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23/03/2015 · The Evidence For The Endosymbiotic ..
This chapter will provide a somewhat detailed review of the Cryogenian Ice Age and its aftermath, including some of the hypotheses regarding it, evidence for it, and its outcomes, as the eon of complex life arose after it. The ran from about 850 mya to 635 mya. This review will sketch the complex interactions of life and geophysical processes, and the increasingly multidisciplinary methods being used to investigate such events, which are yielding new and important insights.
Also, the formation of Pangaea ( regarding what processes ) may have led to the dynamics that broke it apart. The Hawaiian Islands are that began forming more than 80 mya, and is due to a hotspot bubbling up from Earth’s mantle. Although the is , a prominent hypothesis is that the formation of Pangaea plugged hotspots and prevented heat from venting from Earth’s core, which led to a swelling and fracturing Pangaea. Part of the evidence for that hypothesis was relatively sudden and widespread volcanism sprouting up around Pangaea, which followed a known fracture pattern around such crustal upwellings. The volcanism and resultant fracture lines formed today’s continents. As can be seen in the during the late Permian, what became China and Siberia were on the northeast margins of Pangaea, bordering the Paleo-Tethys Ocean, and two volcanic events arising from China and Siberia are currently favored as key proximate causes of the Permian extinctions.
the endosymbiotic theory, and the evidence of similarities ..
Several lines of evidence have converged and more evidence is regularly amassed, which is telling a story of dramatic and rapid climate change spurring vegetation changes that initiated evolutionary adaptations in the cradle of humanity. Sediment cores off of East Africa in the Arabian Sea, land sediment records in East Africa, combined with studies of carbon-12/13 ratios of fossil teeth, are telling an interesting and familiar tale of human origins. Three mya, as Earth was moving toward an ice age and the climate dried, the familiar grasslands of the appeared for the first time. Cgrasses have higher proportions of carbon-13, and so will animals that eat them. The expanding Cgrasslands coincided with the disappearance of Lucy's species and the appearance of the robusts that (or perhaps eating animals that ate those plants), probably from those expanding grasslands.
led to more involved mammalian parenting behaviors and increased female participation, in addition to the great investment that females have in gestating offspring. Larger simian males are more likely to become dominant, and dominant males often get the most and best food and have enhanced reproductive rights, as females are attracted to them. Virtually all monkey and ape societies are male-dominated, and the modern ideal of human females freely choosing their mates (or, perhaps more importantly, non-dominant males choosing their mates, if they get to mate at all) is rarely in evidence in monkey and ape societies, and is a new phenomenon for humans. The phenomenon of attractive women mating with rich and powerful men has deep roots in the simian evolutionary journey.
The Supporting Evidence For The Endosymbiotic Theory Biology Essay
Until the 20th century, people had no idea how their activities impacted a portion of their environment that may end up hastening humanity’s demise more than self-made deserts: the atmosphere. Agriculture and civilization meant deforestation, and there is compelling evidence that the Domestication Revolution began altering the composition of Earth’s atmosphere from its earliest days. The natural trend of carbon dioxide decline was reversed beginning about 6000 BCE. Instead of declining from about 260 PPM at 6000 BCE to about 240 PPM today, which would have been the natural trend, it began rising and reached 275 PPM by about 3000 BCE. At the beginning of the Industrial Revolution, atmospheric carbon dioxide concentrations were about 40 PPM higher than the natural trend would suggest. When a forest is razed and the resultant wood is burned, which is usually wood’s ultimate fate in civilizations, it liberated carbon that the tree absorbed from the atmosphere during . , and human activities began measurably adding methane to the atmosphere by about 3000 BCE, which coincided with the rise of the rice paddy system in China. In nature, methane is primarily produced by decaying vegetation in wetlands, both in the tropics and the Arctic, and human activities have increased wetlands even as they made other regions arid. Domestic grazing animals and human digestive systems also contribute to methane production. Atmospheric alteration by human activities has only come to public awareness in my lifetime, but human activities have had a measurable effect on greenhouse gases since the beginnings of civilization, even though the effects were modest compared to what has happened during the Industrial Revolution, as humans burn Earth’s hydrocarbon deposits with abandon.
People on the edge of starvation will rarely if ever display enlightened activities in relationship to their environment or each other, as they battle for survival. Early farmers could see the effects of deforestation, erosion, and soil exhaustion, but gentle, sustainable practices were often defeated by market forces, imperial prerogatives, and warfare. What could be obvious to farmers was not evident to potentates sitting on distant urban thrones, merchants, or money-changers, and as the city conquered what became the hinterland, short-term economic plunder took precedence over long-term environmental management far too frequently.
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Evidence for the Evolution of Eukaryotic Cells - Sydney
From about 32 kya to 22 kya, prevailed in Europe. That culture produced the and art such as the . By 20 kya, . But as far as human expansion is concerned, the Gravettian (and related cultures) are most notorious as mammoth hunters extraordinaire for those that lived on the near the ice sheets. To , they could not swim to Sahul, but flourished everywhere else they could get to. At , they were the ultimate hunter-gatherer kill. Also, near the ice sheets, meat could be stored in the ground. Cro-Magnons did just that, and that “freezer” full of meat led to the first seasonally sedentary humans. It long predated the Domestication Revolution when people could be sedentary year-round, but while the megafauna lasted, the first signs of what came later appeared as Cro-Magnons created villages around frozen mammoth meat. Gravettians hunted along migration routes and set traps and ambushes for mammoths. For thousands of years, mammoths were the primary focus of Gravettian hunters, and many scientists believe that humans at least . Gravettians probably used the bow and arrow, and using poisoned arrows on mammoths would have been child’s play, not a hazardous undertaking. They also tended to focus on the easy meat: the young, relatively defenseless, tender mammoths. Killing the offspring alone would have driven the slowly reproducing mammoths to extinction, and as the interglacial period began around 15 kya, there would have been new pressures on mammoths. One of them was that fewer mammoths meant that they were not terraforming their environments like they used to, and the warming climate probably reduced their range. For a mammoth facing humans, there was literally no place to hide (except maybe in the living room), and there is little reason to think that hunters would have eased up when mammoth numbers dwindled. If anything, their efforts would have to get the last ones, as they competed and fought over the final mammoths. In one lifetime or even several, the changes would have been barely noticeable, if at all. There was simply no way out for mammoths, and they went extinct south of the European ice sheets under the ministrations of Cro-Magnon hunters. More evidence of their fate is some mammoths surviving in refugia: islands where humans did not arrive until thousands of years later. mammoths survived on in the chain off of Alaska until less than six kya, and went extinct when humans arrived. Several hundred apparently full-sized mammoths survived on near Siberia and went extinct less than five kya, when humans arrived. In today's France and Spain, Gravettians also semi-settled along the migration routes of reindeer and red deer. From Spain across Europe, into today's Russia, Gravettians hunted migrating herds, and not only the mammoth was driven to extinction, but also the wooly rhino, the Irish elk, the musk ox, and steppe bison were driven to extinction as the ice sheets retreated. Neanderthals had been ambush hunting in similar fashion, and those animals, like the African megafauna, grew wary of humans, and killing those animals probably took planning and guile.
(5) What is the evidence for the endosymbiotic hypothesis?
About 30-27 kya, after Neanderthals made their final exit, the only other humans on Earth were “,” hiding in their refugia. They disappeared around when behaviorally modern humans arrived, too. For the “hobbits,” a volcanic explanation has been proffered for their extinction, although they probably coexisted with modern humans. A problem I have noticed with the arguments of human-agency skeptics is that the fossil and archeological record is currently too thin and the dates too equivocal to confidently place closely occurring events in sequence and establish causal relationships that precludes human influence. In all such extinctions, I have seen no convincing arguments and evidence that rules out the involvement of
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