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After Charles Darwin published his theory of evolution about 150 years ago, scientists have continued to study various aspects of evolutionary biology in modern times by forming and testing hypotheses by using observational data and theoretical biology.
According to recent studies, all life on Earth shares a common ancestor called the last universal common ancestor (LUCA) or a long-lost parent. It is also assumed by researches that if humanity has one or more relatives, these sister species might share the same parent at some point. John Hawks, a paleoanthropologist at the University of Wisconsin has said:
Probably the most important thing is that most of the fossils we find aren't actually "missing" links. The number of extinct side-branches is much larger than the number of true genealogical connections in the fossil record, and so when we find a fossil, we don't assume it's an ancestor of anything, we interpret it as a sister group of some things.
History of Failed DiscoveriesVery often evolutionists classified bones or even bone fragments as important “missing links”. It was a common practice in the past for someone to find a piece of a fossilized bone and to immediately assume it to be convincing visual proof that evolution has occurred.
Many evolutionists in the past were trying to prove that humans are 99% chemically similar to apes through blood proteins precipitation. However, after the numerous studies on chemical components, humans may have many common ancestors:
Milk chemistry shows that the donkey is man’s closest relative. Cholesterol level tests revealed that the garter snake is man’s closest relative. Tear enzyme chemistry showed that the chicken is man’s closest relative. On the basis of another type of blood chemistry test, the butter bean is man’s closest relative. (Morris, Henry M., The Twilight of Evolution, Grand Rapids: Baker Book House, 1967)
Over the years, many “missing link” fossils turned out to be a hoax. The most famous “discovery” was the Piltdown Man in 1912, when someone found a skull and jawbone in a gravel pit in England. Scientists declared it to be absolute proof of how apes became humans. More than 40 years later, Piltdown Man was proven to be a fraud. It was nothing more than a lower jawbone of an orangutan combined with the skull of a modern human.
Another famous hoax example is “Nebraska Man” that was discovered in 1920. Archeologists found a single tooth in western Nebraska at the Snake Creek quarry and declared it to be proof of evolution. It made big news until someone asked a farmer to review the fossil. The farmer identified it as a pig’s tooth and further excavation revealed that the rest of the skeleton belonged to a pig.
There are other numerous archeological discoveries that made big news such as “Orce Man” that turned to be the skullcap of a donkey, “Ramapithecus Man” which was actually a baboon skull and “Neanderthal Man” which was severely bow-legged because he had a distortion of the bones (rickets).
Various articles came out with headlines like “How Apes Became Human,” featuring hoax discoveries and an attempt to connect random bones together as proof of evolution. More often, such articles were filled with uncertain phrases like “what appears to be,” “close to answering,” “we are suggesting,” “people have speculated,” and “still something of a mystery,” and featured flimsy artwork and speculative evidence as absolute proof.
Today we have more advanced technology to detect the authenticity, validity, and age of the newly discovered fossils. Radiocarbon and/or radiometric dating, for example, is used to determine the age or date of organic matter, geological specimens and archeological specimens from certain proportions of the carbon and/or radiometric isotopes which decreases the chances of error.
Origin TheoriesIn the 1980s, a group of paleoanthropologists and geneticists began to support a hypothesis that modern humans originated only once and from only one location, which is Africa. In paleoanthropology, this theory is called the Out of Africa Theory (OOA) and this model proposes a “single origin” of Homo sapiens and admixture with archaic humans. According to this theory, Homo sapiens (anatomically modern humans) were assumed to originate around 300,000 years ago, most likely in East Africa. Then paleoanthropologists created a model map of a great migration of newly developed Homo sapiens from East Africa, somewhere between 80,000 and 50,000 years ago, who traveled and settled down along the southern coast of Asia and to Oceania 50,000 years ago.
Until the 1980s, scientists assumed that hominins were restricted to Africa during the Early Pleistocene period. As a result, all major archaeological searches were focused on Africa. However, very few chimpanzee or gorilla ancestors have been found anywhere in Africa, and by seven million years ago the European and Asian apes had vanished.
The few actual fossil remains of prehistoric ape species were named Nakalipithecus, Ouranopithecus, and Sahelanthropus. However, a certain type of species such as S. tchadensis indicates that the last common ancestor of humans is very unlikely to have looked like chimpanzees, as had been previously supposed by some paleontologists.
The evolutionists reasoned that these species did not survive or survived in small numbers and went extinct probably because of the Toba catastrophe theory 74,000 years ago.
OOA Theory ContradictionsMost anthropologists believe that our species originated in Africa around 200,000 years ago and that one group left around 80,000 years later before spreading across the world. But instead of humans purely coming out of Africa, there have been new discoveries which have proven that characteristics of humans actually developed not only in Africa, but also in East Asia and Europe.
According to the recent List of Human Evolution Fossils, the discoveries around the world are not restricted solely to the continent of Africa. For example, a Graecopithecus tooth found in Bulgaria belongs to the Graecopithecus freybergi species, which is considered to be the oldest suggested direct ancestor of modern man. The first original Graecopithecus specimen mandible was found in 1944, at the site known as Pyrgos Vassilissis northwest of Athens and dated to be 5.5 to 7.25 million years old (the late Miocene period).
Additional discoveries in Australia started to contradict the OOA Theory, making researchers begin to doubt it. The earliest hominid skeleton and tool remains that were found in Australia's Lake Mungo showed no evolutionary relationship among the fossils previously found in Africa. They were relatively slender and gracile in form, while younger skeletal finds were much more robust:
The DNA patterns of the Australian and Melanesian populations show that the population evolved in relative isolation. The two groups also share certain genetic characteristics that are not found beyond Melanesia. This would suggest that there was very little gene flow into Australia after the original migration.
From the scientific research, there were no results or traces of genetic analyses based on the Y chromosome and on Mt DNA from previous exits from Africa, which means that certain groups of species in Australia lived in isolation.
Nine Million-Year-Old TeethA recent discovery of 9 million-year-old teeth by German archaeologists suggests a European origin of humanity. The uniquely shaped tooth was found in a dried-up riverbed in Germany’s Rhineland. This type of fossil has never seen before in Europe or Asia, but it has a similar shape and structure of humanoid skeletons found in Africa but are much older than the African’s fossils.
The mayor of the nearby German town where the discovery was made even suggested that scientists should reevaluate the recent model of human evolution:
"I don't want to over-dramatize it, but I would hypothesize that we shall have to start rewriting the history of a humankind after today," Michael Ebling said.
Dmanisi SkullDmanisi skull is another discovery that conflicts with the OOA Theory, making some researchers suggest that Homo erectus originated in Eastern and Southeast Asia. The Dmanisi skull (also known as D4500 or Skull 5) was discovered in Dmanisi, Georgia in 2005 and the discovery was published in Science magazine in October 2013. It is considered to be one of the most complete 1.8 million years old skulls of a Pleistocene Homo erectus, with an estimated height of the person to be between 4.79ft and 5.45ft.76.
The research began in 1991 when Georgian scientist David Lordkipanidze discovered remains of early human occupation in a cave in Dmanisi, Georgia. There were other archeological sites where five early hominin skulls had been found. All skulls residing at different Dmanisi archeological sites have significant morphological variations and if they were put side by side, they would be classified as skulls of different species. However, all Dmanisi skulls are of the same age and were found in exactly the same place.
Based on the research, Asian Homo erectus carries different ancestral traits and may be considered a separate lineage, while Middle Pleistocene remains found in Europe might be a second or third separate lineage.
David Lordkipanidze and other researchers proposed that these skulls belong to a single evolving Homo erectus species, similar to those that have been found in Africa and Asia. Other anthropology researchers that didn’t participate in the excavation said that the Dmanisi fossils were a great find, but they don’t think that this is the same Homo erectus from both Africa and Asia. Dmanisi skull analysis clearly indicates that human origin was not isolated to one place and most likely shares characteristics across the world.
Georgian and University of Zurich researchers examined Dmanisi skulls and normal variations in modern human skulls and chimpanzees skulls and found that they looked different from one another. They discovered that skulls have variations in physical features similar to the diversity found in humans today. This evidence supports the fact that diversification had already happened in Dmanisi 1.8 million years ago. David Lordkipanidze said himself:
If you will put separately all these five skulls and five jaws in different places, maybe people will call it as a different species.
Recent fossils discoveries don’t really show obvious transitional forms between humans and chimpanzees. Dmanisi skulls, for example, looked different from chimpanzee skulls and don’t share any physical features. Even Dr. Leakey, one of the people who discovered “Lucy” (known as Australopithecus afarensis), admitted that Lucy's is so incomplete that there are no firm conclusions about what species she was, even though her skeleton’s age was 3.5 to 4 million years old.
Dali ManThe Dali Man skull was found in China 40 years ago had and contains a mixture of traits from Homo erectus and Homo sapiens. The skull was in very good shape, showing the face and braincase of a person living around 260,000 years ago. The details of the skull and face don’t match European Neanderthals and earlier European hominids. The skull found in China may indicate that ancient human origin took place outside of Africa and that humans actually evolved in East Asia as well as in Europe.
Researchers Xinzhi Wu of the Chinese Academy of Sciences and Sheela Athreya of Texas A&M University also made a proposition that the early modern humans were not isolated in one place as they developed, but instead were sharing common characteristics across the world.
How Did Complex Life Evolve?A December 2017 report concludes that 3.45 billion-year-old Australian rocks once carried microorganisms that make them the earliest direct evidence of life on Earth. The good news is that this discovery should not be assumed to be the first living organisms on Earth:
We have no direct evidence that life existed 4.3 billion years ago but there is no reason why it couldn’t have, this is something we all would like to find out.
Probably the most puzzling part of evolutionary theory is the process of transformation from simple life forms to complex forms. Even Charles Darwin himself asked a question:
Why if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion instead of the species being, as we see them, well defined? (The Origin of Species, Charles Darwin, ch. 6.)
According to a research, multi-cellular organisms evolved independently at least 46 times in eukaryotes, and in some prokaryotes (cyanobacteria, mycobacteria, actinomycetes and Magnetoglobus multicellularis). However, complex multi-cellular organisms evolved only in six eukaryotic groups such as fungi, algae and land plants, and only one or two times in animals. In addition, evolution through the theory of natural selection faces a reproduction puzzle:
To reproduce, true multicellular organisms must solve the problem of regenerating a whole organism from germ cells (i.e. sperm and egg cells), an issue that is studied in evolutionary developmental biology.
Charles Darwin would answer his question if he had a precise knowledge of how regulatory genes work.
Genomes of different animals produce a variety of different types of animals, and many of these species share the same structural genes for organism development like collagen and enzymes. Each group of animals may have its own rules of development which are programmed within the small percentage of genes that shape the bodies of these animals. These regulatory genes work in a precise pattern and any changes can cause adverse consequences to the development of the species. These genes are ancient, highly conserved and shared by all animals.
ConclusionScientists are still in search of the long-lost parent of humanity. They have been looking for the common ancestor for a long time, and they still have not found it. Debates still take place regarding the identification and classification of the ancestral lineage of humans:
In principle, fossilized remains of the last common ancestor might come to light any time. They might even be discovered this very year. But because there is so little agreement on what the LCA should look like, researchers will interpret the fossils differently.
Many are still searching for new fossil evidence and more information in the hopes of finding this “missing link”.
The Last Common Ancestors
4/ 5By Esmi