I think I muddled an answer in a previous post about tridactyl limbs or in this case bigfoot feet with three toes. I have had some internet provider problems lately that has limited my responses of late but I wanted to elaborate my reasons more clearly and at least get my thoughts out on this issue. I think the idea of three toes is an interesting one but it presents some very difficult problems in an evolutionary sense, in my opinion.
Why do primates generally have 5 toes?
Primates feet and hands are primarily used for grasping branches. I think the extra digits help stabilize the grip. A monkey can grab a branch better than a bird for example. But humans and bigfoot have feet adapted to a bipedal gait. Most mammals have what are known as pentadactyl limbs which means they have 5 toes and in the case of primates,5 fingers. This consistency is there for a reason. I think a primary reason is that it was not adaptive to change it. To evolve, a characteristic must be adaptive in every stage of its evolution. A foot consists of phalanges, which are connected to metatarsals, which are in turn connected to tarsals which are your ankle bones. There are numerous genes responsible for the develpement of each bone and therefore a single mutation would not likely result in a more adaptive foot. Many animals, such as horses gradually lost the number of toes as they evolved. Eohippus had 5 toes and modern horses are left with one. But this was a gradual evolution. A mutation reducing the number of toes in a primate would most likely have a negative effect because it would have an influence on so many different structural parts. Such a mutation would not likely get passed on.
Numerous physiological and morphological features are intimately connected with body size and so for several reasons it is necessary to take body size into account when assessing locomotor adaptations. It seems to me that a greater sized animal might have different tendencies for number of toes and yet large bears (for example) still have five toes. Yet bears are quadrapeds and don’t put as much weight on their feet as bigfoot presumably do.
Your feet are built to transport your body as fast as possible, given the limits of your weight and the individual bones must also be thick enough not to break. To suddenly have a reduced number of toes would put extra stress on the remaining ones and a broken foot is a recipe for death to a bipedal animal. So to reduce the toes you would need to increase the remaining bones at the same time and that is the problem.
I have noticed that the size of southern bigfoot is smaller than those of the north. Perhaps in an animal evolving into a smaller variety, the reduced number of digits might not be maladaptive but that too seems unlikely to me.
There is an interesting example of an almost three-toed print of a giant hominid. The famous Yeti footprint photographed by Eric Shipton shows two large toes (the big toe and the second toe) and three remaining toes which when put together may function somewhat as the third toe. If real, Shipton’s footprint shows a very strange foot structure which at least seems to suggest 3 toes might be adaptive. How to get there does present a problem though. I agree with George that any foot with fewer than five toes should be looked at with more skeptism yet I still remain fascinated by the possibility.
Posted on Apr 28, 2002, 9:51 PM from IP address 172.161.139.117