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Why do humans have 400 types of olfactory receptors? The secret behind this will surprise you!
Have you ever wondered why we have as many as 400 types of olfactory receptors? These tiny receptors hide many amazing scientific secrets behind our seemingly basic sense of smell. The diversity of olfactory receptors allows us to distinguish thousands of odorants, making this one of the most evolved olfactory systems in nearly all advanced organisms.
Basics and functions of olfactory receptors
Olfactory receptors, or odorant receptors, are chemoreceptors located on the cell membrane of olfactory neurons and are responsible for detecting odor molecules. Once the receptors are activated by odor molecules, they trigger nerve impulses that carry information about the smell to the brain.
Research shows that olfactory receptors constitute the largest multigene family in vertebrates, with humans having about 400 genes and mice having 1,400. This genetic diversity allows us to identify a variety of different odors.
Why so many receptors?
The reason why there are so many olfactory receptors in the genome is, on the one hand, to be able to distinguish many different odors; on the other hand, because each olfactory receptor does not only correspond to one odor, Instead, it modulates for a range of similar odor structures. This means that even though we have a relatively small number of olfactory receptors, we are relatively flexible in adapting to various odors in the environment.
The evolution of the sense of smell
The gene family of olfactory receptors has evolved over many generations, with gene duplication and switching playing a key role. According to the latest research, the olfactory receptor genes involved may undergo functional adjustments through gene expansion or decline. The consequence of this evolution is that olfactory receptor genes with new functions are established, while others may degenerate into what are termed "pseudogenes."
The diversity of olfactory receptor gene families in all mammals is extremely considerable due to the expansion of different gene encoding methods and functions. There are about 400 functional olfactory genes in humans, and the rest are considered pseudogenes.
How do olfactory receptors work?
The working mechanism of these receptors is very complex. On the one hand, they can show affinity to a wide range of odor molecules; on the other hand, a certain odor molecule may also bind to multiple types of olfactory receptors. Whenever an odorant molecule binds to a receptor, it causes a change in form and activates the olfactory G protein, which leads to a series of biochemical reactions that are ultimately transmitted to the olfactory area of the brain.
The future of olfactory receptors and human evolution
As scientists further study olfactory receptors, more will be revealed in the future about the functions of these receptors and their relationship to the ability to smell. As some scholars have pointed out so far, these functions may continue to change during evolution, affecting our ability to smell.
Research shows that in some cases, the loss of olfactory genes may not necessarily represent a reduction in the ability to smell, as can be seen in animals such as dogs. Examples of this working challenge our understanding of the connection between olfactory genes and perception.
Summary
In summary, the 400 olfactory receptor genes that humans possess are a wonderful result of our evolution, allowing us to dance in a diverse world of smells. This diversity not only sharpens our ability to detect smells, but also opens up a wealth of possibilities for scientific research. Future scientists may be able to unlock more mysteries about olfactory receptors and their evolution. Are you ready to take on the challenge?
