Researchers explain how animals evolved from single cells to a kingdom so diverse

How animals evolved from single-celled life has been of interest to life scientists for decades. Specifically, how did the relatively simple body plan of a single cell give rise to the 40-odd distinct body plans in animals today over a few hundred millennia?A new study published in the journal Proceedings of the National Academy of Sciences sheds light on just this.Researchers have compiled features from thousands of animal groups in the study to find clues and edge closer to an answer. The result? A ‘shape space’ for animal body plans that shows similar and different features over time.Their findings about the shape space revealed that transformative changes at a fundamental level didn’t just come about in a single, epic bout of experimentation. These changes evolved consistently — in fits and starts — over the course of developmental history.This contradicts part of what was previously theorised by Darwin in his theory of evolution.“Our results are important in that they highlight the patterns and pathways in which animal body plans evolved,” Eurekalert quoted Bradley Deline, co-author of the study from the University of West Georgia, as saying.[caption id="attachment_5119821" align="alignnone" width="1280"]

Representational image. Image courtesy: Pxhere[/caption]They also found that major expansions in animal form was seen after the Cambrian era roughly 500 million years ago.The Cambrian is believed to be the main era linked to explosion in diversity of life on Earth. This explosion, the researchers report, could be a result of ecological shifts, like land exploration, at the time.Another observation that the researchers note is that intermediates in the evolution of today’s diverse animal population have been found in fossils, and rarely in living animals.“The distinctiveness of living groups is a consequence of the extinction of their evolutionary intermediates. Therefore, animals appear different because of their history rather than unpreserved jumps in anatomy,” said James Clark, co-author from Bristol's School of Earth Sciences.The data analysed by the researchers in the study include genomes, proteins and regulatory genes from living animals. The researchers found a strong link between the regulatory genes and anatomical designs, which make a strong argument for animal biodiversity being a result of how important genes were regulated at the level of an embryo.“Our study confirms the view that continued gene regulatory construction was a key to animal evolution,” Kevin Peterson, co-author of the study from Dartmouth College, said.