question: How likely is it that Earth is the only planet with living beings, and that humans are the only species that have the intelligence to speak, create, develop etc?
comment: We don't really have great way to actually put a number to it, but the general consensus among scientists is that it's essentially a certainty that there *is* other intelligent life out there. Based on our current knowledge of exoplanets, it's estimated there as many as *40 billion* Earth-like planets in our galaxy alone, and at absolutely minimum, 176 billion galaxies in the observable universe (although actually estimates put the number at an astounding 2 trillion). There's nothing special about life on Earth as far as we can tell, so the odds of it not happening somewhere else in the trillions upon trillions of other worlds out there is just mind-bogglingly infinitesimal.
passages: BULLET::::- Annette Bening as Susan Anderson
  
  BULLET::::- Greg Kinnear as Perry Gordon
  
  BULLET::::- Ben Kingsley as Graydon
  
  BULLET::::- Linda Fiorentino as Helen Gordon
  
  BULLET::::- John Goodman as Roland Jones
  
  BULLET::::- Judy Greer as Rebecca
  
  BULLET::::- Danny Zorn as Randy
  
  BULLET::::- Harmony Smith as Rita
  
  BULLET::::- Richard Jenkins as Don Fisk
  
  BULLET::::- Caroline Aaron as Nadine Jones
  
  BULLET::::- Nora Dunn as Madeline
  
  BULLET::::- Cricky Long as Janice
  
  BULLET::::- Camryn Manheim as Alison
  
  BULLET::::- Ann Cusack as Liz
  
  BULLET::::- Phill Lewis as Other MD
  
  BULLET::::- Janeane Garofalo as upset airline passenger
  
  BULLET::::- Octavia Spencer as baby nurse
  
  Section::::Release.
   BULLET::::- 1989: Bill Watterson's "Calvin and Hobbes" comic strip for November 8, 1989, alludes to the possibility of an ethical threshold for first contact (or at least for the prudence of first contact) in Calvin's remark "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."
  
  Section::::Appearance in fiction.:2000s.
  
  BULLET::::- 2000: In Robert J. Sawyer's SF novel "Calculating God" (2000), Hollus, a scientist from an advanced alien civilization, denies that her government is operating under the prime directive.
   The Drake equation can be modified to determine just how unlikely intelligent life must be, to give the result that Earth has the only intelligent life that has ever arisen, either in our galaxy or the universe as a whole. This simplifies the calculation by removing the lifetime and communication constraints. Since star and planets counts are known, this leaves the only unknown as the odds that a habitable planet "ever" develops intelligent life. For Earth to have the only civilization that has ever occurred in the universe, then the odds of any habitable planet ever developing such a civilization must be less than . Similarly, for Earth to host the only civilization in our galaxy for all time, the odds of a habitable zone planet ever hosting intelligent life must be less than (about 1 in 60 billion). The figure for the universe implies that it is highly unlikely that Earth hosts the only intelligent life that has ever occurred. The figure for our galaxy suggests that other civilizations may have occurred or will likely occur in our galaxy.
   Davies discusses the possibility of multiple biospheres on Earth which evolved separately from normal life, which would be strong evidence for life being a cosmic imperative. He gives several examples of possible shadow lifeforms, as well as various methods to search for them.
  
  Section::::Contents.:Chapter 4: How Much Intelligence is Out There?
  
  In this chapter, Davies analyzes the probability of intelligent life arising on an Earth-like planet and communicating with us. His discussion is centered around the Drake Equation.
  
  Section::::Contents.:Chapter 5: New SETI: Widening the Search.
   This value remains particularly controversial. Those who favor a low value, such as the biologist Ernst Mayr, point out that of the billions of species that have existed on Earth, only one has become intelligent and from this, infer a tiny value for . Likewise, the Rare Earth hypothesis, notwithstanding their low value for above, also think a low value for dominates the analysis. Those who favor higher values note the generally increasing complexity of life over time, concluding that the appearance of intelligence is almost inevitable, implying an approaching 1. Skeptics point out that the large spread of values in this factor and others make all estimates unreliable. (See Criticism).
   The Deadliest Species
  
  The Deadliest Species is a Big Finish Productions audio drama based on the British science fiction television series "The Tomorrow People".
  
  Section::::Synopsis.
  
  "Homo Superior - the next stage of human evolution. Young people with super powers, dedicated to safeguarding planet Earth. From their secret laboratory deep beneath the streets of London, aided by their super-computer TIM, they watch and wait for others like themselves - and guard against threats to all mankind. They are the Tomorrow People."
   Although often mistaken for a planet, Earth is in reality the greatest supercomputer of all time, designed by the second-greatest supercomputer of all time, Deep Thought, to calculate the Ultimate Question of Life, The Universe and Everything (to which the answer is 42). It was built by the then-thriving custom planet industry of Magrathea to run a ten-million-year program in which organic life would play a major role. Slartibartfast, a Magrathean designer, was involved in the project and signed his name among the fjords of Norway (an area that won him an award).
   Cachalot is almost entirely covered by ocean with small ice caps and a few artificial floating islands created by humans. The dominant non-native races are intelligence-enhanced Cetacea (includes whales, dolphins, orcas and porpoises) that were brought to the planet from Terra in A.D. 2300. The name of the planet derives from the Portuguese word cachalote, a common term for head. This word was applied to the sperm whale, for its large head, when the mammals were actively hunted in Earth's oceans.
  
  The novel "Cachalot" (1980) introduced the planet to the Humanx Commonwealth universe.
  
  Section::::Hivehom.
   The frequency of occurrence of such terrestrial planets is one of the variables in the Drake equation, which estimates the number of intelligent, communicating civilizations that exist in the Milky Way.
   Conversely, many skeptics agree that ongoing research into the implications of artificial general intelligence is valuable. Skeptic Martin Ford states that "I think it seems wise to apply something like Dick Cheney's famous '1 Percent Doctrine' to the specter of advanced artificial intelligence: the odds of its occurrence, at least in the foreseeable future, may be very low — but the implications are so dramatic that it should be taken seriously"; similarly, an otherwise skeptical "Economist" stated in 2014 that "the implications of introducing a second intelligent species onto Earth are far-reaching enough to deserve hard thinking, even if the prospect seems remote".
   BULLET::::- Henry Ndede, chairman, Friends of Nairobi National Park, Kenya
  
  BULLET::::- Craig Packer, ecologist
  
  BULLET::::- Martin Palmer, chief executive, Alliance of Religions and Conservation
  
  BULLET::::- Roger Payne, president, Ocean Alliance
  
  BULLET::::- Jonathon Porritt, chair, Sustainable Development Commission, UK
  
  BULLET::::- Sandra Postel, author and global water analyst
  
  BULLET::::- Mark Stanley Price, chief executive, Durrell Wildlife Conservation Trust
  
  BULLET::::- Carlos Quesada, University of Costa Rica
  
  BULLET::::- Adam Ravetch, cameraman & Arctic wildlife specialist
  
  BULLET::::- M. Sanjayan, Lead Scientist, The Nature Conservancy
  
  BULLET::::- Clare Short, former Secretary of State for International Development
  
  BULLET::::- Sakana Ole Turede, Chair, Kitengela Pastoral Land Owners Association, Kenya
   BULLET::::- Ray Kurzweil, a computer pioneer and self-proclaimed Singularitarian, argues in "The Singularity Is Near" that the coming Singularity requires that Earth be the first planet on which sapient, technology-using life evolved. Although other Earth-like planets could exist, Earth must be the most evolutionarily advanced, because otherwise we would have seen evidence that another culture had experienced the Singularity and expanded to harness the full computational capacity of the physical universe.
  
  BULLET::::- John Gribbin, a prolific science writer, defends the hypothesis in "Alone in the Universe: Why our planet is unique".
   Monte Carlo simulations of estimates of the Drake equation factors based on a stellar and planetary model of the Milky Way have resulted in the number of civilizations varying by a factor of 100.
  
  Section::::Estimates.:Has intelligent life "ever" existed?
   First broadcast: 9:00 pm, 21 Oct 2014 on BBC Two
  
  Brian Cox explores mankind's place in the universe. He considers the possibility of alien life – could it exist and will humans ever find it?
   BULLET::::- Using new data from "Kepler", an astrobiologist has attempted to update the Drake equation. It is estimated that a biotic planet may be expected within 10-100 light years from Earth, while the nearest intelligent life is probably a few thousand light years away.
  
  BULLET::::- 4 December – Zig-zag patterns on a shell in Indonesia are believed to be 430,000 years old, making them the earliest known engravings by a human ancestor.
  
  BULLET::::- 5 December
  
  BULLET::::- NASA successfully conducts the first unmanned test flight of its Orion manned spacecraft.
   Extraterrestrial life
  
  Extraterrestrial life refers to life occurring outside of Earth which did not originate on Earth. Such hypothetical life might range from simple prokaryotes (or comparable life forms) to beings with civilizations far more advanced than humanity. The Drake equation speculates about the existence of intelligent life elsewhere in the universe. The science of extraterrestrial life in all its forms is known as exobiology.
   An estimate for the number of planets with intelligent "communicative" extraterrestrial life can be gleaned from the Drake equation, essentially an equation expressing the probability of intelligent life as the product of factors such as the fraction of planets that might be habitable and the fraction of planets on which life might arise:
  
  where:
  
  BULLET::::- N = The number of communicative civilizations
  
  BULLET::::- R* = The rate of formation of suitable stars (stars such as our Sun)
   The planet is currently under edict—all travel to the planet is expressly forbidden—by the United Church, ostensibly to protect the fragile ecosystem. More likely it is to protect the Commonwealth from the emerging world-consciousness that the massive rainforest has spawned. Bits of this plant-based sentience have been placed upon Flinx’s ship "Teacher" allowing the planet-consciousness to now travel the universe.
  
  The novel "Midworld" (1975) introduced the planet and it is also the setting for the novel "Mid-Flinx" (1995).
  
  Section::::Moth.
   Section::::Estimates.:Current estimates.:Fraction of the above that develops intelligent life,.
   Global warming can cause the planet's ice caps to melt and sea levels to rise, but if a planet gets very hot, the oceans boil away until there are no oceans left, only land. A planet without any water can have oceans brought back if hit by an "ice meteor" (a.k.a. a comet). Many things have to be kept within a certain balanced range for a planet to be able to support multicellular animal life; outside this range, only single-celled lifeforms, plants, robots, and lifeforms that have been civilized can survive. This excludes most lifeforms in this game since most are multicellular animals that are not civilized.
   For deliberate communication, the one example we have (the Earth) does not do much explicit communication, though there are some efforts covering only a tiny fraction of the stars that might look for our presence. (See Arecibo message, for example). There is considerable speculation why an extraterrestrial civilization might exist but choose not to communicate. However, deliberate communication is not required, and calculations indicate that current or near-future Earth-level technology might well be detectable to civilizations not too much more advanced than our own. By this standard, the Earth is a communicating civilization.
   Section::::Children.
  
  Section::::Children.:Durc.
   The natural world in which we live is nothing short of entrancing — wondrous really. Personally, I take great joy in sharing a world with the shimmering variety of life on earth. Nor can I believe any of us really want a planet which is a lonely wasteland. br—Reith Lecture, "Biodiversity", 2000.
  
  brbr
  
  It is nothing short of scandalous that we probably only know one out of every ten species on earth, let alone where they are or, various aspects of their biology... br—Reith Lecture, "Biodiversity", 2000.
  
  brbr
   How Much for Just the Planet?
  
  How Much for Just the Planet? is a 1987 "Star Trek" tie-in novel by John M. Ford.
  
  Section::::Plot.
   Danny Webb also appeared in the audio plays "The Girl Who Never Was" and "The Dark Husband". Shaun Parkes previously starred with David Tennant in the BBC's 2005 "Casanova" serial written by Russell T Davies. Silas Carson previously played various alien voices in "The End of the World", while Paul Kasey is a veteran at playing various monsters for "Doctor Who" and "Torchwood".
  
  Section::::Broadcast and reception.
  