According to a 2012 Gallup Poll, almost half of Americans don't believe that evolution occurred. Many of them may have been misinformed about what evolution is and how it works.

Here are some myths about evolution and the facts behind them.

Myth: Evolution says that human beings are descended from apes (or monkeys).

Fact:  Creationists will argue that their ancestors weren't gorillas or chimpanzees, and they are right.

Chimpanzee at typewriter

Gorillas and chimps aren't our grandparents; they are our cousins.   Humans, gorillas, orangutans, chimpanzees and bonobos (which are closely related to chimpanzees) had a common ancestor that lived until between 11 and 16 million years ago.

Our closest relatives, chimpanzees and bonobos, shared a common ancestor with us that lived until about 6 million years ago.

Humans, gorillas, orangutans, chimpanzees and bonobos, all of which are known as "great apes", have many similarities. In addition to having similar physical features, we all live in complex social groups. We all have the ability to use language (although human language ability is much more advanced than in the other great apes.)

All great apes manufacture and use tools, and they all have culture - they pass ideas and traditions down through generations by communicating with one another. These ideas and traditions identify them as members of particular cultures. For example, different chimpanzees in different communities will use different tools to perform the same tasks. Chimpanzees often clasp hands when they groom each other. Different chimpanzee cultures have different "handshakes".

Myth:  Evolution means survival of the fittest - only the strongest survive. The weak die.

Fact:   This might be one of the main reasons why people don't accept evolution - they think it conflicts with religious and moral ideas of compassion and loving your neighbor.

Evolution, however, is not about the survival of individuals.  It is about the survival of genes.

One way to ensure that your genes survive is to make sure that you live long enough to reproduce.

Another way to ensure the survival or your genes is to make sure that your close relatives - your brothers, sisters, nieces, nephews, granddaughter and grandchildren survive.

This is where altruism comes in.

Darwin wrote about altruism and understood its importance.  He noticed that worker bees risk their lives in order to keep their hives safe. He also noticed that some animals that live in social groups will make warning calls when the whole group is in danger, even though this means that the individual who makes the call is exposing itself to predators. Darwin said that this meant that natural selection works at the family level.

Much later, when scientists understood more about genetics, Richard Dawkins explained this behavior, which is known as "kin selection", as a way of ensuring the survival of genes.

Some scientists think that the reason some people, and other animals, become homosexual is so that, instead of caring for their own children, they can help raise the children of others.  They help to ensure that their genes live on by helping to care for their nieces and nephews.

Human women may lose the ability to have children after a certain age so they can focus their time and energy on raising their grandchildren.  A 2012 study performed in Finland, which examined birth and death records for about 200 years after 1700, showed that if a mother-in-law had a child at the same time as her daughter-in-law, the risk of the daughter-in-law's child dying young increased dramatically.

Cooperating with other members of your social group helps to ensure your own survival - whether you are a prey animal giving out a warning call in order to keep your family members out of danger or you are a predator, such as a wolf, a lioness or a chimpanzee, working with other members of your group during the hunt so that you can all have enough to eat and to feed your children.

Compassion for others is part of human prehistory.  We know that Neanderthals, to whom humans are closely related, cared for their elderly and infirm.  In a cave in Iraq, archeologists found the remains of a Neanderthal man who was crippled and possibly blinded when he was young and yet managed to live to an old age. He would not have lived that long without the care of others.

Unfortunately, in the past, the idea of "survival of the fittest" has been used as an excuse to deny help to the weak and to the poor.  Darwin's theory of natural selection does not support such behavior.

Myth: Evolution involves a progression from worse to better.

Fact: This misconception comes from a common interpretation of the word "evolution" as meaning the gradual improvement of something over time.  If I said, "I am evolving as an artist," you and I would both interpret this statement as meaning, "As I continue to studying and practicing my art , my knowledge of how to produce art increases and my artwork gets better.

As living things evolve, their genes have a greater chance of survival. This does not mean that the most recently evolved creatures are the smartest, the strongest or the most morally superior.

For example, bacteria are constantly evolving in response to human beings' use of antibiotics - this is why we now have problems with antibiotic-resistant bacteria.  Because they multiply much faster than we do, these bacteria evolve much more quickly than humans do. The newest strain of bacteria is much younger than Homo sapiens is.  That doesn't mean that bacteria are "superior" to humans.

Myth: Even scientists don't agree that evolution happened. Evolution is just a theory.

Fact: This is another instance where the same word is used in two different ways. In common speech, we sometimes use the word "theory" to mean, simply, an idea.

A scientific theory is different, however.

In science, a theory is a way of explaining something that is observed in nature - such as the existence of fossils or of vestigial organs in living things.  A scientific theory must undergo rigorous testing before it is accepted as a theory. Evolution, for example, is supported by looking at how fossils are arranged in layers of sediment, by radiometric dating of fossils and by examining DNA.

Today, there is a consensus among scientists that all living things on Earth developed through the process of evolution.