In comparison to the highest voted answer, I'll try to find a way how a peaceful and strongly bonded society might not care for it's youth. A lot of those ideas are taken from pack animals (for the social aspect) and insects (for the reproduction mecanics). I don't know if you had a clear idea when you said "not care about it's young".
Why should they not care about the youth
First, there are too many off them. Like insects they lay eggs and forget them until they are adults. Maybe the mothers have so many children that they take so much energy and resources that the packs who did this eventually starved and died. In this case, the adults might live in close-knitted groups, but lay their eggs far away and let the youths come back and rejoin the pack. As pointed in the comments, this setup works if there is not a lot of competition between adult and young. It might work if the adult population inhabit 20% of the land, but in a situation like real-world humanity, children wouldn't have enough space. Or if, for example, the young are aquatic while the adults terrestrial. This also produce the next point.
Second, the children are so different that adults are instinctively disgusted. That society might be naturally xenophobic if they hate their own species on the basis of appearance. Maybe the babies are born as larvae and the adults don't want them.
Third, the children are violent while the adults are social. Imagine that the children are savage, aggressive and hormone driven. So much that they can't live with the rest of society. The adults would birth them, then throw them out where the youth would mature and calm down before coming back to society. This case is similar to how teens are troublesome until they (hopefully) grow up and become adults.
How would an advanced society like these be
If there are too many children or adults reject them. Since the adults don't really hate children, a children would probably form groups on the fringe of society. Because there are so many, they would probably be forced out of the cities and into the wild, living as bandits and hunters. Possibly, they could trade with the adults, being like the natives who traded with white men or some of them hired as labourers by adult. Eventually being accepted back into society in some ways. Those that don't make it might die or survive as wildlings. Society might see those wildlings as not even part of the same specie.
If the youth are violent and a threat. The children would hunt and pillage outside of society. Cities and villages would probably have police or militia to protect themselves. In this case, a youth uprising might actually be a legitimate danger. Eventually, the youth would calm down, realise that they would be better to join adults and try to prove themselves. Once again possibly by trading, creating art, socialising and being hired as labour. Society might also have some groups who would actively look for those acceptable children.