Evolutionary Continuity: Comparative neuroanatomical research shows that all vertebrates have very similar central nervous systems and that this structure has remained relatively unchanged throughout evolution; the neurons, neurotransmitters, hormones are all consistent with each other across the various species; Gross, (2014) notes that the limbic system and amygdala in particularly are strikingly similar. The behaviours shown by these animals will be simpler versions of human behaviours, Psychologists who believe in evolutionary continuity believe that the differences are quantitative not qualitative so to speak.

Sentient: Able to experience emotions, e.g. pleasure and pain.

Speciesism: Perceiving the welfare of one species to be more important than another; those who a for the use of animals experiments may be accused of “speciesism”.