On the Move: Walking for 6 Million Years

The history of mankind is believed to date back to 6 million years ago, in Africa. Two-thirds of that history was spent walking. It was by walking that we conquered the world, spread our kind, explored all manner of ecosystems and put our brains to the test in the harsh game of survival and adaptability. Tangible evidence of the first walking hominins are extremely rare; the earliest footprint “fossils” date to 3.6 million years ago when a hominin performed a memorable feat immortalized in stone.

Traces of footprints left in wet volcanic ash. The hominins crossed the plain of Laetoli in Tanzania 3.6 million years ago.

This event took place at Laetoli in northern Tanzania, when a volcano erupted, forcing bipeds to flee. Mankind’s earliest footprints were left in the wet volcanic ash like a fossil snapshot, a heart-stopping event became a great stroke of luck for palaeontologists. The hominin which left these footprints was Australopithecus afarensis, one of the longest-lived and best-known early human species. Their movement was unquestionably bipedal, based on initial analysis of the arch of the foot and the big toe, which is parallel to the others even thought slightly separated from them.

Artist impression of two Australopithecines (A. Afarensis) on the move. Drawing by Lorenzo Possenti.

More recent analyses, published in 2011, confirmed that the arch of their foot, already similar to ours, was that of a markedly bipedal species. Computer simulations of the prints showed that in movement, these early bipeds were offloading their weight 40 kilos to just three points of support on their feet – from the heel to the hallux along the medial arch and the lateral arch [1]. A succession of hominin species has been on their two feet walking ever since.

The most recent and certainly the most versatile walker has been us, Homo Sapiens, said to first appear on the Earth some 200,000 years ago. Fossil tracks of anatomically modern humans have been found in South Africa dating to about 125,000 years ago. But the greatest journey on foot was undertaken by us. With a pair of long legs and a large brain, our ancestors spread through Africa, then left the continent, and in a span of 100,000 years, crossed the Nile corridor to reach the Mediterranean, then the Levant, followed by Asia and Europe. It did not end there. In the last 100,000 years, Homo Sapiens hunters left their marks as far north as Iceland, Greenland, Canada and the Artic and as far south as the tip of South America, arriving in Tierra del Fuego to found the Yamana culture around 8-9,000 years ago – an incredible journey on foot by a remarkable species.

[1] C.V. Ward, W.H. Kimbel and D.C. Johanson, “Complete Fourth Metatarsal and Arches in the Foot of A. Afarensis”, Science, n0. 331 (6018), 2011, pp. 750-53.

Further Study

See this website for a fuller description of A. Afarensis: http://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-afarensis

Stefania Ricci and Sergio Risaliti (eds), Equilibrium, Skira Editore, 2015.

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