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Conscious experience is a widespread phenomenon. . . No doubt it occurs in countless forms totally unimaginable to us, on other planets in other solar systems throughout the universe.
Thomas Nagle: "What is it Like to be a Bat?"
Philosophical Review, October 1974
Intelligence: Rare or Common?
Of all the questions addressed by astrobiologists, perhaps the most seemingly intractable is that of intelligent life on other planets—how likely is it that sentient, communicating creatures will evolve? In the same year that cognitive theorist Thomas Nagle probed the nature of self awareness while assuming its ubiquity, Dr. Frank Drake transmitted a powerful radio signal from Earth into space. The transmission, dubbed "the Arecibo Message," was a largely symbolic gesture that boldly proclaimed our existence and self awareness to the universe, and more practically, served as a proof-of-concept that radio communication across vast interstellar distances was within our technological grasp—as would surely be the case for other intelligent species throughout the universe.
Today it is clear that exploiting the electromagnetic spectrum allows highly efficient and effective long range communication. But is any species other than ours listening? Are there intelligent beings on other worlds who gaze upon distant stars and wonder whether sentient creatures look back with equal curiosity, or is our technological, communicating civilization a lonely sentinel? While this question has been hotly debated for years, SETI Institute scientist, Lori Marino notes that few of the assumptions underlying the argument have been tested. 'Are other worlds likely to harbor intelligent species?' is a question she and other SETI Institute colleagues are investigating with scientific rigor.
Early Years
Astronomy was an early interest of the young Marino, who always knew she'd "do something in science." As a child, she had a telescope, and fondly recalls visits to the Hayden Planetarium in New York City. She was also fascinated by the rich world of living creatures around her. She remembers her back yard as a "wild forest," full of life in all its many forms. "I used to look at other animals," she says, "and wonder what it was like to be that dog, or that cat, or that butterfly." She also vividly recalls the dioramas in the Museum of Natural History, which further engaged her imagination and broadened her knowledge of animals that were far different than the insects, birds, and domestic animals outside her back door.
Growing up during the years that Carl Sagan's vivid description of the cosmos filled the media, Marino found herself equally interested in both space and the life sciences. As an undergraduate, she decided upon a major in psychobiology (the combined study of psychology and biology) but never abandoned her interest in the stars.
Upon graduation from New York University, Marino made an effort to enroll in the Cornell Astronomy program. The attempt would result in her first encounter with Dr. Frank Drake, then head of the program. "I wrote this brash letter to Carl Sagan," she recalls, "telling him that I wanted to work with him because I was interested in extraterrestrial intelligence, that I had a solid psychology and life science background, and that I was really, REALLY smart." Sagan wrote back to say that he would have Frank Drake respond—which as it turned out, he did. "I don't know if Frank even remembers, but he responded very graciously." Drake explained to the young graduate that the astronomy program required a certain amount of astronomy and physics, and that he wished her well. She marvels that "twenty years later, here I am!"
Undaunted, Marino maintained her interest in the cosmos while entering a Ph.D. program in Biopsychology at the State University of New York in Albany, where she studied brain-behavior relationships in both cetaceans (the marine mammal group that includes dolphins and whales) and primates. She focused on what these relationships can reveal about the evolution of complex intelligence. Her specialization was a perfect match for the nascent science of exobiology and right away, she found herself giving presentations: first, at the Third Decennial US-USSR Conference on SETI in 1991, and two years later at the Bioastronomy Symposium in Santa Cruz, California. By 1995, the newly-minted Ph.D. was a regular presenter at the biennial Bioastronomy Conferences and was also giving invited talks at such prestigious research institutions as the NASA Exobiology Center at the Scripps Institution of Oceanography in San Diego.
Marino has maintained roots in the astrobiology community since, and today, she continues to work with Institute colleagues from her current home institution, Emory University in Atlanta, Georgia, on the question of the evolution of intelligence.
Primates, Dolphins and Big Brains
"Big brains are not unique to humans," says Marino, who has conducted exhaustive studies of cetacean brains using non-invasive imaging techniques and measurements from fossil skulls. The Encephalization Quotient (EQ), which is a measure of brain weight in relation to body weight, allows scientists to make general inferences about intelligence across different species. When EQ is calculated for modern humans, we come out ahead of all the other species measured thus far. But Marino discovered that dolphins are a very close runner up, and it intrigues her that while human and dolphin EQs may be similar, the two brains are organized very differently. According to Marino, the human brain and the dolphin brain represent two alternate ways to build large brains and complex intelligence.
"There is more than one way to evolve an intelligent species," she notes of the phenomena known as "convergence," which describes the appearance of analogous features in widely different biological groups (eg. eyes and wings, which have evolved frequently but independently in divergent animal groups).
Whether or not convergent intelligence is a random coincidence or indicates a trend that is driven by selection pressure, is a question that Marino investigates by examining EQ changes over time in the cetacean fossil record. Today, in a SETI Institute funded project, she and Duke University Co-PI, Dan McShea are conducting statistical analyses to determine whether the observed increase in brain size among the cetaceans is a trend that is "driven," (ie. a result of selection pressure) or random.
Marino notes that her Emory University lab may be one of the very few in the world integrating primate and cetacean studies. "There must have been a cetacean neanderthal or Lucy," says Marino, who adds that the fossil record is "spotty." Using trend analysis, however, she is certain that "we can learn quite a bit," and explains the goals of her work. "We hope to eventually link changes in brain size with occurrences in the environment to learn how a complex brain evolves." She continues, "What sort of circumstances produce complex intelligence?" Marino would like to know whether particular environmental factors were linked to brain size changes in cetaceans. The fossil record shows, for example, that in cetaceans the olfactory organs diminished in size while auditory systems enlarged.
Ultimately, Marino and McShea hope to investigate a wide range of animal groups in this manner. A cross-taxa study will provide strong evidence one way or the other as to whether intelligence is typically driven by natural selection or is a more random phenomenon. With sufficient funding, Marino and McShea can undertake further studies. "We want to look at other large mammals like carnivores and ungulates, along with non-mammalian species, such as birds" Marino notes.
In time, Marino and McShea will likely amass an extensive databank of EQ information across several species and lay to rest the issue of whether intelligent species are inevitable products of evolution. While Marino may never really know what it is like to "be a bat" or a dolphin, she is confident she will know a good deal more about how it is that intelligent species like dolphins and humans came to be on our planet. And from there, we will better understand the possibilities for worlds far beyond Earth.
August 19, 2003