What are these belts behind my rear seats?

I was vacuuming the interior of my '07 DC and noticed these strange belts behind the rear seat backs. There's one behind each seating section. What are they for? I didn't really find something convincing in the OM.

 

Child car seat anchor

 

OK, that's what I thought they could be but they look kind of strange for that purpose. I'm used to the LATCH type anchors which I thing this Tundra has. I guess I'll stuff them back down where I found them.
Thanks.

 

Was reading the manual for my kid's seats and you are suppose to route the seat top latch strap through the loop and to the metal anchor above middle seat. That way there is room to tighten the strap.