130 • Alternatives to Animal Use in Research, Testing, and Education 
zation. In contrast, all birds are subject to some 
type of parental care, and mammalian parent -off- 
spring relations become even more complicated. 
Species differences in external versus internal fer- 
tilization, seasonal breeding, courtship, pair- 
bonding, and nest-building preclude substitutions 
of one species for another in this research. 
Sensation and Perception 
The sensory and perceptual differences among 
species are vast. For example, many snakes’ pri- 
mary mode of prey identification is chemical cues 
transferred from the tongue to a structure at the 
roof of the mouth, called Jacobsen’s organ. Inges- 
tively naive baby snakes appear to have an innate 
preference for prey extracts that represent species - 
typical foods across a variety of different snakes. 
Each species shows unique attack profiles that ap- 
pear to be independent of maternal diet and not 
subject to modification by experience (e.g., baby 
snakes of a minnow-eating species that are force- 
fed liver still show attack responses to minnow 
extracts but not to liver) (34,35). 
In contrast, baby rats seem predisposed to eat 
the same diet as their mother, and the flavor of 
the maternal milk serves as a medium for the trans- 
mission of cues that rat pups use to make their 
initial food choices. Manipulating maternal diet 
during lactation has produced corresponding 
changes in subsequent pup food preferences. 
Moreover, rat pups poisoned in association with 
a mother’s milk later avoid the types of food she 
had been eating (74). 
Reduction of Pain or 
Experimental Insult 
As noted earlier, a general anesthetic is prefer- 
able to a local one for surgical manipulations be- 
cause it suppresses both pain and fear (1 14). Pain- 
relieving drugs should be administered to animals 
after surgery whenever this would not interfere 
with the behavior under study, and animals should 
be carefully monitored so that any complications 
that develop may be treated (197). 
Transection of the spine or brain stem is recom- 
mended for surgical experiments when possible, 
because it renders the animal incapable of feeling 
pain (114). This technique has limited applicabil- 
ity in behavioral research, however, as postsurgi- 
cal behavioral assessment requires a relatively 
intact animal. Similarly, the nonrecovery experi- 
ments on completely anesthetized animals that 
were described earlier, in the biomedical research 
section, are rarely used in behavioral research, 
since most behaviors of interest do not occur when 
the animal is unconscious and behavioral testing 
is typically conducted postsurgically . Multiple sur- 
geries on the same animal are to be avoided when- 
ever possible, because painful consequences may 
be cumulative (197). 
The analysis of pain in behavioral research is 
complicated by recent theoretical and empirical 
developments suggesting that fear and pain acti- 
vate quite different kinds of behavior (25). Rather 
than being on a continuum, as might seem to be 
the case intuitively, data suggest that fear and pain 
are associated with fundamentally different mo- 
tivational systems. Fear activates species-specific 
defensive behaviors, such as freezing, flight, or 
fighting, that serve to minimize encounters with 
pain-producing stimuli (e.g., predators). Pain, on 
the other hand, appears conducive to the kinds 
of behaviors that provide for healing and recuper- 
ation (e.g., rest, grooming, licking the affected area, 
and sleep). A growing body of evidence shows that 
fear takes priority over pain, and that fear can ac- 
tually inhibit pain under some circumstances (pos- 
sibly through the release of endogenous opiates). 
For example, soldiers who are wounded in battle 
frequently continue fighting and feel no pain from 
their injuries until after they are removed from 
the front lines (211). Likewise, a deer wounded 
by hunters may flee the scene with defensive be- 
havior indistinguishable from that of uninjured 
animals. But once the deer is out of danger, pain- 
related recuperative behaviors predominate (25). 
Brain Manipulation 
In studies of the physiological bases of behavior, 
the recording of brain -wave patterns maybe sub- 
stituted for electrical stimulation whenever pos- 
sible, and brain areas may be stimulated instead 
of lesioning or ablating sections of the brain (121). 
These techniques, however, are not completely 
interchangeable. Recording neuronal firing as an 
