Phylogenetic Dimensions Research Articles

Bacteria as Multicellular Organisms

PART I: Conceptual Developments. 1: M. Dworkin: Multiculturalism vs. the single microbe,. 2: J.A. Shapiro: Multicellularity is the rule, not the exception: Lessons from E. coli colonies,. PART II: Intercellular Communication. 3: R.E. Ruhfel, B.A.B. Leonard, and G.M. Dunny: Pheromone-inducible conjugation in Enterococcus faecalis: mating interactions mediated by chemical signals and direct contact,. 4: P.V. Dunlap: N-acyl-L-homoserine lactone autoinducers in bacteria: unity and diversity expanding the prokaryotic paradigm: E. coli colonies teach us that multicellularity is the rule rather than the exception,. PART III: Multicellular Lifestyles. 5: D.G. Adams: Cyanobacteria,. 6: K.F. Chater and R. Losick: The mycelial life-style of Streptomyces Coelicolor A3(2) and its relatives,. 7: R. Belas: Proteus mirabilis and other swarming bacteria,. 8: L.J. Shimkets and M. Dworkin: Myxobacterial multicellularity,. 9: P.E. Kohlenbrander: Oral microbiology and coaggregation,. PART IV: Examining Multicellular Populations. 10: B. Hauer abd H. Eipel: Flow cytometry: a useful tool for analyzing bacterial populations cell by cell,. 11: N.K. Fry, L. Raskin, R. Sharp, E.W. Alm, B.K. Mobarry, and D.A Stahl: In situ analyses of microbial populations with molecular probes: the phylogenetic dimension,. PART V: A More Physical View of Bacterial Multicellularity. 12: N.H. Mendelson, B. Salhi, and C. Li: Physical and Genetic consequences of multicellularity in Bacillus subtilis,. 13: M. Matsushita: The formulation of colony patterns by a bacterial cell population,. 14: E. Ben-Jacob and I. Cohen: Cooperative formation of bacterial patterns,. 15: J.O Kessler and M.F. Wojciechowski: The collective behavior and dynamics of swimming bacteria,

Origins of anthropoid intelligence. III. Role of prefrontal system in delayed-alternation and spatial-reversal learning in a prosimian (Galago senegalensis).

A species of prosimian (bush baby, Galago senegalensis) was tested on delayed-alternation and spatial-reversal learning before and after ablation of prefrontal cortex. The results show that normal performance on the two behavioral tasks depend on different subdivisions of the MD-prefrontal system. Delayed alternation is disrupted by prefrontal lesions which cause degeneration in the lateral division of MD while spatial-reversal learning is disrupted by lesions causing degeneration of the medial division of MD. Therefore, the bush baby prefrontal system can be subdivided either on behavioral or anatomical grounds into at least two chief parts. Because of several similarities in the MD-prefrontal system of bush baby and monkey despite their remote common ancestry, it can be concluded that the differentiation of the MD-prefrontal system into distinct divisions and the involvement of this system in delayed alternation and spatial reversal are features probably as old as the order Primates itself. It can be further concluded that the further evolution of the anthropoid variety of prefrontal system beyond this common primate stage probably depended on selective pressure on abilities other than those measured here.

Origins of Anthropoid Intelligence; pp. 337–353

The development of the extrastriate visual system relative to the striate system was estimated indirectly by measuring the volumes of the lateral posterior-pulvinar complex and lateral geniculate nucleus in six varieties of mammals selected on the basis of their propinquity with Anthropoidea (opossums, hedgehogs, rats, squirrels, tree shews, and bushbabies). The same animals were tested on two related behavioral tasks (spatial and visual reversal learning) whose successful achievement requires a simple sort of abstraction. The results show that the ability to learn visual reversal, but not spatial reversal, corresponds closely to the relative degree of development of the extrastriate system. Since the variation in both these behavioral and morphological characteristics also parallels the phylogenetic dimension, the recency of common ancestry to anthropoids, the evolutionary origin of the anthropoid capacity for visual abstraction is suggested.