One surprising effect of European colonization of the Americas was a cooling of the Earth’s climate, researchers at University College London have determined. The team, led by geographer Alexander Koch, estimates the indigenous population of the Americas at the end of the fifteenth century to have been around 60 million. Over the next century, this population declined by some 90 percent, largely due to epidemics introduced by Europeans. As a result, around 215,000 square miles of cultivated land, roughly the area of France, was left fallow and reverted to forest. This sucked up enough carbon dioxide—a greenhouse gas that traps heat in the atmosphere—to lead to cooling.

This process took place amid an extended cold stretch known as the Little Ice Age, which lasted from around 1250 to 1850. Other factors that contributed to cooling during this period included numerous widespread volcanic eruptions and natural fluctuations in solar radiation. But, Koch says, the effects of colonization played a key role in driving temperatures down in the early seventeenth century, adding, “This is thought to be the coolest part of the Little Ice Age.”

Each spring as new plants sprouted from the ground, the ancient cultures of Mesoamerica, including the Aztecs, understood the event as the earth growing a new skin. This idea was embodied by the god Xipe Totec, who was often depicted wearing a flayed human skin. The deity was thought to cause crops and other plants to grow. Archaeologists led by Noemí Castillo Tejero of Mexico’s National Institute of Anthropology and History recently uncovered the earliest known temple of the “Flayed Lord” at the Ndachjian-Tehuacan archaeological zone in the Mexican state of Puebla.

The temple complex was built by the Popoloca people around A.D. 900. There, the archaeologists have found a large pyramid with two circular altars where, they believe, prisoners of war were given as sacrifices to honor Xipe Totec after they were killed in gladiatorial combat. They also unearthed two large skulls carved from imported volcanic stone, as well as the torso of a ceramic effigy of the god, which appears to have an extra hand hanging from the left arm. The archaeologists suggest this sculpture represents Xipe Totec wearing the skin of a sacrificial victim, a particularly macabre way to commemorate nature’s cycle of life and death. 

A richly furnished grave excavated in 1878 near the Viking town of Birka in eastern Sweden had long been assumed to hold a powerful male warrior. The grave was equipped with an arsenal of weapons, as well as a set of gaming pieces and a gaming board, which were seen as indications that the deceased was a military commander. A pair of horses was also found in the grave, one bridled as if prepared to ride off into battle once again in the afterlife. More than a century later, several osteologists concluded—and genetic analysis confirmed—that this Viking warrior was actually female.

When these results were reported in 2017, skeptics wondered whether there had been a testing mistake, or, perhaps, whether the person in the grave had not been a warrior after all. A new review of the evidence led by Neil Price of Uppsala University concludes that the person in the grave was indeed biologically female, and that there is no reason to doubt that she was a warrior in a position of great authority. “Ever since its excavation, the burial has been interpreted as that of a high-status warrior,” says Price. “We think so, too, for exactly the same reasons as everyone else has always thought so—but in light of the new sex determination, she was a female high-status warrior.”