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Tham khảo tài liệu 'who needs emotions the brain meets the robot - fellous & arbib part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 64 brains benefits that also presented vulnerabilities. For example genes related to the DA system that may have enhanced novelty seeking may have provided advantages in seeking and finding new habitats and resources. In ancestral environments such genetic quirks would be beneficial or at the very least not deleterious however in modern environments with availability of pure drugs such as cocaine disproportionate susceptibility among individuals may occur. Gerald and Higley 2002 have proposed a fascinating model for genetic susceptibility to alcohol dependence in relation to variations in serotonin function. Their research shows that monkeys with lower levels of brain 5-HT tend to be less affiliative and social to be more aggressive and impulsive and to have a higher mortality in the wild. These monkeys drink excessive amounts of alcohol compared to monkeys with high 5-HT levels. Thus heritable traits that may have been advantageous in certain contexts could contribute to susceptibility to alcoholism and excessive alcohol intake. Ultimately it is critical to address the remarkable similarities between plant alkaloids and nervous system chemicals and receptors in animals. Figure 3.8 shows examples of cannabinoid and opiate receptors in the mammalian brain. Sullivan and Hagen 2002 ponder this question and propose that psychotropic substance seeking is an adaptation reflective of a revolutionary relationship between psychotropic plant substances and humans that is millions of years old. Plants containing allelochemicals toxic metabolites used by plants to discourage herbivores and pathogens were widespread in the ancestral environment and these alkaloids were often chemical analogues of vertebrate and invertebrate neurotransmitters. this deep time relationship is self-evident both in the extant chemical-ecological adaptations that have evolved in mammals to metabolize psychotropic plant substances and in the structure of plant defensive chemicals that have evolved to
