In these instances it is often the result of long hours of sitting, where the abdominals become weak, the front of the hips (hip flexors) get super tight, and we develop poor postures.
Often jobs requiring prolonged sitting such as truck drivers and office workers develop these postures, and while often not physically demanding, can develop lower back pain at some point. Thats not to say that non-office workers can't develop these postures, and an anterior pelvic tilt, because they can as well. Dancers commonly walk around in a anterior pelvic tilt.
The anterior pelvic tilt, can relate to a term called ‘the lower cross syndrome’. This is where one side of the line, such as the hip flexors and lower back, become tight and stiff respectively, whilst the abdominals and bottom muscles become weak and tend to stay dormant, until woken up and activated correctly.
AHR's Megan pulled out the whiteboard and some markers, and with her rusty drawing skills, demonstrates below the two pelvic tilts.