May 24, 2013
Terrain Played Evolutionary Role To Upright Walking In Humans
Lee Rannals for redOrbit.com — Your Universe Online
Archaeologists from the University of York have challenged evolutionary theories about why our ancestors began walking upright. Publishing research in the journal Antiquity, the team wrote that our upright gait may have begun in the rugged landscape of East and South Africa, which was a terrain shaped by volcanoes and shifting tectonic plates.
"Our research shows that bipedalism may have developed as a response to the terrain, rather than a response to climatically-driven vegetation changes," Dr. Isabelle Winder, from the Department of Archaeology at York and one of the paper's authors, said in a statement.
"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," she added.
Scientists believe our earliest ancestors went from tree dwelling quadrupeds to upright bipeds capable of walking and scrambling. These hominins would have been attracted to the terrain of rocky outcrops and gorges because it offered shelter and opportunities to trap prey. The terrain also would have required more upright scrambling and climbing gaits.
Previous theories suggest that our ancestors were forced out of the trees and onto two feet when climate change reduced tree cover. However, the new study says it has more to do with terrain and less with tree cover.
"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," Winder said.
The team believes the hands and arms of upright hominins were left free to develop increased mania dexterity and tool use. The development of running adaptations to the skeleton and foot may have resulted from later excursions onto the surrounding flat plains.
"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," Winder said.
Scientists reported in February that when humans adapted to upright walking it resulted in physical challenges like backaches and sore feet. Bruce Latimer, an anthropologist from the Case Western Reserve University School of Dental Medicine says we suffer from these physical ailments in a way that other animals do not because of how we evolved from four-footed walking to two feet.