As I mentioned in my introductory post, this is a paper I wrote recently for my archaeology class. It was written hastily but I hope you find it interesting.
When Charles Darwin published On the Origin of Species in 1859, he presented his idea of speciation by natural selection of random mutations without any way of knowing the mechanism for how traits were inherited. It wasn’t until Mendelian genetics were rediscovered at the turn of the 20th century that biologists had a valid model to understand how traits were passed on to subsequent generations. Despite this missing piece of information, the impact of Darwin’s book on the scientific community – although not a new idea, nor uniquely his own – was profound. In fact it is considered to be the foundation of the field of evolutionary biology.
In the century and a half since the publication of Darwin’s seminal work, while the basic theory he presented has survived basically intact, many developments and discoveries (such as Mendel’s laws of genetic inheritance) have provided new insight into the study of human evolution. Fossil evidence has demonstrated the ancestry of many modern species, including humans from Homo Erectus and Homo Habilis. The development of molecular biology, the discovery of the structure of DNA, and improvements in genetic sequencing methods has given insight into the mechanisms of how new traits are created through mutations, and has provided the means of determining the common ancestry of many species. Modern developments in socio-biology have helped to explain the evolutionary origin of certain human behaviours such as a sense of morality and altruism. Advances in computer hardware and software have allowed the development of more detailed and elaborate evolutionary models. Discoveries in biotechnology have led to the ability to modify entire genomes, and may eventually lead to the synthesis of new artificial organisms. The new field of evolutionary developmental biology promises to provide further evidence and insight into the ancestry of all forms of life, including humans. In this paper I will discuss some of the more recent of these developments and their impact on the future study of human evolution.
Recent Fossil Discoveries
Even after Darwin’s Theory of Evolution was gaining support in the scientific community, there was still some doubt and even skepticism about the evolutionary origins of humans. Very few fossils of ancestral humans had been discovered in the 19th century – only a handful of Neanderthal skulls had been found, and at the time there was no clear indication that Neanderthals were even related to humans. However beginning in the 20th century, fossil sites in central Africa and China began to turn up remains of hominids that were clear indications of human ancestry. Fossils of ape-like human ancestors such as Homo erectus and Homo habilis began to shed light on the common ancestry of humans and other apes. They also helped to develop theories of the origins of modern origins such as the Out-of-Africa model, which suggests that modern humans first developed in Africa and then spread outwards to all currently settled continents in one or more waves of migration.
Other fossil discoveries have revealed the evolutionary origins of many other living species from extinct ancestors as well. Over the past century or more, fossils have been found that demonstrate the evolutionary progression of horses from smaller, five-toed ancestors; of whales from land-walking mammalian ancestors; and even of land-walking animals from water-swimming ancestors.
The discovery of tiktaalik in 2004 was an especially important discovery. This extinct tetrapod, which lived about 380 million years ago, is of particular interest because it represents the evolution of water-based fishlike animals which evolved the ability to move on the land, eventually leading to tetrapod descendants that lived entirely on land. This find was also quite remarkable because of how it was found. Using information from other disciplines such as geology and geomorphology, the paleontologists who found tiktaalik determined the most likely location to find an ancestral link between fish and tetrapods. Based on what they knew about such a species (that it would have lived in a swampy area between 350-400 million years ago), they knew exactly what type of rock formation in which they would find such a fossil. By consulting geological maps of the earth, they determined that the best place to search for this fossil would be on Ellesmere Island in northern Canada. After 3 summers of searching, they finally found exactly what they had been looking for.
This example illustrates perfectly how combining scientific knowledge from many different fields of study will continue to aid paleontologists with future discoveries. These fossil findings continue to flesh out the evolutionary tree, and in the process we will learn more and more about the processes of evolution and speciation that have resulted in the diversity of life forms we see on earth today.
Discovery of the structure of DNA
In the first half of the 20th century, it was understood that the chromosomes played a major role in the manifestation of physical traits in living things, and were also crucial in the inheritance of these traits from generation to generation. However, it was not clearly understood how the chromosomes actually worked. When Watson and Crick discovered the molecular structure of the DNA molecule, biologists were finally able to unlock the mysteries of chromosomes. It was now possible to understand exactly how traits are inherited from previous generations, how mutations which produce new traits can occur, and even to understand how life may have originated. The discovery of the structure of DNA also made possible further discoveries such as the Human Genome Project.
Human Genome Project
In 2003, The Human Genome Project announced that the entire human genome had been sequenced, which consists of about 30,000 genes. Analysis of the human genome and how the genes express themselves will allow us to further understand how certain diseases occur, and will allow us to develop better ways of treating or curing these diseases.
One of the more interesting discoveries resulting from analysis of the human genome is that all humans are genetically 99.99% similar, and that most of the genetic variation occurs within the races and not between them. This implies that there is little or no genetic basis for the separation of humans into the traditional racial groups. This also suggests that all living humans are descended from a single fairly recent common ancestor. Discoveries such as this should in the future provide common ground for better relations between all cultures, and thus allow people of all cultures to better understand themselves and others.
Further study of the human genome and comparison with our closest living ancestors, the non-human apes, will lead to a more detailed and accurate picture of how early humans evolved from ape-like ancestors.
Computers and Evolutionary Studies
Recent advances in computer technology are also leading to new discoveries in evolutionary studies, and should continue to do so in the future at an ever-increasing rate. Improvements in computer hardware and software allows for better and more sophisticated evolutionary models, which can lead to further understanding of the implications of evolutionary theory. Computers are also useful in assisting with the process of genome sequencing (Human Genome Project, for example), and with genetic analysis. Computers make it possible to do detailed analyses of genomes that would not otherwise be possible, due to the enormous amount of genetic information. The human genome, for example, contains just over 3 billion base pairs. Any attempt at identifying patterns in such a huge sample size would be an impossible task without computer algorithms. With the help of the vast processing power of modern computers, we will also be able to analyze and compare the genomes of various species, and by identifying when certain mutations occurred in certain shared genes, we will be able to reconstruct a large part of the evolutionary tree with a fair amount of accuracy.
Evolutionary Origins of Human Behavior
Recent research in the field of socio-biology has attempted to explain the origin of human behaviours such as morality and altruism. In particular, biologist Richard Dawkins has proposed the gene-centric perspective to explain how these cultural phenomena have come about due to evolutionary processes. Future research into this field promises to provide much insight into the nature of human behaviour, and this may have an impact on many other fields as well, such as psychology, medicine and perhaps even sociology or cultural relations.
As demonstrated from the above examples, many discoveries have been made recently in the field of evolutionary studies, and the impact of these findings has been profound. Entirely new fields of study have been created to investigate the implications of these discoveries, and our understanding of ourselves and of humanity’s place in nature have been greatly enhanced. In the future, these studies promise to benefit us through new medical treatments, better international relations, and more fossil discoveries.
Dawkins, Richard. The Ancestor’s Tale: A Pilgrimage to the Dawn of Life. Boston: Houghton Mifflin, 2004.
Dawkins, Richard. The Selfish Gene. Oxford University Press, 1976.
Shubin, Neil. Your Inner Fish: A Journey Into the 3.5 Billion-Year History of the Human Body. Pantheon Books, 2008.
Social Science Research Council. “Is Race ‘Real’?” http://raceandgenomics.ssrc.org/Lewontin/
Wikipedia. “History of evolutionary thought.” http://en.wikipedia.org/wiki/History_of_evolutionary_thought.
 Wikipedia, “History of evolutionary thought”, http://en.wikipedia.org/wiki/History_of_evolutionary_thought.
 Neil Shubin, Your Inner Fish: A Journey Into the 3.5 Billion-Year History of the Human Body (Pantheon Books, 2008).
 Richard Dawkins, The Ancestor’s Tale: A Pilgrimage to the Dawn of Life (Boston: Houghton Mifflin, 2004).
 Richard Dawkins, The Selfish Gene (Oxford University Press, 1976).