A paper published earlier this year appeared to confirm an important role for the formerly junk DNA, suggesting it played a key role in the evolution of the human brain and cognition.
Because other human chromosomes occur in twos, the mutations that occur during the development of sperm and eggs can be mitigated by gene-swapping between the pairs. However, the Y chromosome is too different from the X chromosome to swap out its mutations and as a result has degraded over millions of years from containing the same number of genes as X to its current rump status.
While the Y chromosome is expected to keep shrinking and eventually disappear, scientists have reassured humanity that this does not mean men will cease to exist, as other mammalian species have lost their Y chromosomes and continued to display sex differentiation, with other genes taking over the job as the main determinant of sex.