Evolution is a touchy subject. Unveil a new discovery pointing towards what triggered life on Earth and a whole contingent of evolutionists, the proponents of Intelligent design (ID) and SETI (Search for Extra-Terrestrial Intelligence), spiritualists and those who believe in one "Supreme Being" will rush to reinforce that what they say is true.But one thing becomes clear if examined from a purely scientific point of view: we are close yet still far from knowing when a single-cell organism stopped behaving like a single-cell entity and decided to explode into a multi-cellular being and - millions and millions of years later - became a well-mannered, living, breathing and thinking human beings.
The trigger this time is a fresh and revolutionary finding from the researchers at the University of Oregon in the US who have proposed that all it took was one random mutation more than 600 million years ago to start multi-cellular life on our planet.According to them, a single mutation transformed a key protein that helped our single-celled ancestor transform into an organised multi-cellular organism over a gradual course of time.An interesting fact here is that this puts the origin of life event much closer to the present at 600 million years instead of the widely held scientific consensus that life originated on earth as a single-cellular organism between 3.6 and 4 billion years ago.According to Swagat Ray, an Indian-origin scientist working as research fellow at the University of Sheffield, sporadic mutation in our genetic makeup has been the hallmark of cancer and other genetic disorders over the years."So it's not surprising that it happened in the case of an ancestral protein, which completely changed its function and helped in the advent of organised multi-cellularity," Ray told IANS.
The discovery however does not necessarily mean that this single evolution would have actually initiated multi-cellular life on earth but could be one of the many evolutionary changes or mutations that might be involved in the process.
But life had to start from somewhere at some time. What most scientists have agreed so far is that prior to the formation of life, there existed many simple chemicals in the Earth's primordial soup when it was formed."These chemicals combined to form amino acids and these amino acids then combined appropriately to form a single cell organism - the world's first which has been referred to as LUCA or last universal common ancestor," explained Narayanan Suresh, group editor at Bengaluru-based BioSpectrum that runs a website, magazine and digital media source on the bio-technology industry in India."So it is clear something must have made this two-step transformation. May be, in the next stage, scientists may be able to pinpoint the exact factors and circumstances that led to the mutation," Suresh told IANS.
The next question, according to Suresh, is to ask what factors triggered the mutation that assembled the building blocks of life from a variety of amino acids that led to the assembly of proteins necessary to form the first life.For the new discovery, the US team looked at choanoflagellates -- a group of free-living, single-celled organisms considered to be the closest living relatives of animals."Choanoflagellates are ancestral eukaryotes that can live as single cells and as multi-cellular aggregates as well and are a classical model system to study the origin of multicellularity," said Nitin Sabherwal, PhD, from the faculty of life sciences at the University of Manchester."Evolution of this novel protein through this single mutation just triggered one key aspect of multi-cellularity which was spindle orientation," Sabharwal told IANS.
In spindle orientation, a cell orients its spindle at the time of cell division in a particular way and how this spindle is oriented dictates the outcome of that division.Spindle orientation is one important aspect of multi-cellular life and there are many others such as cell adhesion, cell-cell communication and cell-extracellular matrix (cell exterior) communication and all these feed into spindle orientation.The discovery has also implications in future cancer research."It is true that cancer cells acquire various mechanisms that can help them sustain on their own like glycolysis, angiogenesis and secretion of autocrine or paracrine growth hormones, etc. But none of the mechanism is self regulated thus can be considered primitive in nature," elaborated Dr. Amit Verma, consultant (molecular oncology and cancer geneticist) at Max Hospitals in the capital."It can be inferred that cancer cell does go a step backward in the evolutionary clock but does not reach the nadir behaving like a single cell organism," Verma told IANS.
Coming back to science, was famous naturalist Charles Darwin's theory of evolution right? Was he right in proposing that humans evolved from non-human life as the result of a natural process?For Suresh, Darwin's "Theory of Evolution" has stood the test of time and "any new theory on evolution of life adds to the body of knowledge and Darwin's theory may not be fundamentally wrong."This is what Kenneth Miller, a biologist at the University of Colorado, wrote in a Live Science report recently: "Evolution is not opposed to religion unless people make it so. The message of evolution is that we are just as Genesis told us, we are made out of the dust of the Earth and that we are united in this web of life with every other living creature on the planet, and I think that's a fairly grand notion.While scientists the world over feel elated at the new discovery and are busy analysing its impact on evolution, it is time for the ID or SETI proponents to join the debate and let it "spindle" and "evolve" into a new sphere. Evolution, after all, is a touchy subject, you know!