The earliest multicellular organisms did not have a head, legs, or arms, but their gnome remains partially within us, according to a study by the University of California, Riverside. Oceanic creatures of the Ediacaran period, 555 million years old, turned out to have genes in common with modern animals, including humans.
Well-preserved fossil records have allowed scientists to link the appearance and likely behavior of animals with genetic analysis of living things. For their analysis, the researchers looked at four animals representing over 40 recognized species that have been identified since the Ediacaran era, one of which was called Kimbirella. These creatures ranged in size from a few millimeters to nearly a meter in length.
“None of the ancient multicellular organisms had either heads or skeletons. Many of them probably looked like three-dimensional bath mats on the seabed – like round discs sticking out. These animals were so strange and so different that it is difficult to attribute them to modern categories of living organisms, just by looking at them. “Mary Droser, UCR Professor of Geology
The Kimberells were tear-shaped creatures with one wide, rounded end and one narrow end, which probably scraped the seabed with their proboscis in search of food. In addition, they could walk using a “muscular leg” like modern snails. The study included flat oval Dickinsonia with a series of raised stripes on their surface and Tribrachidium, which spent their lives immobile at the bottom of the sea.
Also analyzed were icaria – animals recently discovered by scientists. They were the size and shape of a grain of rice and represented the first Bilaterians, organisms with front and back parts and holes at both ends connected by intestines. Icarias had mouths, although they were not preserved in the fossil record, and they crawled through organic matter, eating them on the go.
All four animals were multicellular with different types of cells. Most had left and right symmetry, as well as a non-centralized nervous system and musculature. They also appear to have been able to repair damaged body parts through a process known as apoptosis. The same genes are key elements of the human immune system, which helps destroy virus-infected and precancerous cells.
These animals probably had genetic parts that were responsible for the functioning of the system that replaces the head and the senses usually found there. However, the complexity of the interactions between these genes that could cause such traits has not yet been achieved. The fact that we can say that these genes were at work in something that went extinct for half a billion years is fascinating for scientists.