- Traditional theory suggested that our ancestors were forced out of the trees and onto two feet when climate change reduced tree cover
- But new theory shows that upright gait may have its origins in rugged landscape of East and South Africa which provided food and shelter
By RACHEL REILLY
PUBLISHED: 04:25 EST, 27 May 2013 | UPDATED: 06:21 EST, 27 May 2013
Early man began to walk on two feet because of rocky terrain and not climate change, according to a new study.
Researchers have said that our upright gait may have its origins in the rugged landscape of East and South Africa which was shaped during the Pliocene epoch by volcanoes and shifting tectonic plates.
Hominins, our early ancestors, would have been attracted to the terrain of rocky outcrops and gorges because it offered shelter and opportunities to trap prey.
But it also required more upright scrambling and climbing gaits, prompting the emergence of bipedalism.
The new study, carried out by archaeologists at the University of York, has challenged evolutionary theories behind the development of our earliest ancestors from tree dwelling quadrupeds to upright bipeds capable of walking and scrambling.
The study, ‘Complex Topography and Human Evolution: the Missing Link’, was developed in conjunction with researchers from the Institut de Physique du Globe in Paris.
The York research challenged the traditional theory that suggested our early forebears were forced out of the trees and onto two feet when climate change reduced tree cover.
Dr Isabelle Winder, from the Department of Archaeology at York and one of the paper’s authors, said: ‘Our research shows that bipedalism may have developed as a response to the terrain, rather than a response to climatically-driven vegetation changes.
NEANDERTHALS BREASTFED LIKE MODERN WOMAN
‘The broken, disrupted terrain offered benefits for hominins in terms of security and food, but it also proved a motivation to improve their locomotor skills by climbing, balancing, scrambling and moving swiftly over broken ground – types of movement encouraging a more upright gait.’
The research has suggested that the hands and arms of upright hominins were then left free to develop improved dexterity and tool use, supporting a further key stage in the evolutionary story.
The development of running adaptations to the skeleton and foot may have resulted from later excursions onto the surrounding flat plains in search of prey and new home ranges.
Dr Winder said: ‘The varied terrain may also have contributed to improved cognitive skills such as navigation and communication abilities, accounting for the continued evolution of our brains and social functions such as co-operation and team work.
‘Our hypothesis offers a new, viable alternative to traditional vegetation or climate change hypotheses. It explains all the key processes in hominin evolution and offers a more convincing scenario than traditional hypotheses.”
The findings were published in the journal Antiquity.