Evolution is often misused to describe something that undergoes changes to become more complex. However, a development that may seem "backward" or losing complexity may be just as crucial as gaining complexity.
What is Regressive Evolution?
During regressive evolution, organisms may lose certain complex features and thus appear to have evolved backwards or into simpler forms. However, this evolution doesn't actually retrace back to the initial steps of evolution according to experts. It is actually just as newly developed as developing something more complex. The question is, why would organisms lose complex features that should, in theory, improve their lives?
Role of Natural Selection and "Survival of the Fittest"
Ultimately, it all comes down to natural selection which occurs due to "Survival of the Fittest". Natural selection is the process of organisms adapting and changing as time progresses. Natural Selection generally lets organisms with preferred features for survival in said environment thrive and pass down those traits to offspring. Survival of the fittest is what allows natural selection to occur. This concept explains how the organisms with the most ideal traits will survive since they are better suited to the environment while the less "fit" will die, unable to pass on those traits, allowing for evolution to occur. Thus, as the environment changes, traits needed for survival change as well, indicating regressive evolution isn't bad as long as it doesn't inhibit survival.
Losing features that aren't required to survive can actually sustain the life of certain organisms. For example, losing features that aren't needed can save energy as it isn't being wasted on a redundant process and is instead used for something necessary for survival. Losing one feature may be to make room for another, a potentially more crucial feature for survival as well. Penguins are a great example of how survival depends on losing an ability.
Penguins, The Birds Who Can't Fly
Take penguins for example. Many believe penguins are an example of regressive evolution as they have lost the ability to fly despite being birds. This is an example of losing a complex ability or characteristic. However, the loss of this ability is actually advantageous to penguins in terms of surviving the cold climate. The storage of fat is what inhibits the penguin's ability to fly however they evolved to store the fat out of survival. This is an example of how natural selection prioritizes survival over anything else.
Ultimately, losing a feature or progressing "backwards" may sound detrimental to the organism but losing it can be the difference between survival, or extinction.
Written by: Samiha Ahsan
Citations (APA)
M. (2019, January 25). Can Species Evolve Backwards? The Strange Science of 'Devolution' : ScienceAlert. ScienceAlert. https://www.sciencealert.com/what-happens-when-species-evolve-backwards-the-strange-science-of-devolution
Dhar, M. (2023, January 15). Does evolution ever go backward? livescience.com. https://www.livescience.com/regressive-backward-evolution
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