The most recent ice age peaked between 24,000 and 21,000 years ago, when vast ice sheets covered North America and northern Europe, and mountain ranges like Africa's Mt. Kilimanjaro and South America's Andes were encased in glaciers.

At that point, our Homo sapiens ancestors had migrated from the warm African heartland into northern European and Eurasian latitudes severely impacted by the sinking temperatures. Armed with big, creative brains and sophisticated tools, though, these early modern humans—nearly identical to ourselves physically—not only survived but thrived in their harsh surroundings.

For our _Homo sapien_s forebears living during the last ice age, there were several critical advantages to having a large brain, explains Brian Fagan, an emeritus professor of anthropology at the University of California, Santa Barbara, and author of many books, including Cro Magnon: How the Ice Age Gave Birth to the First Modern Humans and Climate Chaos: Lessons on Survival from our Ancestors.

"One of the most important things about Homo sapiens is that we had fluent speech," says Fagan, "plus the ability to conceptualize and plan ahead."

With the advent of language, knowledge about the natural world and new technologies could be shared between neighboring bands of humans and also passed down from generation to generation via storytellers.

"They had institutional memory through symbolic storytelling, which gave them a relationship with the forces of the environment, the supernatural forces which governed their world."

Also through music, dance and art, our ancestors collected and transmitted vast amounts of information about the seasons, edible plants, animal migrations, weather patterns and more. The elaborate cave paintings at sites like Lascaux and Chauvet in France display the intimate understanding that late ice age humans possessed about the natural world, especially the prey animals they depended on for survival.

"When wildlife biologists look at those paintings of reindeer and bison, they can tell you what time of year it was painted just from the appearance of the animals' hides and skins," says Fagan. "The way these people knew their environment was absolutely incredible by our standards."

The last ice age corresponds with the Upper Paleolithic period (40,000 to 10,000 years ago), in which humans made great leaps forward in toolmaking and weaponry, including the first tools used exclusively for making other tools.

One of the most important of these was called a burin, a humble-looking rock chisel that was used to cut grooves and notches into bone and antler, lightweight material that was also hard and durable. The intricate spearheads and harpoon tips made from that bone and antler were small and light enough to be carried on foot by hunters over long distances, and were also detachable and interchangeable, creating the first compound tools.

"Think of the Swiss army knife—it’s the same thing," says Fagan. "The weaponry they made covered an extraordinary range of specialized tools, most of which were made from grooving antler and bone."

But even these sophisticated hunting weapons were useless outside of close-range attacks, which sometimes required the hunter to leap on the back of his massive prey. Once again, our human ancestors used their intelligence and planning skills to take some of the danger and guesswork out of hunting.

In one famed hunting ground in eastern France, ice-age hunters built fires every fall and spring to corral migrating herds of wild horses and reindeer into a narrow valley marked by a limestone tower known as the Roche de Salutré.

Once in the corral, the animals could safely and easily be killed at close quarters, harvesting an abundance of meat that was then dried for the summer and winter months. Archeological evidence shows that this well-coordinated slaughter went on for tens of thousands of years.

When the first humans migrated to northern climates about 45,000 years ago, they devised rudimentary clothing to protect themselves from the cold. They draped themselves with loose-fitting hides that doubled as sleeping bags, baby carriers and hand protection for chiseling stone.

But everything changed around 30,000 years ago with what Fagan argues is the most important invention in human history: the needle.

"If you saw a needle from 20,000 or 30,000 years ago, you'd know what it was in an instant, a very fine-pointed tool with a hole in one end to put thread through," says Fagan. "The miracle of the needle was that it enabled humans to make tight-fitting clothing that was tailored to the individual, and that's vital."

Like modern mountaineering clothing, clothes from the late ice age were meant to be worn in layers. An ice-age tailor would carefully select different animal skins—reindeer, arctic foxes, hares, even birds like ptarmigans—and sew together three or four layers, from moisture-wicking underwear to waterproof pants and parkas.

Thread was made from wild flax and other vegetable fibers and even dyed different colors like turquoise and pink. The result was a fitted, versatile wardrobe that fully protected its wearer from sub-freezing temperatures.

For shelter in the coldest months, our ice age ancestors didn't live deep in caves as Victorian archeologists once believed, but they did make homes in natural rock shelters. These were usually roomy depressions cut into the walls of riverbeds beneath a protective overhang.

Fagan says there's strong evidence that ice age humans made extensive modifications to weatherproof their rock shelters. They draped large hides from the overhangs to protect themselves from piercing winds and built internal tent-like structures made of wooden poles covered with sewn hides. All of this was situated around a blazing hearth, which reflected heat and light off the rock walls.

In the brief summer months, the hunters would move out into the open plains that stretched from the Atlantic coast of Europe all the way to Siberia. With cold temperatures persisting at night, shelter was taken in dome-shaped huts partially dug into the earth.

“The framework was built from a latticework of mammoth bones, either hunted or raided from carcasses,” says Fagan. “On top of it they'd lay sod or animal hides to make a house that was occupied for months on end.”