Martyn J. Fogg rebutted these ideas by delineating four potential rationales on which to evaluate the ethics of terraforming—anthropocentrism, zoocentrism, ecocentrism, and preservationism—roughly forming a spectrum from placing the most value on human utility to placing the most value on preserving nature. While concluding that arguments for protecting alien biota can be made from any of these standpoints, he also concludes with an argument, similar to Zubrin's, that strict preservationism is "untenable", since "it assumes that human consciousness, creativity, culture and technology stand outside nature, rather than having been a product of natural selection. If "Homo sapiens" is the first space faring species to have evolved on Earth, space settlement would not involve acting 'outside nature', but legitimately 'within our nature'."