Why Do You Need Immune System ?

The main reason that your body has an immune system is for your survival. Without immune system, human body is a delightful place for microorganisms such as bacteria, viruses, fungi and parasites to live. The condition of your body is really conducive for microbes bacteria to grow. Your body is warm, moist and full of nutrients, this is the perfect condition for microbes bacteria to survive and reproduce. But do not expect gratitude from those microbes bacteria you have in your body system. Most of them have no idea what happens to you. Some of them can cause illness and some can be deadly.

Immune system is organism mechanism of protection. It consisted of several biological processes that defend against disease. Immune system has the capability to notices a wide diversity of agents like viruses, bacteria, and parasitic worms. The ability to distinguish them from the organism’s own healthy cells and tissues is essential in order to function properly and not to alert false alarm reaction. Detection and recognition are complicated process. This is because microbes and bacteria which are pathogens can evolve rapidly. The process can producing adaptations that deflect the immune system and permit the pathogens to successful infect their hosts.

Microbes bacteria have been around long time before human race. Initially, all life on earth is originating from a single cell organism. Now, many of single cell organism such as bacteria and fungi remain single cell creatures. If some of these single cell microbes bacteria developed into complex multi-celled plants and animals, it was not long before some of the more developed ones who stayed behind gave up living in the hostile environment provided by the still-young earth and took up residence inside their multicellular descendents. They became parasites.

Multicellular life forms had to evolve in an environment full of smaller intruders. To do so, complex organisms had to develop complex systems to protect against invaders. And by the way, human beings are not unique to the immune system. All multicellular organisms, either plant or animal on the planet, are facing the same problems and had to evolve in some form of microbial defense system.

Microbes bacteria did not just sit back and let larger plants and animals develop defense systems which they can not penetrate and take advantage. The story of evolution of larger plants and animals is to a great extent the story of co-evolution of larger multicellular organisms with their microbial adversaries. For every defense strategy and immune response by multicellular organisms to ward off microbes, the microbes developed strategies to counter and evade them. In turn, their hosts were forced to develop new defense mechanisms or perish.

Microbes bacteria have one clear-cut advantage in this race to survive, which are the speed of reproduction. One of the dominant themes in evolution is size. As you probably know over evolutionary time, animals generally became larger. There are a lot of reasons for this, but one of the most obvious is that the bigger you are, the more likely you are to be a predator rather than someone else’s prey. Naturally, the bigger your size, the longer it takes to put you together from scratch. A bacterium, if it can stay warm and get enough to eat and drink, can reproduce itself in less than an hour. We take a dozen years or so at the very least.

The reason this is important is that evolutionary changes, in response to environmental threats like extinction, result from changes in an evolving organism’s DNA—mutations in its genes that give it a reproductive advantage over its brothers and sisters and cousins and aunts. And the major source of these mutations comes into play when DNA is reproduced during the generation of offspring.

Once a cell divides, the DNA from “parent” cell has to be imitated to produce DNA for “daughter” cells. The duplication process is fairly precise; it has to be if the offspring is going to be a viable copy of the parent. But it is not absolutely precise. Mistakes are made during copying of DNA. Nearly all of these copy errors are edited out. But the editing process is also not perfect, and in every generation a small number of changes creep into DNA—into genes. These slight variations of genes between generations provide the raw stuff of evolution and natural selection.

What does this have to do with the competition for dominance and survival, versus submission and death, between single-cell microbes and more complex organisms such as ourselves? Don’t microbes make mistakes, too?

Microbes bacteria can bring forth genetic changes that drive their evolution millions of times quicker than human beings. In this scenario, larger complex organisms like human had to develop a repertoire of tricks to keep up with the microbes’ incredible reproductive and mutational pace. Immune systems of the type we possess, which came into evolutionary existence with the vertebrates (fish, amphibians, reptiles, birds, and mammals like us), have developed a means of recognizing and destroying not only every microbe bacteria that exists in the world today, but also any microbe that might ever evolve any time in the future, whether we had seen anything like it before or not. ©