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Is evolution real?
Question Date: 2005-01-18
Answer 1:

Okay, this is going to be a long answer. You might want to read a paragraph at a time, think about it, and think about how *you* would interpret the evidence scientifically. Remember that science can only test things that obey natural laws.

People all over the world have different stories about where we came from. Almost all of these stories contain some supernatural force such as one or more gods or spirits. Science can not be used to test whether any of these stories is right, or even which supernatural story is the best. Any explanation that is scientific has to explain what we see without using any supernatural explanations. This doesn't mean anyone else's story is wrong, it just isn't science.

Scientists know we didn't actually evolve from modern monkeys, but the evidence we have suggests that we have the same ancestor that they do. There are several lines of evidence that lead scientists to believe that all forms of life evolved from only one or a few forms that first existed about 4 billion years ago. One line of evidence is fossils.

What is a fossil?In the deeper layers of the Earth's crust we find no fossils. Then we find fossils of simple organisms in younger layers. As we go up higher in the rocks, we start finding larger, more complex organisms along with the simple ones. Sometimes we see fossils that look like a step between older fossils and newer ones. As we travel through time (up the layers of rock), we also see some kinds of fossils disappear. These types of plants and animals probably went extinct.

The first primates appeared in the fossil record about 70 million years ago. (What is a primate?) In rocks that are about 3 million years old, the first human-like fossil skeletons were found. They aren't exactly like ours. They are smaller, and their brains would have been rather small compared to ours. They had large canine teeth. In even younger rocks, there are skulls that are larger and had bigger brains. Some of these lines went extinct.

The first skeletons that look like us appear in rocks that are about 200,000 years old.

A second line of evidence comes from looking at the bodies of modern animals. If we look at any primate, we will find exactly the same bones, even in primates that spend all of their time in the trees. We have many other similarities, some you can see on the outside, some are internal, and some are biochemical. We can use a variety of tests to see them. For example, if you compare DNA (what is DNA?), you will find that about 98% of our DNA code is just like that of chimpanzees. The other 2% is what makes us different from them.

Anther kind of evidence is developmental. If we study vertebrates (things with backbones and skulls) as they change before birth (or hatching) we see that at the earliest stage, all look the same. Months before we were born, all of us had gill slits and tails. These things disappeared as we developed inside our mothers. This suggests that our ancestors had a use for these things, even though we don't need them now. Our development is not an exact record of our evolution, but it can give us clues.

Another bit of evidence is found in "useless" structures on living adult animals. For example, some species of snakes and whales have pelvic and leg bones even though they do not now have legs that are visible. These bones do not 'do' anything, so it seems likely that they're 'leftovers' from ancestors that had legs. Our own small fang-like canines don't have any obvious use, but could be a leftover from the early primates. Another such structure is the appendix, which is a "dead end" off your large intestine. In many animals this is a large structure that is used to help digest plants (the cecum). In us it is not only useless, it is dangerous. Many people die from appendicitis.

That is a brief look at the facts that led scientists to come up with an evolutionary explanation for where we came from. While there are many stories of human origin that include supernatural forces, this is currently the only scientific one.

Answer 2:

Yes evolution is real. When Darwin, Wallace, Lamarck and others came up with ideas of evolution in the 19th century, it was based on observation of fossils, of plants and animals in different parts of the world, of the nature of beaks in birds ... In effect, evidence for evolution from a number of different sciences that all tied together nicely. An then experiments by Mendel on pea plants confirmed the notion of inheritance, and today we know that inheritance is through something called genes. In the more recent past, it has become rather easy to directly make lab tests on evolution in viruses, since viruses can mutate (change their genetic characteristics) very quickly and these mutations are carried down the generations, one can actually observe evolution taking place in the time scale of 5-10 years.

Answer 3:

What do we mean by "Evolution" in modern conversation? It derives from the Latin "evolutio", an unrolling. In common usage it is taken to mean three separate things:
1. Change over time - The succession of unique life assemblages as seen in the fossil record, or the development of drug-resistant microbes or pesticide-resistant insects within our own lifetimes.
2. Descent with Modification. That descendants, while most closely related to their parents, always differ from them. This is observable in the fossil record - or in breeding domesticated animals or plants. Or in the fact that, of all living organisms you are most similar to your parents... but you are still different.
3. The Theory of Natural Selection. Note that the word theory is here used in its technical sense, that is a hypothesis which has withstood repeated attempts to dis-prove it. In short, natural selection is the mechanism that explains the diversity and history of life most effectively and which has withstood nearly 150 years of scientific effort to dis-prove it.
4. Numbers 1 and 2 are "facts" that have been repeatedly observed & have withstood testing without falsification. Number 3 is a hypothesis that has withstood 145 years of testing, and is now considered.

Is evolution "real" Yes.

Answer 4:

We often hear of evolution being called a "theory." In science, the word theory means something different than it does in normal language. Scientists use the word theory to mean something that can't be proven (or can't be proven YET), but is otherwise accepted as fact. Evolution is a theory, but in scientific terms that means that it's a fact. We say it's a fact that the Earth revolved around the sun and that everything is made of atoms, but those are theories, too!

Scientists can't prove that evolution is real only because there's no way to go back in time and watch animal populations change over thousands or millions of years. Scientists have seen animals change in the laboratory or in the field in ways that look like evolution inaction, and they have collected huge amounts of evidence that support the theory of evolution. In fact, there is no significant scientific evidence that does not support evolution, although there are religious texts that do not mention evolution. . (Remember that not mentioning evolution is different than saying evolution is not real. Those religious texts don't mention cars or muscle cells or Antarctica either, but we now know that those things are real!)

So the short answer to your question is that, yes, evolution is real.

There's an excellent story about this very topic in the November 2004 issue of National Geographic magazine if you'd like to learn more about it. Thanks for asking!

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