196 
Regal 
ecological correlates, and phylogenetic distri- 
butions of behaviors and of patterns of 
brain organization. 
Foraging vs. Predation 
Predation need not include extensive for- 
aging and vice versa. Lizards that prey on 
insects may simply sit and wait for the prey 
to reveal itself. 
This often misunderstood point is critical. 
Perhaps it can be best understood by refer- 
ence to bats where the neocortex and total 
brain are enlarged in fruit eaters relative to 
insect eaters (Pirlot and Stephan 1970) ; 
Stephan and Pirlot 1970; Stephan, Pirlot, 
and Schneider 1974). This may make no 
sense in terms of the skill and agility re- 
quired to capture the two food types. But, it 
makes good sense in terms of foraging skills, 
since tropical flowering and fruiting trees 
are widely and heterogeneously distributed 
and their efficient exploitation by bats or 
monkeys over the year requires familiarity 
with an extensive area and plant community. 
Environmental Grain 
My use of the term intensive forager im- 
plies much more than simply high activity 
levels or carnivory. It indicates the capacity 
to exploit environments with rare and patch- 
ily distributed prey. 
In the last 15 years, ecologists have made 
important contributions to our understand- 
ing of environmental complexity and its con- 
sequences for the organism. One useful con- 
cept is of environmental “grain” (figura- 
tively the perceived “size” of each resource 
particle). All things being equal, as a habi- 
tat becomes more complex, the grain becomes 
more fine. However, animals may evolve 
that make coarse-grain responses and utilize 
a class of resources from the environment 
as though each particle was large and easier 
to detect or select in a nonrandom fashion. 
Such animals may exploit rare resources and 
complex environments more effectively than 
does a species with fine-grain responses 
(Wiens, 1976). In the development of this 
concept, the emphasis has been upon under- 
standing community structure (e.g., How 
many species can a given class of resources 
support? What determines species diversity 
in a given area?). I propose here that we 
focus upon the physiological and mental 
traits required of animals making fine-grain, 
in contrast to coarse-grain, responses and 
that these traits are relevant to an under- 
standing of the organization and evolution 
of the nervous system in vertebrates. I en- 
vision the physiological and mental qualities 
associated with active foraging in lizards and 
mammals as representing one system for al- 
lowing coarse-grain responses — utilizing 
large spaces and retaining flexibility in feed- 
ing and relative generality in diet at the 
same time. 
Spontaneous Exploration 
The sit-and-wait predator primarily needs 
to occupy a suitable perch until a stimulus 
appears (Askew et. al., 1970), to focus upon 
the stimulus (Ewart, 1974; Ingle, 1975), and 
then to leave its perch to approach and seize 
food objects of appropriate size, shape, and 
speed (for example, an insect within a partic- 
ular size range and of a particular velocity; 
or an herbivorous lizard orienting itself to 
a young leaf, flower, or fruit of a particular 
shape, color, or smell). 
The foraging strategies of cruising and 
intensive-foragers may require the “endogen- 
ous” generation of most locomotor activity. 
Food rewards may eventually result from 
simple patrolling of an area or from curious 
searching, but even searching need not be 
stimulated by the sensing of food. Hence, 
there are advantages to mechanisms that 
will sustain (first) spontaneous locomotion 
and (second) actual searching behavior over 
long periods of time in the absence of the 
ultimate biological reinforcers. Apparently, 
in mammals there is a rearrangement of the 
logic of the nervous system so that move- 
ment, and “purposeful” familiarization with 
