The first multicellular animals were more like ctenophores than sponges, a genetic study showed

The first multicellular animals on Earth were more like modern ctenophores than sponges as previously thought. This was announced by an international team of geneticists from the University of California at Berkeley.

Previously, sponges were considered descendants of the most ancient animals on Earth, since they do not have a nervous system, muscles and other tissues, which makes them look like colonies of many unicellular protozoa. However, the performed chromosomal analysis showed that the ancestors of ctenophores were the first multicellular animals.

As scientists explain, in the process of evolution of multicellular organisms, their chromosomes often changed structure, as a result of which significant parts of their genome changed position, split into parts and underwent other changes. Such shifts in the architecture of the genome are irreversible and are transmitted between generations as new species, genera, families and classes of multicellular organisms appear, which allows them to be used to reconstruct the general tree of life evolution.

The researchers deciphered and compared with each other the arrangement of chromosomes in the DNA of two primitive species of sponges, two varieties of ctenophores, one species of jellyfish and lancelets, primitive chordates, presumably similar to the ancestors of vertebrates. Scientists were interested in how the most ancient genes were located in the chromosomes of these six primitive inhabitants of the seas and how similar they were to each other in this respect.

Calculations show that the ancestors of ctenophores and other animals of the Earth separated approximately 600-700 million years ago as a result of a large-scale rearrangement of the genome, which affected virtually all chromosomes. This resulted in the common ancestor of all sponges and other invertebrates, whose subsequent evolution during the Cambrian era eventually led to the appearance of all currently existing types of multicellular living beings.

“This is a very important discovery that will help us better understand how life evolved on Earth,” said Professor Daniel Rokhsar.

It should be noted that this is not the first study that changes the idea of the antiquity of animals. Previously, scientists had already concluded that the most ancient animals on Earth were not sponges, but multicellular creatures with a nervous system.

“Each new stage of research leads to new discoveries and a change in our understanding of the past. This shows that science is always moving forward and does not stand still,” says evolutionary biologist John Smith.

As the proverb says, “truth is born in a dispute.” It is disputes and discussions that help scientists expand knowledge about the past and present of life on Earth.

A study by geneticists from the University of California at Berkeley showed that the first multicellular animals on Earth were the ancestors of modern ctenophores, and not sponges, as previously thought. This discovery will help scientists better understand the evolution of life on Earth.

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