known to perceive and respond to mechanical stimuli at a cellular level, and some plants such as the venus flytrap or touch-me-not, are known for their "obvious sensory abilities". Nevertheless, the plant kingdom as a whole do not feel pain notwithstanding their abilities to respond to sunlight, gravity, wind, and any external stimuli such as insect bites, since they lack any nervous system. The primary reason for this is that, unlike the members of the animal kingdom whose evolutionary successes and failures are shaped by suffering, the evolution of plants are simply shaped by life and death. See also Feeling, a perceptual state of conscious experience. Hedonic adaptation, the tendency to quickly return to a relatively stable level of happiness despite major positive or negative events Pain (philosophy), the branch of philosophy concerned with suffering and physical pain Pain and suffering, the legal term for the physical and emotional stress caused from an injury Explanatory notes References External links "Pain", Stanford Encyclopedia of Philosophy Acute pain Nociception Sensory systems Suffering Symptoms and signs