[jampekka]

It's not clear whether humans have natural reactions to snakes. https://link.springer.com/article/10.11133/j.tpr.2013.63.4.0...

[cma]

If not, another visual system one in newborns is preference for faces with open eyes and direct gaze:

https://pubmed.ncbi.nlm.nih.gov/17030037/