As much as we have impacted it, we – people – didn’t “create” the earth. Rather, from an evolutionary standpoint, it has evolved us to its specifications.
All concerned agree it started with mud. The Bible’s Book of Genesis instructs us, God “formed man of the dust of the ground.” (1) As he expelled man from the Garden of Eden God decreed, “for dust thou art, and unto dust shalt thou return.” (2) In principle this is no different than the theory of evolution, which posits we had a similar origin.
Astrophysicists have estimated the solar system is approximately 4.6 billion years old. (3) Earth emerged as a habitable planet some 50 – 70 million years later when water in the form of liquid drops first appeared. (4) After some 200 – 700 million more years, water interacted with magma from the earth’s core to form a mineral called zircon. Geologists have discovered tiny microfossils embedded in these zircon crystals. “[I]f liquid water was available to cause … evolved geochemistry …, then such water was also available for possible biological processes. (5)
Life therefore may have started as long as 4.4 billion – 3.85 billion years ago. (6) There is an “apparent relative absence” of any traceable starting-point for how this machinery got started. (7) Once it did get started the process was hit-and-miss. “Evolution has had at least 20 separate attempts at forming multicellular organisms.” (8) In any event it progressed rapidly thereafter, possibly within as few as seven million years. (9) While scientists disagree as to exactly how this happened, most plausibly, cells evolved as virus-like complexes in the loose dirt covering this volcanic rock. (10)
Around 2.7 billion years ago chemical reactions began to manufacture carbon, which started to accumulate. (11) The result was photosynthesis, (12) which is how plants use light from the sun to create food. (13) More complex cells groups developed. (14) Over the next 500 million years they divided and converged to become larger cellular systems. “The remarkable diversity of life on Earth … arises from the cosmic abundance of carbon.” (15) In fact “more varieties of carbon-based molecules exist than of all other molecules combined.” (16)
Larger cell groups responded to thermal stress, oxygen absorption and deprivation, metabolic fuel use and different states of biochemical activity. (17) They arrived at a kind of division of labor – a “transition from cellular autonomy to cellular cooperation.” (18) Specialized cell types developed, each with different functions. (19) To some extent our cellular evolution depended on a Darwinian-style evolution of the human genome. More likely though it involved multiple factors, both genetic and non-genetic (i.e., not involving DNA). (20)
“[G]ene duplication and divergence of multiple ‘specificity-‘ or ‘identity-“ encoding proteins” resulted in extraordinary cellular diversity. (21) Almost two-thirds of animal phyla appeared during the Cambrian period between 530 and 520 million years ago. (22) Around 15 million years ago early hominids evolved and began developing. (23) Like us these transitional humans were subject to the effects of gravity and barometric pressure. Our brains are in our heads and not (say) half-way down our bodies. This required us to develop at least twice as many neural control systems. Our eyes are at the front of our heads (as opposed to, say, whales) and our ears are on the side. We walk upright on two feet. Many of our features (such as arms and legs) are bilaterally symmetrical. We maintain thermal homeostasis enabling us to maintain consistent body metabolism in a range of climates. Our digestive systems permit us to consume a variety of foodstuffs. All of these features gave us an incredible advantage as we peered over the African veldt.
There is no “necessity” or “imperative” to these aspects of our physical bodies or how they have come to develop. They could have been different in some other universe. It would not, however, be ours. For we are creatures “in” and beings “of” this particular one. We literally are “from” its earth.
Having said this, “our” corporeal features are likely to change eventually – particularly as the universe itself evolves. “The ascent of mankind required about four billion years on our particular planet,” and “at least one billion years is required for intelligent life to arise in any case.” (24) There’s no reason why life shouldn’t continue as our galaxy spirals into a black hole, about 32 billion years from now.
“In order to contemplate life in this remote setting,” however, “we must adopt the optimistic point of view that only the basic architecture for life is fundamentally necessary, and not the actual matter that makes up known life forms on earth,” (25) such as carbon. In the black hole epoch, “carbon-based life is simply not a viable option … after all the protons, and hence all the carbon nuclei, have decayed into smaller particles. Life must take other, far less conventional forms.” (26)
Our descendants, then, might be amorphous green blobs, unrecognizable to us. They may lack DNA or other characteristics we now deem essential to life as we know it. It would be interesting to see whether they still deploy tools, interact with each other, and develop culture.
(1) Bible, King James Version, Genesis 2:7. The Hebrew word םָדָא, Ādām, means “mud” or “dust.”
(2) Bible, King James Version, Genesis 3:19.
(3) Allègre, C., Manhès, G. & Göpel, C., “The age of the Earth, 59 Geochimica et Cosmochimica Acta 1445 (1995); Dalrymple, G., The Age of the Earth (1991).
(4) Zahnle, K., Arndt, N., Cockell, C., Halliday, A., Nisbet, E., Selsis, F. & Sleep, N., “Emergence of a Habitable Planet, 129 Space Sci. Rev. 35 (2007).
(5) Wilde, S., Valley, J., Peck, W. & Graham, C., “Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4Gyr ago,” 409 Nature 175 (2001).
(6) Mogzsis, S., Arrhenius, G., McKeegan, K., Harrison, T., Nutman, A. & Friend, C., “Evidence for life on Earth before 3,800 million years ago,” 384 Nature 55 (1996).
(7) Caks, J. & Field, M., “Evolution of the eukaryotic membrane-trafficking system: origin, tempo and mode,” 10 J. Cell Sci. 2977 (Sep’t 2007).
(8) Wolpert, L. & Szathmáry, E., “Evolution and the egg,” 420 Nature 745 (2002).
(9) Lazcano, A. & Miller, S., “How Long Did It Take for Life to Begin and Evolve to Cyanobacteria,” 39 J. Mol. Evol. 546 (1994).
(10) Nussinov, M., Otroshchenko, V. & Santoli, S., “The emergence of the non-cellular phase of life on the fine-grained clayish particles of the early Earth’s regolith, 42 BioSystems 111 (1997); Fry, I., The Emergence of Life on Earth: A Historical and Scientific Overview (2000); Hazen, R., Genesis: The Scientific Quest for Life’s Origins (2007).
(11) Hayes, J. & Waldbauer, J., “The carbon cycle and associated redox processes through time,” 361 Phil. Trans. R. Soc. B. 931 (2006); Archer, C. & Vance, D., “Coupled Fe and S isotope evidence for Archean microbial Fe(III) and sulfate reduction,” 34 Geology 153 (Mar. 2006).
(12) Cavalier-Smith, T.; Brasier, M. & Embley, T., “Introduction: how and when did microbes change the world?”, 361 Phil. Trans. R. Soc. B. 845 (2006); Summons, R., Bradley, A., Jahnke, L. & Waldbauer, J., “Steroids, triterpenoids and molecular oxygen,” 361 Phil. Trans. R. Soc. B. 951 (2006).
(13) Bryant, D & Frigaard, N., “Prokaryotic photosynthesis and phototrophy illuminated,” 14 Trends in Microbiology 488 (2006).
(14) Hartman, H., “Photosynthesis and the Origin of Life,” 28 Origins of Life and Evolution of Biospheres 515 (1998).
(15) Tyson, N. & Goldsmith, D., Origins 28 (2004).
(16) Tyson, N. & Goldsmith, D., op. cit. 28.
(17) Chown, S. & Storey, K., “Linking Molecular Physiology to Ecological Realities,” 79 Physiological and Biochemical Zoology 314 (2006).
(18) Kirk, D., “A twelve-step program for evolving multicellularity and a division of labor,” 27 BioEssays 299 (2005).
(19) Michod, R., “Evolution of individuality during the transition from unicellular to multicellular life,” 104 Proc. Nat’l Acad. Sci. 8613 (2007).
(20) Jablonka, E. & Lamb, M., Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life (2005).
(21) Dacks, J., Poon, P. & Field, M., “Pylogency of endocytic components yields insight into the process of nonendosymbiotic organelle evolution,” 105 Proc. Nat’l Acad. Sci. 588 (2008); Dong, L., Xiao, S., Shen, B. & Zhou, C., “Silicified Horodyskia and Paleopascichnus from upper Ediacaran cherts in South China: tentative phylogenetic interpretation and implications for evolutionary stasis, 165 J. Geo. Soc. 367 (2008).
(22) Sukumaran, P., “Cambrian Explosion of Life: the Big Bang in Metazoan Evolution,” Resonance 38 (Sep’t 2004).
(23) Several recent books trace this process, including: Dawkins, R., The Ancestor’s Tale: A Pilgrimage to the Dawn of Evolution (2005);
(24) Adams, F. & Laughlin, G., The Five Ages of the Universe 196 (1999).
(25) Adams, F. & Laughlin, G., op. cit. 146.
(26) Adams, F. & Lauchlin, G., op. cit. 146. Tyson & Goldsmith disagree; they aver, “Of all the predictions that we can make about life on other worlds, the surest seems to be that their life will be made of elements nearly the same as those used by life on Earth,” Tyson, N. & Goldsmith, D., op. cit. 234.