I was goggling something hair related and came across this site...It has some interesting information about hair. I'm not sure how much credibility this site really has, but it was an  interesting read none the less. :)
http://www.hairscientists.org/hair.htm

Thanks for the link.  It was interesting.  One of the Q & A's  said you should never braid hair - it causes traction alopecia (hairloss which is often irreparable) - this was in response to a question about going to Ghana and braiding hair to prevent heat damage.  I wonder if that is for all braids or for tight cornrows, etc?

They did recommend light oil to protect hair from sun.

Traction alopecia would come from any hairstyle that requires pulling the hair very tight.  Cornrows can cause this.  Even dancers that always pull their hair back into a tight bun, will experience this.  Just look at their hair line and notice the receding hair line.

Thanks for posting the link! Very informative!

Yeah, traction alopecia can definately be caused by tight cornrows. I've seen a few middle-aged African-American women who were had bald patches on the sides of their head because of their cornrows. It was kind of sad because they would've had nice, long hair all over thier scalp if it weren't for this hairstyle.

Traction alopecia, also caused by putting your part in the same place all the time. :-/ (blarg. I like where my part is!)

Anais ;)