The Evolution Debate

Another subfield of biological anthropology that I’ve worked in is palaeoanthropology. Which, very simply, is the study of human evolution.

And one of the most frustrating things I’ve experienced as an anthropologist is not evolution denial, but the very clear inability of people who do believe in evolution to give good answers to the questions put to them by those evolution deniers. I’ve seen Bill Maher laugh off a question posed by Michelle Bachmann about evolution, not because it was too ridiculous to acknowledge but because he didn’t know the answer.  Even people like Bill Nye have trouble articulating answers in an accessible way.  

Evolution has become a dirty word.  Most people who aren’t convinced by evolution have no problem believing in other things that are dependent on evolution. 

If you believe in the flu vaccine, you believe in evolution.

If you believe in DNA, you believe in evolution.

And if you believe that the rhinoceros is almost extinct, then you also believe in evolution. 

I’ll explain.

We know that animals don’t just go extinct for no reason, something always happens to drive that animal to extinction — like drought or overhunting. Another term for that something is pressure. So the pressure for the rhino in this hypothetical scenario could be poachers who take their horns.

We also know that while some animals are on the verge of extinction, other animals are not. This means some animals aren’t affected by this particular pressure like the rhinos. If poachers don’t bother with hippos because they don’t have horns, hippos will last longer than rhinos. 

Recap: some animals can survive more easily in an environment than others.

Most people can accept this, so let’s continue.  

If a rhino was born without a horn, poachers would have no interest in it and leave it alone. Then that rhino could go off and have hornless babies which the poachers would have no interest in either.  Now suddenly, you have a bunch of hornless rhinos happily hanging around while the rhinos with horns dwindle.  

There you go. That’s it. This is all that Darwin was describing (except with birds) and it’s called selection. 

An animal is born with a mutation, like a bird with a strange beak or a rhino without a horn. When this mutation is useful, like it makes it easier to find food or it makes you unattractive to poachers, then that animal can live longer and have more babies who then might also have this mutation.  These useful mutations are called adaptations. 

And there are different types of selection. When the pressure is environmental, we call it natural selection. When humans breed plants or animals for certain traits, it’s called artificial selection. 

Darwin had no sense of how these mutations happened or were passed on, but we do!  When we discovered DNA, everything really fell into place.  We could see that all of our traits were written in our genetics and could be passed down to our children.

The most stunning example of this selection process can be seen (yes actually seen!) when tracking antibiotic resistant bacteria. Please go watch this clip.  

The antibiotic is the pressure, like the poacher to the rhino, and we can see where and when the bacteria mutate, like the hornless rhino.  Flu vaccines get updated every year because the virus adapts very quickly, much in the same way the E. coli adapts in this video.  

Now how does all of this translate to the bigger picture? 

The more rhino babies born without horns, and the more poachers kill rhinos with horns, the more likely it becomes for hornless rhinos to end up mating with other hornless rhinos, as they survive better. If we were to fast forward a million years, the hornless gene could become so separated from the horn gene that if a hornless rhino were to come across a horned rhino and mate, they either would have a sterile baby or no baby at all.  This is called speciation.

These new species will face other pressures, adapt, and maybe speciate again! And this goes on and on and on until the world ends. Which is why we have such a wonderfully diverse world.  All it would take to create the world we see today is one microbe in the right conditions and time. Reproduction, mutation, and adaptation have been happening every single second of every single day for millions and millions of years.

Some common questions/statements I’ve encountered:

Michelle Bachman’s question mentioned above was ‘why are there still monkeys if humans evolved from them?’ 

Good question, Michelle! The monkeys we evolved from existed millions and millions of years ago. We did not evolve from current species of monkey.  We are evolutionary cousins, if you will, with current monkeys because we share what’s called a common ancestor. Say there was another rhino who was born with a mutation that gave it camouflage to hide from poachers. Then it went through the same selection process as the hornless rhino to become its own species.  The hornless rhino and this camouflage rhino would share a common ancestor.   

Another common question is ‘where is the missing link?’ 

Well get ready to have your mind blown.  There is no missing link and there has never been.  We have found numerous remains of our evolutionary ancestors! Each species we’ve identified has multiple samples associated with it.  Before Darwin was even on the scene, neanderthal remains had been discovered!  So never from the inception of evolution as a concept has there been a missing link.

A common misconception is that ‘Lucy,’ the Australopithecus afarensis skeleton from Ethiopia, is the only sample we have. This could not be less true. Lucy is just one great example of many from that particular species.

‘Link’ is also an inappropriate word.  As you can see from the antibiotic resistant bacteria, evolution happens in many places at once. Instead of thinking about evolution as a line, we like to use the phrase rivers and tributaries.  And you can quite literally see what we mean by that as you watch the video.

‘Evolution is just a theory!’  

The word theory has a different definition in the scientific community. A theory is a scientific explanation that is supported by all existing evidence and continues to be supported by new research.  Decrying evolution as ‘just a theory’ is equivalent to saying you don’t believe in gravity because general relativity is ‘just a theory.’

‘I believe in adaptation but not evolution.’

They are literally the same thing.

 

Do you have any questions about evolution? Have you ever had to explain evolution to someone before?  Tell me about your experiences in the comments or on the contact page!

 

 

 

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