Laetoli is an archaeological site in Tanzania, dated to the Plio–Pleistocene epoch around 3.6 million years ago. It is famous for having hominin footprints preserved in volcanic ash.
The site of the Laetoli footprints is 45 km south of Olduvai gorge. It was excavated by archaeologists Louis and Mary Leakey in 1978. “The Laetoli Footprints” got a lot of attention from the public because they are convincing evidence that Pliocene hominins walked upright.
When they were found, the 3.6 million-year-old Laetoli footprints were the oldest known evidence of hominin bipedalism. Now older evidence has been found, including fossils of Ardipithecus ramidus.
The footprints and skeletal structure excavated at Laetoli were clear evidence that bipedalism evolved before enlarged brains in hominids. Although it is debated, it is believed the three individuals who made these footprints belonged to the species Australopithecus afarensis. Together with the footprints were other hominin and animal skeletal remains and Acheulean artifacts (hand-axes).
After debate among scholars, it was decided that Australopithecus afarensis is the species of the three hominins who made the footprints at Laetoli. This is based on the reconstruction of the foot skeleton of a female A. afrarensis hominin.
Detailed footprint analysis compared both human and bipedal animals such as bears and primates. Gaits (stride pattern) and foot structure were analysed. Step length, stride length, stride width and foot angle showed that A. afarensis was more human-like in gait than ape-like.
Scientists now classify A. afarensis is called an obligate bipedal hominid: a hominid who mostly walked upright, just like the genus Homo. That means it was adapted to living in open woodland and savannahs, not tropical rainforests.
A. afarensis was different from Homo in important ways. For example, A. afarensis's brain was about the same size as modern chimpanzees and gorillas. This situation, where different traits of an animal evolve at different rates, is known as mosaic evolution.
The oldest hominin footprints in Europe are in the United Kingdom. They are about 800,000 years to a million years old. They were found on Happisburgh beach, East Anglia. The archaeologists describe them as "the oldest known hominin footprint surface outside Africa at between ca. 1 million and 0.78 million years ago".
The site in known for its preservation of sediments with early Pleistocene fauna and flora. Since 2005 flint tools have been found. This means humans occupied northern Europe at least 350,000 years earlier than was thought before.