The "memories" that flash before one's eyes might just be a byproduct of how the brain is built ― imagine if it had to just dump all the electric charge that was saving all that data.
Whatever it is, however, there's no way the evolutionary mechanisms are going to have any impact. Why? Because memories or no memories, the person is just dying and will not be able to pass this characteristic to their offspring.
I remember reading somewhere that our health degrades as we get old because the factors that cause this degradation occur too late in the human's lifetime, so that no matter if they get them or not, they probably have already passed them (or not) to their children.
Also, maybe this comment[0] can offer a hypothesis on why this is may *be* important evolutionary-wise: https://news.ycombinator.com/item?id=31059618.
Traits that don't impact fitness are selected neither for nor against. And there's no distinction you can draw between traits that arise by happenstance and those for any other reason, because there never is any other reason.
So why be surprised that such a (presumably) durable epiphenomenon of human neural complexity, having once arisen by happenstance, should persist? There is quite literally no reason for it not to.
For a complex feature to pass through generations, it has to have some relative positive fitness associated with it. If it didn't provide some survival or fitness advantages, random genetic mutations would simply prevent the effect from being created. It is likely a very ancient survival mechanism based on these NDE existing through many different cultures and eras, and possibly not even specific to humans.
This is in fact not true. There are "coincidences" of evolutionary biology and if there is not selective pressure to change them, they remain for millions of years.
Spend some time looking and you’ll find everything evolution has crafted contains patterns seemingly too intricate to be purely random. In my opinion this is an artifact of our collective laughably poor understanding of the powers of recursive formulae, especially those that have undergone countless rounds of differential optimizations. In fact, the question “could this have been created by evolution” is eerily similar to the halting problem. Suffice to say, our feeble “human intuition” is of little use against true uncomputability.
Less abstractly, it’s been proposed that by flashing through all your memories you might pick up on some prior experience that lets you recover and go on to have some more kids (or provide for existing kids a bit longer)
Again, there are genetic mutations which make certain other mutations more likely. A beneficial mutation which spreads widely can eventually cause a plurality to carry a gene that is neutral or even harmful by giving it a ride on its own selective pressure.
Furthermore, complex systems are susceptible to emergent behavior. For example, is our brain selected by nature to undergo altered consciousnesses in the presence of some chemical substances? Probably. Should we then believe that nature has "selected" our brains to be altered by every psycho-actice drug that exists? Probably not. Some of these are certainly "happy" accidents by which the chemical function of our brain also happens to be impacted or interfered with by some other chemicals, thus inducing a "high".
The argument could be made that this serves some vast evolutionary purpose, but then we're back to inventing gods for ourselves again. (And in any case, such a theory would need also to explain why wasps also enjoy getting drunk, this being after all another example of the same behavior. Evo-psych types being as anthropocentric as they are, this never seems to be addressed, but it needs to be if they want the intellectual coherence to which they so anxiously pretend.)
Not everything happens is a result of evolutionary guidance. Many things are just side effects.
> Why would the brain evolve to do this? it has no evolutionary purpose.
Maybe it's nothing to do with dying but more to be mentally stable if you don't die?