Some people oppose the concept of animal emotions and suggest that emotions are not universal, including in humans. If emotions are not universal, this indicates that there is not a phylogenetic relationship between human and non-human emotion. The relationship drawn by proponents of animal emotion, then, would be merely a suggestion of mechanistic features that promote adaptivity, but lack the complexity of human emotional constructs. Thus, a social life-style may play a role in the process of basic emotions developing into more complex emotions.