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For the Evolution of Mankind, the transition from walking on all fours to two legs was monumental in history. The change from all fours to upright changed the trajectory of potential for the homo-sapien species. New studies have found that this adaptation dates as further back as 7 million years ago.
This calls for a revision of data that studies have presented prior about human ancestors’ adaptations. Through detailed analysis of the thigh (femur) and forearm (ulna). The fossils were found in the Sahelanthropus tchadensis.
The fossils were found in Toros-Menalla in Chad in 2001. This discovery could be proof of human intelligence dating back even further than scientists assumed. Based on a detailed analysis of thigh (femur) and forearm (ulna) fossils from Sahelanthropus tchadensis, is the oldest representative species of humanity. Researchers can assume that these early hominins (species more related to humans than chimpanzees) climbed trees using all four limbs.
The limbs found explained the upright posture of the hominin, the cranium of the creature connects to the spinal cord in a downward position, making it unlikely that they walked on all fours. These primitive human predecessors practiced bipedalism, making them adept at both walking and climbing trees harmoniously.
Bipedalism was not ideal for this ancestral species as it could have become a weakness in their known habitat. Daniel Lieberman, a professor of human evolutionary biology and paleoanthropologist at Harvard University believes that the Hominins would be too slow, unbalanced, and in constant back pain if they walked on all twos feet instead of four.
Lieberman also hypothesized that their reason for transitioning to an upright posture is due to the rainforests in Africa breaking up, scattering resources and causing them to travel further out to retrieve food and water.  His theory is that walking upright allowed the mammals to preserve more energy when traveling as opposed to constantly walking on all fours utilized energy for two more limbs.
By abandoning the idea of walking on all fours, hominins evolved into what history knows today as humans. By deciding to utilize an upright posture, the doors of evolution opened and allowed the trail to be blazed in the progression of humanity.
Written by Mikal Eggleston
Edited by Sheena Robertson
Sources:
CNN: A 7 million-year-old practice set our ancestors on the course to humanity, new study finds; by Madeline Holcombe
SCIENCE: Human ancestors were walking upright 7 million years ago, ancient limb bone suggests; by Ann Gibbons
Featured Image Courtesy of Adam Foster’s Flickr Page – Creative Commons License
Inset Image Courtesy of Adam Foster’s Flickr Page – Creative Commons License
