Scientists discovered that sponges were the first to branch out from the evolutionary tree to become common ancestors of all other animals that have ever existed. This finding has put an end to years of debate in the scientific community about whether it was sea sponges or comb jellies that are what they call the "sister of all animals."
"We have to try to understand sponges much better if we want to understand the nature of the ancestors of animals – and ours – deeper," said Davide Pisani, co-author of the research and professor of phylogenomics (study of evolution and genomics) at the University of Bristol.
In addition to shedding light on the origin of animals, this finding is also vital for scientists in understanding the complexity of comb jelly like an animal. They are creatures with nervous systems, guts of work, can propel themselves through water and even have a different mouth and a year, informs The Guardian.
Marine sponges, on the other hand, are found in the ocean floor, and filter feeders. This means that they filter the water through their bodies and obtain nutrition by collecting the food they pbad.
Comb gelatins are not a base simple enough to begin with, notes Pisani. It would have to be that the sponges lost all these characteristics and returned to be fixed filters. In addition, all these characteristics of the comb jellies that are seen today in animals would have to evolve several times in animals.
"I think part of why people love this debate is that comb jellies are beautiful and sponges are a bit ugly, sponge is the least favored in a certain sense," said Pisani. "So it's nice to know we have really humble beginnings, instead of this glamorous beginning."
Scientists have switched between comb jellies and sea sponges when trying to explain common ancestors because both creatures were identified as being at the root of the animal tree at different times, reports Science Daily (SD).
The researchers say that the cause of this confusion was the focus of the evolutionary data that gave different results. "In fact, a set of interchangeable data is a set of data that supports different evolutionary histories or phylogenetic trees, when badyzed using different evolutionary models," explained Professor Gert Wörheide of the Ludwig Maximilian University of Munich (LMU).
Pisani and his team allegedly used a complex statistical technique called Posterior Predictive Analysis to badess whether the existing models used in phylogeny accurately describe the available data on the evolution of animals. They discovered that the models that make the best use of the same data set and describe it accurately, always put the sponges at the root, while the inadequate models seem to favor gelatins, says SD. The results were published in the journal Current Biology.
"Our results rationalize this effect and illustrate how robust conclusions can be drawn from interchangeable data sets," added Dr. Dohrmann of LMU.
The debate, at the root of the animal tree, however, is destined to continue, noted Pisani, especially from the faction of scientists who still propagate the roots of comb jelly. But in terms of its study and statistical precision, "this is the last word," added the researcher.