hypothesis

Examples of hypothesis in the following topics:

• The Scientific Method

  • Recall that a hypothesis is an educated guess that can be tested.
  • A prediction is similar to a hypothesis but it is truly a guess.
  • A valid hypothesis must be testable.
  • It simply eliminates one hypothesis that is not valid.
  • If a hypothesis is not supported by experimental data, a new hypothesis can be proposed.

• Evolution of Viruses

  • While most findings agree that viruses don't have a single common ancestor, scholars have yet to find one hypothesis about virus origins that is fully accepted in the field .
  • One possible hypothesis, called devolution or the regressive hypothesis, proposes to explain the origin of viruses by suggesting that viruses evolved from free-living cells.
  • A second hypothesis (called escapist or the progressive hypothesis) accounts for viruses having either an RNA or a DNA genome and suggests that viruses originated from RNA and DNA molecules that escaped from a host cell.
  • A third hypothesis posits a system of self-replication similar to that of other self-replicating molecules, probably evolving alongside the cells they rely on as hosts; studies of some plant pathogens support this hypothesis.

• Endosymbiotic Theory and the Evolution of Eukaryotes

  • A lot of skepticism still surrounds this hypothesis; the ideas are still debated within the biological science community.
  • Another hypothesis, the nucleus-first hypothesis, proposes the nucleus evolved in prokaryotes first, followed by a later fusion of the new eukaryote with bacteria that became mitochondria.
  • Only time and more experimentation will determine which hypothesis is best supported by data.
  • Three alternate hypotheses of eukaryotic and prokaryotic evolution are (a) the nucleus-first hypothesis, (b) the mitochondrion-first hypothesis, and (c) the eukaryote-first hypothesis.
  • Describe the genome fusion hypothesis and its relationship to the evolution of eukaryotes

• Superphylum Ecdysozoa

  • The first is called the Articulata hypothesis.
  • The other idea about the phylogeny of the Ecdysozoa is called the coelomate hypothesis.
  • With the introduction of molecular phylogenetics, the coelomate hypothesis was abandoned, although some molecular, phylogenetic support for the Coelomata continued until 2005.

• Evolution of Birds

  • Two main theories exist: the arboreal ("tree") hypothesis and the terrestrial ("land") hypothesis.
  • The arboreal hypothesis posits that tree-dwelling precursors to modern birds jumped from branch to branch using their feathers for gliding before becoming fully capable of flapping flight.
  • In contrast to this, the terrestrial hypothesis holds that running was the stimulus for flight, as wings could be used to improve running and then became used for flapping flight.

• Scientific Reasoning

  • Deductive reasoning or deduction is the type of logic used in hypothesis-based science.
  • Both types of logical thinking are related to the two main pathways of scientific study: descriptive science and hypothesis-based science.
  • Descriptive (or discovery) science, which is usually inductive, aims to observe, explore, and discover, while hypothesis-based science, which is usually deductive, begins with a specific question or problem and a potential answer or solution that can be tested.
  • Descriptive science and hypothesis-based science are in continuous dialogue.

• Biodiversity Change through Geological Time

  • The main hypothesis for its cause was a period of glaciation followed by warming.
  • This hypothesis, proposed first in 1980, was a radical explanation based on a sharp spike in the levels of iridium (which rains down from space in meteors at a fairly constant rate, but is otherwise absent on earth's surface) at the rock stratum that marks the boundary between the Cretaceous and Paleogene periods .
  • It was a radical explanation, but the report of an appropriately aged and sized impact crater in 1991 made the hypothesis more credible.
  • Now, an abundance of geological evidence supports the hypothesis.

• Genus Homo

  • The multiregional hypothesis holds that humans first arose near the beginning of the Pleistocene two million years ago and subsequent human evolution has been within a single, continuous human species.
  • The hypothesis contends that humans evolve through a combination of adaptation within various regions of the world and gene flow between those regions.
  • Proponents of multiregional origin point to fossil and genomic data and continuity of archaeological cultures as support for their hypothesis.
  • The primary alternative hypothesis is the recent African origin of modern humans, which holds that modern humans arose in Africa around 100,000–200,000 years ago, moving out of Africa around 50,000–60,000 years ago to replace archaic human forms with limited interbreeding: at least once with Neanderthals and once with Denisovans.

• Mitochondria

  • These features all support the hypothesis that mitochondria were once free-living prokaryotes.
  • The endosymbiotic hypothesis suggests mitochondria were originally prokaryotic cells, capable of implementing oxidative mechanisms.

• The Pleistocene Extinction

  • The possibility that the rapid extinction of these large animals was caused by over-hunting was first suggested in the 1900s; research into this hypothesis continues today.
  • In general, the timing of the Pleistocene extinctions correlated with the arrival of humans and not with climate-change events, which is the main competing hypothesis for these extinctions.