Y chromosome – Wikipedia, the free encyclopedia

“Today, the human Y chromosome itself contains only 78 working genes,^[9] compared to close to 1500 working genes on the X chromosome. In some animals, Y degradation is even more severe. The dunnart, a marsupial carrying a 10-12 Mb Y chromosome, has only four characterised genes; among them the SRY gene, is the smallest known mammalian Y chromosome.”

Via [wikipidia while writing a dirty rap and forgetting which chromosome the mens have]