The oldest signs of human occupation in the area of Mexico City are those of the "Peñon woman" and others found in San Bartolo Atepehuacan (Gustavo A. Madero). They were believed to correspond to the lower Cenolithic period (9500–7000 BC). However, recent studies place the age of the Peñon woman at 12,700 years old, making her one of the oldest human remains discovered in the Americas. Studies of her mitochondrial DNA suggest she was either of Asian origin, or Caucasian having an appearance like Western Europeans, or Aboriginal Australian.