Elephants who are past reproductive age often lose their teeth in old age, then slowly starve to death as a result. Explain why there is no evolutionary pressure for this terrible and seemingly maladaptive situation to change.

There is no benefit to change this from happening

Explanation:

Typically elephants live until they are over sixty years old. At this age the teeth are worn down and become unusable; some of them may even fall out. When this happens the animal finds it difficult to acquire nutrients and typically becomes malnourished. The animal slowly starves to death and eventually leaves the herd.

There is no reason for this to change from an evolutionary stand point because this animal has already contributed to the herd as a younger elephant. If the older animals continue to live longer this will slow down the movement of the herd as well as consume the resources that the younger elephants need to keep strong and resist predation.

The sick elephants leave the herd and go to the elephant grave yard to pass away and allow the herd to move on.

not only is it colder, it also becomes darker, less salty, and more dense.