Mate choice avoidance

While mate choice for unfamiliar partners might be explained by the fitness benefits of multiple mating, inbreeding avoidance, and favouring rare genotypes, preference for familiar males is also sometimes observed. Why would females choose relatively familiar males as mates, given the benefits outlined above of avoiding such males ... 

It has been known for many decades that odors influence animal behavior, including foraging, predator avoidance, alarm response, social dominance, cohort recognition, and courtship. Darwin (1871) initially proposed chemical signals as a key mechanism in mate choice by which sexual selection is promoted. However, it was not until the discovery of the silkworm moth pheromone bombykol by Butenandt et al. (1959)... 

Recent research has shown that among humans MHC type plays a role in the selection of heterosexual mates. Studies on the North American Hutterite community (a reproductively isolated, cultural and religious group of Austrian ancestry) revealed that mate choice was influenced by an avoidance of spouses with a high degree of haplotype overlap with self (Ober, this volume). In another study, Wedekind, Seebeck, Bettens and Paepke (1995), typed female and male students for their MHC haplotypes. Each male subject wore a T-shirt for two consecutive nights, after which the T-shirts were collected and placed in identical cardboard boxes for the female subjects to sniff and evaluate. For each female, half of the boxes contained T-shirts from men who were similar to her in MHC-type, and half contained T-shirts from men who were dissimilar. The results revealed that females who were not on birth control pills preferred the smell of males who were most dissimilar from them in MHC-type, indicating that female preferences for male body odor correlates with MHC dissimilarity. These women also reported that the body odor of the males they preferred reminded them of their current and/or ex-mates. Thus, as with rodents, human mate selection appears to be related to female preferences for male body odors that correlate with MHC dissimilarity (complementarity). 

As these things came to light, the rubber processing industry was the obvious first choice to remove the nitroso compounds from the raw material pallet since substitutes were available in order to eliminate one of the components in the material itself. On the other hand, the nitrous oxides, which are adsorbed to the active surfaces of the fillers or present in the air we breathe as combustion gases from vehicle engines, cannot be eliminated. These particular substances can be reduced by optimized combustion and catalysts, but not avoided completely. Substances that form nitrosable amines include, among others, di-n-alkyl dithiocarba-mates, di-n-aUcyl thiurame sulfides, A,V -dialkyl benzothiazyl sulfenamides and benzothiazyl sulfene morpholide. 

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