The evolution of primate locomotion and body configuration

 

                                                            Introduction

            The evolution of primate is dependent on the changes that occurred in their body structures which in return enhanced their adaptation to locomotion. Evolution is one of the primary factors that have enabled animals to adapt well to changing environments so as to take advantage of the newly exploited resources. As a result of body configuration and improvement in movement speed, primates have had the propensity of withstanding changing or hostile environment and escape predators much easier than before (Fleagle, 1999).  The changes that primates underwent are significant for survival and existence.

            Evolution and body configuration enables primates to increase the chances of survival. Primates that only managed to evolve dental structures and brains and not their body structure have minimal rates of survival. In the animal kingdom, primates have various variations in terms of their behavioral and physical characteristics which in return make evolution to occur. Each primate encounters fierce competition for the little natural resources available so as to survive. In case primates manage to develop changes, it means that the evolution pathway they might have will also be impacted (Fleagle, 2014). Lifestyle, geological, and climatic conditions are the main factors the evolution of primates largely depends on. In this essay, the four grades of primate evolution will be used as the basis for analyzing and discussing how their bodies have been modified over time so as to make primates to be well adapted to their environment.

                                                Grade I- The Lemuroids

            Over the years, lemuroids have exhibited evolutionary changes that have enabled them to increase the chances of survival. During the early stages of evolution, lemuroids have bent structures. Naturally, their spine was horizontal. Although they were relatively slow in movement, they dependent on feet and hands to walk. At the same, they used these structures not only to escape their predators but also to carry food. With time, a group of lemuroids started to stand in the process of trying to reach higher tree branches to access food. Eventually, transformation of their spine started to occur to facilitate vertical mobility (Haviland, 2013). Research regarding the evolution of lemuroids indicates that they are the only primates having a flexible or an elastic vertebral column.

            As time went by, lemuroids have managed to develop relatively stronger body muscles that ease the task of leaping from one tree branch to another. With the aid of their hind legs, they have the ability to jump across for a long distance. The development of this skill occurs when they are young and continue to perfect it before attaining adulthood. In most cases, perfecting leaping by young ones is the duty of their parents because at that younger they could have not developed strong muscles. According to the fossil records collected, they indicate that although lemuroids were initially leapers, they were not efficient in leaping (Lewis et al., 2010).  This is because before attaining adulthood, their limb muscles used to wear off quickly. As a result of that, it was difficult for them to escape predators because of getting tired easily. As a result of developing elongated hind legs tissue muscles, lemurs are given the propensity of running faster and leap faster and easily from one tree branch to another. According to paleontologists, the reason as to why lemurs developed those flexibilities is because of fear of their predators and competition for natural resources. Often, lemurs were always in danger when searching for food from the predators that tried to attack them. As one of their adaptations, lemuroids developed the capabilities for standing straight and running using their posterior or hind legs.

            An example of lemuroids is the Sclater blue-eyed lemur. This primate can grow and attain a body length of ranging from 39 cm to 45 cm and a tail length ranging from 51cm to 65 cm. after they have attained maturity, its body weight can range from 1.8 to 1.9 kilograms.  Sclater blue-eyed lemur grows and develops strong hands and having palms resembling that of humans. The rubbery texture of their palms enables them to have a firm grip on tree branches. Although its tail is relatively longer as compared to its body, it is non-prehensile. Males have a solid black color with a little tinge brown color, particularly at their roots while females' hair color is a reddish brown color. Even though the eyes of both sexes are blue, the back of their feet and hands are dark in color with a gray or dark brown colored muzzle. Nonetheless, according to the information collected by experts, lemuroids drop abruptly from trees and run at an astonishing speed bushes when threatened by their predators. This adaptation makes predators fail to adjust their vision quickly before the lemurs have dashed off for its safety.

            For about six million that have passed, fossil records gathered indicate that the ancestors of lemurs had thicker and shorter hands. For instance, their phalanges were relatively shorter estimated to be approximately half an inch. Because of that, lemurs couldn't walk or leap from one tree branch to another while carrying a lot of food. Leaping from one tree to another was difficult because of their weaker grip. In the process of the desire to carry loads of food and leap from one tree to another, ancestral lemurs were forced to stretch their hands further. In return, their hands continued to develop longer phalanges, especially females. Whenever lemuroids fold or cup their hands, research indicates that they have extra space as compared to other species.

                                                            Grade II: Tarsiers

             Regions of South Eastern Asian forests are the main area considered to support the survival of tarsiers' species. Giant serpents and nocturnal predators were the main enemies of Tarsiers centuries ago.  During this time, the Tarsiers were bright in color thus making them be easily susceptible to predation. The fossil information collected indicates that they had elongated body structures with the least being 20cms. It this relatively smaller length of Tarsiers' body structures that proved to be the reason why they were vulnerable to predators particularly when were at rest. During an attack, it was difficult for Tarsiers to move swiftly to evade predators. As time went by, tarsiers started folding themselves to have the propensity of avoiding predators. The bending act was to make their cervical vertebrae to become shorter (Lewis et al., 2010). With time, the length of the Tarsier continued to be reduced as they can be seen currently. Their length is proximate to be at most 13 cm thus making it difficult for them to be sported when hiding in bushes.

             The study conducted regarding the structure of their muscle tissues and bones suggests that during the Eocene period, Tarsiers were free to move within their habitat. Since the tree branches were relatively shorter, the Tarsiers could swing from one tree branch to another. The shortness of the tree branches also guaranteed Tarsiers the required protection from predators. Although their movements were somehow quick, predators could easily spot and attack them because of the distance they had to cover to reach their hiding places. One of the techniques developed by Tarsiers is lying closer to the trees with their bodies folded and remaining immovable for hours (Haviland & Haviland, 2008). As a result of that, it was difficult for predators to spot them. Successive generations, over the centuries, managed to develop relatively stronger arm muscle tissues. This evolution was important for Tarsiers because it gave them the potential of hiding within the trees, remain immobile for long hours, and without losing grip from tree branches or getting tired (Haviland, 2013). The Tarsiers' aptitude to hide in crevices or tree branches for a long period is their primary means of survival. Unless when the Tarsiers were illuminated with light, it was difficult for predators to spot and attack them.

            Despite that, the reason as to why Tarsiers fake to be walking slowly is just a means of fooling their predators. From their lazy outlook, predators assume that they are slow and decide to attack them with little speed and force. This continues to be the survival means of Tarsiers. However, the Tarsier can manage to maneuver quickly between the tree branches. Since they have smaller body structures, such an adaptation enables them to easily evade their predators and hide quickly. They have a strong physique because of the structure of their body muscles. According to paleontologists, during the late year of evolution, the mechanisms that mostly Tarsiers used to attack predators entailed scratching them with their bodies (Wright et al., 2003). However, due to the fact that the presence of thick fur on their predators’ skin, the animal managed to develop stronger muscles. Such an adaptation was advantageous because it could enable the animal to throw the predator off balance.

             To protect young ones, females have developed a deep sense of awareness and have the potential of attacking predators that are much larger than them. In the process of using their body mass to throw the predator of balance, the female and her young one have a chance of scampering off to safety by hiding in small cracks where such an attacker cannot fit.

Grade III – The Monkeys

            Monkeys feature dominantly in the evolution theories of species. Present-day species habit varied environments throughout the planet such as tropical forests to mountainous terrains exhibiting adaptive features to survive. Anthropologists place the existence of the species to have originated way back in the Eocene period. Fossil records dated indicate Africa as their cradle of existence and evolution. Early fossils of monkeys were in the Zaire River where experts postulate that they had to compete with chimpanzees for food to ensure their survival. With the advent in molecular studies, experts place the chimpanzee and the bonobos as phylogenetically and genetically being closest to humans than monkeys. For example, examinations of the hand of the last common ancestor of the chimpanzees and humans correlate it to that of the modern-day African ape (Mitani et al., 2012). Old world monkeys have hands that exhibit similarities to that of humans than those of chimpanzees though they differ to those of early humans. However, the feet of the monkeys show significant differences from that of the bipedal human foot.

 For the monkeys to survive, they developed great muscle strength to guard themselves against predators. The stature of the monkeys was such that they were small, hence the need to develop muscle strength. It enabled them to swing from tree to tree that was characteristic of the densely forested environments they lived. As the environment changed due to climate factors, the unequaled muscle strength became vital in facilitating fast movement to escape predators (Glenn & Cords, 2002). The monkeys today, show different adaptations according to the environment they habit such as those in sub-Saharan Africa and the snow-covered mountains of Japan.

            The monkeys have evolved over time to develop long hands and legs that aid in movement. The long hands allow the monkeys that habit the equatorial forest to swing from branch to branch (branchial locomotion) to escape predators and reach for food. The long legs are an adaptation to conform to the changing habitation environment. They are spending more time on land as the forests become sparsely populated enabling them to move at a speed greater than the average monkey. In the forests, the monkeys were often at risk from small carnivorous predators that could move much faster (Nina, 2004). There was also the susceptibility to losing their hard-earned foods to small habitats that stole it. The increased speed was a way of protecting themselves and their stash of food from such threats.

Their hind muscles have increased to over 1 meter enabling them to move much faster than most of the predators in the forest. The primates which utilize their hind limbs dominantly such as the colobus monkeys and the langurs employ leaping in their movements unlike quadrupeds such as guenons. They exhibit suspensory locomotion in which they suspend themselves from branches by their arms. They regularly climb, leap, swing, and run in diverse ways (Glenn & Cords, 2002). However, changes in climate and geography have led to structural changes such as the chimpanzees in woodland savanna climate in Africa that have adapted to living on the ground.

            They also exhibit elongated bodies that were not characteristic of old world monkeys. The spine elongation has lengthened their bodies to at least 2 feet. The elongated bodies allow them to leap longer distances compared to other primates. The adaptation developed over 2 million years ago when the number of predators increased substantially in the forest biome. The capability to access far off branches enabled them to access better quality food. The monkeys have evolved to exhibit the most unique tail that is long and strong. The tail has stronger muscles than other primates. It not only enables them to leap but also as a means of protection from predators. The strong tail holds its weight as it reaches far off branches and as a limb as it carries food with both arms while still swinging from branch to branch (Nina, 2004). The tail has evolved to have a furry end that distracts potential predators. For instance, the predators may be watching the movement of the feet and hands when attacking, but may not consider a fast, strong-muscled, and furry tail that can knock off any opponent.

Grade IV – Apes and Man

            Paleontologists often correlate the evolution of man and apes as going hand in hand. They consider apes to be the early ancestors of man. The fossil bodies of the apes and man show similar elongations in that they were much shorter and exhibited thinner width. Due to their massive weights, the apes walked on all fours for increased support. Their fingers could not carry anything since they exhibited joint phalanges from which things slipped easily. The evolution of man showed significant differences to that of apes because of their desire to hold equipment and tools (Tuttle, 2014). The apes weighed over 200 kilograms becoming heavier than normal primates due to their thicker bodies and developed muscle tissues. Climate changes necessitated the apes to develop thick muscles in order to survive in cold weather. To survive in such climates, they developed thick furs with long multi-colored hairs (Huffman et al., 2013). All these adaptations enabled the apes to survive in the cold climates they inhabited.

            Contrarily, the evolution of man between Homoerectus and Neanderthal man enabled the development of elongated spines. Their general structure changed in that they began to depend more on their feet to support the weight of their bodies. The body mass of humans reduced significantly from 250 kilograms to the range of 100 kilograms. Similarly, man desired to handle tools and equipment leading to their hands developing elongated phalanges and separates. In the early Pleistocene period, Homohabilis’s brain developed, which enabled them to discover ways to make their lives better (Taggart, 2005). For example, due to its bigger brain, homohabilis discovered fire allowing them to cook their foods and scare away predators at night. As man continually used fire more and more, they began to shed their fur that had long enabled them to keep warm in cold climates. In the late Pleistocene era, however, both apes and man adorned reduced tails and eventually did away with the feature. Man and apes used the tails to gain a significant advantage over predators as they hunted and gathered. An interesting fact I found in the research is that experts in the paleontology field believe that both man and ape lost their tails by cutting them off in their young ones (Tuttle, 2014). It led to subsequent generations that had shorter tails leading to complete disappearance in the eventual generations of the species.

                                                Critique of literature review

            Sources containing the evolution of primates are extensively available. The argument presented concerning the fact that improvement in primates’ locomotion speed and body structures is the one that facilitated their survival means is clearly verified. With time, primates have managed to restructure their bodies to increase the chances of survival. During the Oligocene period, the monkeys’ population had reduced drastically as a result of the decrease in the number of their predators. The changes that occur in the movement speed and muscle strength is the one that leads to an increase in their population. This can be evidenced by the number of fossils that were retrieved.

            The information collected regarding lemuroids and tarsiers is relatively difficult to obtain. It is easier to obtain their fossil records. Although, the information collected by paleontologists indicates that the origin of tarsiers was South East Asia, it can be argued that once they immediately started changing, it is when their population started increasing. The literature concerning the evolution of apes and man is wide and readily available. The evolutionary changes that man has undergone are the one that is noted to have saved generations from extinction. The primordial fossils of man and apes prove to be a good source of evidence of their evolution.

                                    Personal observations at the LA Zoo

            To have firsthand information regarding the validity of the LA Zoo, I decided to visit the LA Zoo. During my visit, I had an opportunity of viewing chimpanzees as they were swinging on tree branches and bars. Their nurturing behavior is also another thing that appeared to be more interesting to me. I realized that one of the factors that make them resemble human beings is how the chimps took care of their young ones. The efforts of the mother chimps to care for their young ones reminded me how human beings' traits resemble that of primates.

 Another fascinating fact is that all the female mammals showed their young ones love. For instance, the traits of the gorilla, monkeys, and chimps were similar to that of man. What this suggests is the fact that mammals dedicate a lot of time taking care of their young ones as they grow. The reason for that is to teach them how to independently feed, avoid enemies, and survive. That is what reminded me of the true human connection and affection. Since they are intelligent creatures, they have developed techniques to aid them grasp food with their hands, use tools, or walk. The experience I had in the process of observing them during that day cannot be comparable to what I initially had from reading books, articles, and so on.

 One of the main challenges I encountered during that day was that some exhibits had been closed. The reason for that is because they were not scheduled to be open for public viewing. As a result of that, I only managed to view only 14 exhibits out of the 20 I had planned to view. The presence of noisy and disorderly children proved to be a challenge because they kept on banging cages thus irritating and frightening the animals. Finally, since it was a sunny day, some of the primates were hiding or had fallen asleep under shades.

                                                            Conclusion

            My research paper, I have validated the fact that changes in body structures and locomotion as a result of evolution are what give primates a competitive advantage to resources. Some primates such as monkeys have elongated body structures while others such as tarsiers have evolved and developed much shorter body structures. It is this evolution trait that I believe has increased the primates' chances of survival. Those primates that have not managed to evolve and improve their body structures and movement or locomotion faced extinction. The need to run away and hide from predators that have stronger muscles and limbs for leaping or running is what facilitated locomotion changes. Last but not least, the primate that does not manage to develop more and more adaptable body features and fastens their speed will not be able to adapt well with the ever-changing environment.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                            References

 Fleagle, J. (1999). Primate Adaptation and Evolution, New York: Academic Press

Fleagle, J. G. (2014). Primate Adaptation and Evolution. San Diego: Elsevier Science.

Glenn, M. E., & Cords, M. (2002). The guenons: Diversity and adaptation in African monkeys. New York: Kluwer Academic/Plenum Publishers.

Haviland, W. A. (2013). The essence of anthropology. Australia : Wadsworth Cengage Learning

Haviland, W. A., & Haviland, W. A. (2008). Evolution and prehistory: The human challenge. Belmont, CA: Wadsworth/Thomson Learning.

Huffman, M. A., Nakagawa, N., Go, Y., Imai, H., Tomonaga, M., & Kyōto Daigaku. (2013). Monkeys, apes, and humans: Primatology in Japan. Tokyo : Springer Press

Lewis, R. B., Jurmain, R., & Kilgore, L. (2010). Understanding humans: Introduction to physical anthropology and archaeology. Belmont, Calif: Wadsworth Cengage Learning.

Mitani, J. C., Call, J., Kappeler, P. M., Palombit, R. A., & Silk, J. B. (2012). The evolution of primate societies. Chicago: The University of Chicago Press.

Nina, G.J. (2004). Shaping Primate Evolution: Form, Function, and Behavior. Volume 40 of Cambridge in Biological and Evolutionary Anthropology. Cambridge University Press

Taggart, R. (2005). Biology the unity and diversity of life (DME/BS/08-104(1). Cengage Learning Press

Tuttle, R. H. (2014). Apes and human evolution. Cambridge, Massachusetts : Harvard University Press

Wright, P. C., Simons, E. L., & Gursky-Doyen, S. (2003). Tarsiers: Past, present, and future. New Brunswick, N.J: Rutgers University Press.