Laetoli

**Laetoli** is an archaeological site in Tanzania, dated to the PlioPleistocene 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.

## Evidence of bipedalism

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).

### Who made the footprints?

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.

## Footprints in Europe

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.

## Other websites

- Footprints to fill : flat feet and doubts about makers of the Laetoli tracks. _Scientific American_ 2005. http://www.scientificamerican.com/article.cfm?id=footprints-to-fill
- Leakey M.D. &  Hay R.L. Pliocene footprints in the Laetolil Beds at Laetoli, northern Tanzania. _Nature_ http://www.nature.com/nature/ancestor/pdf/278317.pdf
- Footprints from the past. WebCite https://web.archive.org/web/20090829001759/http://encarta.msn.com/media_461543938_761566394_-1_1/Footprints_From_the_Past.html