Charley Lineweaver, a provocative cosmologist with The Australian National University, believes the "Planet of the Apes Hypothesis" -a theory subscribed to by Carl Sagan and the astronomers involved with the Search for Extraterrestrial Intelligence (SETI), that human-like intelligence is a convergent feature of evolution -that there is an intelligence niche, into which other species will evolve if the human species goes extinct is based on a flawed notion of evolution, a notion that could have serious implications for our search for intelligent life elsewhere in the Milky Way Galaxy.
Let's take a quick look at the plot of the 1968 movie, "Planet of the Apes," with Charlton Heston playing the role of Taylor, an astronaut on an interstellar journey. After traveling for over two thousand years at nearly the speed of light (during which the astronaut crew ages only 18 months due to time dilation), the spacecraft crash lands on a planet that has oxygen comprising 20 percent of the atmosphere, and a 23 hour 56 minute sidereal period.
Unsure of where in the galaxy they are, they soon discover that on this strange new world, chimpanzees and other primates have evolved to become human-like both physically and in the development of their society. Human beings, mute beasts that are captured and used for scientific experimentation, occupy a lower rung in this intelligence hierarchy.
This planet has corn, horses, and gorillas who use rifles and chimpanzees who use photographic equipment. It never occurs to them that this is, in fact, the Earth. Charlton Heston falls in love with a mute Homo sapien, and they ride away and discover the remnants of the Statue of Liberty. Only then do they realize this is planet Earth, there's no going home. They're there; as a subordinate species.
In an interview with Astrobiology, Lineweaver emphasizes that the "Planet of the Apes" hypothesis is that "such a niche exists - that human beings developed a big brain because there was selection pressure to move into this evolutionary niche. Another way of saying it is that smart organisms are better off and more fit than stupider organisms in all kinds of environments, and therefore we should expect any species anywhere in the universe to get smarter like we consider ourselves to be.
"Carl Sagan called them "functionally equivalent humans." That's what the SETI program has been based on. There is a big polarization in science between physical scientists like Paul Davies and Carl Sagan and Frank Drake on the one hand, and biologists like Ernst Mayr and George Gaylord Simpson who say that life is so quirky that human beings would never evolve again. If a species goes extinct, it doesn't come back. There may be a niche that opens when a species goes extinct, but the same species or even anything similar to it does not re-evolve into that niche.
If intelligence is good for every environment, we would see a trend in the encephalization quotient among all organisms as a function of time. The data does not show that. The evidence on Earth points to exactly the opposite conclusion. Earth had independent experiments in evolution thanks to continental drift. New Zealand, Madagascar, India, South America... half a dozen experiments over 10, 20, 50, even 100 million years of independent evolution did not produce anything that was more human-like than when it started. So it's a silly idea to think that species will evolve toward us.
"If you go to these other continents and ask zoologists, Lineweaver continues, "What do you think is the smartest thing there? Is it trying to become human? Is it any closer today than it was 50 million years ago to building a radio telescope? I think the answer would be no. If that's the answer, then there is no trend toward human-like intelligence, and this whole idea of intelligence being convergent is just an empty claim based on what we want to believe about ourselves."
Only one species of the billions of species that have existed on Earth has shown an aptitude for radios and even we failed to build one during the first 99% of our 7 million year history.
"When you look at the tree of life, it's really a bush, Lineweaver says. "All the things that are alive today are on the top, and down on the bottom we have a convergence because all life evolved from some LUCA, last universal common ancestor. If you look at all the species 600 million years ago, there'd be only one that had a head. We now see them everywhere, but only because this one species radiated. Species are quirky, like languages. The DNA sequence of one particular species is very unique. It's not something deterministic, like planetary formation. We're in the realm of biology, not in the realm of physics."
"If heads are as quirky as a species, then you can ask yourself, do we expect Indian elephants in outer space?" Linewever contines. "Not African elephants, but Indian elephants. Now, if you do not expect to find an Indian elephant on a planet orbiting Alpha Centauri, then you can not expect anything else that is species specific out there. It's important to realize that building radio telescopes is a species-specific feature. Yet we insist on maintaining that this is something intelligence does in general. We've all been brainwashed into believing that our intelligence is so wonderful that every other species would want it, including all the extraterrestrials out there."
Current estimates say that are some 100 billion stars just in our Milky Way galaxy and 10 billion trillion stars in the observable universe.There are more stars in existence than days since the universe was formed. Yet, the deafening silence from space is not surprising. There must be other radio transmitters out there, but perhaps none in our galaxy. If homo sapiens survive long enough, time will tell.
We should not expect to see any other forms of life that are genetically, functionally and intellectually similar to us." Lineweaver emphasizes. "I strongly suspect that our closest relatives in the universe are here on Earth, and they're not likely to be elsewhere."
But NASA was listening and our future searches have been reconfigured to explore for non-carbon forms of life and the totally unknown.
Source: The Daily Galaxy via spacedaily.com