For what purpose did the human brain evolve is a question that has puzzled scientists for decades.In 2010 Colin Blakemore, an Oxford neurobiologist argued that a mutation in the brain of a single human being 200,000 years ago turned intellectually able primates into a super-intelligent species that would conquer the world. Homo sapiens appears to be a genetic accident.
We failed to build a radio during the first 99% of our 7 million year existence
We are the only species of the billions of species that have existed on Earth that has shown an aptitude for radios and even we failed to build one during the first 99% of our 7 million year history, according to Australia National University’s Charles Lineweaver.
Genetic studies suggest every living human can be traced back to a single woman called “Mitochondrial Eve” who lived about 200,000 years ago, Blakemore said in an interview with The Guardian. He suggested that “the sudden expansion of the brain 200,000 years ago was a dramatic spontaneous mutation in the brain of Mitochondrial Eve or a relative which then spread through the species. A change in a single gene would have been enough.”
Some scientists, Blakemore pointed out, “believe that skills like language have a strong genetic basis, but my theory stresses the opposite, that knowledge, picked up by our now powerful brains, is the crucial mental component. It means that we are uniquely gifted in our ability to learn from experience and to pass this on to future generations.”
“There is no sign that the human brain has reached its capacity to accumulate knowledge,” adds Blakemore, “which means that the wonders we have already created – from spaceships to quantum computers – represent only the start of our achievements.”
The huge and logical downside to Blakemore’s theory is that a single generation starved of knowledge, thanks to some global disaster. for example, would be cast back to the Stone Age. “Everything”, Blakemore observes, “would be undone. On the other hand, there is no sign that the human brain has reached its capacity to accumulate knowledge, which means that the wonders we have already created – from spaceships to computers – represent only the start of our achievements.”
Sagan–human-like intelligence is a convergent feature of evolution
Carl Sagan, and later astronomers involved with the Search for Extraterrestrial Intelligence (SETI), suggested 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. A notion that could have serious implications for our search for intelligent life in the Milky Way Galaxy and beyond.
Charles Lineweaver was once attending a conference with Frank Drake– an astronomer who conducted the first radio search for extraterrestrial intelligence and was Director of the SETI Institute’s Center for the Study of Life in the Universe. On the flight to the conference, Lineweaver asked: “Frank, why do you think there are intelligent aliens who have built radio telescopes? What do you think is the strongest evidence for the idea that such human-like intelligence is a convergent feature of evolution?”
Evolution should produce not just one intelligent species, but many
Drake’s answer, says Lineweaver, went something like the following: “The Earth’s fossil record is quite clear in showing that the complexity of the central nervous system – particularly the capabilities of the brain – has steadily increased in the course of evolution. Even the mass extinctions did not set back this steady increase in brain size. It can be argued that extinction events expedite the development of cognitive abilities, since those creatures with superior brains are better able to save themselves from the sudden change in their environment. Thus smarter creatures are selected, and the growth of intelligence accelerates. We see this effect in all varieties of animals — it is not a fluke that has occurred in some small sub-set of animal life. This picture suggests strongly that, given enough time, a biota can evolve not just one intelligent species, but many. So complex life should occur abundantly.”
Once there is life of any kind, Lineweaver asks “what is the probability that it will evolve into a human-like intelligence that can build and operate radio telescopes? We define intelligence this way not out of some geeky technophilic perversity but because posed this way, we have the ability to answer the question by searching for other telescopes with our telescopes. So far, no signals from intelligent aliens have been identified.”
“Planet of the Apes” hypothesis
In an interview with NASA’s Astrobiology, Lineweaver emphasized 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 type of critters anywhere in the universe to get smarter like we consider ourselves to be.”
Harvard’s evolutionary theorist, Stephen Jay Gould, who argued in his book Wonderful Life: The Burgess Shale and the Nature of History, that with a slightly different roll of the Darwinian dice, earth would have been inhabited by creatures unimaginable, while others such as Charles S. Cockell, an astrobiologist at the University of Edinburgh and Director of the UK Center for Astrobiology, conjecture that if there is biology elsewhere in the universe we would find it strikingly familiar down to the carbon-based machinery in its cells. All life is simply living matter, “material capable of reproducing and evolving.”
Functionally equivalent humans
Echoing Cockell, 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 Colin Blakemore 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,’ says Lineweaver, “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.”
A Cosmic Perspective
“The volume of space-time within range of our telescopes—what astronomers have traditionally called ‘the universe’—is only a tiny fraction of the aftermath of the big bang,” says astrophysicist Martin Rees. “We’d expect far more galaxies located beyond the horizon, unobservable, each of which –along with any intelligences it hosts– will evolve rather like our own.”
Image credit top of page: ALMA Observatory by photographer Adhemar Duro
Editor, Jackie Faherty, astrophysicist, Senior Scientist with AMNH. Jackie was formerly a NASA Hubble Fellow at the Carnegie Institution for Science. Aside from a love of scientific research, she is a passionate educator and can often be found giving public lectures in the Hayden Planetarium. Her research team has won multiple grants from NASA, NSF, and the Heising Simons foundation to support projects focused on characterising planet-like objects. She has also co-founded the popular citizen science project entitled Backyard Worlds: Planet 9 which invites the general public to help scan the solar neighbourhood for previously missed cold worlds. A Google Scholar, Faherty has over 100 peer reviewed articles in astrophysical journals and has been an invited speaker at universities and conferences across the globe. Jackie received the 2020 Vera Rubin Early Career Prize from the American Astronomical Society, an award that recognises scientists who have made an impact in the field of dynamical astronomy and the 2021 Robert H Goddard Award for science accomplishments.