Why we have tonsils is an excellent question which has not been adequately answered by the medical community. This is not for lack of trying or research. Theoretically, they should promote better health, but for some, this is not always the case.
Tonsils are the two bumps or rounds of tissue located in the back of the throat, and are made up of what is called lymphoid tissue. Lymphoid tissue produces lymphocytes — white blood cells that help fight infections. Traditionally, doctors would consider the production of lymphocytes a good thing, since it would seem to help people fight off illness with greater ease.
Medical experts summarize that tonsils may have once been more useful than they are now, and they may be more effective against certain kinds of infections — for example, infections by parasitic agents. Yet especially in children, this tissue can’t handle the barrage of viral exposures common in suburban and urban life. Instead of helping the body fight infection, tonsils can swell and begin to obstruct breathing. Alternately, some children appear to have chronic infections as a result of trying to fight off illnesses.
From the beginning of the 20th century through the 1960s, doctors simply removed tonsils that appeared enlarged. It was almost standard for most children to have them removed in a procedure called a tonsillectomy. This led to a backlash of concern about whether the surgery was necessary, resulting in a reduction in operations from the 1970s onward.
After 20 years of not routinely performing tonsillectomies, doctors began to find that children with chronically infected tonsils had some recurring problems. The tissue's impact on breathing was especially interesting. Some studies looked at how children who snored were often classed as having behavioral problems in school or considered ADHD. When tonsils were removed, these children generally slept better and many of them behaved better in school and clearly were not ADHD.
These studies suggested that by not performing tonsillectomies, doctors were actually doing a disservice to some children who truly would benefit from the procedure. Tonsillectomies have become a more acceptable procedure, especially for those children with chronically enlarged tonsils. In most cases, removal of the tissue benefit the health of children instead of making them more susceptible to illness.
This suggests that some children really don’t need tonsils, and that they are perhaps a “leftover” evolutionary enhancement that is not practical to modern day. Children with tonsillectomies generally have fewer instead of more illnesses. Chronic tonsil infection (tonsillitis) might actually weaken the body, making children predisposed to getting more illnesses.
For other people with tonsils, they may not pose any problem. If they don’t get infected frequently, they may perhaps provide a little immunity boost in fighting off illnesses. This is actually not proven, since many other areas of the body also create lymphocytes to fight infection. From years of studying tonsils, most doctors conclude that they may be beneficial to some and detrimental to others. Therefore, we may not all need them.
Whether tonsils provide additional immunity in adulthood is also hard to determine. Research on people who still have them as opposed to those who don’t hasn’t clearly defined whether having this tissue keeps people healthier as they age. Tonsils tend shrink in size as children hit their teens, but adults can still have chronic tonsillitis and may have snoring or sleep problems when they are enlarged. Many adults who missed the “standard” tonsillectomy phase of medicine now have sought out tonsillectomies to reduce sleep problems or chronic throat infections.