Hey Fasulye,
I'm studying socio-cultural anthro. I emailed the department too and was told:
"Congratulations on being accepted! At this point, you are on our
waiting list for financial aid. We have to wait until one person
declines before we can offer the aid package (tuition and fees plus
stipend) to another candidate.
Although this becomes a waiting game, you may well find it worth the
wait. If you have to make a decision about another school, please let
me know. We can always push for faster results (it doesn't always
work, but it is always worth while to try and help you)."
In a follow-up email he told me that I technically had until April 15th to give my decision but that sometimes changes depending on funding and other issues (if they give funding they want to know sooner.)