The Kinks in Evolution Options

[Call911Quick]

I've been studying AP bio at a private international high school. We've learned a little bit about evolution, and after learning about it, I realize that there are problems with the theory. Here I will show you why Evolution is credible, and why it is also not "proven fact".

***If you are already fairly familiar in detail with the theory of Evolution, skip down to my series of dotted lines.***

First of all, let me inform you about DNA. 1.5% of your DNA are genes. Genes are what code for proteins and RNA molecules (enzymes). These are the mini machines in your body that regulate everything from the distance between your eyes to the length of your toes. There are around 30,000 genes in a human cell, give or take.

So, what is the other 98.5% of your DNA? It is actually composed of many different things. Random segments of non-coding DNA, transposons, satellite DNA, etc. At any rate, all you need to know is that the rest of your DNA does absolutely NOTHING good for you.

Now, I may be exaggerating, but 99% (or somewhere around that number) of our genes are identical to a fruit fly's genes. This is one of the bases for the theory of evolution; we are so similar to primates, flies, and even sea cucumbers. We must have a common ancestor.

The theory of evolution states that over the course of 1.5 billion years (That's a REALLY LONG TIME!), single cell procaryotes eventually evolved into simple multicellular organisms composed of specialized eucaryotic cells. The first animal: sponges.

From sponges, it went to worms. Worms were the first animals to have a central nervous system, radial symmetry, and most importantly, a head. From there it's a really long story but basically we evolved over the course of 1.5 billion years. This is actually quite probable; lots can happen in such a long time.

This is my mini introduction to the theory of evolution, just to clarify some things. It may be 1% of what is actually known, because I could write a 10-page essay on this thing.

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The problem with evolution likes in your DNA.

As you all know, genetic mutations cause diseases. Genetic mutations can occur in many different ways. The most common causes are mutagens, such as x-rays, car exhaust, etc. They're chemicals that cause genetic mutation.

Another way is from viruses. AS you know, viruses insert a segment of double-stranded DNA into your cell, which integrates itself with that particular cell's DNA. This causes the cell to produce more viruses, etc.

The step in which the virus' DNA integrates itself with your human DNA is where mutations can occur. Your cell doesn't produce viruses, but maybe it grows uncontrollably and eventually develops into a malignant tumor. Viruses are a leading cause for cancer.

Secondly, and more curiously, is your own DNA is capable of mutating itself. I mentioned earlier that a part of your DNA is transposons. Approximately 15%. If you have knowledge in Latin roots, you can figure out that transposons are segments of DNA that can be cut out and re-inserted by the enzyme transposase. This has no known positive benefit, and is just a formula for genetic mutations. Another cause for cancer.

If evolution were true, why did we develop this kind of DNA? The only reason why we don't have cancer is because a cell firstly needs 13-17 mutations in order to become cancerous, and the probability of transposons affecting a gene is low, because your cell's growth cycle has two restriction points, and if something is wrong, the it will commit suicide. Your mutated cell kills itself, unless the... well, if you want to know about cancer, PM me.

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Are you curious why human cells stop metabolism? Why do we age? Why do we die? Well, part of the cause is once again, ourselves. Our cells have receptors for hormones with, basically, tell the cell to stop metabolizing. A scientist (forget her name, she's a genius tho) experimented with roundworms. She ended up being able to DOUBLE the life of a roundworm (from two weeks to four weeks) by mutating the gene that codes for said receptors on the cell. The cells are incapable of receiving the hormones, and thus don't die THAT way.

There are other ways our cells die. Our sex cells, or gametes, also have a way of causing our body to stop metabolism. I wasn't paying much attention during this part of the lecture, so I can't go into detail.

Anyway, why does this happen? If evolution were true, we'd have never developed this aging process. We strive for survival. The animals that mutated and began aging should have died, while the animals that didn't would live much longer. According to Darwin, that is.

Think on it. Sleep on it. Take some aspirin.

[sheridan_whitesi...]

Top of your head? I'm pretty sure you're getting this stuff from elsewhere in your anatomy.

However, think about it this way. A theoretical way to cure cancer is to manipulate siRNA (short interference RNA) in order to stop the uncontrolled cell division. The thing is that we don't understand how the restriction points in the cell cycle work.

Could you be a bit more clear? What are you getting at? What is this "manipulation" we could do to a piece of 25bp RNA to make cancer a thing of the past? Are you saying that we could introduce siRNAs that will hybridize with oncogenic mRNA, shutting down its translation via the Dicer RNAi pathway? The reason this isn't happening now isn't because we "don't understand the restriction points in the cell cycle." Our cell cycle checkpoints are actually pretty well elucidated. The problem lies in RNAi itself; it works well in nematodes and yeast, but not so much in mammals. It wouldn't form a good cancer treatment right now the way we have it working; it deactivates non-target sequences too much for any practial anti-cancer application.

WHY do we have genes that code for receptors on our cells that stop metabolism?

Weren't you just on about how much you knew about apoptosis? Stopping metabolism can have useful applications, like killing off cancer cells or cells which have degraded past the point of usefulness. If you want me to double your life like whats-her-face did with C. Elegans by making your telomeres infinite, we can do that. Gee, why would we ever want to stop cells from dividing indefinitely?

WHY do we have SO MUCH unused DNA? Perhaps a segment of transposable DNA can be inserted into our gene to give us mind-reading abilities (exaggeration, don't take me seriously), but 98.5%? That's too outlandish of a number.

Your 98.5% figure is based off of the fact that 1.5% of our genome is exons, sequences that code for proteins. There is a considerable amount of promoters and other regulatory regions, regions that code for useful RNAs, like ribozymes or ribosomes. These guys account for another 1.5%. Other than that, there are introns which, while not directly translated, are often regulatory motifs, i.e. there's an exon, 10kb of intron, and another exon, and if it's 9 or 11kb, the exons won't work. Introns make up a considerable portion of the genome, about 23%. These figures are not static. The human genome isn't "all figured out" yet. Every year Craig Venter and company put out a new version of the genome, each successive version has had more genes than the last, from a strictly quantitative view, i.e. kb of DNA. Qualitatively, the definition of gene has shifted and the number is more volatile. So this leaves us with the nongenic, nonregulatory DNA that still makes up over 75% of the genome. Why is it there? Again, it absorbs mutations, and the energy spent replicating it is infinitesimal enough that it doesn't pose an evolutionary disadvantage. It makes sense that we have this much non-coding DNA. The genes that code for vestigial functions, biochemical pathways, and limbs posed no evolutionary disadvantage when mutations sprung up all over them so they just drifted out of our genome and into nongenic DNA. This has happened since life on earth evolved from prokaryotes, so we've got a considerable backlog of old genes that now bear no resemblance to anything useful.

@Ersatz, people are boy or girl due to whether they have XX or XY chromosomes. In a girl, one X is turned off and becomes a barr body. Nothing is turned off in a boy. Your gender isn't determined by genes being controlled...

You are wrong. We will default to female unless the gene products from the Y chromosome, SRY in particular, go to work at regulating genes to make us male. SRY protein is a TRANSCRIPTION FACTOR. It's job is CONTROLLING GENES. If somehow I got a Y chromosome with a bad SRY gene, I'd be a girl, because there would be no SRY protein to shut off girly hormone production and girly organ development. Or maybe the SRY bit of the Y chromosome translocated into my father's X, and I got two X chromosomes, one with a functional SRY gene, I'd still be a boy, albeit one with no reproductive future. With manipulation of the SRY gene, it can be a mixed-up, muddled-up shook-up world, girls will be boys and boys will be girls.