The international collaborative team led by Pennsylvania State University and the National Institute of Human Genomics in the United States has generated the complete chromosome sequence of non-human primates for the first time. The related paper was published in the journal Nature on the 29th. These sequences reveal significant differences between the Y chromosomes of different species, revealing their rapid evolutionary history, and also revealing previously unexplored regions of the ape genome, providing important insights into species diversity and evolution. Primate species are the closest living relatives to humans. This time, researchers sequenced the chromosomes of chimpanzees, bonobos, gorillas, Borneo gorillas, Sumatran gorillas, as well as another primate species with a distant relationship to humans - the ape, with a focus on studying their X and Y chromosomes. It was found that among the six primate species, The variability of Y chromosome in various characteristics (including size) is much greater than that of X chromosome. The number of nucleotide letters contained in the X chromosome ranges from 154 million in chimpanzees to 178 million in gorillas, with a difference of approximately 24 million; In contrast, The number of nucleotide letters contained in the Y chromosome ranges from 30 million in the primate to 68 million in the Sumatran gorilla, with a difference of approximately 38 million. The number of shared DNA sequences among species is also more variable on the Y chromosome. In order to compare the chromosomal sequences of primates with human X and Y chromosomes, researchers used a computational method called "alignment". Jin Xin, Vice President of Shenzhen Huada Institute of Life Sciences, said in an interview with Science and Technology Daily, "Alignment refers to the comparison between one sequence and another. If the similarity is relatively high, we say 'alignment successful' or 'alignment on'. Research has found that over 90% of primate X chromosome sequences have been successfully aligned with human X chromosomes, indicating that the evolution rate of the X chromosome is slower over millions of years of development.". In contrast, only 14% -27% of primate Y chromosome sequences were successfully aligned with human Y chromosomes. In addition, the percentage of duplicated sequences on the Y chromosome also varies greatly. Depending on the species, repetitive sequences account for 62% -66% of the X chromosome and 71% -85% of the Y chromosome. The lead researcher and professor at Pennsylvania State University, Katerina Markova, stated that the significant differences in the Y chromosome of these species are very surprising. Some of these species only differentiated from the human lineage 7 million years ago, which is not a long time from an evolutionary perspective, indicating that the Y chromosome evolved very quickly. (Lai Xin She)