In interior populations of the oldfield mouse, as in related mouse species, the majority of copies of Mc1r are active during pup development, and fur on the backs of these mice is brown. But when Hoekstra’s team looked at mice from the Gulf coast, they found that Mc1r was much less active. When coastal pups developed, less melanin was produced and fur on their backs was mostly white. Hoekstra’s team compared, base pair for base pair, the DNA sequences of the genes coding for Mc1r and its activator and inhibitor (the inhibitor is called Agouti) in inland and beach mice, and they spotted two differences. Animals sampled from coastal populations carried copies of Mc1r and Agouti genes that were just a little bit different from the copies carried by inland mice. At some point in the past, mutations altered the sequences of these two genes, and these changes caused beach mice to develop with lighter fur. Hopi E. Hoekstra, Rachel J. Hirschmann, Richard A. Bundey, Paul A. Insel, and Janet P. Crossland, “A Single Amino Acid Mutation Contributes to Adaptive Beach Mouse Color Pattern,” Science 313 (2006): 101–4; Cynthia C. Steiner, Jesse N. Weber, and Hopi E. Hoekstra, “Adaptive Variation in Beach Mice Produced by Two Interacting Pigmentation Genes,” Public Library of Science (PLoS) Biology 5 (2007): e219; Cynthia C. Steiner, Holger Römpler, Linda M. Boettger, Torsten Schönenberg, and Hopi E. Hoekstra, “The Genetic Basis of Phenotypic Convergence in Beach Mice: Similar Pigment Patterns but Different Genes,” Molecular Biology and Evolution 26 (2008): 35–45.
The beach mouse mutation to the Mc1r gene made this receptor spend less of its time in its active state, tipping the delicate balance in favor of lighter fur. The beach mouse mutation to the Agouti gene increased its activity, resulting in higher concentrations of circulating Agouti protein. Because Agouti inhibits the activity of Mc1r, mice with the beach allele of the Agouti gene showed lower levels of Mc1r activity, and pups with this mutation also developed with lighter fur. Both of these mutations lightened the color of mouse fur, and together they yielded very white mice.
8. Task Force Devil Combined Arms Assessment Team (Devil CAAT), “The Modern Warrior’s Combat Load, Dismounted Operations in Afghanistan, April–May 2003,” U.S. Army Center for Army Lessons Learned (2013).
9. A. Dugas, K. J. Zupkofska, A. DiChiara, and F. M. Kramer, “Universal Camouflage for the Future Warrior,” U.S. Army Research, Development, and Engineering Command, Natick Soldier Center, Natick, MA 01760 (2004); K. Rock, L.L. Lesher, C. Stewardson, K. Isherwood, and L. Hepfinger, “Photosimulation Camouflage Detection Test,” U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, MA (2009), NATICK/TR-09/021L.
10. Ibid.
11. Eric Coulson, “New Army Uniform Doesn’t Measure Up,” Military.com, April 5, 2007; Matthew Cox, “UCP Fares Poorly in Army Camo Test,” Army Times, September 15, 2009.
12. U.S. Government Accountability Office, “Warfighter Support: DOD Should Improve Development of Camouflage Uniforms and Enhance Collaboration Among the Services,” Report to Congressional Requesters, September 2012.
13. Ibid. See also L. Hepfinger, C. Stewardson, K. Rock, L. L. Lesher, F. M. Kramer, S. McIntosh, J. Patterson, K. Isherwood, G. Rogers, and H. Nguyen, “Soldier Camouflage for Operation Enduring Freedom (OEF): Pattern-in-Picture (PIP) Technique for Expedient Human-in-the-Loop Camouflage Assessment,” report presented at the 27th Army Science Conference, JW Marriott Grande Lakes, Orlando, FL, November 29–December 2, 2010; Joseph Venezia and Adam Peloquin, “Using a Constructive Simulation to Select a Camouflage Pattern for Use in OEF,” Proceedings of the 2011 Military Modeling and Simulation Symposium, Society for Computer Simulation International (2011).
14. A. Bartczak, K. Fortuniak, E. Maklewska, E. Obersztyn, M. Olejnik, and G. Redlich, “Camouflage as the Additional Form of Protection During Special Operations,” Techniczne Wyroby Włókiennicze 17 (2009): 15–22; M. A. Hogervorst, A. Toet, and P. Jacobs, “Design and Evaluation of (urban) Camouflage,” Proc. SPIE 7662, Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXI, 766205 (April 22, 2010).
15. This book focuses on morphological weapons of animals, and does not have space to cover the rich repertoire of chemical weapons. For interested readers I recommend Thomas Eisner, For Love of Insects (Cambridge, MA: Belknap Press of Harvard University Press, 2005), and Thomas Eisner, Maria Eisner, and Melody Siegler, Secret Weapons: Defenses of Insects, Spiders, and Other Many-Legged Creatures (Cambridge, MA: Belknap Press of Harvard University Press, 2007).
16. P. F. Colosimo, C. L. Peichel, K. Nereng, B. K. Blackman, M. D. Shapiro, and D. Schluter, “The Genetic Architecture of Parallel Armor Plate Reduction in Threespine Sticklebacks,” PloS Biology 2 (2004): E109; M. D. Shapiro, M. E. Marks, C. L. Peichel, B. K. Blackman, K. S. Nereng, B. Jónsson, D. Schluter, and D. M. Kingsley, “Genetic and Developmental Basis of Evolutionary Pelvic Reduction in Threespine Sticklebacks,” Nature 428 (2004): 717–23.
17. T. E. Reimchen, “Injuries on Stickleback from Attacks by a Toothed Predator (Oncorhynchus) and Implications for the Evolution of Lateral Plates,” Evolution 46 (1992): 1224–30.
18. Michael Bell, Matthew P. Travis, and D. Max Blouw, “Inferring Natural Selection in a Fossil Threespine Stickleback,” Paleobiology 32 (2006): 562–77.
19. Pamela F. Colosimo, Kim E. Hosemann, Sarita Balabhadra, Guadalupe Villarreal Jr., Mark Dickson, Jane Grimwood, Jeremy Schmutz, Richard M. Myers, Dolph Schluter, and David Kingsley, “Widespread Parallel Evolution in Sticklebacks by Repeated Fixation of Ectodysplasin Alleles,” Science 307 (2005): 1928–33; Rowan D. H. Barrett, Sean M. Rogers, and Dolph Schluter, “Natural Selection on a Major Armor Gene in Threespine Stickleback,” Science 322 (2008): 255–57.
20. Jun Kitano, Daniel I. Bolnick, David A. Beauchamp, Michael Mazur, Seiichi Mori, Takanori Nakano, and Catherine Peichel, “Reverse Evolution of Armor Plates in the Threespine Stickleback,” Current Biology 18 (2008): 768–74.
21. F. Wilkinson, “Arms and Armor,” Journal of the Royal Society of Arts 117 (1969): 361–64; Trevor N. Dupuy, The Evolution of Weapons and Warfare (New York: Da Capo Press, 1984).
22. Ibid.
23. Ibid.
24. F. Kottenkamp, History of Chivalry and Ancient Armour (London: Willis and Sotheran, 1857); Wilkinson, “Arms and Armor,” 361–64; Dupuy, Evolution of Weapons and Warfare; Robert L. O’Connell, Of Arms and Men: A History of War, Weapons, and Aggression (Oxford: Oxford University Press, 1989).
25. Wilkinson, “Arms and Armor,” 361–64; Dupuy, Evolution of Weapons and Warfare; Dave Grossman and Loren W. Christensen, The Evolution of Weaponry: A Brief Look at Man’s Ingenious Methods of Overcoming His Physical Limitations to Kill (Seattle: Amazon Publishing, 2012).
26. Dupuy, Evolution of Weapons and Warfare.
27. John Keegan, The Face of Battle: A Study of Agincourt, Waterloo, and the Somme (London: Penguin Books, 1983); Dupuy, Evolution of Weapons and Warfare.
28. Dupuy, Evolution of Weapons and Warfare; Grossman and Christensen, Evolution of Weaponry.
29. Dupuy, Evolution of Weapons and Warfare.
30. Grossman and Christensen, Evolution of Weaponry.
2. Teeth and Claws
1. S. B. Williams, R. C. Payne, and A. M. Wilson, “Functional Specialization of the Pelvic Limb of the Hare (Lepus europaeus),” Journal of Anatomy 210 (2007): 472–90.
2. Benjamin T. Maletzke, Gary M. Koehler, Robert B. Wielgus, Keith B. Aubry, and Marc A. Evans, “Habitat Conditions Associated with Lynx Hunting Behavior During Winter in Northern Washington,” Journal of Wildlife Management 72 (2007): 1473–78; John R. Squires and Leonard F. Ruggiero, “Winter Prey Selection of Canada Lynx in Northwestern Montana,” Journal of Wildlife Management 71 (2007): 310–15.
3. Christopher J. Brand, Lloyd B. Keith, and Charles A. Fischer, “Lynx Responses to Changing Snowshoe Hare Densities in Central Alberta,” Journal of Wildlife Management 40 (1976): 416–28; Kim G. Poole, “Characteristics of an Unharvested Lynx Population During a Snowshoe Hare Decline,” Journal of Wildlife Management 58 (1994): 6
08–18; Brian G. Slough and Garth Mowat, “Lynx Population Dynamics in an Untrapped Refugium,” Journal of Wildlife Management 60 (1996): 946–61.
4. Ronald E. Heinrich and Kenneth D. Rose, “Postcranial Morphology and Locomotor Behaviour of Two Early Eocene Miacoid Carnivorans, Vulpavus and Didymictis,” Palaeontology 40 (1997): 279–305; Blaire Van Valkenburgh, “Déjà vu: The Evolution of Feeding Morphologies in the Carnivora,” Integrative and Comparative Biology 47 (2007): 147–63.
5. L. D. Martin, “Fossil History of the Terrestrial Carnivora,” in Carnivore Behavior, Ecology, and Evolution, ed. J. L. Gittleman (Ithaca, NY: Cornell University Press, 1989), 335–54; Van Valkenburgh, “Déjà vu,” 147–63; Julie Meachen-Samuels and Blaire Van Valkenburgh, “Craniodental Indicators of Prey Size Preference in the Felidae,” Biological Journal of the Linnean Society 96 (2009): 784–99.
6. Van Valkenburgh, “Déjà vu,” 147–63.
7. Blaire Van Valkenburgh, “Skeletal Indicators of Locomotor Behavior in Living and Extinct Carnivores,” Journal of Vertebrate Paleontology 7 (1987): 162–82; Van Valkenburgh, “Déjà vu,” 147–63; Julie Meachen-Samuels and Blaire Van Valkenburgh, “Forelimb Indicators of Prey-Size Preference in the Felidae,” Journal of Morphology 270 (2009): 729–44.
8. Van Valkenburgh, “Déjà vu,” 147–63.
9. Ibid.
10. I experienced this proclivity firsthand when I was in high school, camping with my dad in Kenya’s Samburu National Reserve. We’d pitched our tent beneath a sprawling tree in a clearing by the river. The wardens stopped by while we were setting up to tell us that three weeks prior, two women had been killed in that spot by a hippo walking through their tent on the way to the water. But there was nowhere else to put the tent (that little clearing was the official campground), so there it sat.
We left camp for an hour at sunset to drive through the park, and when we returned we found chaos. A troop of baboons had raided our tent, shredding everything in sight. They had torn through the side leaving a great, gaping hole, and they had bitten clean through two of the poles. They had even scent-marked our sleeping bags with urine. But by then it was dark and we had no place to go, so we patched the pieces together as best we could and tried to sleep.
Falling asleep in a situation like that is not easy. Modern tents rely on long, bowed poles to support them, and when these are snapped the design truly fails. The patchwork of foul-smelling fabric and string we’d salvaged was not very convincing. Also, I can attest from experience that any sense of security you derive from a tent comes from the visual barrier of fabric. Animals on the outside can both hear you and smell you, tucked away in your nylon shell. The only thing they can’t do is see you. A predator has no way to know that the shell you’ve erected is less than a millimeter thick, and for this reason tents really do protect you from most things that go bump in the night (unless, of course, that thing is so huge, like an elephant or hippo, that it squashes you by accident). This night, however, our barrier was broken. We could see out and they could see in. We did finally sleep, after watching giraffe silhouettes drift by, black against the starlight in our newly torn “window.”
Sometime in the night we woke to a scream, followed immediately by shrieks and hoots and loud crashing branches in the tree above us. The baboons had returned to roost fifteen feet over our heads, and a leopard was attacking them! We learned later that this happens often. Leopards like to pull baboons away from their troop while they’re perched helplessly in trees at night, and there we sat directly beneath with a four-foot gaping hole in our tent. I panicked, grabbing my sleeping bag and racing for the car, which, in hindsight, was the worst thing I could have done since I was completely exposed to the leopard above my head as I ran.
11. Sharon B. Emerson and Leonard Radinsky, “Functional Analysis of Sabertooth Cranial Morphology,” Paleobiology 6 (1980): 295–312; Martin, “Fossil History of the Terrestrial Carnivora,” 335–54; Van Valkenburgh, “Déjà vu,” 147–63; Graham J. Slater and Blaire Van Valkenburgh, “Long in the Tooth: Evolution of Sabertooth Cat Cranial Shape,” Paleobiology 34 (2008): 403–19.
12. Van Valkenburgh, “Skeletal Indicators of Locomotor Behavior,” 162–82; Blaire Van Valkenburgh and Fritz Hertel, “Tough Times at La Brea: Tooth Breakage in Large Carnivores of the Late Pleistocene,” Science 261 (1993): 456–59.
13. Ibid.
14. Martin, “Fossil History of the Terrestrial Carnivora,” 335–54.
15. P. W. Freeman and C. A. Lemen, “The Trade-Off Between Tooth Strength and Tooth Penetration: Predicting Optimal Shape of Canine Teeth,” Journal of Zoology 273 (2007): 273–80.
16. Blaire Van Valkenburgh and Ralph E. Molnar, “Dinosaurian and Mammalian Predators Compared,” Paleobiology 28 (2002): 527–43.
17. Van Valkenburgh and Hertel, “Tough Times at La Brea,” 456–59; Van Valkenburgh, “Feeding Behavior in Free-Ranging, Large African Carnivores,” Journal of Mammology 77 (1996): 240–54; Van Valkenburgh, “Costs of Carnivory: Tooth Fracture in Pleistocene and Recent Carnivores,” Biological Journal of the Linnean Society 96 (2009): 68–81.
18. Francis Juanes, Jeffrey A. Buckel, and Frederick S. Scharf, “Feeding Ecology of Piscivorous Fishes,” chapter 12 in Handbook of Fish Biology and Fisheries, vol. 1, Fish Biology, ed. Paul J. B. Hart and John D. Reynolds (Malden, MA: Blackwell Publishing, 2002), 267–83.
19. P. W. Webb, “The Swimming Energetics of Trout. I. Thrust and Power Output at Cruising Speeds,” Journal of Experimental Biology 55 (1971): 489–20; P. W. Webb, “Fast-Start Performance and Body Form in Seven Species of Teleost Fish,” Journal of Experimental Biology 74 (1978): 211–26; Patrice Boily and Pierre Magnan, “Relationship Between Individual Variation in Morphological Characters and Swimming Costs in Brook Charr (Salvelinus fontinalis) and Yellow Perch (Perca flavescens),” Journal of Experimental Biology 205 (2002): 1031–36.
20. Bent Christensen, “Predator Foraging Capabilities and Prey Antipredator Behaviours: Pre-Versus Postcapture Constraints,” Oikos 76 (1996): 368–80; Frederick S. Scharf, Francis Juanes, and Rodney A. Rountree, “Predator Size-Prey Relationships of Marine Fish Predators: Interspecific Variation and Effects of Ontogeny and Body Size on Trophic-Niche Breadth,” Marine Ecology Progress Series 208 (2000): 229–48.
21. Susan S. Hughes, “Getting to the Point: Evolutionary Change in Prehistoric Weaponry,” Journal of Archaeological Method and Theory 5 (1998): 345–408.
22. Michael J. O’Brien, John Darwent, and R. Lee Lyman, “Cladistics Is Useful for Reconstructing Archaeological Phylogenies: Palaeoindian Points from the Southeastern United States,” Journal of Archaeological Science 28 (1991): 1115–36; Briggs Buchanan and Mark Collard, “Investigating the Peopling of North America Through Cladistics Analyses of Early Paleoindian Projectile Points,” Journal of Anthropological Archaeology 26 (2007): 366–93; R. Lee Lyman, Todd L. VanPool, and Michael J. O’Brien, “The Diversity of North American Projectile-Point Types Before and After the Bow and Arrow,” Journal of Anthropological Archaeology 28 (2009): 1–13.
23. George C. Frison, “North American High Plains Paleo-Indian Hunting Strategies and Weaponry Assemblages,” in From Kostenki to Clovis: Upper Paleolithic–Paleo-Indian Adaptations, ed. O. Soffer and N. D. Praslov (New York: Plenum Press, 1993), 237–49; Hughes, “Getting to the Point,” 345–408; Briggs Buchanan, Mark Collard, Marcus J. Hamilton, and Michael J. O’Brien, “Points and Prey: A Quantitative Test of the Hypothesis That Prey Size Influences Early Paleoindian Projectile Point Form,” Journal of Archaeological Science 38 (2011): 852–64.
24. Hughes, “Getting to the Point,” 345–408.
25. G. H. Odell and F. Cowan, “Experiments with Spears and Arrows on Animal Targets,” Journal of Field Archaeology 13 (1986): 195–212; George C. Frison, “Experimental Use of Clovis Weaponry and Tools in African Elephants,” American Antiquity 54 (1989): 766–84; J. Cheshier and R. L. Kelly, “Projectile Point Shape and Durability: The Effect of Thickness: Length,” American Antiquity 71 (2006): 3
53–63; M. L. Sisk and J. J. Shea, “Experimental Use and Quantitative Performance Analysis of Triangular Flakes (Levallois Points) Used as Arrowheads,” Journal of Archaeological Science 36 (2009): 2039–47.
26. D. C. Waldorf, The Art of Flint Knapping (Cassville, MO: Litho, 1979); Hughes, “Getting to the Point,” 345–408.
27. Stuart J. Feidel, Prehistory of the Americas (Cambridge, MA: Cambridge University Press, 1992).
28. Buchanan et al., “Points and Prey,” 852–64.
29. Ibid.
30. Lyman, VanPool, and O’Brien, “The Diversity of North American Projectile-Point Types,” 1–13; Douglas H. MacDonald, Montana Before History: 11,000 Years of Hunter-Gatherers in the Rockies and Plains (Missoula, MT: Mountain Press Publishing Company, 2012).
31. Hughes, “Getting to the Point,” 345–408.
32. Ibid.
33. Ibid.
34. Ibid.
3. Claspers, Graspers, and Giant Jaws
1. Unfortunately, our trip was short-lived. On the third day I broke out in hives, itching all over. I’d never had an allergic reaction before, but I knew what they were and I couldn’t imagine a worse place to go into anaphylaxis. I travel prepared for catastrophes—I had antibiotics, painkillers, sutures, burn bandages, and a snakebite kit with me on that trip—but this was an emergency I hadn’t anticipated, and I didn’t have an EpiPen or antihistamines. Had my reaction been instant, as they so often are, I never would have lived. But the symptoms came on gradually. My eyelids and fingers began to swell, then my throat started to get tight. Within a few hours my voice was down to a crackly whisper and I was having trouble breathing from the swelling. That was the tipping point. We collapsed camp in a dash and, as the sun set, began racing back upriver toward Coca.
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