Scientists say lie on earth began with jellyfsh
Boffins have presumed for almost a century that the earliest form of animal life was a sponge because it is such a simple kind of life.
But in a paper in the journal Nature Ecology & Evolution, scientists described how they designed a new kind of genetic analysis to try to settle the question once and for all.
The researchers, from Vanderbilt and Wisconsin-Madison universities, said that previously scientists trying to work out the relationships between different animals had collected large amounts of genetic data then built a plausible family tree.
Boffins had previously thought sponges were the earliest forms of animal life
Professor Antonis Rokas, of Vanderbilt, said: “This has worked extremely well in 95 per cent of the cases, but it has led to apparently irreconcilable differences in the remaining five per cent.”
Instead, they focused on comparing genes that were shared by all the organisms.
Professor Rokas said: “The trick is to examine the gene sequences from different organisms to figure out who they identify as their closest relatives.
“When you look at a particular gene in an organism, let’s call it A, we ask if it is most closely related to its counterpart in organism B? Or to its counterpart in organism C? And by how much?”
This still involved examining hundreds or thousands of genes.
Researchers designed a new kind of genetic analysis
The results of this analysis found a so-called “phylogenetic signal” that favoured comb jellies over sponges with considerably more genes supporting the former’s claim to be the original animal.
Get Quotes on Home Insurance
The same ‘phylogenetic’ technique was used to try to find out if crocodiles are more closely related to birds or turtles.
Some 74 per cent of the shared genes backed the idea that turtles were a sister species, while birds were more like close cousins.
Our oldest ancestors were jellyfish
10 amazing facts about Jellyfish
Fri, March 10, 2017
Dive into these 10 interesting about jellyfish, you never know you might learn something new
1 of 10
A group of jellyfish is called a bloom or swarm,
However the researchers said some controversies, such as the origins of modern birds and flowering plants, may remain unsolved.
This was because a single ‘opinionated’ gene was enough to flip the results of the analysis from one species to another, suggesting evolution may have happened too quickly to leave enough of a trace in the genes.
But Professor Rokas said: “We believe that our approach can help resolve many of these long-standing controversies and raise the game of phylogenetic reconstruction to a new level.”