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84 We humans still share our planet with at least one other form of life widely regarded as intelligent: certain species of dolphins. To some research- ers, dolphin intelligence and communicativeness strongly suggest that these traits are not limited to humans. If intelligence has evolved more than once on our planet, the value of f(i) in the Drake equation may be higher than a unique evolution to intelligence would imply. Medical researcher John Lilly argued more than 40 years ago that the existence of large-brained dolphins showed that more than one intelligent species had evolved on Earth. “Within the next decade or two the human IW ane Link wn aD La en dined wel4h nent we species will establish communication with another species,” he predicted, “nonhuman, alien, possibly extraterrestrial, more probably marine.” He hoped that his book would spark public and private interest in time for us to make some preparation before we encounter such beings.” Genetically, we are no closer to dolphins than we are to large cats or rodents; dolphins emerged from a much older evolutionary branch. For millions of years, dolphins and their relatives far exceeded the intelligence of all other animals. The sudden enormous increase in their brain size was not seen again until humans began to emerge.™ Mind-Stretcher. Physicist and science fiction author Gregory Benford hypothesized that an alien visiting Earth before humans emerged might have found dolphins the obvious evolutionary path for high intelligence. Who would have taken the time to scour African forests for elusive tribes of tool-using primates?™ Behavioral biologist Lori Marino thought it significant that dolphin brains, which metabolically are ruinously expensive, have been maintained for as long as 20 million years, far longer than in hominids. Dolphins and primates are not closely related, yet they both have large brains and similar behavior capacities. This supports the idea that convergent evolution can lead to intelligence.* The convergent evolution of cognition was not built on convergent evolu- tion of brains. Complex cognitive abilities have evolved in distantly related species with vastly different brain structures.*° Dolphin researcher Diana Reiss, finding evidence that there might be similar strategies for processing, storing, and using information in widely divergent life-forms, argued that intelligence cannot be conceived only in human terms. Scientists must find a delicate balance between being anthro- pomorphic (assigning human traits to other animals) and anthropocentric (assuming that we are unique in our abilities and that only our kind of intelligence is “real” intelligence).*” Some researchers believe that dolphins display such traits as advanced social behavior, an extended childhood, self-awareness, and language. Others disagree, arguing that we may be seeing what we want to see. Sea mammal researcher Ian Boyd warned of a danger that biologists who Probabilities: Intelligence