Inbreeding, Incest, and the Incest Taboo: The State of Knowledge at the Turn of the Century

Inbreeding, Incest, and the Incest Taboo: The State of Knowledge at the Turn of the Century . Arthur P. Wolf and William H. Durham, eds. Stanford: Stanford University Press, 2004. 228 pp.     

The Precultural Basis of the Incest Taboo: Toward a Biosocial Theory

The literature on the origins of the incest taboo is characterized by controversy over the nature/nurture issue, and fears of reductionism. In recent years work emanating from such diverse disciplines as cultuml and physical anthropology, ethology, and neuropsychology warmnts a new look at this intriguing issue. It is probable that incest avoidance is widespread among the vertebrata and is "built into the wiring." As learned behavior becomes more important phylogenetically, curiosity and exploration plays a larger role in adaptation and has manifest survival admntages. Incest awidance functions as a mechanism to propel the individual into new relationships and "social territory." For humans, incest avoidance and its later elaboration into a cultuml taboo serve to motivate exploration of and attachment to a wider social nexus than the family. It also prevents fixation at a relatively undifferentiated psychological stage of development     

Comments on a phylogenetic system of the Platyhelminthes

Using the principles and methods of phylogenetic systematics, the phylogenetic relationships among the basic closed descendent communities (monophyla) of the taxon Platyhelminthes are discussed.A phylogenetic system of the Platyhelminthes is presented and several hypothesized autapomorphies of the well-known main subordinated monophyla of free-living and parasitic platyhelminths are named. A monophylum Turbellaria does not exist in reality.     

Comments on a skeleton design paradigm for a demosponge

The ball-shaped marine sponge Cinachyrellalevantinensis is 3-5 cm in diameter. It filters large quantities of seawater for feeding. Sponges contain numerous, hydrated, brittle amorphous SiO? spicules of several types that form 70-80% by weight of the sponge. We performed mechanical tests to determine the functionality of the sponge skeleton. The potential effect of habitat on skeleton properties was investigated by comparing sponges from 0.5 m and 30 m depth. We determined how spicules contribute to maintaining the strength and macroscopic structural integrity of a sponge, and studied their deformation mechanisms under external loading, and their microscopic design parameters. Compression tests of cylindrical samples cut from sponges revealed their macroscopic deformation mechanisms. Experiments solely with the organic material (following spicules dissolution) revealed the contribution of the spicules to the load carrying capacity and structural integrity of the sponge. Cantilever bending tests of anchored spicules determined the strength of individual spicules, the sponge's main skeletal elements. As the strength of brittle spicules is statistical in nature, we used Weibull Statistics to define their strength and evaluate their Young's modulus. Shallow and deep-water sponges did not differ significantly neither in response to compression, nor in spicule strength under bending and tension. Spicule weight fraction within a sponge was significantly higher in shallow-water individuals. We conclude that the structural integrity and strength of this sponge's skeleton is derived from its low-strength, small spicules, produced by a cost-effective process. The operating deformation of the spicules (bending) and their design parameters make them highly efficient.