The understanding of trypophobia is limited.[1] Several possible causes have been proposed.[3] Geoff Cole and Arnold Wilkins believe the reaction is an "unconscious reflex reaction" based on a biological revulsion, rather than a learned cultural fear.[2] Imagery of various venomous animals (for example, certain types of snakes, insects, and spiders) have visual characteristics similar to trypophobic imagery. Because of this, it is hypothesized that trypophobia has an evolutionary basis meant to alert humans of dangerous organisms.[3][8][9] Can et al., however, believe the connection between trypophobia and evolution as a result of a threat from deadly creatures to be weak and that, if it does exist, it manifests later in life.[3]