Broca's Brain - Carl Sagan [60]
Reading the text is made still more difficult by the apparent conclusion (page 366) of Martian polar caps made of manna, which are described ambiguously as “probably in the nature of carbon.” Carbohydrates have a strong 3.5 micron infrared absorption feature, due to the stretching vibration of the carbon-hydrogen bond. No trace of this feature was observed in infrared spectra of the Martian polar caps taken by the Mariner 6 and 7 spacecraft in 1969. On the other hand, Mariner 6, 7 and 9 and Viking 1 and 2 have acquired abundant and persuasive evidence for frozen water and frozen carbon dioxide as the constituents of the polar caps.
Velikovsky’s insistence on a celestial origin of petroleum is difficult to understand. Some of his references, for example in Herodotus, provide perfectly natural descriptions of the combustion of petroleum upon seepage to the surface in Mesopotamia and Iran. As Velikovsky himself points out (pages 55–56), the fire-rain and naphtha stories derive from precisely those regions of the Earth that have natural petroleum deposits. There is, therefore, a straightforward terrestrial explanation of the stories in question. The amount of downward seepage of petroleum in 2,700 years would not be very great. The difficulty in extracting petroleum from the Earth, which is the cause of certain practical problems today, would be greatly ameliorated if Velikovsky’s hypothesis were true. It is also very difficult to understand on his hypothesis how it is, if oil fell from the skies in 1500 B.C., that petroleum deposits are intimately mixed with chemical and biological fossils of tens to hundreds of millions of years ago. But this circumstance is readily explicable if, as most geologists have concluded, petroleum arises from decaying vegetation, of the Carboniferous and other early geological epochs, and not from comets.
Even stranger are Velikovsky’s views on extraterrestrial life. He believes that much of the “Vermin,” and particularly the flies referred to in Exodus, really fell from his comet—although he hedges on the extraterrestrial origin of frogs while approvingly quoting from the Iranian text, the Bundahis (page 183), which seems to admit a rain of cosmic frogs. Let us consider flies only. Shall we expect houseflies or Drosophila melanogaster in forthcoming explorations of the clouds of Venus and Jupiter? He is quite explicit: “Venus—and therefore also Jupiter—is populated by vermin” (page 369). Will Velikovsky’s hypothesis fall if no flies are found?
The idea that, of all the organisms on Earth, flies alone are of extraterrestrial origin is curiously reminiscent of Martin Luther’s exasperated conclusion that, while the rest of life was created by God, the fly must have been created by the Devil because there is no conceivable practical use for it. But flies are perfectly respectable insects, closely related in anatomy, physiology and biochemistry to the other insecta. The possibility that 4.6 billion years of independent evolution on Jupiter—even if it were physically identical to the Earth—would produce a creature indistinguishable from other terrestrial organisms is to misread seriously the evolutionary process. Flies have the same enzymes, the same nucleic acids and even the same