Chromosome 2

Human Chromosome 2 is an interesting example of evidence that suggests God used evolution to create humanity. Darrel Falk has made a series of YouTube videos that explain why he believes that Chromosome 2 is evidence for God using evolutionary processes.[1] Here I will explain the basic concepts and leave it to the reader to investigate further.

To understand this evidence, we must first understand a little bit about genetics, chromosomes, and DNA. Chromosomes are the structures that keep our DNA organized. In every cell of our bodies there are strings of 3 billion base pairs of DNA. DNA is a string of adenine (A), guanine (G), cytosine (C), and thymine (T) molecules strung together in a variety of combinations that can be represented like this:

(Click on images to enlarge)

Notice that the strings of molecules can be put together in many permutations and allow for an amazing amount of information to be stored in this format. The image shown above is a representation of one side of the DNA ladder. DNA pairs in such a way that A pairs with T and C pairs with G, so the two sides of a DNA double helix can be represented in the following way:

Chromosomes organize and constrain this DNA into discreet packages that allow the DNA to be copied, moved around, and accurately passed from one cell division to another and from one generation to the next. The ends of the chromosomes have distinct DNA structures called telomeres. In humans, the sequence of these telomeres is a number of repeats of TTAGGG and these telomeres prevent DNA from unraveling, much like the tips on the end of shoelaces prevent our shoelaces from fraying. Chromosomes have centromeric structures near the centre of the chromosomes where proteins look for specific conformations or shapes of DNA on the chromosome to grab the chromosomes and pull them in a specific direction when cell division such as mitosis or meiosis occurs (two forms of cell division in which the appropriate amount of DNA must be segregated into each cell).

Most humans have 23 pairs or a total of 46 chromosomes that look something like this when painted with fluorescent dyes:

Telomeric structures would be at the ends of each chromosome and centromeric structures would be at the darkened and pinched-in point generally toward the middle of the chromosome.

Different species of animals have different numbers of chromosomes. Here is a list of some animals and their chromosome number. I will continue to speak of the number of pairs of chromosomes in the typical animal, rather than the total number of chromosomes.

Mice have 20 pairs of chromosomes;

horses, 32 pairs;

donkeys, 31;

cows, 30;

tigers, 19;

lions, 19;

orangutans, 24;

gorillas, 24;

chimpanzees, 24;

and bonobos (pygmy chimpanzees), 24 pairs.

These last four entries represent the great apes and are especially interesting to the rest of this article and we will pursue this topic more in the next few paragraphs. But before we get there, let me remind the reader that plants also have distinct numbers of chromosomes and we could list some of those as well. The coffee plant has 22 pairs of chromosomes whereas the pineapple has 25 pairs. The number of pairs of chromosomes is one mechanism that acts as a boundary between species and prevents the crossing of one species with another. There are a few rare exceptions such as horses and donkeys in which cross-breeding is possible despite different chromosomal numbers, but for the most part, such crossings fail. This is sufficient background regarding our DNA and its packaging into chromosomes to remind us that our bodies are fearfully and wonderfully made and that there is still much to learn about how the mechanisms of genetics work.

Now we come to the interesting instance of human Chromosome 2. As noted above, humans have 23 pairs of chromosomes while the great apes have 24 pairs. If we look closely at and compare the chromosomes of humans and the great apes, a good deal of similarity is noted. G-banding patterns are a crude method of looking at the overall structure of chromosomes, but they are instructive in showing the similarities of chromosomes. Traditionally, this G-banding technique has been used to uniquely identify and arrange each of our 23 pairs of chromosomes.

Of particular note is the similarity between human chromosome 2 and ape chromosomes 12 and 13. The picture below shows the similarity in banding patterns of the human chromosome 2 compared to the banding patterns of two chimpanzee chromosomes.

What becomes immediately apparent at a crude structural level (and is further borne out in the actual DNA sequence of the chromosomes) is that human Chromosome 2 looks like a fusion of two chimp chromosomes. In fact, as we analyse the DNA sequence of human Chromosome 2, we find telomeric repetitive structures in the middle of Chromosome 2 (when they should only be at the ends of the chromosome) and a second, non-functional, centromeric structure where one would expect it would be if the chromosome resulted from a fusion event.

What this suggests is somewhere in the evolutionary development of humans, a fusion event occurred which resulted in the reduction of the number of chromosomes to 23 pairs for the humans and human-like species, while the great apes continue to have 24 pairs. The following diagram represents the phylogeny (or family-tree) with regard to this one feature (note, this diagram speaks of 46 and 48 chromosomes rather than 23 and 24 pairs). The question mark next to Neanderthals in the diagram represents the fact that, although the chromosomal number for humans and Denisovans has been experimentally confirmed, we do not presently have DNA of sufficient quality from Neanderthals to experimentally confirm that Neanderthals indeed had 23 pairs of chromosomes.[2]

[3]

Such evidence supports the idea that God used an evolutionary process to create species including the human species. It would indicate that we share a common ancestor with the great apes and that at a certain point in the evolutionary process our line diverged from the family tree of our ape cousins. It does not detract from God as creator and does offer insight into the mechanisms he used as he created.

A blog of this nature can only whet the reader’s appetite for further investigation into such topics. As previously stated, Darrel Falk’s YouTube videos may be the next place to turn for further understanding. The BioLogos website at biologos.org is always a great resource. Perhaps this blog might also open doors for respectful conversation, logical analysis, and a hunger and thirst for truth wherever it may be found. God is indeed the great creator and the mechanisms of biology are no surprise to him. We can continue to be confident that he is guiding the universe and guiding his revelation to those who seek him.

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[1] Darrel Falk series of YouTube videos regarding the human chromosome 2 fusion:

Part 1 - https://bit.ly/2JUIKeq

Part 2 - https://bit.ly/2HJbTEz

Part 3 - https://bit.ly/2HJsRCJ

[2] See “Denisovans, Humans and the Chromosome 2 Fusion” September 06, 2012, BioLogos Blog, Dennis Venema,  

https://biologos.org/blogs/dennis-venema-letters-to-the-duchess/denisovans-humans-and-the-chromosome-2-fusion

[3] The diagram is from “Denisovans, Humans and the Chromosome 2 Fusion” September 06, 2012, BioLogos Blog, Dennis Venema, https://biologos.org/blogs/dennis-venema-letters-to-the-duchess/denisovans-humans-and-the-chromosome-2-fusion