Ice Age Animals Early Humans Encountered: From Homo erectus to the First Americans

The ice age animals early humans encountered were not one fixed cast of creatures. Each human group — Homo erectus in the tropics, Neanderthals on the European tundra, Denisovans from Siberia to the Tibetan Plateau, the first Homo sapiens in Africa, and the Paleoindians who reached the Americas — walked into a different world of giants. Some hunted these animals; some were hunted by them; nearly all of them shared the landscape with beasts that, in most cases, no longer exist.

This is a tour of those vanished menageries, group by group. It ends with the first Americans and the American lion — Panthera atrox, the largest cat the New World ever produced — and with the great extinction that swept most of these animals away as the last Ice Age closed.

Homo erectus: the first hominin among giants

Homo erectus was the first member of our genus to leave Africa, spreading across Asia between roughly 1.9 million and a few hundred thousand years ago. In the African grasslands where it arose, and along the routes it followed east, it lived among predators and herbivores that dwarf anything alive today.

In Africa, erectus shared the savanna with Deinotherium, a distant elephant relative with strange downward-curving tusks, and with Pelorovis, a buffalo whose horns spanned close to three metres. The most dangerous neighbours were the sabertooths — the scimitar-toothed Homotherium and the dirk-toothed Megantereon — and Pachycrocuta, a giant short-faced hyena powerful enough to crack open a carcass and drive early humans off a kill.

Further east the cast changed. At Zhoukoudian near Beijing, the "Peking Man" population of Homo erectus lived alongside Stegodon, another elephant relative, giant deer, and the same giant hyena. In the forests of southern China and Southeast Asia, erectus overlapped with Gigantopithecus, the largest ape that ever lived — a three-metre relative of orangutans that survived until around 250,000 years ago before it, too, went extinct.

Neanderthals and the mammoth steppe

Neanderthals evolved in Europe and western Asia and thrived there from around 400,000 until 40,000 years ago, through some of the harshest phases of the Ice Age. Their world was the mammoth steppe: a cold, dry grassland that stretched across the north of the continent.

The defining animal was the woolly mammoth (Mammuthus primigenius), but it shared the steppe with the woolly rhinoceros (Coelodonta antiquitatis), wild horses, reindeer, steppe bison, aurochs, and the giant deer Megaloceros — an elk whose antlers spanned up to 3.6 metres. Neanderthals were formidable big-game hunters: the site of La Cotte de St Brelade on Jersey preserves heaps of mammoth and rhino bone at the foot of a cliff, hinting at mass kills driven over the edge.

They also shared their caves with rivals. The cave bear (Ursus spelaeus), cave lion (Panthera spelaea) and cave hyena all denned in the same landscapes, competing for shelter and for meat. Living on the mammoth steppe meant hunting the largest land animals in Europe while avoiding some of its largest carnivores.

Denisovans: from a Siberian cave to the roof of the world

Denisovans are the ghost lineage of human evolution — known mostly from DNA and a handful of bones, yet once spread across a vast swathe of Asia. The first fragment, a finger bone, came from Denisova Cave in the Altai Mountains of Siberia, a site whose Ice Age layers preserve woolly mammoth, woolly rhinoceros, bison, wapiti and cave hyena.

But Denisovans also reached extraordinary extremes. At Baishiya Karst Cave on the Tibetan Plateau, more than 3,000 metres above sea level, a 2024 study of thousands of bone fragments showed Denisovans butchering blue sheep, wild yak, woolly rhinoceros, gazelles and even spotted hyenas and birds. Far from clinging on, they were skilled hunters of high-altitude megafauna in one of the most punishing environments on Earth. You can follow where each group ranged on the interactive migration map.

The first modern humans in Africa

Anatomically modern Homo sapiens appears in the African fossil record by around 300,000 years ago, at sites such as Jebel Irhoud in Morocco. Uniquely among the groups in this article, the first modern humans grew up among megafauna much of which is still alive — the elephants, hippos, rhinos, giraffes and lions of the African savanna.

That is not a coincidence. Africa lost far fewer of its large animals at the end of the Ice Age than the Americas or Australia did, and many researchers think it is because African megafauna evolved alongside toolmaking hominins for millions of years and learned to be wary of them.

Even so, early Homo sapiens knew giants that are now gone. The giant long-horned buffalo Syncerus antiquus (often called Pelorovis) carried horns spanning around three metres and survived in North Africa until just a few thousand years ago; the giant Cape zebra Equus capensis and the huge wildebeest relative Megalotragus grazed the same plains; and Theropithecus oswaldi, a baboon relative approaching the size of a female gorilla, foraged alongside them. The predators, though, were the ancestors of today's — lion, leopard and spotted hyena — which makes Africa the one place where the Ice Age predator guild never truly ended.

The first Americans and the American lion

The Americas were the last continents people reached, and they saved the most spectacular megafauna for last. Humans were in the New World by at least 15,000 years ago — and fossil footprints at White Sands, New Mexico, may push that back beyond 20,000 — walking into a continent that had never seen a human hunter.

The herbivores were staggering: the Columbian mammoth, the American mastodon, giant ground sloths the size of a car, the armoured glyptodonts (car-sized relatives of armadillos), native horses and the American camel, Camelops. And the predators matched them. The American lion, Panthera atrox, was the largest cat the Americas ever produced — perhaps a quarter larger than a modern African lion, at an estimated 250–350 kg. Alongside it hunted the saber-toothed cat Smilodon fatalis, the dire wolf (Aenocyon dirus), and the giant short-faced bear (Arctodus simus), which stood over three metres tall on its hind legs.

For the first Americans, the American lion and its fellow carnivores were both rivals and dangers — every predator on the continent, people included, was chasing the same herds. Within a few thousand years, nearly all of them were extinct. For a closer look at one corner of this world, see the Ice Age predators of North Carolina.

Why the giants disappeared

By around 10,000 years ago, most of the animals in this article were gone. The end of the last Ice Age saw one of the largest extinction pulses in the history of large mammals: the Americas lost roughly three-quarters of their big genera, Australia most of its giant marsupials, and Eurasia its mammoths and woolly rhinos.

Two explanations dominate, and they are not mutually exclusive. The overkill hypothesis blames human hunting of slow-breeding giants; the climate hypothesis points to the rapid warming and habitat upheaval at the close of the Ice Age, including the cold snap of the Younger Dryas. The geography is telling: extinction was worst exactly where modern humans arrived suddenly, and mildest in Africa, where animals had millions of years to adapt to us. Most researchers now favour a combination of the two — a natural climate shock delivered to faunas that were, for the first time, also facing an efficient new predator.