Changes

Convergionism, on the other hand, while acknowledging that chance and circumstances play a part in shaping how life evolves, places greater emphasis on the fact that natural selection is subject to universal laws. Therefore the same motifs will tend to recur, in subtly different guises, as evolution keeps discovering the same best solutions to survival in different environments on different worlds. At the level of gross anatomy, for example, it would be surprising if certain features, such as legs, wings, fins, eyes, and ears, or their near-equivalents, did not evolve independently in many different locations in space. The phenomenon of convergent evolution on Earth suggests that this is true. On the other hand, there is the danger of anthropomorphism and we need to consider carefully the bold attempts by both scientists and science fiction writers, over the past century, to explore the outer limits of what life elsewhere might be like. H. G. Wells offered an early vision of something disturbingly alien with his Martians and selenites, while his Victorian contemporary, Arthur Conan Doyle raised the prospect of a single planet-wide organism in "The Day the Earth Screamed"-a concept given some scientific credibility by the Gaia Hypothesis. Wildly unanthropomorphic aliens go back at least as far as the Lensmen novels of E. E. "Doc" Smith in the 1930s and Olaf Stapledon's Starmaker of 1934, and earlier if one includes the now-neglected late 19th century writings of J. H. Rosny. Biologists have mused on whether life could have an entirely different chemical basis - silicon, perhaps, instead of carbon (see silicon-based life), or ammonia in place of water (see ammonia-based life). Some scientists have speculated further. Fred Hoyle described an intelligent nebula in The Black Cloud, while Frank Drake, an early pioneer of SETI, wondered if life might evolve on a neutron star (see neutron star, life on), an idea taken further and cast into fictional form by the aerospace engineer, Robert Forward.  

Convergionism, on the other hand, while acknowledging that chance and circumstances play a part in shaping how life evolves, places greater emphasis on the fact that natural selection is subject to universal laws. Therefore the same motifs will tend to recur, in subtly different guises, as evolution keeps discovering the same best solutions to survival in different environments on different worlds. At the level of gross anatomy, for example, it would be surprising if certain features, such as legs, wings, fins, eyes, and ears, or their near-equivalents, did not evolve independently in many different locations in space. The phenomenon of convergent evolution on Earth suggests that this is true. On the other hand, there is the danger of anthropomorphism and we need to consider carefully the bold attempts by both scientists and science fiction writers, over the past century, to explore the outer limits of what life elsewhere might be like. H. G. Wells offered an early vision of something disturbingly alien with his Martians and selenites, while his Victorian contemporary, Arthur Conan Doyle raised the prospect of a single planet-wide organism in "The Day the Earth Screamed"-a concept given some scientific credibility by the Gaia Hypothesis. Wildly unanthropomorphic aliens go back at least as far as the Lensmen novels of E. E. "Doc" Smith in the 1930s and Olaf Stapledon's Starmaker of 1934, and earlier if one includes the now-neglected late 19th century writings of J. H. Rosny. Biologists have mused on whether life could have an entirely different chemical basis - silicon, perhaps, instead of carbon (see silicon-based life), or ammonia in place of water (see ammonia-based life). Some scientists have speculated further. Fred Hoyle described an intelligent nebula in The Black Cloud, while Frank Drake, an early pioneer of SETI, wondered if life might evolve on a neutron star (see neutron star, life on), an idea taken further and cast into fictional form by the aerospace engineer, Robert Forward.  

 

==References==

==References==