8 
MacLean 
TABLE 1. COMMON PATTERNS 
OF BEHAVIOR* 
(1) selection and preparation of homesite 
(2) establishment of territory 
(3) trail making 
(4) marking of territory 
(5) showing place preferences 
(6) patrolling territory 
(7) ritualistic display in defense of terri- 
tory, commonly involving the use of 
coloration and adornments 
(8) formalized intraspecific fighting in de- 
fense of territory 
(9) triumphal display in successful defense 
(10) assumption of distinctive postures and 
coloration in signalling surrender 
(11) foraging 
(12) hunting 
(13) homing 
(14) hoarding 
(15) use of defecation posts 
(16) formation of social groups 
(17) establishment of social hierarchy by 
ritualistic display and other means 
(18) greeting 
(19) grooming 
(20) courtship, with displays using colora- 
tion and adornments 
(21) mating 
(22) breeding and, in isolated instances, 
attending offspring 
(23) flocking 
(24) migration 
■"Based on examples from Auffenberg (1972); 
Bellairs (1970); Ditmars (1965); Evans (1938, 
1951); Eibl-Eibesfeldt (1961); Coin and Goin 
(1962); Greenberg (1977a, 6); and Harris (1963). 
or inanimate, and includes what ethologists 
refer to as imprinting and fixed action pat- 
terns. Deceptive behavior involves the use 
of artifice and deceitful tactics such as are 
employed in stalking a prey or evading a 
predator. 
EXPERIMENTAL WORK IN PROGRESS 
Thus far most of our experimental work 
on the R-complex has been conducted on 
squirrel monkeys. As I mentioned in the 
introduction, the finding that large destruc- 
tions of the R-complex may result in no 
impairment of movement, speaks against the 
traditional clinical view that it is primarily 
involved in motor functions. Thus far, cru- 
cial findings relevant to prosematic behavior 
have developed from experiments on more 
than 100 monkeys. Squirrel monkeys per- 
form a characteristic display of the erect 
phallus in a show of aggression, in court- 
ship, and as a form of greeting. (Ploog and 
MacLean, 1963) Members of one species con- 
sistently display to their reflections in a 
mirror, providing a means of systematically 
testing the effects of brain ablations on the 
incidence and manifestations of this particu- 
lar display ritual (MacLean, 1964). I have 
found that bilateral lesions of paleo- and 
neomammalian parts of the forebrain may 
have either no effect or only a transitory 
effect on the display. After bilateral lesions 
of the pallidal part of the R-complex (Mac- 
Lean, 1973a; 1978), however, or interrup- 
tions of its main pathways (MacLean, 
19756), monkeys may no longer show an 
inclination to display. Without a test of the 
innate display behavior, one might con- 
clude that they were unaffected by the loss 
of the brain tissue. These experiments pro- 
vide evidence that in mammals the R- 
complex and its major pathways play a basic 
role in forms of behavior involving con- 
specific recognition and prosematic com- 
munication. 
In the past, relatively few investigations 
have been conducted on reptiles in an at- 
tempt to identify specific structures of the 
forebrain involved in the various behaviors 
listed in Table 1. All that is known thus far is 
that the neural guiding systems for complex 
species-typical behavior lie forward of the 
midbrain. Greenberg, Ferguson, and I are 
conducting experiments on the effects of le- 
sions of the striatal complex on the display 
behavior of the green Anolis lizard (1976). 
The results have been of particular interest in 
regard to the so-called challenge or territorial 
display characterized by pushups, extension 
of the throat fan, and profile changes, that 
