If it is of any interest to you, Keely, I come from a b-feeding country (or at least it was this way 30 years ago).
When I was a baby, there was no babyfood/formula for babies under 4 months in Moscow so I
, like many other kids, had a milk "brother". My mother pumped and fed another little boy, a total stranger. This continued until he was about 4-5 months old. He then was switched to table food and cow milk and grew up very healthy. When i was weaned or stopped bfeeding, I'm not exactly sure, but i know for a fact, that we do not have 7 year olds drinking breast milk.
I think the latests a child is b-fed over there is when he or she starts having interest in private body parts, which is around 3 or 4. The average age of bf in russia
was 15 months. I think bmilk is very important, but some kids are ready for table food very early on - I could eat a whole apple for a snack at 4 months of age - i was one fat kid! Over there most people introduce cow-milk products at 3-4 months, kefir and yogurt are very popular starter baby food.
I don't care how advanced we are, we are still a part of animal kingdom and every animal gradually weans their offspring when the kids start eating other foods. If this was damaging to the offspring, it probably would not be done.
I'm against early weaning, but imo 4 - 5 year old does not need breastmilk to function.