Now, after some three billion years, the Darwinian era is over. The epoch of species competition came to an end about 10 thousand years ago when a single species, Homo sapiens, began to dominate and reorganize the planet. Since that time, cultural evolution has replaced biological evolution as the driving force of change.
Freeman Dyson -Institute for Advanced Study
It has become part of the accepted wisdom to say that the twentieth century was the century of physics and the twenty-first century will be the century of biology.
Freeman Dyson predicts that the domestication of biotechnology will dominate our lives during the next fifty years at least as much as the domestication of computers has dominated our lives during the previous fifty years.
Dyson's mentor in the field of biology, Carl Woese, professor of microbiology at the University of Illinois and the world's greatest expert in the field of microbial taxonomy is the creator of the Three Domain Hypothesis, which explored the ancestry of microbes by tracing the emergence of defined species from the pool of primitive gene-swapping cells that characterized the early history of life.
Woese and other scientists began to find evidence for a previously unknown group of prokaryotic organisms. These organisms lived in extreme environments - deep sea hydrothermal vents, "black smokers", hot springs, the Dead Sea, acid lakes, salt evaporation ponds.
Because they appeared prokaryotic, they were considered bacteria and named "archaebacteria" ('ancient' bacteria). However, it eventually became obvious from biochemical characteristics and DNA sequence analysis that there were numerous differences between these archaebacteria and other bacteria. Before long, it was realized that these archaebacteria were more closely related to the eukaryotes (including ourselves!) than to bacteria. Today, these bacteria have been renamed Archaea.
Woese’s big idea is that primitive life existed as a community of cells that freely exchanged genes. They shared a basic translation system for making proteins, but had little else in common. These cells evolved as a community and not as distinct lineages. Before Woese, the tree of life had two main branches called prokaryotes and eukaryotes, the prokaryotes composed of cells without nuclei and the eukaryotes composed of cells with nuclei.
Woese refers to this time as the “progenote era” where the word “progenote” refers to a cell that has not yet established a definite link between a stable genotype and a heritable phenotype. At some point in time, certain cells make the transition from progenote to the founders of a stable lineage. The transition point is known as the “Darwinian threshold.”
"The real mystery, however," writes Woese, "is how this incredibly simple, unsophisticated, imprecise communal progenote—cells with only ephemeral genealogical traces—evolved to become the complex, precise, integrated, individualized modern cells, which have stable genealogical records. This shift from a primitive genetic free-for-all to modern organisms must by all accounts have been one of the most profound happenings in the whole of evolutionary history. Although we do not yet understand it, the transition needs to be appropriately marked and named. “Darwinian threshold” seems appropriate: crossing that threshold means entering a new stage, where organism lineages and genealogies have meaning, where evolutionary descent is largely vertical, and where the evolutionary course can begin to be described by tree representation."
According to Woese, bacteria were the first species to emerge from the pool. From that point onwards, the evolution of bacteria was “Darwinian” and could be represented by a bifurcating tree.
Woese asks a profound question: When did Darwinian evolution begin? In his "New Biology" article in the journal Nature, Woese describes a "golden age of pre-Darwinian life, when horizontal gene transfer was universal and separate species did not yet exist."
By Darwinian evolution Woese means evolution as Darwin understood it, based on the competition for survival of non-interbreeding species. He underscores the radical observation that Darwinian evolution does not go back to the beginning of life. When Woese compared genomes of ancient lineages of living creatures, he found evidence of numerous transfers of genetic information from one lineage to another. In early times, Dyson emphasizes, horizontal gene transfer, the sharing of genes between unrelated species, was prevalent. It becomes more pronounced the further back we go in time.
"Life was then a community of cells of various kinds," Dyson points out "sharing their genetic information so that clever chemical tricks and catalytic processes invented by one creature could be inherited by all of them. Evolution was a communal affair, the whole community advancing in metabolic and reproductive efficiency as the genes of the most efficient cells were shared. Evolution could be rapid, as new chemical devices could be evolved simultaneously by cells of different kinds working in parallel and then reassembled in a single cell by horizontal gene transfer."
In the Earth's history of cell evolution, some three billion years ago, a single cell separated itself from the community and its offspring became the first species of bacteria—and the first species of any kind—"reserving their intellectual property for their own private use."
Dyson describes the next stage of cell evolution: "With their superior efficiency, the bacteria continued to prosper and to evolve separately, while the rest of the community continued its communal life. Some millions of years later, another cell separated itself from the community and became the ancestor of the archea. Some time after that, a third cell separated itself and became the ancestor of the eukaryotes. And so it went on, until nothing was left of the community and all life was divided into species."
The Darwinian interlude an interlude between two periods of horizontal gene transfer that had begun two to three billion years is over. The basic biochemical machinery of life had evolved rapidly during the few hundreds of millions of years of the pre-Darwinian era, and changed very little in the next two billion years of microbial evolution. Darwinian evolution is slow because individual species, once established, evolve very little. With rare exceptions, Freeman states, Darwinian evolution requires established species to become extinct so that new species can replace them.
The epoch of Darwinian evolution based on competition between species ended about ten thousand years ago, when a single species, Homo sapiens, began to dominate and reorganize the . Since that time, cultural evolution has replaced biological evolution as the main driving force of change.
Cultural evolution is not Darwinian. Cultures spread by horizontal transfer of ideas more than by genetic inheritance. Cultural evolution is running a thousand times faster than Darwinian evolution, taking us into a new era of cultural interdependence which we call globalization.
As with any other species, reports the New York Times, human populations are shaped by the usual forces of natural selection, like famine, disease or climate. A new force is now coming into focus. It is one with a surprising implication — that for the last 20,000 years or so, people have inadvertently been shaping their own evolution. People adapt genetically to sustained cultural changes, like new diets. And this interaction works more quickly than other selective forces, “leading some practitioners to argue that gene-culture co-evolution could be the dominant mode of human evolution,” Kevin N. Laland and colleagues wrote in the February issue of Nature Reviews Genetics. Dr. Laland is an evolutionary biologist at the University of St. Andrews in Scotland.
And now, as Homo sapiens domesticates the new biotechnology, we are reviving the ancient pre-Darwinian practice of horizontal gene transfer, moving genes easily from microbes to plants and animals, blurring the boundaries between species.
In a recent article in the New York Review of Books, Dyson sees the world as moving rapidly into the post-Darwinian era, "when species other than our own will no longer exist, and the rules of Open Source sharing will be extended from the exchange of software to the exchange of genes. Then the evolution of life will once again be communal, as it was before separate species and intellectual property were invented."
The nonliving universe is as diverse and as dynamic as the living universe, and is also dominated by patterns of organization that are not yet understood. This picture of living creatures, as patterns of organization rather than collections of molecules, applies also to sand dunes and snowflakes, thunderstorms and hurricanes.
The reductionist physics and the reductionist molecular biology of the 20th century will continue to be important in the 21st century, but they will not be dominant. The big problems, the evolution of the universe as a whole, the origin of life, the nature of human consciousness, and the evolution of the earth's climate, cannot be understood by reducing them to elementary particles and molecules. New ways of thinking and new ways of organizing large databases will be needed, Dyson adds.
The way will be open for biotechnology to move into the mainstream of economic development, to help us solve some of our urgent social problems and ameliorate the human condition all over the earth. Open Source biology could be a powerful tool, giving us access to cheap and abundant solar energy.
The shifting balance of wealth and population between villages and cities is one of the main themes of human history over the last ten thousand years. Freeman sees the shift from villages to cities coupled with a shift from two kinds of technology: green and gray.
Green technology is based on biology, gray technology on physics and chemistry. For the first five of the ten thousand years of human civilization, wealth and power belonged to villages with green technology, and for the second five thousand years wealth and power belonged to cities with gray technology.
Green technology gave birth to village communities ten thousand years ago, starting from the domestication of plants and animals, the invention of agriculture, the manufacture of textiles and cheese and wine.
Gray technology gave birth to cities and empires five thousand years later, starting from the forging of bronze and iron, the invention of wheeled vehicles and paved roads, the building of ships and war chariots, the manufacture of swords and guns and bombs. Gray technology also produced the steel plows, tractors, reapers, and processing plants that made agriculture more productive and transferred much of the resulting wealth from village-based farmers to city-based corporations.
Beginning about five hundred years ago, gray technology became increasingly dominant, as we learned to build machines that used power from wind and water and steam and electricity. In the last hundred years, wealth and power were even more heavily concentrated in cities as gray technology raced ahead. As cities became richer, rural poverty deepened.
Within a few more decades, as the continued exploring of genomes gives us better knowledge of the architecture of living creatures, we shall be able to design new species of microbes and plants according to our needs. The way will then be open for green technology to do more cheaply and more cleanly many of the things that gray technology can do, and also to do many things that gray technology has failed to do.
In his book The Sun, the Genome, and the Internet, Dyson describes a vision of green technology enriching villages, halting the migration from villages to mega cities. There are three key components of the vision: the sun to provide energy where it is needed, the genome to provide plants that can convert sunlight into chemical fuels cheaply and efficiently, the Internet to end the intellectual and economic isolation of rural populations. With all three components in place, every rural village in the world could enjoy its fair share of the blessings of civilization. People who prefer to live in cities would still be free to move from villages to cities, but they would not be compelled to move by economic necessity.
Posted by Casey Kazan.