A six-million-year story

Relatives and species

The woolly mammoth, the Natural History Museum says, is an ice age icon, but it was only the very last chapter in a six-million-year-long story. Natural History Museum In total, there were around 10 species of mammoth that roamed the planet long before the iconic ice age woolly mammoth. Natural History Museum

Mammuthus subplanifrons is the oldest mammoth found so far. It lived about five million years ago. Fossils of its teeth have been found in South Africa. Natural History Museum There was a pivotal moment about 3.5 million years ago when mammoths broke out of Africa, moved through the Middle East and spread rapidly across Eurasia. Mammuthus rumanus is the first mammoth found outside of Africa. Natural History Museum The mammoth’s ancestors arose in Africa, and were tropically-adapted browsing animals closely related to the living elephants. Around 3 million years ago, they spread into the northern hemisphere and began a process of transformation leading to the highly-specialised woolly mammoth of the late ice age, adapted to cold, treeless environments and a diet of grass. Natural History Museum

About two million years ago, Lister says, a species called Mammuthus meridionalis appears. It survived for about a million years, and there are very abundant fossils all the way from Britain to China. It is also known as the southern or ancestral mammoth. Natural History Museum Micro-wear patterns on their teeth show that southern mammoths were mostly browsers, eating from shrubs and trees. Steppe mammoths’ teeth, on the other hand, indicate they were mostly grazing on grass. Natural History Museum

Woolly mammoths, Mammuthus primigenius, evolved about 800,000-600,000 years ago in northeast Siberia. Scientists think a population of steppe mammoths that were well-adapted to the incredibly harsh conditions evolved into the woolly mammoth, which then spread west across Eurasia and east into North America. Natural History Museum Morphological and genetic studies suggest that woolly mammoths evolved from steppe mammoths (Mammuthus trogontherii) between about 800,000 and 600,000 years ago in Asia. Britannica

Columbian mammoths, Mammuthus columbi, lived in North America, from southern Canada down to Costa Rica. Natural History Museum The shape of Columbian mammoth teeth indicates they are descendants of steppe mammoths. DNA, however, tells a slightly different story: a study of 13,000-year-old fossils showed that Columbian mammoths were a hybrid species, with half steppe mammoth DNA and half early woolly mammoth DNA, stemming from a hybridisation event 400,000 years ago. Natural History Museum The Museum has also shown how the North American or Columbian mammoth arose from relatively advanced Eurasian mammoths that dispersed across the Bering land bridge some 1.5 million years ago. Natural History Museum

Southern and steppe mammoths, the Museum says, weighed some 10 tonnes, making them heavier than any land animal alive today. They were also up to four metres tall. Natural History Museum Most mammoths were about as large as modern elephants. The North American imperial mammoth (M. imperator) attained a shoulder height of 4 metres (14 feet). At the other extreme were certain dwarfed forms whose ancestors became isolated on various islands. Britannica Some very small mammoths have also been found, such as the 1.7-metre-tall Californian pygmy mammoth, Mammuthus exilis, and the 1.5-metre-tall dwarfed Sardinian mammoth, Mammuthus lamarmorai. These have experienced insular dwarfism, where species shrink due to living on isolated islands with limited resources and few large predators. Natural History Museum

The first species where we find fossils in the Arctic Circle, Lister says, is the steppe mammoth. By then the climate had deteriorated significantly and there was extensive tundra. With the DNA, steppe mammoths were already quite cold adapted in their physiology. Then woolly mammoths pushed it to an extreme. Natural History Museum In 2021, Lister collaborated with a team who extracted and sequenced DNA from a 700,000-year-old woolly mammoth tooth and a 1.2 million-year-old steppe mammoth tooth. They found that genes that could help an animal survive in the Arctic Circle — such as those coded for long hair, fatty deposits and a tolerance to cold — were present in the older steppe mammoth DNA. Natural History Museum

Museum researchers have traced this process in most detail using fossilised molar teeth, finding an increase in crown height and in the number of enamel grinding ridges — an increasing adaptation to a tougher diet. Natural History Museum In particular, it appears that the first major step in the origin of the woolly mammoth occurred in China as much as 2 million years ago, while the final changes took place in north-east Siberia about a million years later. In both cases it is plausible that the changes were driven by known changes in climate and vegetation. Natural History Museum