Y chromosome has been occuping attention in scientific community for a long time, primarily because of its role in spermatogenesis and sex determination that depends on the testes, which differentiation depends on the Y chromosome. It is unique because it contains only a few active genes and many pseudogenes that are not transcribed in the product (protein or RNA). The assumption about the evolution of the Y chromosome is that it becomes smaller, loses functional genes and could disappear in a few million years. A recent interspecies studies have shown that the evolution of the human Y chromosome is much faster than the rest of the genome (mainly due to the transfer of the Y chromosome only through male line) and along with a lack of recombination led to a reduction of the Y chromosome, or loss of genes positioned on the Y chromosome. One hypothesis speaks about the Y chromosome as a genius, the dominant chromosome that determines male individuals, of selfish Y chromosome that attracts genes (with growth factors) responsible for male development. The second model shows the Y chromosome as wimp and weakling, a shadow of itself as it once was, degrading in almost nothing. Comparison of chimpanzee and human Y chromosome have shown that their Y chromosomes differ in structure and content of genes in a very large percentage, in contrast to other genes which show a great match. This fact indicates a rapid evolution and major structural changes in Y chromosome (and chimps and humans) in the last 6 million years, after the divergence of two evolutionary lines. Research in this area continue; scientists hope to be able to determine exactly when will Y chromosome disappear, and which processes are most responsible for the reduction of the Y chromosome.