that no evidence of early fires was ever found, his hypothesis could begin looking shaky.
supported the hypothesis of continental drift?
Just as the reason why our may have and why may have , that founder group may well as an act of desperation, driven to the margins by their neighbors. If they left about 60-50 kya, as seems the most likely timeframe in light of today’s evidence, by 10 kya the entire planet had been conquered. Behaviorally modern humans were atop all terrestrial food chains outside of Africa, and in Africa megafauna avoided them, so there was nothing on Earth that threatened human existence except for other humans. Like the way in which the australopithecine Tesla who made the first stone tool the that emerged from his/her act a half-million years later, by 10 kya (about a tenth as long as the previous epochal innovative interval). Several million descendants of that founder group were spread across the planet, from tundra to desert to rainforest, and they filled all inhabitable continents. The people existing 10 kya would have been anatomically recognizable and all had , as they do today. However, with , versus what the founders left Africa with (several million people versus ), the immensely diverse climates and the tools used to survive in them, as well as their mutually unintelligible languages, the founder group’s members would not have comprehended a tour of their descendants’ world. The founder’s descendants even began to look different as evolution marched onward, and many racial differences would have been noticeable, although the bizarre had yet to appear in . Some people of 10 kya even had companions called (first domesticated as long as 33 kya, wolves were domesticated more than once, and the modern dog was domesticated about 15 kya), which would have seemed a miracle, terror, or strange beyond imagining. The world’s large animals paid the ultimate price for fueling that expansion, and the thus began.
The Andamans are members of a racial group called , which appear to be remnant populations of the original migration from Africa. They all survived in marginal environments where they subsisted as hunter-gatherers, while later agricultural immigrants dominated arable lands. About 50 kya, a few thousand years before the migration to Australia happened, the sea level was lower and the islands of , , and formed a contiguous peninsula today called . , Australia, and were also connected and formed a continent today called . Deep water lay between those two “lost continents,” and biologists drew lines between them that noted the distribution of animals and plants that did not cross open water. is farthest north, followed by , and is farthest south. Those lines mark the limits of migrations from Sundaland toward Sahul, which followed sea level changes. About 48-46 kya, behaviorally modern humans crossed the water in boats to Sahul, and the peoples of New Guinea, Australia, and Tasmania largely lived in isolation until Europeans arrived. Those peoples have remnants in their DNA, which probably means that they interbred with them while driving them to extinction on Sundaland and Southeast Asia, before some migrated to Sahul. Aboriginal Australian isolation was almost certainly maintained in the way that Andaman Islanders did it: by killing strange peoples who came ashore. However, in 2012, a paper was published regarding evidence of contact about four kya with people probably from India, when the , , and some Indian DNA admixture were introduced into Australia, which seems related to a colonization of northern Australia by an immigrant population. More of those kinds of migrations of human DNA, technology, and domesticated species have yet to be discovered, and some may even be significant.
Wegener’s evidence for continental drift was that: ..
After full Mode 3 industries appear in Africa, there is a rapid dispersal into Eurasia between 250-200 Kyr. A northward dispersal around 250 Kyr would be consistent with polacoclimatic events, as it corresponds to the onset of interglacial conditions during Stages 7a and 7W An interesting aspect of this expansion is the subsequent relationship between Mode 2 and Mode 3 industries in either continent. The Levallois technique represents a shift of key artefacts from core to flake, so that any one core can be made to produce a number of tools, thus representing a far more efficient and task-specific technology. In Africa this technological innovation appears in relatively discrete populations during the stringent arid conditions of gladal Stage 8. The rapid expansion and associated disappearance of Mode 2 industries in eastern and southern Africa suggests a clear demographic and competitive advantage. Populations with Mode 3 industries were clearly also successful in Europe, for they rapidly became established. Nevertheless, Mode 2 industries did persist suggesting that any compteitive advantage provided by Mode 3 industries was not sufficient to replace the local populations. It is possible that more than one hominid population was present in Europe during Stage 7. If so, any biological or behavioural interactions that may have occurred between them are important for interprethig subsequent evolutionary patterns in Europe. The absence of archaeological assemblages from this peziod in southeast Asia precludes the reconstruction of events there. Eastern Asia clearly remained predominantly an area with Mode 1 populations, but there is some evidence in the northeast for the spread of Mode 2 technology.
Another discordant pattern for the Mode 4 hypothesis is the co-occurrence of modern humans and less developed technologicaI systems. The actual associations between modern humans and Mode 4 industries are either relatively young (50 Kyr), ephemeral (e.g. Pre-Aurignacian) or partial, such asthe fact that the Howiesons Poort is very much a Middle Stone Age industry with some blades. Theearliest fossils recognized morphologically as modem (Omo 1, Masks River Mouth and Border Cave inAfrica, and the Skhul and Qafzeh series in Israel) are all associated with Middle Palaeolithic or Middle Stone Age industries (Mode 3) (Allsworth-Jones 1993; Bar-Yasef 1993). The case of Skhul and Qafzeh, and their apparent association with local Levallois-Mousterian artefacts is perhaps the most cited example of a mismatch between technology and biology (Foley 1987). All the caves for the period 120-50 Kyr in Israel show a Mousterian technology, and it is only after this date that the Upper Palacolithic makes its appearance (Bar-Yosef 1992; Marks 1990). The fossil evidence, though, is not so simple. Both early modern humans (110-90 Kyr) at Skhul and Qafzeh, and later Neanderthals at Tabun, Kebara and Amud, are associated with Levallois-Mousterian assemblages. In Israel at least modern humans and Neanderthals may not have shared genes, but they do seem to have shared stone tools. This mismatch is a major problem for the SOM as generally formulated, although it does not necessarily follow that it provides support for the MM, since the alternating morphologies do not imply continuous gene flow (Foley 1987).
continental drift is being supported by various evidences ..
Learn how Alfred Wegener developed the theory of continental drift
18/09/2006 · What evidence supported wegenes hypothesis of continental ..
Continental Drift Hypothesis - Tectonophysics - Great …
14/01/2018 · What evidence does NOT support the continental drift ..
The theory of Continental Drift is also one of the ..
25/01/2008 · name three pieces of evidence wegener used to support his hypothesis of continental drift
Layers of the Earth and Continental Drift - Quizizz
But the branch of the that readers might find most interesting led to humans. Humans are in the phylum, and the last common ancestor that founded the Chordata phylum is still a mystery and understandably a source of controversy. Was our ancestor a ? A ? Peter Ward made the case, as have others for a long time, that it was the sea squirt, also called a tunicate, which in its larval stage resembles a fish. The nerve cord in most bilaterally symmetric animals runs below the belly, not above it, and a sea squirt that never grew up may have been our direct ancestor. Adult tunicates are also highly adapted to extracting oxygen from water, even too much so, with only about 10% of today’s available oxygen extracted in tunicate respiration. It may mean that tunicates adapted to low oxygen conditions early on. Ward’s respiration hypothesis, which makes the case that adapting to low oxygen conditions was an evolutionary spur for animals, will repeatedly reappear in this essay, as will . Ward’s hypothesis may be proven wrong or will not have the key influence that he attributes to it, but it also has plenty going for it. The idea that fluctuating oxygen levels impacted animal evolution has been gaining support in recent years, particularly in light of recent reconstructions of oxygen levels in the eon of complex life, called and , which have yielded broadly similar results, but their variances mean that much more work needs to be performed before on the can be done, if it ever can be. Ward’s basic hypotheses is that when oxygen levels are high, ecosystems are diverse and life is an easy proposition; when oxygen levels are low, animals adapted to high oxygen levels go extinct and the survivors are adapted to low oxygen with body plan changes, and their adaptations helped them dominate after the extinctions. The has a pretty wide range of potential error, particularly in the early years, and it also tracked atmospheric carbon dioxide levels. The challenges to the validity of a model based on data with such a wide range of error are understandable. But some broad trends are unmistakable, as it is with other models, some of which are generally declining carbon dioxide levels, some huge oxygen spikes, and the generally relationship between oxygen and carbon dioxide levels, which a geochemist would expect. The high carbon dioxide level during the Cambrian, of at least 4,000 PPM (the "RCO2" in the below graphic is a ratio of the calculated CO2 levels to today's levels), is what scientists think made the times so hot. (Permission: Peter Ward, June 2014)
Layers of the Earth and Continental Drift
As with previous critical events, , life helped terraform Earth. But the late Devonian is an instance when the rise of land plants may have also had effects. , which reduced the atmosphere’s carbon dioxide concentration by up to 80%, may have cooled Earth’s surface enough so that an ice age began and another one of Earth’s mass extinctions began. As with the , the ultimate cause for the Devonian extinctions seems to have been rising and falling sea levels, associated with growing and receding ice caps, as . Devonian extinction events began happening more than 380 mya, and a major one happened about 375 mya, called the . The reasons for the Kellwasser event are today generally attributed to the water becoming cold and anoxic.A bolide impact has been invoked in some scientific circles, but .Mountain-building and volcanic events also happened as continents began colliding to eventually form Pangaea (and the resultant silicate and basaltic weathering removed carbon dioxide from the atmosphere), and those dynamics may have been the previous major mass extinction. Black shales abounded during and after the Kellwasser event, and they are always evidence of anoxic conditions and how the oil deposits initially formed. However, the Kellwasser event anoxia may have not only been due to low atmospheric oxygen, but was also the result of eroding the newly exposed land and the detritus of the new forest biomes, which created a vast nutrient runoff into the oceans that may have initiated huge that caused anoxic events near shore.
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