Science places ctenophores among the first animals on the planet

A study published in Nature on Wednesday identified the most ancient relatives of the wide range of animals living on Earth today.

These are the ctenophores, creatures that resemble jellyfish.

This research was led by the Monterey Bay Aquarium Research Institute (MBARI, USA), the agency said. EFE. This contrasts with another theory of evolution that suggested that evolution began with porifera, also known as sea sponges.

For this work, the experts have analyzed groups of genes that always occur together on one chromosomewhether humans, rodents, molluscs or corals, until they have verified that ctenophores are the so-called “sister group” of “all other animals,” they expose in a statement.

This finding about genetic links will help, they emphasize, to understand how key features of animal anatomy have evolved over time, such as the nervous or digestive systems.

“We have developed a new way of looking back as far as possible to the origins of animal life. We turned to genetics to go back about a billion years and obtain the clearest evidence yet for the earliest events in animal evolution,” said Darrin Schultz, an MBARI alumnus and researcher now at the University of Vienna. (Austria).

The expert reminds that all genes are organized in sequences on chromosomes, and while their location can change over time, changes in the linkages between genes on a given chromosome are “rare and largely irreversible.”

So far, however, researchers have focused only on similarities in the “sequencing of individual genes” to answer questions about “relationships between older animals.”

Instead, Schultz and his team looked at links between genes on specific chromosomes, which remain intact over time.

In doing so, they identified patterns now present in a wide variety of animals, links that they traced back to the “earliest point in evolution.”

Using this data, the researchers found “strong evidence” showing that ctenophores represent “a unique lineage” whose ancestors “diverged before the common ancestor of all other animals.”

This event can be described, they specify, as “a genetic split” that took place “hundreds of millions of years” on “the path of evolution.”

“A single-celled organism, the ancestor of all animals, walked that path with its two offspring. One of them, which would become today’s ctenophores, took a path and as it evolved, the genes on its chromosomes remained in a specific order and underwent little change.

The “other son,” on the other hand, followed the second path, until he became “sea sponges and all other animals as we know them now.”