Godlessheathen's Kids Page on Evolution, 6

Evolution 6: Kid's Page 8: Evolution of Germs

Living things evolve, including the living things that make us sick. Do you know what makes us sick? Germs that get passed from one person to another can make us sick. Germs are living things that are so small we can't see them unless we use a microscope.

Two kinds of germs are bacteria and viruses. Actually, scientists don't agree on whether or not to call a virus a living thing because it needs to live inside another living thing, a host, in order to reproduce (make more of itself). There are many different kinds of viruses some of which cause colds and flus.

There are also many different kinds of bacteria. Some bacteria is harmless and even useful to your body where many bacteria normally live. But some bacteria can cause sicknesses, many of which are usually treated with a type of medicines called antibiotics. Antibiotics do not kill viruses.

However, sometimes doctors mistakenly give antibiotics to treat a virus causing illness like a cold or flu. Because of this, antibiotics sometimes don't work on illnesses they used to be able to treat. Plea Made For Anti-biotic Research is a news article from a general news source (Infobeat) about the problems with anti-biotic resistant bacterias that ran on 12/15/98.

Here is why this happens. Earlier in this series I explained that the theory of Natural Selection states that living things that live longer (and reproduce more) will pass on more of the genes that helped them to survive. So suppose there is some bacteria and it is attacked by an antibiotic. Some of the bacteria might be stronger than other bacteria, and so the weaker bacteria would die. Some of the stronger bacteria will live, and reproduce more bacteria. The stronger bacteria will pass on it's genes for being strong to the younger bacteria. The weaker bacteria are dead, and so can't pass on the weaker genes. So the new generation of bacteria would be stronger than the older one and each generation would get stronger still. In this way, the species of bacteria evolves into much stronger bacteria. (It's actually more complicated than stronger versus weaker because a bacteria can become stronger or more resistant against one antibiotic but not another.)

The more the bacteria are exposed to the antibiotics, the more this will happen. That is why taking antibiotics for a sickness which is not caused by bacteria but by something else like a virus, is a bad idea. Bacteria may still be present even though it's not causing the illness and through Natural Selection the bacteria will evolve into new bacteria that can not be killed by that particular medicine.

Another important thing to know about antibiotics is if you do have a bacterial illness and your doctor prescribes an antibiotic you MUST take ALL the medicine. You will most likely feel better after a few days but do NOT stop taking it even if you do. Just because the symptoms go away and you don't feel sick anymore, doesn't mean that the bacteria that caused the sickness went away. It is still there and will stay there until you take all the medicine. If you stop taking it too early, you will just get sick again. Also, if you stop taking it too early, the bacteria that are left will be the stronger ones which will make more strong bacteria and a new bacteria that could make you even sicker could evolve. So always follow the directions on how to take medicine.

Another word for living things that are so small we need a microscope to see them , regardless of whether or not they make us sick, is microbe. To learn more about microbes and even see some pictures of them go off-site to The Microbe Zoo.

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