New Delhi, Jan 16: 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 revolutiory 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 origited 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 evolutiory 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 rayan 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. (IANS)