"My bear reads books, yours eats carrots."
Translation:Ursul meu citește cărți, al tău mănâncă morcovi.
Skye is exactly right. If you think about the way definitive articles are most commonly used, to indicate the uniqueness of an object, then it only makes sense that if you indicate this object is yours or someone elses you refer to a very specific one.
In English it's inferred that objects with possessive pronouns mean logically specific and unique objects and act as if they were articulated