Irish and American scientists have redrawn the Tree of Life – and settled a long running scientific dispute as well as explaining the emergence of a new species 530 million years ago.
The Irish Times reports that researchers from Ireland and the USA have finally proved that the Cambrian Explosion did occur at a time when ‘evolution on Earth went into top gear’.
Their report, published in the Science journal, states that single-celled organisms which had dominated 580 million years suddenly gave way in ‘no more than a geological heartbeat’ to a level of species complexity visible today.
Charles Darwin did note the explosion of new life forms in the mid-1800s when scientists knew of a wealth of fossils dating back to the Cambrian Explosion but then nothing.
The Irish Times report says: “The dramatic appearance of so many novel Cambrian species over such a short time also seemed to fly in the face of Darwin’s new explanation for life on Earth, a process of gradual rather than cataclysmic evolution.
“For this reason scientists have long doubted whether the Cambrian explosion was real at all.”
Maynooth-based university lecturer in bioinformatics, Dr David Pisani, collaborated with scientists from Harvard, Yale, Dartmouth and the Smithsonian Institution to settle the dispute.
Their findings have also confirmed that Darwinian evolution did hold sway despite the explosion after the researchers combined two ways of looking back through time.
The paper states that: “One involved looking at the fossil record and what it told them about when species arose.
“The second involved using genetic markers in all sorts of animals living today as a way to look backwards using something called the molecular clock.”
Dr Pisani told the Irish Times “Nature loves a good idea and once found it tends to leave it alone. This means it survives in generation after generation as a limb of the tree of life grows and branches.
“But this allows researchers to peer backwards in time as well, looking for the places where two smaller limbs join to form one. Using this method, researchers know a common ancestor of mammals and birds lived 310 million years ago.
“When the fossil record and data from the molecular clock were matched up it became clear that things were actually happening in the millions of years before the Cambrian.
“The first sponges were thought to have arisen about 700 million years ago on the basis of the molecular clock. Gradual evolution was taking place despite the lack of fossils in the record.
“Before the split between the jellyfish and vertebrates the evolutionary system was there. We had gradual evolution that allowed species to develop.
“What we showed is that it, the Cambrian explosion, is actually real but it is not in disagreement with the gradual development of evolution.”