Why do vestigial structures not always disappear and still show up in organism? For example humans still have a tail bone, even though we don't have a tail. 1) The organism depends on them to survive

2) The structure is not harmful to the organisms survival

3)Sticks around just incase we need it again

4)The structure makes the organism look cooler

3 would be my best guess

Explanation:

we dont depend on it

its not harmful but that wouldn't be a reason to have it

it doesnt look cool

it is a

explanation:

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.