One "useful paper" that provides deep insight into why "mature" females are critical to wild populations is:
A landmark study on African elephants showing that groups with older matriarchs are much better at distinguishing between the calls of friends and strangers, reducing unnecessary stress and energy expenditure for the herd.
Older females often possess critical information about the location of food and water during rare environmental events like droughts.
In species like elephants and orcas, the presence of mature females reduces aggression within the group and improves the survival rates of calves.