does not depend upon the units used to measure basal metabolic rate or mass, as should indeed be the case for a true physical law. In Escala (2022) he improved upon his result by including temperature as a variable. Escala’s work may be of particular interest to creationists for reasons explained in Section VB. V.AVENUES FOR FUTURE CREATIONIST RESEARCH Metabolic scaling theories suggest real possibilities for future creation research. Obviously, creationist biologists and biophysicists could work on improving such theories by incorporating still more design constraints in biological models. However, this may make the mathematics of such models intractable, at least for the foreseeable future. Ontogenetic scaling theories, however, offer much more practical opportunities. A. Ontogenetic growth theory and giantism Allometric scaling may be helpful in explaining the phenomenon of giantism, which has long been of interest to creationists. Giantism is likely caused by multiple factors. Biologists have long noted the “island rule” that small vertebrates living on islands are often larger than their mainland counterparts, while larger vertebrates shrink in size when they colonize islands (Lomolino 2005). This insular giantism/dwarfism is often accompanied by longer life spans and smaller reproductive outputs (Baxter-Gilbert et al. 2020). Reduced reproductive output in island populations makes sense as an innate design feature, as this could be a means that the Lord uses to prevent overpopulation in island settings. If so, insular giantism and dwarfism might be adaptive design features, as well. It is worth noting in passing that evolutionists worried about “overpopulation” seem to fail to consider the possibility that living things might self-adjust reproductive rates to adjust to higher or lower population densities. The ability of organisms to modulate their sizes and reproductive rates in response to changing environmental conditions could be another example of the ability of organisms to self-adjust as they continuously track their environments (Guliuzza and Gaskill 2018). Likewise, Ice Age megafauna (birds and mammals) may have grown larger to minimize heat losses in cold environments, per “Bergmann’s rule” (Bergmann 1847). It is also possible that at least some animals were still experiencing relatively long lifespans in the immediate post-Flood world. Hence, longer lifespans might have contributed to larger sizes for some of these animals. As discussed above, West et al. (2001) have developed a general model for the growth of an organism over the course of its lifetime, and it, combined with biblical considerations, may be helpful in explaining the large sizes of many animals in the pre-Flood world. Before continuing this discussion, we define the terms determinate growth and indeterminate growth. Organisms with determinate growth stop growing at maturity, whereas organisms with indeterminate growth do not. Of course, growth is really only apparently indeterminate, as there are physical limits to how big an organism can become. For example, J. B. S. Haldane (1927) used Galileo’s area-volume law to observe that a giant ten times the height of a normal man would be physiologically impossible, since increasing a man’s height by a factor of ten would make him a thousand times heavier, but the strength of his bones and muscles, being proportional to their cross-sectional area, would only become one hundred times stronger. Since a stress ten times greater than that due to body weight is sufficient to fracture a bone, such a giant would be in danger of breaking his leg simply by taking a step! Of course, this problem does not necessarily apply to the giants described in Scripture, with their much more realistic and physically plausible heights (e.g., I Samuel 17:4). It is also possible that these biblical giants were not precisely “scaled up” versions of normal-sized humans. At these larger sizes, allometric factors may have come into play, such as the development of somewhat thicker bones. In any case, it would seem that within a creationist paradigm, all growth is determinate growth, as God in His wisdom would put limits on the maximum sizes that could be attained by living creatures. This is especially clear when we consider that there was no death in the pre-Fall world. Organisms not subject to death simply could not keep growing without limit, as their sizes would eventually become physically untenable. Hence, God must have placed pre-determined limits on the sizes of living things. So what we observe as apparently indeterminate growth might simply be the result of much shorter lifespans than those attained to in the pre-Flood and immediate post-Flood worlds. Creationists have long noted the large sizes of many now-extinct animals (Nelson 2017) and have suggested (Beasley 1990) that longer lifespans allowed pre-Flood creatures to attain larger sizes at maturity than in today’s world. It may be that creatures today with (apparently) indeterminate growth simply don’t live long enough to attain their maximum possible physical sizes. For instance, sharks and reptiles are generally indeterminate growers (Hariharan et al. 2016). It is not hard to imagine that the megalodon may have been a fully mature great white shark of extreme age, and we discuss evidence for this possibility in Section VC. In an online pre-print of a paper that has admittedly not yet been peer-reviewed, Escala (2021) makes predictions about the time for an organism to reach maturity compared to its maximum possible lifespan. Hence it may be of interest to creationists attempting to explain the great longevity of pre-Flood humans. For simplicity, his predictions, unlike Escala (2022), do not take into account possible variations in temperature or oxygen consumption, but it might be possible to take those variations into account in future studies. Both evolutionists and creationists have long-speculated that higher atmospheric oxygen concentrations may have contributed to past giantism of some organisms (Dillow 1982; Harrison et. al. 2010, Wieland and Sarfati 2011). Likewise, creationists (Whitcomb and Morris 1991, Dillow 1982) have long suspected that average global temperatures in the pre-Fall world were higher than today, even if the cause of a warmer climate is unknown. Hence, a more sophisticated version of Escala’s work might enable creation researchers to at least partially explain why post-Flood lifespans are so much shorter than pre-Flood lifespans. B. Longevity: linking theory to observations In Genesis 5, the youngest age listed at which a patriarch’s son is born is 65 (Genesis 5:15, 21). Although some, perhaps many, of these sons were probably not first-born, it seems unlikely that none HEBERT Allometric and metabolic scaling 2023 ICC 214
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