A Brief History
On July 10, 1997, British scientists in London, England, reported that the DNA analysis of a Neanderthal skeleton gave credibility to the “Out of Africa” theory of human origins, including the likelihood of an “Eve” ancestress to all modern humans dated back to 100,000 to 200,000 years ago. Some other scientists have since pushed back the possible date of origin of the human species to over 300,000 years ago, still believed to have originated in Africa.
The idea that every single human being on Earth has a common ancestor, the fabled “Eve,” is supported by DNA studies of modern humans and those prehistoric human samples capable of providing testable DNA samples. According to the generally accepted scientific theory, humans evolved in Africa and migrated across the world, becoming the humans we are today.
One fascinating and contentious aspect of human evolution is the relationship between human species. Today, the only species of humans is Homo sapiens, formerly referred to as Homo sapiens sapiens what we call “Modern Humans.” Extinct varieties of humans included the much celebrated Neanderthals, Homo neanderthalensis if you consider them a separate species of humans, or Homo sapiens neanderthalensis if you consider these stereotypical “cave men” to be s sub-species of modern humans.
For many decades, scientists argued about the role played by Neanderthals in human evolution, generally labeling the beetle browed “cave men” as something other than our ancestor, a product of parallel evolution. Some scientists persisted in the contention that Neanderthals were either our ancestor that evolved into modern humans, or a sub-species of humans that either died out or became mixed with remaining modern human populations.
Current DNA analysis suggests that Neanderthals were not the brutes often depicted in cartoons and literature, but highly intelligent human beings with brains larger than modern humans, though perhaps not quite as complex. For many years scientists believed Neanderthals did not possess language skills, based on the absence of a hyoid bone in the throat that enables modern humans to speak. In 1989, scientists confirmed the discovery of a Neanderthal hyoid bone, a delicate bone that was dated back to about 60,000 years ago. Thus, it is largely assumed Neanderthals had the physical capability to speak and make the sounds modern humans can make. (Note: Brain size is not necessarily indicative of how smart a person is. This author has known men with really big heads, meaning big brains inside, that were considerably less intelligent than women or smaller people with much smaller skulls, so lets not start bragging about hat size!)
Many scientists still insisted that Neanderthals had become extinct, possibly driven to extinction by the emergence of modern humans or by climate change, as the Neanderthal body type was adapted for success in cold weather, and as the world warmed, modern humans became the better adapted species.
DNA analysis of modern humans alive today indicate that Neanderthals must have engaged in interbreeding with modern humans, with traces (about 2%) of Neanderthal DNA found in modern people of European and Asian descent. Oddly enough, modern Africans generally do not exhibit any Neanderthal DNA! The assumption is that Neanderthals had migrated from Africa prior to modern human migration from Africa, and those modern humans that migrated to Europe and Asia met and interbred with the Neanderthals they found. Meanwhile, in Africa, no Neanderthals remained, and modern humans in Africa did not have the opportunity to meet and breed with Neanderthals.
The only other relatively modern species of humans, known as the Denisovans, is believed to have become extinct, though not before leaving DNA traces in modern humans. Denisovans, a species of human discovered in Siberian paleontological sites, are believed to have interbred with Neanderthals and modern humans. Denisovans and Neanderthals may have had a common ancestor, and the 2 species split, with Neanderthals in Europe and Denisovans in Asia. Further study is needed to answer these issues definitively.
Based on the best and most convincing analysis of scientific evidence available today, it would seem almost a certainty that all humans alive today are related by having a common ancestor, traceable back to a single female human in Africa that has not been found, but is usually referred to as “Eve,” an allusion to the Biblical “first woman.” Creationists may challenge this theory, arguing that people did not evolve at all in the manner described by modern science, but were purposely created as they are by God. Others, especially with ethnocentric or racist motives, may challenge the common theory of human evolution to support their alternate theory that justifies their belief that one branch of the human tree is superior to other branches. What do you believe?
Questions for Students (and others): Do you believe ancient humans such as Neanderthals and early modern humans could have been on the average smarter than humans are today? (Remember, intelligence is not the same as knowledge.) Do you believe all humans come from the same source in Africa? Please let us know in the comments section below this article.
Update: On July 10, 2019, news of new analysis of ancient human skulls found in a cave in Greece identified a Neanderthal skull from 170,000 years ago and a modern human skull dating back to 210,000 years ago. The exciting analysis released on July 10th means the modern human skull is the oldest indication of modern humans outside of Africa (in Europe) by an incredible 160,000 years! Previously, modern humans were not known to have migrated from Africa until about 50,000 years ago. The implication of modern human and Neanderthal coexistence in Europe (and perhaps Asia as well) makes for an exciting new realm of potential theories about the evolution of modern humans and our history. The reason detailed analysis of the 2 ancient skulls found in 1978 took so long to become more definitive is because the skulls were both partial and imbedded in in a sort of amalgam of rock mixture called “breccia.” Not until recently did modern scientific analysis techniques advance enough to gain the more detailed picture of the nature of both skulls. It had previously been assumed both skulls were from the same time period, but in fact the finding now is that each became part of the breccia at different times. Cutting edge dating techniques such as Uranium dating was used in determining the age of the respective fossils found in the Greek cave, and although no DNA samples could be recovered from the fossils, scientists are hopeful about using modern techniques to analyze proteins found in the fossils. The science of human evolution and history is a fluid story, changing as new information and theories become available due to new discoveries and new investigative techniques. Whatever we believe today may radically change tomorrow. Meanwhile, researchers will keep plugging away to unravel the mysteries of the human species.
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For more information, please see…
Roberts, Alice. Evolution: The Human Story. DK, 2018.
Seddon, Christopher. Prehistoric Investigations: From Denisovans to Neanderthals; DNA to stable isotopes; hunter-gathers to farmers; stone knapping to metallurgy; cave art to stone circles; wolves to dogs. Glanville Publications, 2016.
Paabo, Svante. Neanderthal Man: In Search of Lost Genomes. Basic Books, 2015.
Swamidass, S. Joshua. The Genealogical Adam and Eve: The Surprising Science of Universal Ancestry. IVP Academic, 2019.