William H. Press made some estimations in `"Man's Size in Terms of Fundamental Constants," Am. J. Phys., 48, 597-8 (1980). Press acknowledges "interesting and helpful discussions" with Victor Weiskopf.
You might check Barrow and Tipler's The Anthropic Cosmological Principle. It has quite a few references.
Rick
Richard G. Strickert, Ph.D.
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