There are other etiological factors involved in preeclampsia and ours is not the only evolutionary account. Takiuiti, Kahale, and Zugaib (2003) have advanced the hypothesis that preeclampsia is a maladaptation to stress. They argue that because pregnant females are more vulnerable to predation as a consequence of being slower, heavier, sleepier, and less agile, higher blood pressure during pregnancy and a heightened alarm response mayminimize the risk of predation. However, this hypothesis fails to explain why human females are the only mammals that are prone to preeclampsia, and it does not account not for the evidence implicating semen unfamiliarity as a risk factor for preeclampsia.