Computer animations on the Discovery Channel were quite misleading about how Ardi (Ardipethicus ramidus) walked. Dr. Mark Blais, a podiatrist, explains.
Keywords: human evolution, Ardipithecus ramidus, evolution, biology, podiatry, feet, gait, Owen Lovejoy, fossils
The missing link is still biomechanically missing. On October 11 the Discovery Channel aired a documentary on the findings of a 15-year study of the skeletal remains of Ardipithecus ramidus or Ardi. Ardipithecus is believed to be a woodland creature with a small brain, long arms, and short legs. The study concludes that Ardipithecus’s pelvis and feet show a primitive form of two-legged walking on the ground, which allowed Ardipithecus the capability of using its feet for tree climbing and grasping like an ape. It is hoped that these discoveries will answer old questions about how hominids became bipedal.1
In podiatry school and during my residency, I was trained in the detailed study of lower extremity human anatomy and proper analysis of the biomechanics of gait, whether it be walking or running. As a podiatrist I have studied the gait of thousands of humans.
The understanding of the bipedal biomechanics of humans is not a simple process.1 There are 26 bones, approximately 30 joints, over 100 ligaments, and 15 different muscles in three layers in each foot, along with tendons from the lower leg that attach to important biomechanical areas of the foot. All these structures must be assessed, both in a weight-bearing and non–weight-bearing positions, in order to adequately assess the biomechanical capabilities of a subject.
Ardi researchers have retrieved only some of the foot bones. While some bones were whole, others were partial bones with many being only fragments of possible foot bones. No soft tissue (musculature, ligaments, or tendons) are available for analysis.
The few intact foot bones are not adequate to make any determination as to the type of gait Ardi displayed. The researchers have based their conclusions on incomplete data and given a biomechanical analysis that is more bias than fact and should not be considered credible.
The research group even hired a biomechanical lab (LifeModeler, Inc.) to run computer animations of Ardi’s gait. On the LifeModeler website, it states that the world’s leading anthropologists use LifeMOD to reconstruct millions of years of evolution and understand the origins of humankind.
The LifeModeler team was engaged to provide information on the age-old question of how early hominids became bipedal for the Discovering ARDI television special featured on the Discovery Channel. The study, not unlike a forensic investigation from an episode of CSI, entailed examining a set of bones from the discovery and recreating a LifeMOD biomechanical model using clues discovered from the bones. LifeModeler engineers, working in conjunction with Professor Owen Lovejoy, built Ardi’s musculoskeletal structure using LifeMOD software. Using the software to control various muscular activities, the model was used to provide insight into a foot structure which could both climb a tree and walk effectively.2
The researchers admit in the Discovery video that part of the phase of gait called propulsion, which involves toe off, is a difficult issue to overcome as a result of the opposable big toe. The lab researchers state that they would have to adjust their software to produce an animation of Ardi.3 One can only imagine why.
The presence of a live ambulating specimen is the only accurate process of evaluating gait. Imagine bringing a skeleton to a foot specialist and asking him or her to evaluate the gait. It would be impossible to accurately assess the gait without knowing the weight bearing load, muscle size, and angulations of attachment, along with normal and/or abnormal neuromuscular activity. What Owen Lovejoy asked the programmers to do was to program a gait based on a skeleton, absent musculature and ligament attachments. The results of the gait analysis presented in the video are therefore biased on the artificial input data supplied to replace the missing parts of the specimen.
As a podiatrist I have listed six gait problems from the findings on Ardi as seen from the pictures of the bones found.
The above six points make the gait analysis by the lab and Discovery Channel presentation no more than a software creation.
In conclusion, one may be impressed by the scientific procedures that this group undertook to find and preserve the artifacts. The hard work and determination to preserve the artifacts should not be questioned. One might also be excited by the finding of a new species. One must, however, be concerned about a presentation made to the world based on incomplete data and the manipulation of that via biased input of data into a software program in order to present an animation of a gait. The results are merely a product of hopeful human speculative input rather than scientific fact. Perhaps one should rather see Ardipithecus ramidus as another unique example of God’s creation rather than trying to artificially fill in the missing links of the evolutionary tree.