In August 1942 a students’ nursing brigade discovered 12-year-old Tanya Savicheva, weak with hunger, living alone in an apartment in Leningrad, which had been besieged by Hitler since September 1941. She had kept this diary:

1. Zhenya died on December 18, 1941, at twelve noon.
2. Grandma died on January 25, 1942, at three in the afternoon.
3. Leka died on March 17, 1942, at five o’clock in the morning.
4. Uncle Vasya died on April 13, 1942, at two o’clock at night.
5. Uncle Lesha on May 10, 1942, at four o’clock in the afternoon.
6. Mama died on May 13, 1942, at 7:30 in the morning.
7. The Savichevs are dead.
8. Everyone is dead.
9. Only Tanya is left.

The nurses evacuated her along the narrow lifeline that had been opened that summer by the Soviet army and placed her in an orphanage in a nearby village, but she died there, probably of chronic dysentery, in July 1944. The diary is kept today in the St. Petersburg Museum of History.

Around 1275, a native culture known as the Gallina vanished from northern New Mexico. And almost every Gallina skeleton ever found has been that of someone brutally murdered. No one knows why.

“[Someone] was just killing them, case after case, every single time,” U.S. Forest Service archaeologist Tony Largaespada told National Geographic News in 2007.

Seven skeletons found in a remote canyon paint a typical picture — one had a fractured skull, forearm, jaw, thighbone, pelvis, and several broken ribs; another bore cut marks on the upper arm that suggested blows from an ax. A 2-year-old child had had its skull crushed.

In other cases the victims’ necks have been broken, and the bodies are commonly thrown into a house, which is then burned to the ground.

Possibly this was a genocide, or possibly internecine conflict within the Gallina. Either could have been exacerbated by a drought that is known to have gripped the area around this time. But, so far, no one knows the reason.