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86 Our closest genetic relatives are other primates, particularly chimpan- zees. We differ from chimps by 1.2% in single nucleotide changes; duplica- tions and rearrangements of larger DNA segments add another 2.7%. The implications of those statistics lie in the mind of the beholder. Some scien- tists emphasize that chimpanzees share nearly all of our DNA; others see the genetic differences as significant.* Researchers have found that nonhuman primates show signs of emergent intelligence, suggesting that there are many different levels of intelligence rather than a rigid division between intelligent and nonintelligent. Chim- panzees may be in a transitional stage. They can simulate or image actions, suggesting a preexisting capacity for later development that appears only in humans. They can represent what they perceive; humans can represent what they imagine.“ We judge chimpanzee intelligence on our terms, particularly through their ability to understand our languages. After years of effort, researchers have been able to teach chimps only very simple linguistic concepts. Even when taught analogies, they cannot use them to form words. Psychology professor David Premack noted the contrast between human intelligence, which is flexible, and animal intelligence, which is specialized. Individual species such as bees and beavers are well adapted to certain specialized behaviors, but they are imprisoned by their adaptations. Nonetheless, the potential for intelligence may exist; some monkeys appear to have precursor areas of the brain that process species-specific vocaliza- tions that may have evolved into language areas in human precursor species.” Some believe that the dividing line between humans and other primates has grown increasingly blurry; in his book Significant Others, anthropologist Craig Stanford wrote about what he called “the ape— human continuum.” Yet, most humans do not consider chimps to be intelligent; some even eat them. Researcher Jane Goodall warned in 2004 that this practice, which she described as a crime bordering on cannibalism, could drive chimpanzees to extinction within 10 to 15 years.** A Mirror Image. The threshold between intelligence and nonintelligence may lie in the mind of the beholder. What if that beholder is an extrater- restrial whose intelligence far surpasses our own? Superior aliens might regard us as precursors of advanced species, as we look upon higher pri- mates other than ourselves. Our efforts to converse with dolphins and chimpanzees are tests of our ability to communicate across species lines. So far, we have shown only a modest talent for doing this. Probabilities: Intelligence