A Universal Code?

Richard Dawkins, probably the most well-known biologist in the world, said in his book The Greatest Show on Earth that “…the genetic code is universal, all but identical across animals, plants, fungi, bacteria, archaea and viruses.”1 (screenshot).  This echoes his earlier thoughts from his book The Blind Watchmaker where he says that “The genetic code is universal,” and that he regards this “as near-conclusive proof that all organisms are descended from a single common ancestor”2 (screenshot).

We can plausibly summarize his statements as follows:

1. If there is a universal code, then there is a single common ancestor.

On February 12th, 2011 The Science Network hosted a panel discussion entitled The Great Debate – What is Life? (link) The guests of the panel were Richard Dawkins, J. Craig Venter, Nobel laureates Sidney Altman and Leland Hartwell, Chris McKay, Paul Davies, and Lawrence Krauss.

In one of the exchanges (here) between Davies and Venter, Venter (who specializes in genetic sequencing) states that there is more than one genetic code. And that the particular code he was referring to (mycoplasmas) would not work in the human body. He went on to say to Davies that “there is not a tree of life.” And he called the tree of life an “artifact of early scientific studies that aren’t really holding up.”

Dawkins responded to Venter shortly after the exchange with this comment and question, “I’m now intrigued by Craig saying … that the tree of life is a fiction. The DNA code of all creatures that have ever been looked at is all BUT identical. Surely that means that they are all related. Doesn’t it?” Venter just chuckles, and the audience laughs.

So, just how many genetic codes are there? When I first stumbled across this information on 1/18/16 there were 18 codes. As of 5/16/18 there are 24 codes. These codes are listed on The National Center for Biotechnology Information website here.

Perhaps we can continue with the logic that these discoveries suggest.

2. There is not a universal code.

Then it would follow that, therefore,

3. There is not a single common ancestor.

This conclusion would pose a significant problem for Dawkins’ earlier suggestions as well as for the idea of LUCA (last universal common ancestor). Now of course this is provisional. Maybe some other type of evidence will come up showing that there is a single common ancestor. But as it stands right now, that hypothesis doesn’t seem to be holding up to the latest discoveries from genetic sequencing.

There’s a lot more than can be said about this topic, but I think we’ll leave it at this for now.

H/T
Jay Wile’s blog (link) is where I first discovered this information.
Evolution News (link).

 

What is Evolution?

Definitions matter.

How often have you had a discussion with someone where a misunderstanding was instantly cleared up by the words, “Oh! You meant _____! Fill in the blank with just about any concept. The point here is how the other person’s perspective was immediately understood with the clarification on what was meant. I have both had and observed this same moment of clarity regarding the topic of evolution.

Considering that the topic of evolution is so … heated, it would be good idea to get our definitions from a reputable, authoritative source. And to be clear, this will not be an illegitimate appeal to authority. There are legitimate appeals to authority. As Wesley Salmon states,

There are correct uses of authority as well as incorrect ones. It would be a sophomoric mistake to suppose that every appeal to authority is illegitimate, for the proper use of authority plays an indispensable role in the accumulation and application of knowledge. If we were to reject every appeal to authority, we would have to maintain, for example, that no one is ever justified in accepting the judgment of a medical expert concerning an illness. Instead, one would have to become a medical expert oneself, and one would face the impossible task of doing so without relying on the results of any other investigators.1 (screenshot_1 & 2)

The particular authority that is to be cited here is very prominent in the scientific community related to the topic of evolution. His name is Francisco J. Ayala (wiki). Here is the link to his faculty page at University of California, Irvine, where you can see a detailed list of his published books and his journal articles. Among his numerous awards and honorary degrees, he was also awarded the National Medal of Science in 2001. Surprisingly, few people outside of the scientific community are aware of his name.

“The theory of evolution”, as defined by Dr. Ayala, “makes statements about three different, though related, issues:

(1) The fact of evolution, that is, that organisms are related by common descent;
(2) Evolutionary history—the details of when lineages split from one another and of the changes that occurred in each lineage;
(3) The mechanisms or processes by which evolutionary change occurs.”2 (screenshot)

Further down the same page, Ayala then provides more clarity on these definitions. Regarding the first issue he says that it “is the most fundamental and the one established with utmost certainty.” It is this definition, he says, that “is implied when biologists say that evolution is a ‘fact’…”

Ayala adds that regarding “The second and third issues—seeking to ascertain evolutionary history, as well as to explain how and why evolution takes place—are matters of active scientific investigation.” (emphasis mine).

Many of the discussions I have seen and been a part of have not done a very good job of clarifying definitions. And since I started using these definitions in my discussions, it has helped prevent some of the confusion and misunderstandings. Hopefully these definitions from a very prominent biologist will help clear up some of the confusion and misunderstandings in your discussions as well.