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The Y chromosome is one of the two sex chromosomes in humans and most other mammals.
It's typically found in males, who have one X and one Y chromosome (XY), while females have two X chromosomes (XX).
The Y chromosome contains genes that determine male characteristics and fertility. Research suggests that the Y chromosome is shrinking and losing genes over time.
The Y chromosome has fewer genes than the X chromosome, making it more vulnerable to genetic mutations and deletions.
Unlike the X chromosome, which can swap genes with its partner X chromosome in females, the Y chromosome doesn't have a matching partner to recombine with.
Some scientists believe that the Y chromosome's decline is an evolutionary response to the fact that males don't need a second X chromosome to survive.