Written by: Aidin Beck
Two Distinct Species of Humans
Humans vs. Neanderthals: Brains vs. Brawn
We all know Darwin proposed the theory of Natural Selection in 1859 stating, Differential contribution of genotypes to the next generation due to differences in survival and reproduction (USGS, 2008). That is to say that all living organisms go through Natural Selection by Evolution to produce offspring that are more adapt to the surrounding environment. The more evolved species of an organism will ultimately prevail. More recent scientific discoveries have shown that our species of humans did exactly that, beating out “the other humans” known as Neanderthals, through Natural Selection. There were many previous species before modern humans but Neanderthals and modern humans were two species that diverged for a period and then overlapped (McHenry, 2009). Neanderthals (belonging to the genus Homo) are the closest ancestors to modern humans, leading just in front of Chimpanzees (belonging to the Genus Pan) in the similarities of DNA (Hall, 2008). The earliest remains that have been discovered were of a group of Neanderthals that died in a cave in Gibraltar about 28,000 years ago (Gooch, 2000). The mystery surrounding the Neanderthals is one which questions the difference in lifestyle and behaviour from modern humans – Who were the Neanderthals? How were they different? Why did we prevail and they didn’t?
Are modern humans related through inter-breeding between the two species?
The Beginning
To investigate the chronologic life of Neanderthals you must first start at the beginning of all human life. Discoveries are still being made which widen our view of how humans came into being but so far, scientists and archaeologists alike say that the first species of humans originated from the Sterkfontein region in South Africa about 5-7 million years ago, aptly calling this area the ‘Cradle of Life’ (Gray, 2010). The species discovered was part of the group, Homo habilis. The Neanderthals’ species belongs to Homo Genus whose earliest fossils, found in Europe, are about 600,000-350,000 years old (Bischoff et al. 2003). Homo sapiens appeared to have originated into Europe from Africa about 400, 000 – 250, 000 years ago. The remains of modern humans and Neanderthals have been found in different areas of Europe which suggests that the two species lived isolated from each other in Europe for some time (Than2006). Evidence from DNA samples has allowed scientists to assume that the two species diverged in Africa, and migrated to Europe at different times. The Neanderthals first went north of the Mediterranean and ruled Eurasia for almost 200, 000 years, after which modern humans migrated to Europe and surpassed their rival species.
Body Structure
It has been speculated that the Neanderthals may have died out because of poor physical and mental structure. Coincidentally, fossil finds have showed that Neanderthals were in fact much more physically adapt to the surrounding climate and environment than modern humans (Larsen, 1998). So, did brains really beat brawn and were modern humans actually smarter? To analyze this we must first understand and compare the structure of a Neanderthal to a human. After the two species diverged in Africa, Neanderthals moved through Europe, spanning from Siberia to Gibraltar (where the youngest trace of Neanderthal fossil found is only 28, 000 years old) (Dalton, 2010). Through evolution, the Neanderthals’ physique became more adapt to climate and only slightly differed from modern human body structure. The robust bodies of Neanderthals were better adapted to the cold as seen by their strong, stout bodies revealed by fossils. The skull of a Neanderthal was much more defined with a large brow and receding forehead which jutted out quite profoundly. To conserve heat in cold climates, the bodies of Neanderthals were much wider with bigger ribcages to support bigger lungs needed for strenuous activity (Trinkaus, 1999). These primitive beings also appear to have been much stronger than modern humans, with larger muscles allowing maximum leverage for strength. They have also been identified to have stronger, shorter limbs which helped reduce surface area to retain body heat (Trinkaus, 1999). Because of these generally larger bodies, Neanderthals required much more food and an average of 4,034 calories per day while modern humans only require 2,200 cal/day (Hall, 2008). This requirement for food made the Neanderthals, even women and children, excellent hunters. In terms of their intelligence, Neanderthals are usually perceived as dumb and slow-witted but archaeologists have identified that their brains were in fact slightly bigger than modern human brains with which they even shared a gene called FOXP2 which contributes to speech and language ability (Hall, 2008). This gene acts on the brain and the nerves that control facial muscles, which does not mean Neanderthals could talk but they definitely had the ability to communicate. So how could such a well-rounded species be beat by us? Many believe it was due to the overall ways of their primitive society and culture.
Neanderthal Society
A relatively significant fact about Neanderthal society is that their population was never really quite big at all, only reaching a maximum of 15, 000 which can pose as a threat when living in an isolated and extreme environment (Gooch, 2000). Many believe the Neanderthals’ system of society and culture played a big factor in their extinction. This consists of their communication skills, diet, living locations and population growth (or lack thereof). What this means is that Homo sapiens had a better and more diverse lifestyle. Neanderthals needed meat as a main source of food and energy which compelled women and children to join the hunt and in turn contributed to the faster development of muscle but delayed sexual maturity (Ravilious, 2008). The difference with modern humans arriving from Africa is that women and children were not as physically strong so instead they dedicated their time to learning new things and created a more diverse diet and lifestyle. The term ‘cultural buffering’ was used in a 2008 National Geographic article that explains that by diversifying diet and having different personnel doing different tasks, you increase the risk of being introduced to new factors that can help a population evolve or shrink, or most likely both. This diverse lifestyle lead by modern humans provided an ever-changing culture that was more susceptible to mutations and development Another ‘cultural buffer’ was the way each society interacted upon itself. Neanderthal groupings were very small and usually only
as big as an extended family while modern human societies were much larger which allowed greater variation of biological and social repercussions (Trinkaus, 1999). Larger populations meant more social interactions which could have greatly developed communication skills for a growing adolescent (Tarko, 2005). Through communication, societies can grow while passing down survival information to following generations. So it appears that Neanderthals were dealt the short end of the stick by having smaller populations with less diversity and only basic communication development. Add the cold climate, the lack of adolescent maturity adaptation and the simple diet and it becomes apparent why a society like this was in such danger of extinction. The modern humans did things right by taking risks and exploring new ideas which engaged the mind and allowed diverse development and variety.
Relatedness
Scientists have clearly been able to identify that the species of Homo sapiens and Homo Neanderthals diverged in Africa and went their separate ways. This is to say that the two societies were isolated from each other and never blended until about 45, 000 years ago. Many wonder if modern humans today are actually related through inter-breeding between the species when they overlapped. By comparing the Neanderthal structure and the modern human structure, inter-breeding seems unlikely or very rare because of the prominent physical differences. Many scientists had their doubts about inter-breeding as well, but a recent study has showed that the people of today may actually share Neanderthal genes in their DNA (Dalton, 2010). 1,983 people from 99 populations in Africa, Europe, Asia, Oceania and the Americas were studied and 614 microsatellite positions were analyzed (Dalton, 2010). These microsatellite positions are sections of the genome that can be used as fingerprints that indentify genetic variation (Dalton, 2010). From this genetic variation evidence, researchers explained that interbreeding happened twice, 60,000 years ago in the Eastern Mediterranean and about 45, 000 years ago in eastern Asia (Dalton, 2010). This means interbreeding happened after the species left Africa which makes sense because no evidence of interbreeding was found in the genome of modern African people.
Recent Discoveries and Applications
The most recent progress seen with Neanderthal DNA is the Neanderthal Genome Project. This project began in 2006 when the Max Planck Institute for Evolutionary Anthropology headed by Svante Pääbo announced that they were sequencing the Neanderthal Genome, which is about the same size as the Human Genome (3.2 billion base pairs) (Dalton, 2009). The entire Genome of a 38, 000 year old Neanderthal was completed in February of 2009 but is still waiting to be reviewed and assessed before publication. The Neanderthal genome was practically created from a single bone discovered in a cave in Croatia. The bone was so degraded that it consisted of fragments that were only about 50-60 base pairs long, but new sequencing technology created by 454 Life Sciences of Connecticut made the segments possible to analyse (Dalton, 2009). This new technology uses pyrosequencing which differs greatly from the rapid ‘shotgun sequencing’ technique which was better used for longer stands of about 800-1000 nucleotides (Powledge, 2002). To understand the 454 Life Science’s method, we must first understand pyrosequencing. There are four enzymes in the system, DNA polymerase, ATP sulfurylase, Luciferase and Apyrase, which are used to sequence by the process of synthesis (Ronaghi, 2001). This means that a single stranded template strand is sequenced by synthesising the complementary strand along it. The DNA polymerase begins by attaching to the single strand which promotes the nucleotides A, T, C, and G. When a nucleotide is synthesized the energy from this bond is converted to ATP by ATP sulfurylase. The ATP is then converted to light by Luciferase and the remaining nucleotides are disposed by Apyrase (Ronaghi, 2001). Four of the same base pairs are added at a time, so if no light is emitted then the nucleotides were not incorporated and are removed and a new set is introduced (Ronaghi, 2001). This process is much more advanced and quicker for full genome sequencing. This technology showed that Neanderthal and Human DNA are 99.5% (Thangham, 2009) identical and researchers hope it will provide more detail on how this species developed their physical traits, adapted to the environment and evolved to resist certain disease (Green, et al. 2008).
Another technique that researchers rely on for precise examinations of fossils is the particle accelerator called a synchrotron. This device is located in a lead-lined room in France and exudes a 50,000-volt x-ray beam on any fossil without disturbing even a single molecule (Hall, 2008). In October 2007, scientists gathered at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, and examined the set of teeth from a Neanderthal child (Hall, 2008). This detailed x-ray revealed the secrets of periodic growth that teeth contain. When teeth are imaged at a high resolution they express certain periodic growth lines and stress lines, which can indicate the age of the individual, much like tree rings. The three dimensional dental exam showed daily growth lines on the teeth between thicker eight-day bands in the tooth’s enamel (Hall, 2008). By counting these growth periods the researchers at ESRF determined the child died shortly after his 12th birthday. They also discovered that his molars were very developed for such a young age which may suggest that Neanderthals had shorter childhoods and less time for brains to develop and adapt.
Modern research is still discovering new fossils and DNA from prehistoric humans but already many breakthroughs have been made. We now understand Neanderthals much more and the mystery of how they became extinct is getting clearer. Neanderthals were very similar to modern humans and had much of same capabilities but it can be said that Natural Selection favoured the modern humans because of their diversity and culturally buffered society. The Neanderthals may have become extinct but there is proof that many of today’s people are more related than was originally suspected. As technology advances, researchers of prehistoric humans are finding new, easier and advanced techniques to analyze fossils and archaic DNA. So, we have examined these questions that pertain to our ancient
ancestors and have discovered that they were very much like us and in some ways more advanced.
We now know who the Neanderthals were and how they were different from modern humans but it is still unsure what happened to them. There are many theories and a great deal of evidence for possible explanations. One question that lingers is, “Are we related through inter-breeding?” It seems very likely indeed that most of us are related to Neanderthals so perhaps the question is, “Are they truly extinct?”
Bibliography:
Than, Ker. MSNBC, Science and Technology. Nov . 15, 2006. April, 2010.
James L. Bischoff, Donald D. Shamp et al.”The Sima de los Huesos Hominids Date to Beyond U/Th Equilibrium (>350 kyr) and Perhaps to 400–500 kyr: New Radiometric Dates” Journal of Archaeological Scienc. Volume 30, Issue , March 2003, Pages 275-280. April, 2010.
Trinkau, Erik.” The early Upper Paleolithic human skeleton from the Abrigo doLagar Velho (Portugal) and modern human emergence in Iberia” Proceedings of the Natural Academy of Sciences of the United States of America. June 22, 1999 vol. 96no. 13. April, 2010.
Neanderthal Brain Size at Birth Sheds Light on Human Evolution. September 9, 2008. April, 2010.
Kreger,C. David. Homo neanderthalensis. April 2010. May, 2010.
Larsen ,Clark Spencer. Human Origins: The Fossil Record. Waveland Pr Inc; 2nd edition (April 1991). April, 2010.
Gray, Richard. “Missing link between man and apes found”. 03, Apr. 2010. May, 2010.
Gooch , Stan. “The Way We Are”. The Spectator. 2000. April, 2010.
Ravilious, Kate. “Neanderthals Grew Fast, but Sexual Maturity Came Late”. National Geographic New. September 8, 2008. April, 2010.
Tarko, Vlad. “Neanderthals Were Too Smart to Survive”. Sci-Tech News. 21st of December 2005. April, 2010.
Thangham, Chris V. “Neanderthal DNA 99.5% Similar to Humans”. Digital Journal. February 16, 2009. May, 2010. < http://www.digitaljournal.com/article/267388>
Synchrotron Microtomography Analysis of Human vs. Neanderthal Tooth Development. October 13, 2007. April, 2010. < http://anthropology.net/2007/10/13/synchrotron-microtomography-analysis-of-human-vs-neanderthals-tooth-development>
Dalton, Rex. “Neanderthal Genome to be unveiled”. NatureNews. 4 February 2009. April, 2010.
Powledge ,Tabitha M. “Shotgun sequencing comes of age”. The Scientist. 31 December 2002. April, 2010.
Ronaghi, Mostafa. “Pyrosequencing sheds light on DNA Sequencing”. Genome Research. 2001, 11. April, 2010.
Green, R. Krause, J et al. “A Complete Neandertal Mitochondrial Genome Sequence Determined by High-Throughput Sequencing”. Cell. Volume 134, Issue 3, Pages 416-426, 2009. April, 2010.
Hall, Stephen S. “Last of the Neanderthals”. National Geographic. October 2008. April, 2010.
Images:
Fig 1: “Neanderthal Recreation”. National Geographic. April, 2010.
Fig 2: Trinkaus, Erik. “The early Upper Paleolithic human skeleton from the Abrigo doLagar Velho (Portugal) and modern human emergence in Iberia”. Proceedings of the National Academy of Sciences of the United States of America. April 26, 1999. April, 2010.
Fig 3: “Neanderthal Genome”. National Geographic. April, 2010.
Fig 4: “Synchrotron”. National Geographic. April, 2010.
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