Friday, May 29, 2009

Bad Reason #1 – You can’t see evolution happening

This is the first article in my series of 10 bad reasons to reject evolution, this post deals with the objection that "you can't see evolution happening".

Well this one is simply not true, evolution is a common occurrence, it happens all the time and affects our lives directly. The most prevalent example is that of microbes becoming resistant to drugs (for example malaria) and new types of bacteria and viruses emerging that thwart our best efforts at developing vaccines, for example the H1N1 strain of flu is a natural mutation of previously existing strains of flu.

What people often mistakenly mean by "evolution" in this context is not actually evolution in the wider sense it is a small component of it called "speciation", i.e. the changing of one species into another for example dinosaurs into birds or fish into reptiles; speciation of this kind occurs very slowly over hundreds of thousands if not millions of generations, because of this fact we will never actually witness it, so lets explore why.

Just because we can't see something doesn't mean it isn't true, in life we know this to be a generally accepted state of affairs, for example we can't see gravity or ultra violet rays, but if we fall off a building or lie in the sun too long then we can see and experience the after-effects of these things all too clearly. This is the same for evolution, after-effects like the fossil record, the distribution of animals and plants over the planet and the genetic record cannot be explained any other rational way than by accepting that evolution has happened, all of these separate things point overwhelmingly to the fact that speciation has occurred in the past and is still happening today.

So how does speciation happen? In the summer of 1995, at least 15 iguanas survived Hurricane Marilyn on a raft of uprooted trees. They rode the high seas for a month before colonizing the Caribbean island, Anguilla. These few individuals were perhaps the first of their species, Iguana iguana, to reach the island. If there were other intrepid Iguana iguana colonizers of Anguilla, they died out before humans could record their presence. As these 15 individuals reproduce and die they will gradually change, the mechanism that causes these changes is the same tiny genetic changes between generations that makes a new flu virus. Tiny changes in genes caused by mutation may lead to changes in bodies, for example a slightly longer jaw (this has actually been observed in another species of lizard that became isolated on a tropical island) or perhaps a slightly different colour, or shorter legs etc. Should any such change (say a bigger jaw) confer a survival advantage for the lizard then that individual will be more likely to pass on his genes to the next generation. Over hundreds of generations the frequency of the "bigger jaw" gene will gradually become greater in the whole population and you end up with an island full of large jawed lizards. Give this process enough time and eventually you end up with a population of lizards that are so different that a member of the remote population could no longer mate with a member of the original population of lizards, and then you have a brand new species.

This is called allotropic speciation, there are 3 other kinds.

Expecting to actually witness speciation would be like expecting to witness the precise moment that a child becomes an adult, it's not possible because it simply doesn't happen like that, there is no precise moment of change, the process is one of tiny increments (clearly for legal purposes we put an artificial "moment" in place which is normally on the 18th birthday) but we all know and accept that it is a gradual process. Speciation happens even slower than this, typically over a time scale that extends beyond many generations of human life and is therefore impossible to witness.

What is the key evidence for speciation?

-Animals marooned on tropical islands are often are very similar but not quite the same species as animals of the same kind on the mainland, the older the island the more differences there are. It's not just water that acts as a barrier between species, deserts, mountains and ice are all effective mechanisms for separating populations of animals.

-When we look at lineages of common fossils over many generations we see gradual changes, sometimes we find fossils that have characteristics of both their ancestors and what they will eventually become in the future, these special examples are called "transitional" fossils, although this is somewhat of a misnomer because every fossil is transitional, no two animals are ever identical.

-The distribution of animals over the world fits exactly with what you would expect if speciation occurred.

-The DNA in our cells contains the precise history of our species, it proves that we are related to every other living thing on the planet, the closer the animal the more similar the DNA is, for example human DNA is 98% the same as chimpanzees, even intuitively and from the fossil record we can see that we are closely related to the higher primate, the DNA confirms that we are in fact a branch of the ape family itself and that many millions of years ago there was a speciation event that separated us.

If you argue that speciation did NOT happen, then you are left with the daunting task of explaining how these things occur some other way.


Lisa said...

I've never heard this objection. I guess these people don't believe in erosion then, or plate tectonics?

Steve Borthwick said...

Lisa, exactly, the list of things not to believe in would be quite long wouldn't it.

Funnily enough the person I was chatting with was a Geology grad. and plate tectonics was the first thing I thought of, he was most indigent, "of course I believe in plate tectonics, you can see the zones of subduction and the ocean floor spreading", I challenged him asking if he'd actually seen the ocean floor spreading himself, at which point he said "of course not it happens too slowly" doh!

I really don't get why evolution is such a problem for people when they accept so many other things, it has to be something to do with religious indoctrination at an early age IMO, although people never admit it.

Anonymous said...

Adaptation is different than evolution. Origin is what is coming into question, how new data was added to a pool of single cell organisms. Mutations and adaptations do not account for how a fish could develop new genetic information to becoming a lizard. Or how a monkey would develop new information during certain weather conditions to becoming a human, philosopher, or scientist desperately trying to discover the meaning of things.

Job 38:4: where was thou when I (God) laid the foundations of the earth, declare if thou hast understanding.

Steve Borthwick said...

Anon, and knowledge derived from evidence is different from superstitious babble.