query: Why have whales and dolphins not evolved to have gills?
positive_passages.docid: 83300
positive_passages.text: Why don't mammals have more than 4 limbs?
negative_passages.docid: 61040
negative_passages.text: Why has grey hair evolved?
negative_passages.docid: 59760
negative_passages.text: Could cancer be in itself a evolutionary process?
negative_passages.docid: 23799
negative_passages.text: How can homosexuality evolve despite natural selection?
negative_passages.docid: 4169
negative_passages.text: Why do eukaryotic organisms have introns in their DNA?
negative_passages.docid: 101746
negative_passages.text: Auras on creatures with protection
negative_passages.docid: 33385
negative_passages.text: Why can't cloaked vessels shoot?
negative_passages.docid: 139235
negative_passages.text: Do unconcious people who fall in water die?
negative_passages.docid: 82909
negative_passages.text: Are there animal species that sense infrared light with their eyes?
negative_passages.docid: 39401
negative_passages.text: What evolutionary explanations are there for death?
negative_passages.docid: 80702
negative_passages.text: Do any sea creatures exist in The Lord of the Rings?
negative_passages.docid: 105800
negative_passages.text: Why only female mammals have well developed mammary glands?
negative_passages.docid: 15250
negative_passages.text: Why do some bad traits evolve, and good ones don't?
negative_passages.docid: 56219
negative_passages.text: Why are oxygen and hydrogen compressible, but water is barely compressible
negative_passages.docid: 23474
negative_passages.text: How can the number of genes increase through evolution?
negative_passages.docid: 122185
negative_passages.text: Why are there no organisms with metal body parts, like weapons, bones, and armour? (Or are there?)
negative_passages.docid: 132359
negative_passages.text: Does the Crumple-Horned Snorkack exist?