Evolution

Yesterday I wrote about why we have eyebrows. In explaining how early humans hunted or were being hunted, and how eyebrows aided them by diverting the sweat from their foreheads, I concluded that "nature has a way of selecting the humans who have eyebrows over the ones who don't." Which got me thinking: how does evolution, or nature as it is also often called, exactly work? As with my posts that took a deeper look at the story of Jesus (parts 1 and 2), I'll try not to rely on sources that are biased. Thank you, How Stuff Works.

There are three basic parts to evolution:

An organism's DNA can change (mutation). Mutations change the organism's offspring either immediately or several generations down the line.

There are either beneficial, harmful, or neutral mutations. If the modification is harmful then the chances of the offspring surviving decrease. If the change is beneficial then the offspring will likely do better than its ancestors. The process of gathering the good and bad mutations is called natural selection.

As natural selection occurs, new species arise. In Earth's history of a few billion years, new species, including bacteria and humans, have been formed from natural selection.
I won't bore you with all the details of reproduction and mutations; you can read all of that in the HSW article I linked above.

Three questions about this theory emerge:

1. How does evolution add information to a genome to create progressively more complicated organisms?
2. How is evolution able to bring about drastic changes so quickly?
3. How could the first living cell arise spontaneously to get evolution started?

Let's explore these.

1. How a genome is created is not yet fully explained by evolution. For example, how are new chromosomes created and how can a strand of DNA be lengthened?

One area of research as to how this can be answered focuses on transposons, or transposable elements, or jumping genes. This is a gene that has the ability to move or copy itself from one chromosome to another.

Another reason entails polyploidy. This is a process in which the total number of chromosomes can double, or a single chromosome can clone itself. Polyploidy illustrates why some plants can have a hundred chromosomes.

2. According to current fossil evidence, we evolved from a species known as Homo erectus, which appeared 2 million years ago. Its skull was about 800 or 900 cubic centimeters (CCs). Modern human brains are 1,500 CCs. So in 2 million years evolution doubled the size of the human brain. It also added 50 billion neurons (our brains right now have about 100 billion neurons). That could bring up one of these scenarios: 250,000 new neurons were added every generation; 2.5 billion new neurons every 100,000 years; 500,000 years ago there was a burst of approximately 20 closely-spaced generations that supplemented the Homo erectus brain with 2.5 billion neurons per generation; one day, 50 billion new neurons were added.

Since none of these seem realistic, and because we don't see children being born with 250,000 new neurons, the current theory of evolution still has some questions to answer. (Although, you can read this article about how minute changes in an amino acid in one gene can a have a huge impact on the speech process of humans. So small alterations in genes do have big consequences.)

3. Life obviously had to come from somewhere. Evolution states that it came spontaneously out of the inert chemicals of the earth.

Cells are very complex. They have to contain, at a bare minimum, a long list of prerequisites. Maybe the first living cells encompassed something other than DNA. At any rate, only two things can help explain life on earth: spontaneous creation in which random chemical processes created the first cell, or God created the first cell.

DNA was discovered about 50 years ago so it'll probably be a long time if we'll see any progress made in this field. Newton was the source for centuries before Einstein developed relativity. Let's just wait and see.