Design Hypothesis: DNA and Dysteleology

Creationism, evolution, and the Design HypothesisDysteleology is the idea that life or nature does not show compelling evidence of design, in contrast to the Christian perception of purpose or design (teleology). Recent discoveries in DNA verify that life looks more haphazard than designed.

Let’s consider four aspects of DNA that make it look not designed.

DNA Size

Human DNA has 3.42 billion base pairs. You might imagine that humans need the most DNA since God(s) said, “Let us make man in our image,” but we’re not even at the top of the list of mammals—cows, mice, and bats have more.

And mammals don’t have as much DNA as other animals. One kind of salamander has 126 billion base pairs in its DNA. Does it really need 37 times more DNA than humans? Or is there a lot of waste?

There’s quite a bit of variability in fish DNA. The longest DNA (for the marbled lungfish) is almost 400 times the size of the smallest (the green puffer fish).

There are grasshoppers, beetles, ticks, worms, and snails that have more DNA than we do. There are plants that have more than we do—the onion, for example, has five times more. The record holder, with 400 times more DNA than humans, is a protozoa.

The wide variability in DNA size is shown in this chart:

This is a logarithmic chart of the weight, or c-value (a proxy for DNA length), of the DNA of many categories of animals. Humans are in the “mammals” category at the top.

Either DNA is all useful and length is proportionate to the complexity of the organism—and many animals are much more complex than we are—or there’s a lot of waste in DNA. That’s not a clue to a designer.

Pseudogenes

All mammals synthesize vitamin C. They produce it internally and don’t have to eat it. All mammals, that is, except a handful, such as humans. We get scurvy if we go too long without eating vitamin C.

When you look in human DNA, you find a pseudogene (a broken gene) for vitamin C production, right where most other mammals have a functioning gene. Apparently, ancestors of humans (and a few other primates) once ate a diet rich in vitamin C so that a random mutation that broke the gene didn’t convey a selective disadvantage. The pseudogene spread through the population, and here we are, with every cell carrying a useless gene.

Smell is another area where humans have a lot of pseudogenes. Of our roughly 100 odorant receptor genes, most don’t work. Many other mammals have working versions of these pseudogenes. At the other end of the scale is the dolphin, which has no working odorant receptor genes. They’re all pseudogenes.

Overall, human DNA has 20,000 pseudogenes—again, not evidence of the hand of a designer.

Endogenous Retroviruses

A virus can’t reproduce by itself and must force a cell to do it, which causes disease. Where it gets weird is when the virus infects a germ cell (egg or sperm). Then the viral DNA, usually inactivated by mutation, is passed on to succeeding generations. Becoming part of the genome is the “endogenous” part.

DNA keeps a record of these invasions. Human DNA has thousands of endogenous retroviruses, mostly just fragments, which compose 8% of our genome. One, the 5-million-year-old “Phoenix virus,” was intact enough within human DNA that it has been reconstructed.

Atavisms and Vestigial Structures

Birds don’t have teeth, but their ancestors did. In fact, the ancient genes for teeth are still present in bird DNA. Scientists have been able to tweak chicken DNA to turn on these genes and get chickens with conical, dinosaur-like teeth.

When archaic genes are switched on in nature, those are called atavisms. Snakes can have legs, dolphins can have a hind pair of limbs, and people can have tails.

Vestigial structures are those that have lost most or all of their ancestral function. Note that they’re not necessarily useless (Creationists delight in pointing out the value in the human appendix or tailbone); they’re just not used for what they were originally used for. For example, ostrich wings are vestigial because they can’t be used to fly (that’s what wings do).

Other examples are eyes in blind mole rats or cave fish, the pelvis (for nonexistent legs) in the baleen whale, and goose bumps (to raise nonexistent fur) in humans.

None of this proves that God doesn’t exist. What it does make clear is the difference between complexity, which we do see in DNA, and evidence of a careful and skillful designer, which we don’t.

Yes, evolution by descent from a common ancestor is clearly true.
If there was any lingering doubt about the evidence from the fossil record,
the study of DNA provides the strongest possible proof
of our relatedness to all other living things.
— Francis Collins, evangelical Christian and head of NIH

Photo credit: U.S. National Library of Medicine

About Bob Seidensticker
  • Nebuladancer

    “Creationists whine about the term “junk DNA,””

    Not to quibble, but my Genetics professor as well as our faculty molecular biology professor really dislike the “junk DNA” phrase too. And neither one are creationists. One of the fascinating things about this DNA we learned is that for a long time they assumed DNA was only read in one direction. Now they find it can be read the other way. So a segment of exons, separated by introns of ‘junk’ can actually be exons when read the other direction. This could of course be twisted into evidence for design, but our instructor never gave it that spin. It is just more fair to call it DNA with an undetermined purpose at this time, rather than to call it junk.
    Additionally, pseudogenes are only one portion of this DNA. Much more of it had yet to be determined function and origin. But because mutation is the mechanism for evolution, this array of odd DNA sequences is actually very valuable. It makes up the raw material for future mutation. It’s a matter of perspective. (The minimalist might think the hoarder’s collection is junk, but to the hoarder it’s stuff that might be useful later.)

    • http://www.patheos.com/blogs/crossexamined/ Bob Seidensticker

      Nebuladance: I’ve heard the term “junk” defended by noting that it’s not a synonym for “garbage.”

      A junk yard has stuff you’re not using at the moment, but when you need that front-left quarter panel from a ’58 Chevy, that “junk” suddenly looks pretty valuable. I think that parallels how this unused DNA works.

  • Denny I

    I’m a programmer. So if I took the analogy between the programming library with the human DNA then it make sense that the complexity doesn’t relate to the program length. Take a look for example .Net Framework and J2EE library which is the base library for all the Windows and Java software is much more longer and complete then upper layer component or the GUI interface. Although from user perspective the GUI is more advance in complexity but from programming perspective it’s not necessarily more complex, it just get more compact and could call some of the base library function that they need. So it does really make sense that the base DNA in protozoa are the longest once because it’s the base for all the upcoming species, contains more complete information required for the evolution to take places.

    • http://www.patheos.com/blogs/crossexamined Bob Seidensticker

      Mammals were not built starting from protozoa. Modern protozoa and modern mammals have a common ancestor long, long ago. I don’t know how long that organism’s DNA was, but I know of no reason to imagine that it was immense, like today’s protozoa.