Introduction: Modern humans, known scientifically as Homo sapiens sapiens, have evolved over time from other forms of life. Scientists are able to study some of this evolution through DNA and fossil research, but the exact process by which humans evolved and migrated across the world is still unknown. Genetic and archeological evidence can help scientists learn more about human history and create accurate timelines from human evolution and migration. Mitochondrial DNA plays an instrumental role in pinpointing how and when modern humans evolved from other hominid species as well as how and when large-scale human migrations likely occurred.
What is Mitochondrial DNA? Although most of a person’s DNA is contained with the nuclei of their cells,
…show more content…
Approximately 100,000 years ago, a morphologically diverse group of hominids occupied Earth, unlike now, when only one hominid species exists. By approximately 30,000 years ago, these diverse hominids had evolved into morphologically similar, anatomically modern humans. Within the scientific community, there are two main hypotheses as the how and where this evolution occured: the Out of Africa hypothesis and the Multi-regional hypothesis. Evidence like fossils and mitochondrial DNA research may help scientists determine if either of these theories is correct or to what extent they are correct. The Out of Africa hypothesis is currently more widely …show more content…
While the multi-regional hypothesis highlights the roles of interbreeding and parallel evolution, the Out of Africa hypothesis, also known as the Recent African Origin hypothesis, does not (Johanson, 2001). According to this theory, previous hominids evolved into Homo sapiens approximately 150,000 to 200,000 years ago before migrating to Eurasia and the other continents of the world. This theory is sometimes referred to as the Recent African Origin hypothesis because it “considers all living humans as descending from a relatively recent…ancestral population” (University of Maryland Department of Geology, 2016). Although there would still have been interbreeding between populations over time, this hypothesis contends that the evolution of modern humans occurred in Africa first, rather than simultaneously across different
Paabo’s team discovered an mtDNA sequence from a finger bone they found from around 40,000 years ago, as carbon dating is one of the most commonly used methods of determining a fossil’s age. (Hammer, 70). Also, Neanderthal mtDNA is differs severely from modern human mtDNA. For example, Microcephalin is a gene for brain size during the development of the organism.
“Analyses of the hominid indicate that they belonged to a previously unidentified species, which anthropologist Yohannes Haile-Selassie of the Cleveland Museum of Natural History and his colleagues are calling this species Ardipithecus Kadabba. Previous fossil finds from the identical genus has suggested that hominids called kadabba were instead a subspecies of the only other known Ardipithecus species, Ardipithecus ramidus”(Bower 2004). This new hominid is being addressed presently as Ardipithecus ramidus kadabba. “While Ardipithecus ramidus kadabba is not the sought-after link—the yet-undiscovered creature that lived at the cusp of the evolutionary division between man and chimp—Yohannes Haile-Selassie, also a doctoral candidate at the University of California at Berkeley, said the hominid certainly is very close to the branching point.” (Rickman 2001)
It is said that the humanoid existence begins in Africa. It is no coincidence that Africa is also the home to Chimpanzees, Pan troglodytes, and Bonobos, Pan paniscus. These are humans’ two closest living relatives, both sharing almost 99% of the human genome through common descent. While humans were said to have separated from Chimpanzees around 5-7 million years ago , Bonobos separated from its Chimp cousins around 2 million years ago . Bonobos inhabit a single part of Africa, Democratic Republic of Congo South of the Congo River, unlike the Chimpanzee, which inhabits Across West- and Central Africa, with remaining populations distributed over several countries. While these two apes where once thought to be the same species, up until the beginning of the 20th century , there are many differences socially, as well as physically, that make Bonobos more than a Pygmy Chimp. With disparities in morphology, behavior, perhaps even emotions and cognition, and known as the “make love, not war chimp” , how can this ape be so vastly different from its notoriously violent Pan cousin, but yet share the same amount of similar DNA to Homo sapiens? And what does this mean for the studies of human and past humanoid behavior?
Vigilant, Linda. Stoneking, Mark. Harpending, Henry. et al. 1991. African Populations and Evolution of Human Mitochondrial DNA. Science 253: 1503-1507.
Australopithecus afarensis who existed 3.5 million years ago and a 4.4 million year old skeleton of an Ardipithecus ramidus are the closest science has come to discovering the human lineage. Shattered Ancestry an article written by Katherine Harmon discusses the remains of two hominids found within Ethiopia. These skeletal remains have created a huge controversy within the topic of evolution questioning many assumptions that have been made referencing the human lineage. The skeleton of the Australopithecus afarensis was named Lucy and was discovered in 1974. The evidence of her walking upright on her two feet essentially guaranteed her a spot in the human lineage line. Lucy was a chimplike ape that was said to walk upright making scientists believe the human ancestry was simple. The complete skeleton found in Ethiopia of an Ardipithecus ramidus named Ardi completely changed all assumptions made from scientists about the complexity of the human lineage. These remains have encouraged researches that the human line is not the only lineage to have evolved but the chimpanzee line has undergone drastic changes as well. There are many traits that researchers have always directly linked to the human lineage however since these discoveries occurred researchers are reconsidering. The recent discoveries that have shattered what has always suggested what linked a species to the human lineage have changed the certainty of whether it is possible to confidently identify the human’s last common ancestor. Majority of scientist had forgotten that there would have been many hominid species living together at one time. New theories have been suggested since scientists revealed that the foot of a hominid found called the Burtele site was found ju...
Stringer, C. B. & Hublin, J-J. (1999). New age estimates for the Swanscombe hominid and their significance for human evolution. Journal of Human Evolution 37, 873–877.
This paper has shown how Homo sapiens had several advantages over the Neanderthals including better diets, better tools and just better luck. The Neanderthals could not survive the harsh climates they were thrust into and eventually died out. In this paper I looked at how Homo sapiens and Homo neanderthalensis had co-existed but the disappearance of the Neanderthal ius due in some part to the appearance of the more culturally advanced and genetically superior Homo sapiens. Although the How and Why of how Neanderthals went extinct, it is clear that Homo sapiens had a part in their demise. In the last one hundred and fifty years that we have been studying humans we have seen them come from savage brutes, to Homo sapiens respectable contemporary. If we had not gotten lucky in the past, Neanderthals could be studying us today.
Humans know or understand the theory of evolution and how they evolved from apes, but there is always talk of a missing link between apes and modern humans. Apes did not just suddenly evolve into modern day humans. Apes evolved into another species that fall into the relation of modern humans. This is what the missing link is referring to; we call the species hominins. Hominins comprised of many species actually, including but not limited to, Australopithecus afarensis and Homo erectus. Homo erectus may have been a direct descendant of modern Homo sapiens. These species hold strong evidence that they are the missing link between apes and modern humans. There are many pieces of evidence that lay the path of evolution from these species to modern humans, “…these include anatomy, living primate behavior, and genetic relationships” (Stanford, 237). Australopithecus afarensis comes first, existing about 3.9 to 2.9 million years ago, with intermediate anatomical traits between living apes and modern humans; their fossils were found in Africa (Yukimoto). About a million to two million years later, the species Homo erectus came into existence and lots of evidence has been found about this particular species, in fact, it was probable that it was the first species to leave Africa (Yukimoto). These species are significant in the evolution of modern humans. We do not have a clear path or even understand why these species emerged when they did or how they, in theory, eventually evolved into modern humans. We can only assume these things, by using various evolutionary processes such as natural selection, genetic bottleneck, and many more.
From the ancient bones of the Neanderthals, scientists have been able to extract small amounts of DNA. The DNA comparisons to modern humans show no relationship, implying evolutionary separation (Kunzig, 159). Some anthropologists say the small sections of DNA found are not conclusive evidence, because modern humans show just as much variation in DNA. These people point out that individuals such as the “Portugal Kid” are hybrids of Neanderthals and modern humans, showing there was gene trading. One argument against this is that there is no skull from the ‘Portugal Kid” so it is hard to compare it to Neanderthals. Also, it is known that closely related species can breed and their offspring can be fertile, but they are still separate species (Kunzig, 161).
contained mitochondrial DNA (mtDNA), completely intact. Mitochondrial DNA is tougher than the DNA found in cell nuclei; it is also found in the cytoplasm of a fertilized egg and is passed only through maternal lineage. This makes it much easier for the team to study and makes testing more accurate.
Paleoanthropology: Pliocene and Pleistocene Human Evolution. Paleobiology, 7:3:298-305. Frayer, David W. and Milford Walpoff 1985 Sexual Dimorphism. Annual Review of Anthropology, 14:429-473 Key, Catherine A. 2000 The Evolution of Human Life History.
My research strives to answer the presence and degree of interbreeding between Neanderthal and Modern humans. Researchers use different comparisons of the fossil record, phylogenetic, morphological, and genetic methods to explore these questions in more detail. The literature provided many positive correlations to my hypothesis that Neandertals and Modern Humans interbred on a small-scale basis after the dispersal of modern humans from Africa. The literature also predicts a time frame of likely interbreeding. To explore this question it is important to research article’s explaining the statistical, genetic, and physical evidence associated with possible interbreeding.
According to Stringer and Andrews, the Out-of-Africa Model suggests that there is a fairly recent common ancestor that shares many of the anatomical characteristics displayed by modern Homo Sapiens (1263). This version is more parsimonious with regard to the fact that it ...
What evidence shows the changing from the early hominids to the modern humans? Throughout the human evolution body parts like legs and harms have changed for the better. By the early hominids being biped, meaning they are able to stand and even walk on two feet, it helped them to be able to do more things like getting around more and help with their tool making and hunting. A lot of the fossils discovered were found in the Great Rift Valley in East Africa, which contained many different lakes and small rivers. For many years researchers have been finding new species. These species have been named Australopithicus, robust australopithecines , Orrorin tugenensis, Homo habilis, Homo erectus, neanderthal, and Homo sapiens. These early hominids and modern humans really show off how the features and behaviors have really changed in time.
The evidence for human evolution begins with the australopithecines. All the australopithecines were bipedal and therefore possible hominines. In details of their teeth, jaws, and brain size, however, they modify enough among themselves to be divided into five species: Australopithecus anamensis, A. afarensis, A. africanus, A. robustus, and A. boisei. Genus Homo are also divided in five different spices: Homo erectus, H. habilis, H. sapiens, and H. sapiens sapiens.