Reflections & Conclusions

As a team this semester we created a blog. Through this blog we are able to reflect upon our research and conclude what we have learned.

We have concluded that the extinct bipeds survived because of various characteristics they had or inherited and extant bipeds, that is modern humans have survived because they learned to adapt to the circumstances they were put under. Their physical characteristics progressed with time to better their survival. Although there is simply no right answer to this question, we can also consider our biology and culture. Without these two factors, evolution would be nearly impossible. 

A reason that bipedal primates survived is because of their social nature. The ability to form cohesive groups, to help raise our offspring together, strengthens the ties between each other. In the present day, we can see that we all exist by coexisting. The simple reliance we have on each other resembles how we are here today. 

How can we explain modern humans?

What is the relationship between culture and biology in humans?

Culture can be best described as a learned social system consisting of our structure, behavior, and beliefs. As humans we live in a society mediated by culture. In an attempt to understand our evolution through biology we have to consider our culture as well.

Humans in general have a highly developed ability or capacity for symbolic thought, invention, and learning. But we also display learned social representation, and anticipation of social facts and norms. All of these could fall under the umbrella of human culture. The relationship between human culture and human biology converge and overlap. Culture determines how one will be influenced by and react to the environment surrounding them. Biology affects culture almost naturally. Our biology is fundamental to our existence. It defines who we are chemically and how we function as human beings. Culture and biology are basic properties for life. That is why to understand one you must understand the other. 

 (http://anthro.palomar.edu/synthetic/images/map_of_sickle_cell_frequencies.gif)

What situations exemplified how this works?

• One example of how the relationship between culture and biology works is malaria. In WWII, the World Health Organization started spraying DDT, this killed off the majority of the mosquito population that were not resistant to the chemical. Consequently, the mosquito's that were resistant to the chemical were able to reproduce and pass on the resistance to their offspring. This created a generation of resistant mosquitoes. In an attempt to fight malaria, the use of DDT shrunk the population of mosquitoes temporarily but also led to a platform for stronger new mosquitoes who are now immune to the disease. The homozygote with sickle-cell traits didn't allow the person to survive and those that did not have sickle-cell alleles and were infected with malaria could not survive either.
  Subsequent to the rise of malaria, many died of this disease. Although, those with the heterozygote trait that produced some abnormal hemoglobin had an advantage. And the surviving population passed on this advantage. This exemplifies the variety between culture and biology and how you cannot get rid of one problem without creating a new one (Jurmain, pg. 319-320).

• Relative to human biocultural evolution, lactose intolerance is not found in all adults but many. The ability to digest milk in infants and babies is normal. Around the age of ten, humans ability to digest lessens. There are many factors to consider with the ability to digest milk. Geographically, some Africans and Europeans are lactase persistent, and many other African and Asian populations are lactose intolerant. Lactase persistence is relative to the historical cultural dependence of milk (Jurmain, pg. 319-320).

How can we explain the survival and success of bipedal primates?

What are/were the survival issues?

The main survival issues of the past were disease, starvation, dehydration, war, and successful reproduction.

What traits may have helped survival (physical and behavioral characteristics)?

A particularly important trait in regards to the survival of primates is their bipedal pelvis and locomotion. Primates and humans have a tendency towards walking upward. Humans have a bipedal pelvis and therefore, walking upright on two legs is the way humans effectively move. Primates can move in bipedal motion as a result of their specialized pelvis, which allows for such a specific type of movement (Jurmain pp 122).

Another factor in the survival of primates is in regards to their movement as a result of their generalized limb structure. A generalized limb structure in primates and humans allows for various forms of locomotion using all of the limbs. Primates can move in different ways based on their skeletal structures (climbing, swinging in trees, etc.) while humans mainly walk on two feet. Humans and primates alike do have a generalized use of their limbs in order to function based on various situations (Jurmain pp. 122).

Primates and humans have prehensile hands and feet. Humans and primates can meticulously manipulate objects with their five-fingered hands and feet. This differs from other mammals as primates and humans exhibit a much higher level of control over objects with their hands and feet then all other mammals. Both have opposable thumbs and partially opposable big toes. Humans have nails on their fingers and toes instead of claws. Primates also have nails on all of their fingers. Every species of primate has nails instead of claws except for New World monkeys (Jurmain pp. 123). This is crucial to the degree of digital manipulation that primates can accomplish (Dr. Chipley’s Lecture).  Also, all lemurs and lorises have a claw on one digit. Both have tactile pads with fingerprints and nerve endings at the end of their digits. The fingerprints and palm prints allow primates and humans to more successfully hold onto things (branches, anything that is held). The increased sensitivity at the end of the digits in primates and humans assist in safety and manipulation of things with the hands and feet (Jurmain pp. 123).

A primates diet is of crucial importance in their survival because of its versatility. Primates do not have a specialized diet. Primates and humans have the ability to eat and metabolize plants and meats. Both have generalized dentition. This means that their teeth are not specialized for any one type of food (Jurmain pp. 123-124).

Another factor of survival is in the primates' visual abilities.

Primates and humans rely on their vision in order to live. They both have color vision, although nocturnal primates do not. Both also have stereoscopic vision, which allows for depth perception. Visual information in humans and primates is transmitted to both hemispheres of the brain. This allows for more detailed visual information. This information is organized into three-dimensional images by specialized structures in the brain (Jurmain pp. 124-125).

(http://athinklab.com/2011/03/18/sxsw-panel-does-the-internet-make-you-happy/)

The neocortex in a primate’s brain is essential in their survival because it allows for different senses and a more advanced sensory system.

Humans and primates have a decreased reliance upon the sense of smell. The olfactory glands (allow for smell) in primates and humans are smaller than they are in other mammals. This occurs because of the higher dependence that primates and humans have on their sense of sight. Some primates do have large noses for the purpose of accommodation for canine teeth or to attract mates.

Both have an increased complexity of their brains. This is most evident in the visual and association areas of the neocortex (part of the brain that allows for more advanced thinking). Humans have larger, more complex brains although the structures are quite similar in both humans and primates (Jurmain pp. 125-126).

The fetal nourishment in primates and humans is far more efficient than that of other mammals. Both have longer gestation periods (humans have longer gestation periods). They also have fewer offspring compared to other animals.  Both primates and humans have delayed rates of maturation and extension of their entire lifespan. Humans live much longer than other primates although primates live for a relatively long amount of time in comparison with other mammals (Jurmain pp. 126).

Humans and primates have a greater dependence and flexibility on learned behavior. This occurs because of their delayed maturation, which causes longer periods of infant and adolescent dependency on at least one parent. Because of this, the parents in both humans and primates invest more in their offspring. As a result both offspring receive more intense parental care (Jurmain pp. 126).

Humans and primates have a tendency to live in social groups.  Primates differ in that the males in the groups are permanent associations within social groups. Nocturnal primates tend to have smaller social groups. Humans have various sizes of social groups (Jurmain pp. 126).

Each of the above traits are important separately and in tandem with one another. These traits have allowed for primates to survive and become more adept at survival than other species.

How does the theory of evolution apply to bipedal primates?

Evolution is the process of change all organisms go through. Humans are no less animals than other animals on this Earth. Our culture and self views are what lead us to believe we are separate from the animal kingdom
So as a participating member of the animal kingdom the natural order of change effects us too. Evolution is a perpetual change of a population. When one individual develops a mutation that can help it survive or reproduce in its environment; it can successfully pass on its mutation, eventually the mutation can spread across generations where it becomes common place. We are all subject to this, all subject to change.
(Jurmain pages 6, 10, 28)

What impacts has the evolutionary process had on physical & behavioral characteristics?

An excellent example is the developing bipedalism. It's possible that there was environment pressure to remain upright and the ability to walk on two legs is high. Early hominins lived in Africa as the forest retreated from the early and middle Pleistocene era when inter-glacial period would help woodlands and grasslands grow with the increase in rain. Imagine migrating from thick dense jungle and moving into a flat savanna. Now the best method of movement isn't swinging on branches (brachiate), assuming nothing would impede, running would be a much more efficient way to get around.
Walk on two limbs, leaves two limbs free from locomotion, free to do other things, hold things and manipulate them for utilization. Leading to more cultural uses of hands, there is the manipulation of objects in the environment, turning them into tools. Behaviorally this would have been excellent to begin holding your offspring instead of letting them hold onto you, especially considering that these offspring would be relatively premature compared to other primates.

For better upright walking nature, there are those selected with a mutation for the femur bone to point inward to the knee and a reduction in the pelvis bone. Chimps in comparison have a relatively straight femur bone and longer pelvis. This reduction in the pelvis affects the birth canal. This would make pregnancy shorter and child birth profoundly more difficult to other animal, even other primates. In turn this made our gestation shorter than it could be. Most brain development happens outside of the womb. To have others around you nurturing you during the child birth process would strengthen the ties with them and the newborn. This short gestation and communal sense gave rise to the cultural idea of childhood, where a child is surrounded by caretakers and learns from them.
(Jurmain in pages 131, 199-205, 254-255, 354-356)

http://evoanth.wordpress.com/2012/08/13/lucy-the-knuckle-walking-ape-misguided-mondays/

What is the theory of evolution?

(http://wolfevolution.webs.com/images/evolutionhumans.jpg)

Definition: The theory of evolution, in a modern sense, can be described as a two-stage process. The production and redistribution of variation, throughout many generations and natural selection, acts on variation determining how successfully one will reproduce (Jurmain pp.85).

Explain how it works:Evolution works in way that it is a change in allele frequency from one generation to the next.Genetic variation must be produced first by mutation, which is then acted upon by natural selection. The driving force in natural selection, in determining whether a specie is going to reproduce successfully or not, is the environment(Jurmain pp.85).

These process help increase variation:

• Mutation: A change in DNA is a type of mutation, and many genes have two or more forms called alleles. If one allele changes to another , that is if the gene itself is altered, a mutation has occurred (Jurmain pp.86).

• Examples among domesticated and wild animals in regards to mutation: Some examples of animals that have been domesticated are foxes, chickens, cats, horses, and ferrets. Examples of wild animals would be jaguars, lions, and bears. An experiment was performed on domesticating foxes, this article explains more of the finer details when changing its behavior and picking out traits that we want from a species ( http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763232/ ). In this article, experiments were performed on foxes that were cage bred to see if they would increasingly become friendlier with humans socially throughout many generations. Researchers picked only the most tamed foxes out of the group that were friendly with human contact. The ones that showcased aggressive behavior were put in a another group. Throughout many generations the foxes began to exhibit dog like behaviors like whimpering, tail wagging, and licking in a dog like manner. They also formed physical characteristics of dogs as well too. Although, only a very small amount of foxes were able to become fully domesticated. Once this point was reached, the amount of domesticated foxes began to increase generation after generation. By the end of the experiment almost all of the foxes of the domesticated population were categorized as the behavioral elite. This took a little more than 30 generations to do so. In a sense we forced evolution on these foxes and changed their behavior overtime to benefit us as humans. The foxes adapted more dog-like behavior. Dogs generally have the association of a "man's best friend". The real question is if a fox could ever be one too.

(http://www.animalgalleries.org/Small-Land-Mammals/Fox-Galleries/Red-Fox-Gallery/Red+Fox+Vulpes+vulpes+face.jpg.php)

• Crossing Over: The definition of crossing over is described by (http://anthro.palomar.edu/synthetic/glossary.htm) as the exchange of genetic material (DNA) between homologous chromosomes at the beginning of meiosis.  This results in sperm and ova with greater genetic diversity due to a recombination of genes.  Specifically, a portion of the end of a chromosome is broken and reattached on another chromosome.

• Gene flow:Gene flow is the exchange of genes between populations. This only occurs when immigrants interbreed. An example of how gene flow influences micro evolutionary changes are present in human populations such as African Americans. While most of them are descendant from west African decent, there is also European American genes mixed in with them also. We can determine this by measuring the allele frequencies for specific genetic loci, then estimating the amount of migration of European alleles in the gene pool of the African Americans(Jermain pp.86). 

Processes that decrease Variation:

• Genetic Drift and Founder Effect:Another component of the theory of evolution  is Genetic Drift. This can be defined as evolutionary changes, or changes in allele frequencies, that are produced by random factors in small populations. Genetic drift mainly happens in small populations in which if an allele is rare, it could completely disappear and not be passed on at all. A certain kind of genetic drift, also called the founder affect, is present in modern and non human populations. The founder effect happens over time in which "founders", which are the offspring of the parent group, leave and create a new population and form another colony elsewhere. As long as member of that colony reproduce within their own group, they will all be descended from the initial group of founders (Jurmain pp.87-88).

 

• Non-random mating: This occurs when no classification criteria of possible mates are considered, its is mainly a matter of chance. One example of this is rape of randoms victims because no known group of humans legally mate randomly. An effect of non-random mating is a significant alteration in gene frequency that can occur through long term patterns of mate selection.(Chipley, Unit 1)

   

Introduction

We are CLEAK (Edgar Delgado (leader), Layla Jooya (communicator), Andrew Dominguez, & Chris Gassett). We represent a group from Professor Chipley's Physical Anthropology (ANTH 2301) course from Austin Community College in Round Rock. Our mission is to explain the existence of bipedal primates from the past and present, through academic lends of anthropology. As anthropology students our goal is to explain the fossil record of the extinct bi-pedal primates and the existence of extant bipedal primates. Through research and various resources, this semester, we have come to explain the connection between modern humans and our ancestors. As a class, we formed a foundation of our understanding of physical anthropology. As a team, we created a pedestal for further knowledge and advancement. This blog was created, to allow our audience of the world-wide web to gain knowledge of how we became to be by explaining the theory of evolution and how it applies to bi-pedal primates,the survival and success of bi-pedal primates, and explaining modern humans.