Introduction
Physical anthropologists have for a long time been conducting research on the evolutionary forces responsible the range of human variation throughout the world. In physical anthropology, one of the most important questions is on what it means to be human. The anthropologists also seek to know how we became human. To answer these questions in a scientific way, they normally draw upon data from a wide range of fields. The same approach should be used in efforts to understand the evolutionary forces that have led to far-reaching human variation around the world.
The scientific process is always refining human ideas through the acquisition of new information and insights. The objective of acquiring this new information and insights is to increase the accuracy of findings. However, the general features of these fundamental answers have already been established during the last sixty years. Nevertheless, there are still many things for physical anthropologists to learn regarding these evolutionary forces and their impact on wide-ranging human variation. The aim of this paper is to investigate the general features of the fundamental answers to the question of the evolutionary forces that have been causing human variation in the world.
Understanding the history of the human species
One of the best ways of understanding the process of evolution and differences among humans in different parts of the world is to acquire information regarding the history of the human species. The history of the human species is also understood by adhering to the idea that the range of physical and biological processes that continuously shape our lives are still the same evolutionary forces that have always been operating in the past (Henrich, 2004). It is widely assumed that if these processes are properly studied and understood, human beings can gain insights into the events that occurred in the past and their impact in terms of magnitude of time. Another perspective is that of biological continuity. In this perspective, the main assumption is that all forms of life share a common descent. In this case, it is held that living beings simply pass life along by reproducing; they do not create new life.
From the point of view of physical anthropology, different themes are normally expounded on. These themes include evolution as a process, the chemistry of life, the role of culture in the process of adaptation by human beings, and the interdependence of different participants within the global ecosystem. By focusing on each of these themes, it is possible to gain important insights about the evolutionary forces that have brought about human variation in the world as we know it.
Biological explanations of evolutionary forces
In physical anthropology certain presumptions about humans are made. Physical anthropologists, like other scholars, have the option of combining several approaches to create a better understanding of the universe (Laland & Odling-Smee, 2010). Science is one of the ways of understanding the world. By using the scientific methods, the objective is to attempt to understand the various natural processes that shape the universe. Scholars simply put up conjectures and the set out to verify them through experience or observation. Whenever a conjecture is faced with simply explanation or contrary evidence, it is discarded.
It is common for anthropological studies on the evolutionary forces responsible for human variation to be undertaken by combining insights from both natural sciences and social sciences. The main concepts being debated in natural science include natural selection, mutation, and random genetic drift (Durham, 2001). Although evolutionary biologists agree on these forces, disputes sometimes arise regarding their importance relative to each other. Although these forces are normally explained independent of each other, they work in interaction in order to bring about human variation.
Natural selection is the process through which differential reproduction takes place among organisms because of heritable traits, thereby influencing the way the organisms adapt to the environment. Charles Darwin observed that if species continued reproducing at an unchecked rate, exponential population growth would occur (Durham, 2001). He also observed that this unchecked growth is rarely achieved in nature because some organisms simply do not reproduce (Durham, 2001). Those organisms that reproduce pass off the traits that lead the species towards the direct of improved adaptation.
The concept of reproductive fitness is normally used to index natural selection (Keita, 2004). This is defined either in terms of the number of offspring transmitted successfully to the next generation or simply the gene copies transmitted (Keita, 2004). For species that reproduce sexually such as humans, one of the best ways of calculating the absolute fitness of both the man and the women is to calculate the number of children born and then divide by two, such that a person with two children is said to have an absolute fitness of 1.0 (Keita, 2004). This means that the individual has left only one member of the alleles (alternative forms of a specific gene arising through mutation), who will move on to the next generation.
In genetic drift, allele frequencies encounter change over time as a matter of chance alone (Henrich, 2004). When this change occurs, the probability that the allele will be transmitted to the next generation is altered. However, the specific role of genetic drift in evolution remains a hotly contested issue. In contrast, mutation occurs when an error occurs in the process of copying the DNA. DNA is the genetic material contained in organisms. Mutation tends to have a negative impact on the evolution process. In other words, it brings about hazardous consequences to the organisms in which it occurs. However, occasionally, mutations bring about benefits to a species by increasing fitness. In many instances, human variation among humans in different parts of the world is attributed to mutation. For example, people in certain parts of the world may be susceptible to a specific disease that occurs because of mutation.
Integrating cultural aspects of evolution
It is important for cultural aspects to be integrated into explanations of evolutionary forces because it is not unique to humans. Species of apes and monkeys and possibly other mammals as well as some birds can have the ability to transmit behavioral information from the present generation to the next. However, culture has exerted influence on human evolution to an extent unprecedented in all other species.
One clear example is that of medicine (Richerson, 2005). The contemporary knowledge about antibiotics and sanitation among humans has radically reduced disability and death from infection (Richerson, 2005). However, access to antibiotics and sanitation is not uniform among all peoples of the world (Richerson, 2005). Some people tend to be better than others in terms of access to healthcare and sanitation. For example, many children below the age of five from poor countries die of preventable diseases such as malaria because of inaccessibility to healthcare. Such deaths do not occur in rich countries, adequate mechanisms have been put in place to prevent such deaths. The resulting human variation has elements of culture rather than being purely biological.
There are many examples that demonstrate the impact of culture on human evolution. These examples have led to the emergence of the concept of co-evolution. Co-evolution may be defined in terms of a phenomenon in which the dynamics of culture and genes are continuously interacting throughout the evolution process (Richerson, 2005). Traits that have culturally evolved have been observed to have an impact on the relative fitness of individual organisms in terms of their genetic constitution in numerous ways. For example, culturally evolved norms of moral behavior can have an impact on fitness if violators of those norms are subjected to punishment by others. In ancient, small-scale societies, men with no ability to control their antisocial behavior were being exiled into the wilderness; today, such men are being sentenced to prison. Furthermore, throughout history, cultural variations have been creating differences in evolutionary forces, thereby contributing in a significant way to human variation.
Conclusion
In conclusion, the evolution process has been impacted by biological, natural, and cultural factors. In physical anthropology, focus is on all these factors and how they have contributed not just to evolution but also to the range of human variation. The concept of co-evolution can greatly help physical anthropologists understand this human variation. Similarly, the evolutionary forces of mutation, natural selection, and genetic drift, which have been widely discussed in natural sciences, provide valuable insights about the variations among humans around the world.
References
Durham, W. (2001). Coevolution: Genes, Culture, and Human Diversity. Stanford: Stanford University.
Henrich, J. (2004). Cultural group selection, coevolutionary processes and large-scale cooperation. Journal of Economic Behavior & Organization, 53(1), 3–35.
Keita, S. (2004). Conceptualizing human variation. Nature Genetics, 36, 17-20
Laland, K. & Odling-Smee, J. (2010). How culture shaped the human genome: Bringing genetics and the human sciences together. Nature Reviews Genetics, 11, 137-148.
Richerson, P. (2005). Not By Genes Alone: How Culture Transformed Human Evolution. Chicago: University of Chicago Press.