Analyzing on the Origin of Modern Man - Article Example

Today, the origin of modern man is explained by two different hypotheses- the multiregional and the out-of-Africa hypothesis. Scientists have discovered numerous fossils of human ancestors the traits of which are partially similar and sometimes very similar to that of the modern day man. However, the best way to determine the extent of accuracy of the ancestral relation and closeness of each fossil to one another and that to the modern man is by genetic studies. Since, the genetics of humans are 99% similar, it is already established that the modern man must have come from some common ancestor. Genetic analysis using the most modern methodologies alone can help recreate the ancestral relation of modern man to each of its ancestors and help track down the origin of man. Introduction Based on the study of fossils by paleoanthropologists, it was established that Homo Erectus was present in East Africa nearly 2 million years ago (Pic1). Homo Erectus is known to have large cranial capacity and was conversant with hunting however was still unfamiliar with methods of building or agriculture. Most scientists believe that Homo Erectus moved out of Africa where they slowly developed into Neanderthals and other homo erectus groups. Out of the two proposed hypotheses for the origin of man, the out-of-Africa hypothesis, though debated upon, is largely supported with fossil evidences and genetic analysis. According to the article selected, genetic analysis of homo sapiens or the modern man shows that Homo sapiens descended from Homo erectus in Africa nearly 200,00 years ago. Post this, Homo sapiens moved out of Africa to different places such as Asia, Europe and later to Australia and America. Thus, gradually Homo Sapiens are said to have replaced all the Homo Erectus according to the out-of-Africa theory. One of the most important evidences to support this is mt DNA analysis of African and non-African populations. Mitochondrial analysis clearly reveals that the mt DNA (mitochondrial Dna), which is the DNA extracted from mitochondria, sequence diversity is greater among Africans than that of non-Africans thereby establishing the point that the ancestors of Homo Sapience must have had diverged in the African region. DNA sequences obtained from Y-chromosome or mitochondria support the fact that the roots of the modern man are based in east Africa. DNA analysis also establishes that large scale migration of Homo sapiens occurred out of the East African region to Ethiopia, Eurasia, Asia etc More advanced genetic analytic studies like that of single nucleotide polymorphism (SNP) or microsatellite study also supports the fact that the modern man originated in Africa and then spread to other parts of the world.However, there are several unanswered questions regarding this migration and the out-of-Africa hypothesis. BODY 1. Mark Stoneking and Johannes Kruase compared the DNA sequence of Neanderthal to that of modern day mani. The mt DNA of the Neanderthals differed vastly from that of Homo sapiens. Newer studies suggest admixture i.e. interbreeding of species where genetic material exchanges are seen. The out-of-Africa theory was tested according to which “a single dispersal from Africa followed by separate migrations from this ancestral non-African source population, and this scenario receives the strongest support from the data (P = 0.74)” (Stoneking & Kruase). I feel that the previous out-of-Africa theory needs to be modified since genome analysis provides a direct relationship according to which it is seen that Neanderthals and Denisovan genomes diverged from hominin genome. After this the sister groups i.e. Neanderthal and Denisovan diverged and migrated as admixtures while the rest of the hominins in Africa gradually became the modern man. Therefore, the prior belief that Homo sapiens evolved entirely in Africa before migrating to other places is modified into the fact that hominins diverged into groups which interbred and this admixture migrated to other places whereas some of the hominins became homo sapiens in Africa itself (Pic 2). 2a. However, it must be noted that even though all populations around the world do share common ancestors, we have developed strikingly different physical traits and racial differences. Rosenberg et al conducted AMOVA studies on individuals in a population and saw that 93% genetic difference was seen among individuals while 5% of genetic difference was seen among major groupsii. AMOVA stands for Analysis of Molecular variance and it is done to measure the extent of difference between two things at the molecular level. Molecular and computational biology was utilized to were used to draw up clusters to determine the extent of relation between different races..Low heterozygosity was seen in some populations owing to genetic drifts. Low hereterozygosity shows that most alleles in the gene pool of the population were homozygous and therefore indicated low interbreeding. However, the challenge in such studies is that availability of data especially genetic data. In my view, the AMOVA study conducted by Rosenberg et al reveling the difference between populations is a strong evidence that we all, no matter from which part of the world, come from a common ancestor. I believe owing to migration to different parts of the world our genetic makeup changed gradually somewhat like Darwin’s finches. 2b. The concept of races is also modified by modern day genomics. It is no longer a characterization of the human species. According to Lewontiniii, clustering of population may be seen in races which gives us an account of things such as color of skin, hair type, shape of face etc. This clustering is achieved by using microsatellites which are non-functional part of the DNA. Microsatellites are not exactly like genes but are actually like markers which tell us a lot about a group and give us maximum information about them. For example, by utilizing the suitable microsatellite it is possible to cluster African population, Asian population , American populations etc. Modern genomics which uses microsatellites also help us understand the extent of interbreeding among populations as a result of migration or other factors. 3a. Today, geneticists rely on mitochondrial DNA and Y chromosome for genetic analysis. Mt DNAiv is widely used since mutations accumulate in the DNA it becomes possible to get a a magnified view of genetic diversity available in a gene pool. Since mt DNA is inherited maternally there is no scope for it to recombine. Lastly a typical normal human has about mt DNA and each of these are almost identical to each other. Therefore, mt DNA is most widely used for molecular and genetic analysis. Again Y-chromosome is widely used because Y-chromosme is also regarded as an important evolutionary study tool. The sequence of Y-chromosome helps us draw up a catalogue of genes and moreover SNP are easily studied in Y-chromosome. 3b. The terms “mitochondrial eve” and “Y chromosome Adam” (Pic 3) to whom we owe the modern day concept of mt DNA analysis and Y-chromosome analysis did exist in Africa. Mitochondrial eve is known to be a woman who is said to be the ancestor of all human beings. She lived in Africa some 100,000-200,000 years ago. She is called “mitochondria eve” since scientists determined her identity from mitochondrial DNA which is passed on from mother to daughter only. Similarly, scientist believes that like mitochondrial eve there is also a Y-chromosome Adam.v This Y-chromosome Adam’s Y-chromosome is said to have been passed to all men and boys. However till date there is no accurate knowledge about Y-chromosome Adam’s origin. Recent research teams have however discovered the genetic trail which reveals the existence of Adam somewhere near the time of Mitochondrial Eve’s existence. CONCLUSION Reading the selected article and other recommended articles it is clear to me that the cradle of human origin was indeed Africa. I especially am fascinated about the Adam and Eve concept because here we can almost feel science meet mythology and I perceive a deep connection and possible interaction between the two.However, the migration patterns of the early human races are yet not clear. The papers that I have read have also revealed the exemplary usage of modern analytical methods and genetics tools are essential to derive accurate information from the fossils that are discovered. Future research areas must be set on to track down the accurate migration patterns from Africa to other parts of the world and also simultaneously determine the genetic changes that occur during the process of migration or interbreeding between two different groups. Moreover, more research must be done to trace the existence of Y chromosome Adam. Future research prospects maybe sought at determining the inheritance pattern of both Adam and Eve’s chromosome to the modern man and detect changes if any. The topic also relates to St.Leo University’s core values such as integrity and personal development. Integrity because the DNA structure over centuries were integrated well and did not change much among humans. I have used personal development since; the topic helped enlighten our individual’s minds too and helped us understand our origin. REFERENCES Read More