Bigfoot Gait. Part 2. The Patterson Video: Human or Gigantopithecus ?
Last week on the blog we discussed some of the unique gait characteristics we saw in the famous Patterson Bigfoot video and how many of them are seen in humans as compensatory strategies. Today we will mention a few more interesting things that will have you think about your human gait assessments a little differently.
Renowned chimpanzee researcher Jane Goodall last year surprised an interviewer from National Public Radio when she said she was sure that large, undiscovered primates, such as the Yeti or Sasquatch, exist.”
Why does Jane believe this ? Well, Gigantopithecus blackiwere, the largest apes that ever lived (10 feet tall, 1000+ lbs), lived as recently as 100,000 years ago. Giganto can be placed in the same time frame and geographical location as several hominin species. Its means of locomotion are uncertain since no pelvis or leg bones have ever been unearthed however the dominant view is that it walks on all fours like modern day gorillas and chimpanzees. There are those however that believe that Gigantopithicus also walked bipedally just like many of today’s apes do. There was a fascinating theory brought to light by Grover Krantz who made the bipedal assumption from jaw bones which were U-shaped and widened posteriorly leaving room for the windpipe to be located within the jaw, just like in humans. This had to translate to bipedal ambulation to afford the skull to squarely sit upright on a completely erect spine as compared to being carried anteriorly (when on all four limbs) as in the great apes and chimpanzees. It is a fascinating theory, but none the less, there are researchers on either side of the debate and proof may never occur … . until perhaps one day we find a full skeleton or the real life version. Maybe someday we can get a team of Gait Geeks together and create a “Squatching Team” to head out deep into the Pacific northwest on a discovery mission.
1- Vertical Oscillations:
Today, in the video above, we draw your attention to the lack of vertical oscillations of the head. Take a moment to watch this in the video once again. You should see that there is very little vertical displacement of the body (focus on the head). This minimal vertical type gait can only occur with a continuous slightly bent knee gait and we could make the case that a midfoot strike will dampen the vertical parameter even further. In humans, and in bigfoot here, limiting terminal hip extension also buffers some of the vertical movement, just as you see in the video. Humans use a slight degree of knee flexion at foot strike to accomplish the same task, it is partly a strategy to keep the eyes steady on the horizon and some anthropological papers have suggested that this was a necessity in order to be able to run, visually track and accurately launch a spear at prey back in our plains hunting days.
2. Heel Strike vs Heel Contact
A midfoot strike and heel strike are different. A midfoot strike is often accompanied by a heel contact phase, which is different than a heel strike. With heel strike, the heel is the first point of contact, whereas heel contact can occur if the entire foot is placed flat all at once or it can occur after a forefoot or midfoot strike occurs (ie. placing the heel down).
By many sources, only great apes exhibit a true heel-strike, other primates present with a heel contact after a midfoot strike first occurs. As determined in this study heel contact is a by-product of an active posterior weight-shift mechanism involving highly protracted hindlimbs at touchdown.
From the Schmitt study a variety of primates (32 species) were viewed walking on the ground and on simulated arboreal supports at a range of natural speeds.
“The study’s results indicated that Pongo as well as the African apes exhibit a "heel-strike” at the end of swing phase. Ateles and Hylobates make “heel contact” on all supports shortly AFTER mid-foot contact, although spider monkeys do so only at slow or moderate speeds. No other New or Old World monkey or prosimian in this study made heel contact during quadrupedalism on any substrate. Thus, heel contact occurs in all apes and atelines, but only the great apes exhibit a heel-strike.“
Schmitt also concluded that "although heel contact and heel-strike may have no evolutionary link, it is possible that both patterns are the result of a similar weight shift mechanism. Therefore, the regular occurrence of heel contact in a variety of arboreal primates, and the absence of a true biomechanical link between limb elongation, heel contact, and terrestriality, calls into question the claim that hominid foot posture was necessarily derived from a quadrupedal terrestrial ancestor.”
Shawn and Ivo……. when not making crop circles we are just two guys in ape suits……. walking the night forests, keeping folks believing…..
PS: here is an interesting excerpt on vertical oscillations from an old blog post we did. It seems pertinent here.
This study’s findings findings clearly demonstrate that human walkers consume substantially more metabolic energy when they minimize vertical motion.
Anyhow, the summary of this peer reviewed article by Ortega concluded that :
“in flat-trajectory walking, subjects reduced center of mass vertical displacement by an average of 69% but consumed approximately twice as much metabolic energy over a range of speeds . In flat-trajectory walking, passive pendulum-like mechanical energy exchange provided only a small portion of the energy required to accelerate the center of mass because gravitational potential energy fluctuated minimally. Thus, despite the smaller vertical movements in flat-trajectory walking, the net external mechanical work needed to move the center of mass was similar in both types of walking. Subjects walked with more flexed stance limbs in flat-trajectory walking, and the resultant increase in stance limb force generation likely helped cause the doubling in metabolic cost compared with normal walking.Regardless of the cause, these findings clearly demonstrate that human walkers consume substantially more metabolic energy when they minimize vertical motion.”
J Appl Physiol. 2005 Dec;99(6):2099-107. Epub 2005 Jul 28. Minimizing center of mass vertical movement increases metabolic cost in walking. Ortega JD, Farley CT. Source–
References:
-http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2409101/
-http://thegaitguys.tumblr.com/post/46851286689/more-on-the-great-debate-does-decreased-step-height
-http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571309/
