"This pre-RNA world hypothesis has been ..
The RNA world
There was a pre-RNA world whose inhabitants ..
Nucleotides are the fundamental molecules that combine in series to form RNA. They consist of a nitrogenous base attached to a sugar-phosphate backbone. RNA is made of long stretches of specific arranged so that their sequence of bases carries information. The RNA world hypothesis holds that in the / there existed free-floating nucleotides. These nucleotides regularly formed bonds with one another, which often broke because the change in energy was so low. However, certain sequences of base pairs have catalytic properties that lower the energy of their chain being created, causing them to stay together for longer periods of time. As each chain grew longer it attracted more matching nucleotides faster, causing chains to now form faster than they were breaking down.
Although , when the late-Eocene cooling began, Africa became the primary primate refuge. Around the early Oligocene, a from Africa and evolved in isolation for the next 30 million years. Just as , simians marginalized prosimians, beginning in the Oligocene. Today’s prosimians either live where simians do not, or where they coexist with simians, they are nocturnal. Prosimians have simple social organization; most nocturnal prosimians lead solitary existences. have societies of up to 20. Monkeys have far more complex social organization than prosimians, and , although societies of about 50 are typical. Capuchins are considered the most intelligent New World monkeys, and their societies have . Studies of simian societies have shown them engaging in crude versions of human politics, which , which has caused some to .
Structural Biochemistry/RNA World Hypothesis
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.
The genetic testing that has been performed on humanity in the past generation has shown that the founder group’s pattern of migration was to continually spread out, and once the original settlement covered the continents, people did not move much at all, at least until Europe began conquering the world (and there were some ). There is little sign of warfare in those early days of migration, and the leading hypothesis is that people moved to the next valley rather than be close enough to fight each other. Any conflict would have been easily resolved by moving farther out, where more easily killed animals lived. Also, in those virgin continents, people need not have roamed far to obtain food. Today, an !Kung woman will carry her child more than 7,000 kilometers before the child can walk for himself/herself. If an !Kung woman bears twins, it is her duty to pick which child to murder, because she cannot afford to carry two. That demonstrates the limitations of today’s hunter-gatherer lifestyle, but in those halcyonic days of invading virgin continents (which had to be the Golden Age of the Hunter-Gatherer), those kinds of practices probably waned and bands grew fast. When they they split, and the new group moved to new lands where the animals, again, never saw people before. Unlike the case with humans, there would not have been a grapevine so that animals told their neighbors about the new super-predator. The first time that those megafauna saw humans was probably their last time. It is very likely, just as with all predators for all time, and as can be seen with historical hunting events such or , that those bands soon took to killing animals, harvesting the best parts, and moving on. To them it would not have been a “blitzkrieg,” but more like kids in candy stores. After a few thousand years of grabbing meat whenever the fancy took them, or perhaps less, those halcyonic days were over as the far coasts of Australia were reached and the easy meat was gone. When that land bridge formed to Tasmania about 43 kya, people crossed and were able to , until all the megafauna was gone on Tasmania. They also may have worked their way through the food chain, in which the first kills were the true mother lode. Nobody even deigned to raise a spear at anything less than a until they were gone. Then they started killing smaller prey, which eventually did wise up and were harder to kill, so humans had to work at it again and the brief golden age was over. The as they shaped the new continent to their liking, maybe recreating the savanna conditions that they left in Africa, may have also been used to flush out animals if they began to avoid humans.
Apologetics Press - The RNA World Hypothesis Explained …
For the hypothesis of "RNA world" to be credible, we must imagine a precursor sufficiently long RNA capable of replication, and it should emerge spontaneously in the prebiotic soup.
It was also hypothesized the emergence and development of life in icy environments, RNA developing more easily in ice than in high temperatures (nucleotides naturally assemble into RNA strands when they are in a frozen environment)
RNA as an enzyme
RNA enzymes, or ribozymes, are found in today's DNA-based life and could be examples of living fossils.
The problems associated with the RNA world hypothesis are well known
17/08/2011 · What is the origin of life on Earth
The RNA World Hypothesis is ..
Teach Astronomy - Pre-RNA World
The RNA world
without pre_rRNAprocessing as an RNA-world discusses the ..
30/09/2015 · Are there any serious alternatives to the RNA world ..
The RNA World and other origin-of-life theories. by Brig …
It is known that the RNA is an efficient catalyst and like DNA it has the ability to store information.
A slightly different version of the hypothesis is that a different type of nucleic acid, called "pre-RNA" was the first to come as self-replicating molecule to be replaced later by RNA.
Today, research in the RNA world is a medium-sized industry
Many other ribozyme functions exist; for example, the hammerhead ribozyme performs self-cleavage and an RNA polymerase ribozyme can synthesize a short RNA strand from a primed RNA template.
Among the enzymatic properties important for the beginning of life are:
• The ability to self-replicate, or synthesize other RNA molecules;
• The ability to catalyze simple chemical reactions
• The ability to catalyse the formation of peptide bonds to produce short peptides or longer proteins.
Biology: Biology, study of living things and their vital processes
However RNA is less stable.
The phrase "RNA World" was first used by the novel prize Walter Gilbert in 1986, commenting on the recent observations of the catalytic properties of various forms of RNA.
The field deals with all the physicochemical aspects of life
The RNA world hypothesis is a theory which proposes that a world filled with (ribonucleic acid) based life predates current (deoxyribonucleic acid) based life. RNA, which can store information like DNA reactions like (), may have supported cellular or pre-cellular life. Some theories as to the present RNA-based catalysis and information storage as the first step in the evolution of cellular life.
There is no evidence for pre ..
The RNA world is proposed to have into the DNA and protein world of today. DNA, through its greater chemical stability, took over the role of while protein, which is more flexible in catalysis through the great variety of amino acids, became the specialized catalytic molecules. The RNA world hypothesis suggests that RNA in modern cells, in particular (RNA in the which production), is the evolutionary remnant of the RNA world.
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