At about two to three years of age, young lions are no longer tolerated by their family ― the pride. Their mothers are usually ready for their next litter of cubs, which often drives them out to become nomads. This mostly happens to young males, but it happens to females as well; if the pride is too large and has difficulty supporting itself, young females will also be driven to become nomads.
This driving out of young lions is vital to the survival of the pride. For females, it keeps the pride at a size that requires less support. For males, there are two other advantages. First, there is less competition for the prime male over mating in the pride. Second, it helps avoid incest. By leaving the pride, the young males will move to mate with other lionesses rather than those related to them, thus the gene pool is kept healthy.
Nomadic life usually consists of a period of scavenging and wandering over a large area until the young lion is ready to join another pride. For females, this means inclusion. They may be included in a new pride once they have come into estrus (in heat) and are mated by another male. For males, it means conquering; though their story is more dramatic.
After being kicked out, young male lions either roam alone or in small bands ― often with their brothers or cousins. At such age, their only option is to survive the unknown lands or perish. In fact, this is the time when most of them die; only about one in eight male lions make it to adulthood.
Those who do survive and find a new territory have to take over another pride. This means fighting with the resident males ― frequently to death. That's yet another evolutionary challenge for them to stay alive.
So when a male lion goes through all such troubles and finally makes it, he ends up by being a fit, strong, intelligent, and skilled leader. Only then is he ready and capable of having his own pride and protect it; only then can he become the King of the Jungle. This is how lions come to grow and become the majestic creatures they are.
The other, slightly darker side of the coin for evolution is that when males take over a new pride, they kill all the cubs. Not because they are heartless, ferocious monsters. But because as long as the cubs are alive, the mother will not be receptive to mating. The males care about passing on their genes and will not spend energy on cubs who are not biologically related to them. Lions do not play the step-father game. So killing the little ones in such cases is for the sake of evolution. It is known that 75 percent of lion cubs die at young age.
Note that lions are the only big cats to live in family units. This group social structure increases the chance for successful hunt and provides protection of cubs. All others big cats live solitary lives except when breeding or raising cubs.
The saga of the young big cats, used here as an allegory, deals with one of the main problems facing young humans, which is never getting the chance to be nomad lions. They leave the pride ― the family home ― only to get married and to start a family of their own without exploring unknown territories or experiencing true independence.
This usually happens where young ones cannot afford to live by themselves or to travel away from their home towns. Others, can afford to get away but possibly are afraid to leave their comfort zone of familiarity, so they end up by settling for certainty; for the safety of the territories they already know. In the process, they usually lose their individuality and become another version of their parents.
A third group are those who have controlling parents who force them to stay with them as they grow up, either by threatening to cut them off or by using emotional blackmail. Yes, this still happens today...in the human world. And it's caused by the attachment of the parents to their offspring.
You see, unlike love, attachment is selfish. Many parents want the children to have the life they have imagined for them, which, oftentimes, contradicts what the children may have in mind. So they attempt to dominate and control them. This is a grave problem because the young ones grow up believing they are dependent on that control, and they likely end up being weak, unhappy adults.
The sudden transition from a young, dependent member of a pride to a pride leader doesn't give the necessary strength or tools needed to endure a novel life away from the family. How would they know how to properly take care of their own pride if they haven't tried taking care of themselves first?
Without surviving the unknown and conquering the difficulties, the young do not get to know their true selves. The lack of experience renders them feeble, unfit, and insecure to be successful family leaders. This consequently causes lots of distress to their relationship and new life, which in many instances leads to unhappiness and divorce.
To be the King of the Jungle, well-worthy of the title, one has to first wander like a nomad. This is the natural course of things. This has always been the Tao.