Cycle of violence hypothesis definition by Bethany …
Scientists often measure extinction rates at the and levels of the taxonomy; families and genera are far harder to kill off than species. Some genera/families beat the odds and survived for hundreds of millions of years. They are called , and usually all of their close relatives went extinct long ago. The ubiquitous and lowly is a living fossil that first appeared nearly 400 mya. There have been recent calls to retire the "living fossil" designation, as the survivors of their lines have evolved somewhat over the years. However, it was not all that much, as they were very recognizable decedents of nearly identical-looking ancestors, and if those "living fossils" were graphically represented on the tree of life, they might instead be called the last leaves on their branch. Perhaps "sole survivor" conveys the meaning better. However scientists want to term it, the fact is that those "living fossils" have an ancient lineage, have not appreciably changed in millions of years, and the large "family" that they descended from all went extinct; their branch is bare except for them. The survivors evolved since their close relatives died out, but there is nothing close to them on their branch of the tree of life.
What is the cycle of violence hypothesis by Mary …
In the historical period, when technologically advanced humans encountered less advanced ones, there was cultural and genetic interchange, but in the end, the technologically advanced peoples . If any place on Earth could have been used as an illustration of the climate change hypothesis for the megafauna extinctions, ice age Europe would have been it. Ice sheets extended so far southward that Neanderthals lived in relatively few refugia, but I highly doubt that it caused their extinction. Neanderthals lived for at least 300,000 years and survived radical climate changes just fine. Human-agency skeptics have invoked unusually violent climate changes that coincidentally appeared when behaviorally advanced humans arrived around the world, but that seems to be grasping at straws. Again, there is nothing climatically unique about the past 60,000 years, , so invoking climate-change effects for humans and animals that weathered the ice age’s vagaries just fine seems to be a huge conjecture that may be politically motivated. Human-agency skeptics have crafted different kinds of climate explanations for each major extinction, such as drying in Australia, getting colder and dryer in Europe, or getting when most of the extinctions happened. At , climate was a proximate cause, not the ultimate one. The ultimate one was people virtually every time.
Recent environmental studies show that disturbed ecosystems can have cascading failures, as the removal of one part of a food chain can in , and entire ecosystems can go extinct. Cascades in today's world usually begin when the apex predator is removed (by humans, and called a ), but not always. Those cascading events can happen in aquatic and environments. Food chains are essentially energy chains , and the more complex they are, the more energy is required to sustain them. The leading hypothesis for why is also an energy-scarcity dynamic. Also, the most compelling findings that I have encountered regarding degenerative disease in humans shows that if individual cells no longer have their nutritional needs met by the organism, they stop acting out their role as specialized cells and “.” It may be difficult-to-impossible for scientists to reconstruct and test cascading failure hypotheses in ancient mass extinction events, but they may have played a major role in them, if not the dominant role.
The Controllers: A New Hypothesis of Alien Abduction
To briefly revisit , to that speculation above, scientists ideally want persuasive evidence that humans drove and to extinction. They want Acheulean or later technological artifacts associated with kills of those species. All that scientists have found for so far are some teeth and jawbones. Although such deductive reasoning is sound, the fossil and artifactual record is so thin that such evidence will probably never be adduced, even if it was a common event 150-100 kya. survived for nine million years and disappeared around when more lethal humans arrived, and a , soon after anatomically modern humans arrived in the vicinity. Is that a coincidence? There is genetic evidence that behaviorally modern humans interbred with , , and perhaps , and they all went extinct soon after those behaviorally modern humans arrived. That they interbred put to bed the hypotheses that they went extinct before arrived on the scene. If they went extinct after behaviorally modern humans arrived, as the genetic evidence clearly tells us, the implications are obvious, and any extinction hypothesis that invokes climate change or some other natural catastrophe has some high hurdles to overcome. Those events were probably early salvos of the .
essay of violence I decide hypothesis writing ..
Anthropologists and primate researchers , but relatively recent scientific findings have disproven that notion. , and it is more sophisticated with great apes. It took a few million years after the human/chimp split for our ancestors to learn to , and that culture then spread widely in Africa. The , , and were probably all closely related and at least partly interdependent, but little seemed to change . Then the and possessed a larger brain, and new tools and behaviors are evident . The timeframes continually shrank between major events in the human journey. Only 200 thousand years later, and , and new behaviors are in evidence. Only 100 thousand years after that, anatomically modern humans appeared. Only 30 thousand years after that, about 170 kya, , probably due to necessity, where life once again was eked out on the margins, and those humans may have decorated their bodies. About 100 kya, innovation seems to have accelerated again, and by 75-60 kya there is evidence of . Needles and perhaps even arrowheads first appeared about 60 kya. There is no doubt among scientists that members of made those advances, and their artifacts provided evidence of increasing cultural and technical sophistication, which soon left Neanderthals and all other land animals far behind. About 75-70 kya, a , and there is controversy today whether that eruption was partly responsible for the that passed through not long afterward. What became today’s humanity seems to have nearly gone extinct at that bottleneck.