# New Insights into the Evolution of Bipedalism Uncovered
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Chapter 1: Understanding Bipedalism in Evolution
Bipedalism has been a focal point of research within the evolutionary field, representing the way humans move from one place to another. While it is established that bipedal locomotion among hominids emerged around 4 million years ago, some experts speculate that it could have originated as early as 7 million years ago. In late 2019, however, German scientists made a groundbreaking discovery: they unearthed remarkably preserved bones of a previously unknown ape species named Danuvius guggenmosi, estimated to be approximately 11.6 million years old—much older than the known bipedal organisms. This ancient primate exhibited long arms for tree-hanging and leg-like limbs, suggesting that if these appendages were used for upright walking, it would shift the timeline of bipedalism by 5 million years, consequently raising numerous intriguing questions. To grasp the importance of this finding, it’s essential to explore the background of early hominids.
Section 1.1: The Earliest Hominins
The earliest known hominins are Sahelanthropus tchadensis and Orrorin tugenensis, which lived in Chad and Kenya, respectively, around 6 to 7 million years ago. Notably, S. tchadensis is recognized for its well-preserved skull, which provided significant clues regarding the orientation of the foramen magnum—the large opening in the occipital bone—indicating a vertical spinal alignment. This suggests that S. tchadensis likely stood upright and moved through bipedal locomotion. Similarly, O. tugenensis, known from a partial femur, exhibited features akin to modern human femurs, leading to the hypothesis that it too was bipedal.
Subsection 1.1.1: Ardipithecus Ramidus
A more widely recognized hominin, Ardipithecus ramidus, dates back to approximately 4.4 million years ago. Its nearly complete skeleton and dental remains, discovered in Ethiopia, offer valuable insights into the evolutionary trajectory of bipedalism. A. ramidus displayed a fragmented pelvis with a bowl-like shape that strongly supports the idea of bipedal movement. Furthermore, its foramen magnum's position resembled that of S. tchadensis, indicating a vertical spinal column. A. ramidus also had long upper limbs and fingers, suggesting a significant time spent in trees while also adopting bipedal locomotion on land. This duality aligns with the findings associated with the newly discovered fossils, although there exists a 7 million-year gap between the two hominids.
Section 1.2: The Discovery of Danuvius Guggenmosi
The bones uncovered in Bavaria, Germany, tell a compelling story. Between 2015 and 2018, researcher Madelaine Böhme from the University of Tübingen stumbled upon these fossils, recognizing their significance. Collaborating with David Begun, a paleoanthropologist from the University of Toronto, they concluded that Danuvius guggenmosi belongs to the genus Dryopithecus, which existed in Europe during the middle to late Miocene epoch. The fossils, estimated to be about 11.6 million years old, hint at a small primate with elongated arms, resembling a mix between a baboon and a bonobo. However, due to incomplete fossil records, determining the exact locomotion of this extinct primate remains challenging. Scientists are speculating on movement mechanics based on the size and shape of the available bones.
Section 1.3: Locomotion Characteristics of Danuvius Guggenmosi
- guggenmosi exhibited a diverse range of upper and lower body characteristics, providing adaptability both in arboreal and terrestrial environments. Its upper limbs were robust and flexible, ideal for grasping and swinging through trees, while the elbow allowed for various movements, including pronation and supination. The hands were capable of powerful grips, featuring curved digits and a deep joint at the first metacarpal, indicating opposable thumbs. The lower limbs, in contrast, bore striking similarities to human anatomy, with extended hips and knees capable of bearing weight, suggesting a plantigrade walking style on flat surfaces. Additionally, its long, curved big toe indicates adaptations for balancing on branches. These observations are consistent with the behavior of A. ramidus, although the 7 million-year gap between the two species remains a point of contention.
Chapter 2: Extended Limb Clambering
As researchers analyzed the unique features of D. guggenmosi, they proposed a distinct form of locomotion, termed “extended limb clambering.” This method involved utilizing all limbs for balance when navigating trees, while employing only the lower limbs for walking on flat surfaces. This hybrid locomotion indicates that D. guggenmosi relied equally on both forelimbs and hindlimbs, contrasting with most primates, which tend to favor hindlimb movement. This innovative locomotion approach may help scientists better understand the evolutionary transitions leading to fully bipedal movement.
Section 2.1: Comparative Analysis with Other Fossils
After the careful excavation and cleaning of D. guggenmosi’s bones, researchers compared them with other Dryopithecus specimens, intrigued by their distinct anatomical features. The bones were well-preserved due to their burial in clay, which protected them from decay. Among the recovered remains were an ulna, a tibia, portions of the jaw, and various smaller fragments such as vertebrae and phalanges. This analysis led scientists to conclude that the skeleton likely belonged to a male.
These bones reveal previously unrecognized anatomical traits of Miocene apes, suggesting a morphological connection between great apes and humans. For instance, the ulna had a straight shaft and an anterior-facing trochlear notch, indicating adaptations for swinging or hanging. Continued analysis and future discoveries of complete specimens may further elucidate the locomotor mechanics of D. guggenmosi and their implications for the evolution of bipedalism.
Section 2.2: Rethinking Evolutionary Approaches
To establish the evolutionary context of these findings, researchers, including Darwin, have employed a top-down approach, examining existing primate species for clues about the evolution of bipedalism. While this method is sound, it is limited by the available fossil record. A. ramidus provides substantial evidence of specialized locomotion forms, but the evolutionary history of living African apes remains obscured due to limited fossil evidence. A shift to a bottom-up approach may prove more effective, focusing on fossils predating the most recent common ancestors. The discovery of D. guggenmosi could be pivotal in deciphering the evolutionary history of human bipedalism.
In conclusion, the discovery of D. guggenmosi has ignited excitement in the scientific community, advancing our understanding of bipedal locomotion. The implications of an 11.6 million-year-old primate capable of upright walking prompt new inquiries into the timeline and evolutionary changes preceding the emergence of bipedalism. As ongoing research continues, we may soon uncover answers to pressing questions surrounding the evolution of human locomotion.
REFERENCES:
Kivell, Tracy L. Fossil ape hints at how walking on two feet evolved, nature, 6 Nov. 2019. Google Scholar, www.nature.com/articles/d41586-019-03347-0.
Offord, Catherine. Ape Fossils Shed New Light on Evolution of Bipedalism, TheScientist, 7 Nov. 2019, www.the-scientist.com/news-opinion/ape-fossils-shed-new-light-on-evolution-of-bipedalism-66695.
Pontzer, Herman. Overview of Hominin Evolution, edited by Jessica Rothman, Katy Gonder, Holly Dunsworth, and Kieran McNulty, nature, 2012. Google Scholar, www.nature.com/scitable/knowledge/library/overview-of-hominin-evolution-89010983/.