Cambiar a Español


Endosymbiotic Theory: How Nature Steals Genes To Evolve

Por: María Isabel3 de septiembre de 2021

The endosymbiotic theory bases the evolution of beings on 'stealing' innovations from other organisms instead of building them.

How we came to be what we are today remains an incomplete puzzle. Despite the advancement of human knowledge and the growing area of genomic research, we are still standing on a puzzle with missing pieces. The endosymbiotic theory first emerged as a fallacy for biology; however, with the advancement of technology, we now know that evolution is based on 'stealing' innovation in a good way.

New configurations in the name of evolution

Perhaps when we think of the concept of innovation, the technology developed by man immediately comes to mind. But innovation also exists in nature; in fact, it is thanks to it that we evolve. However, it is how we obtain these innovations that raise doubts. It was thought that organisms built from scratch the biological devices needed to adapt to new environments. However, this changed in 1960, when Lynn Margulis, then a graduate student at the University of California-Berkeley, postulated a theory that caused a minor earthquake in the scientific community.

When we think of what humanity has achieved in terms of modernity, it becomes obvious that it all lies in the evolution of technologies. If we think of a car, we can first imagine the complex machinery and the combustion system to generate energy from fuel and achieve movement. But the most elementary mechanism of an automobile is based on the wheel, which emerged millennia ago. Thus, in one way or another, the implementation of established elements has led to the evolution of transportation from the ancient Mesopotamian chariots to the electric cars of today.

Endosymbiotic theory

Margulis used this same logic when she began to analyze the cellular diversity of living beings, and from these studies, the endosymbiotic theory came by. At first, her research did not receive good criticism from her colleagues, who did not take it seriously. But this did not make her give up, and she kept examining the cells that form the bodies of animals and plants.

These cells possess a structural complexity that bacteria do not. Cells of complex life have a nucleus in which the genome resides, and around it, there are a series of small organs called organelles that perform different functions. The most outstanding are those that provide energy to the cell. In the case of plant cells, chloroplasts contain chlorophyll. These carry out the photosynthetic reactions necessary to transform sunlight into energy. In animal cells, there are the mitochondria that feed their cell from oxygen and sugars.

A borrowed cell

After analyzing the cells, Margulis noticed something that caught her attention: each of these organelles seemed to have its own membrane. From her perspective, it was as if he was looking at smaller cells composing a more complex one. Suddenly she understood that she had seen these same similar structures in other organisms, namely bacteria. Thus, his endosymbiotic theory emerged. In plain words, it explains how organisms tend to steal innovation from other beings instead of building it from scratch.

Chloroplasts were originally a species of cyanobacteria, which later, over millions of years, ended up being incorporated into another cell and provided its services. And although Margulis' theory was not well received, later, with technological progress, it was proven that neither mitochondria nor chloroplasts were genetically related to the DNA of their own nuclei. Therefore, they must have come from somewhere else, and therefore, the endosymbiotic theory turned out to be true.

To think that we are formed from the cellular basis of bacteria and other organisms is extremely surprising. Our immune system, for example, probably came from a virus that infected a vertebrate 450 million years ago. In the end, our evolution is made up of little thefts or borrowings from microscopic beings to adapt to new environments.

Text courtesy of Ecoosfera

Translated by María Isabel Carrasco Cara Chards

Cover photo: Carol & Mike Werner/Visuals Unlimited, Inc/Science Photo Library

Recomendados: Enlaces promovidos por Taboola: