Since it was discovered in 1991, preserved in 5,300 years’ worth of ice and snow in the Italian Alps, the body of the so-called Tyrolean Iceman has yielded a great deal of information. Scientists have learned his age (about 46), that he had knee problems, and how he died (by the shot of an arrow).

Now, researchers have sequenced the complete genome of the iceman, nicknamed Ötzi, and discovered even more intriguing details. They report in the journal Nature Communications that he had brown eyes and brown hair, was lactose intolerant and had Type O blood.

The lactose intolerance makes sense, said Albert Zink, an anthropologist at the European Academy of Research in Bolzano, Italy, who was one of the study’s authors.

“In early times, there was no need to digest milk as an adult because there were no domesticated animals,” Dr. Zink said. “This genetic change took hundreds of years to occur.”...