Giant panda Tian Tian is seen at the Smithsonian's National Zoo in Washington, D.C., the United States, Aug. 22, 2020. Mei Xiang was artificially inseminated in March this year with frozen semen collected from Tian Tian. Mei Xiang, who's of an advanced maternal age, gave birth to a cub at Smithsonian's National Zoo here on Friday. (Xinhua/Liu Jie)