Laetoli Footprints: The Oldest Trail of Upright Walkers

The Laetoli footprints are a trail of early human ancestor tracks pressed into volcanic ash in northern Tanzania roughly 3.66 million years ago. They are the oldest widely accepted evidence that our relatives walked fully upright on two legs, with a heel strike, an arched foot and a big toe in line with the others, much as we do. Most researchers attribute them to Australopithecus afarensis, the species best known from the skeleton nicknamed Lucy in Ethiopia.

The main trail is around 27 metres long and holds some seventy prints left by at least two, probably three, individuals walking in the same direction. Discovered by Mary Leakey's team in the late 1970s, they remain one of the most moving finds in the study of human origins, because they capture not a body but a moment.

How the Laetoli footprints were preserved

Laetoli lies roughly 45 km south of Oldupai Gorge, in the Ngorongoro Conservation Area. Millions of years ago a nearby volcano, usually identified as Sadiman, puffed out fine ash that settled across the land. Light rain dampened it into something like wet cement. Animals crossed it: hares, birds, antelopes, ancestors of elephants and horses, and a few upright walkers. The sun hardened the surface, and further ash falls buried it. Because the ash contains minerals that can be dated, geologists can place the trackway with unusual confidence at around 3.6 to 3.7 million years old.

Thousands of animal tracks were noticed first, in 1976. The famous hominin trail was identified and excavated in 1978 and 1979. Its quality is extraordinary: in places you can see the impression of the heel, the ball of the foot and the toes.

What footprints tell us that bones cannot

Bones are evidence of anatomy. A thigh bone or a pelvis tells scientists what a body was capable of. Footprints are evidence of behaviour: what one particular body actually did, on one particular day.

• Gait: the prints show weight passing from heel to toe in a way that is broadly human, not the bent-legged shuffle of a chimpanzee walking upright. Researchers still debate how fully extended the legs were, but the trail is clearly the work of habitual walkers.
• Size and company: different print sizes suggest individuals of different builds moving together, one apparently stepping in the tracks of another. Whether they were a family, a mixed group or simply travelling near each other cannot be known.
• Pace: stride length allows estimates of walking speed, which appears unhurried.
• Setting: the surrounding animal tracks show who else shared the landscape that same season.

There is something no skull can offer here: the sense of company. Upright walking was never only a physical trick. It was a way of moving through open country, carrying things, and travelling with others.

Who made them? Evidence and debate

Fossil jaws and teeth from Laetoli itself helped define Australopithecus afarensis; one Laetoli jaw is the species' reference specimen. Since that species is the only hominin firmly known from the region at the right time, it is the leading candidate for the main trail. But footprints do not come with names attached, and scientists are careful to say "attributed to" rather than "made by".

New evidence keeps refining the picture. In 2016 a team led by Tanzanian archaeologist Fidelis Masao reported further hominin footprints from a nearby part of Laetoli, including prints from an individual considerably larger than those in the original trail, which reopened questions about body size and group make-up. In 2021 a reanalysis of a separate set of prints, excavated in the 1970s and long set aside as possibly made by a bear, argued that they were left by a hominin with an unusual cross-stepping gait. If that is right, more than one kind of upright walker may have crossed Laetoli at about the same time. That idea is still being tested, and it is an honest example of how this science works: careful claims, revised as evidence grows.

Reburial, conservation and casts

Many visitors are surprised to learn that the original prints are not on display. After they were recorded and cast, the trail was reburied in 1979 to protect it from erosion. That was not the end of the story. Acacia seeds in the covering soil took root, and tree roots began to push into the ash layer. In the 1990s, Tanzanian antiquities authorities and international conservators re-excavated the trackway, removed the trees, documented the prints again in detail and reburied them under engineered layers designed to keep roots and water out. The site continues to be monitored.

So what you see in museums, including at the site museum on the rim of Oldupai Gorge, are casts and replicas. They are faithful copies, but it is worth keeping three things distinct:

1. The originals: the hardened ash itself, buried and protected at Laetoli.
2. Casts: moulds taken from the prints, used for display and study.
3. Interpretation: the reconstructions and artworks of figures walking, which are educated imagination, not evidence.

Whether the trail should ever be uncovered for public display is a fair question. Most conservators argue that burial is the only way to keep it safe for future generations, and that the decision belongs above all to the Tanzanian authorities responsible for it.

Why this matters on foot

Wandering Through Mankind is, at heart, a walking project. Leon plans to cover roughly 175 km a week on foot, 30 to 35 km on a walking day, from Cape Agulhas to Windsor. It is hard to think of a more fitting place to stop and reflect than the oldest clear trail of upright walkers on Earth. Our article on how far you can walk in a day looks at the human side of that question today.

Later in the walk, the line crosses Tanzania from Zambia towards Rwanda, well to the south and west of Laetoli. The plan is a research trip away from the route, returning to the exact point where walking paused, with transport never counted as walked distance. Leon hopes to learn about the footprints from qualified Tanzanian specialists and to explain clearly what is known, what is debated and what is imagination. It sits alongside the nearby story of Oldupai Gorge. You can read about Leon, follow the journal once he sets off, or support the walk.

Frequently asked questions

How old are the Laetoli footprints?

About 3.66 million years old, dated from the volcanic ash layers above and below the prints.

Who made the Laetoli footprints?

Most researchers attribute the main trail to Australopithecus afarensis. A separate set of prints at the site may belong to a different hominin, which is still debated.

Can you see the Laetoli footprints?

The original trackway is reburied for protection. Visitors see casts and replicas, including at the museum at Oldupai Gorge and in museums abroad.

Why do the footprints matter so much?

They are the oldest widely accepted direct evidence of habitual upright walking, recording behaviour that bones alone cannot show.