Teleology and Dysteleology: Multiple Functions for Antlers?
| Author: John Woodmorappe Subject: Biology |
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In earlier “Clippings,” we speculated about how the carnivory (flesh-eating) of cats (BSN 32:4) and vultures (BSN 32:5) might have a behavioral basis that could be fairly easily modified, without completely “redesigning” the animals. If, as biblical creationists believe, there was a time of no carnivory (before the Fall), and furthermore, that carnivory will not exist in the renewed creation (Is. 11; Rev. 21:4), they should try to learn how biological systems, used in part for destructive purposes, might be modified. Here, we suggest yet another potential avenue for such research.
Many herbivorous (plant-eating) animals have defensive weapons. Hooved animals, for instance, often possess antlers. Could these structures have had non-defensive functions before the Fall? And how might antlers function in the future, when there will be no predators to defend against? If antlers had a different function before the Fall, we needn’t suppose that God gave the hooved animals antlers only after He cursed the ground. Instead, antlers may have been present right from the time when God first created hooved animals. What happened after the Fall was a change, not in structure, but in function.
We could, of course, suppose that antlers were originally created as artistic decorations (for God’s aesthetic purposes) on animals, and had no other function. They could later have been turned into features which serve during mating (that is, as secondary sex characteristics for sexual display, and/or social dominance).
However, antlers serve other functions besides combat or sexual display (see Clutton-Brock 1982 for review). For instance, rhinos use their front horn to pull down branches that would otherwise be out of reach, as well as to dig up roots, bulbs, and tubers as a food source (Merz 1991, p. 101). Elands, large antelopes, use their horns to break and pull down high branches. In fact, elands break branches so effectively that their destruction of bushes resembles that done by elephants (Posset 1963, p. 86). Various other horned animals also use their horns or antlers for digging or parting undergrowth (Stonehouse 1968).
Antlers may also serve, or once have served, as thermoregulators. We now realize that antlers are highly vascularized: far from being just pointed appendages, they have a great deal of living tissue and extensive networks of blood vessels (Stonehouse 1968). Moreover, this blood-engorged tissue appears to have a much richer blood supply than is necessary simply for its growth (Stonehouse 1968, p. 871).
For this reason, a hooved animal can dissipate much body heat by regulating the amount of blood passing through its antlers. The antler has a large surface area in relation to the volume of blood passing through it. Like a radiator, blood flowing through an antler can dissipate heat rapidly.
This can be seen even in cattle, with their relatively short horns, which dissipate the heat equivalent of two extra legs! (Stonehouse 1968, p. 871). It is also interesting to note that in goats, blood cooled in the horns is part of a heat-exchange network involving the carotid flow of blood to the brain. Blood going to the brain is cooled before reaching this sensitive organ (Stonehouse 1968).
Of course, the females of most cervid (deer-like) species do not have antlers. Stonehouse (1968) argues that because males are much more active than females, especially during rutting season, they undergo heat stress, and need to dissipate more heat. He cites the large Arctic deer as the exception which proves the rule: both males and females carry antlers because, in this species, the body size is large, and members of both genders carry thick deposits of insulating fat. Thus, both genders require the heat-dissipative antlers.
Clutton-Brock (1982, p. 114), however, has discounted the role of antlers as thermoregulatory structures on behavioral grounds. He points to their frequent use in combat, and finds inconsistencies between the time of antler growth in the animals on one hand, and the degree and timing of high environmental temperatures on the other hand. Yet Clutton-Brock’s argument shows the stultifying effects of uniformitarian thought. He assumes that present conditions always applied in the past. Creationists of course realize that antlers now serve purposes, like combat, needed for survival in the Post-Fall world. We do not assume, however, that other important functions may not exist, or have once been the primary use for a structure. By looking for multiple functions, on the basis of their scientific worldview, creationists may discover important new biological truths.
REFERENCES
Clutton-Brock, T. H. 1982. “The functions of antlers.” Behaviour 79:108-125.
Merz, A. 1991. Rhino. Harper Collins Publishers, London, Glasgow.
Posset, J. 1963. “The domestication of the eland.” Rhodesian Journal of Agricultural Research 1: 81-89.
Stonehouse, B. 1968. “Thermoregulatory function of growing antlers.”
Nature 218: 870-872.
Topics: Teleology, Dysteleological Arguments, Strange But True, Faith and Science, Isaiah 11, Problem of Suffering and Evil, Nature Red in Tooth and Claw