Page "Arachnophobia" Paragraph 8

Arachnophobes will spare no effort to make sure that their whereabouts are spider-free, hence they would have had a reduced risk of being bitten in ancestral environments.

Therefore, arachnophobes may possess a slight advantage over non-arachnophobes in terms of survival.

However, this theory is undermined by the disproportional fear of spiders in comparison to other, potentially dangerous creatures that were present during Homo sapiens environment of evolutionary adaptiveness.

Studies with crickets have shown that a fear of spiders can develop before birth.