"Loss of information" in human evolution

Posted 24 January 2005 by Nick Matzke

↗ The current version of this post is on the live site: https://pandasthumb.org/archives/2005/01/loss-of-informa.html

Creationists often dismiss examples of evolutionary change as “that’s just a loss of information.” There are many problems with this claim (see also here and here), but here is a new one: it appears that in at least one case, humans evolved by “loss of information” (in this case, loss of a gene) from their apelike ancestors. Carl Zimmer mentions this in passing in a post on the cell-surface sugars, Neu5Ac and Neu5Gc:

Ajit Varki of UCSD led the research that established that Neu5GC is missing from humans. He decided to figure out how it disappeared. Other mammals make Neu5Gc by tinkering with Neu5Ac. The enzyme that does the actual tinkering is known as CMAH. This enzyme is pretty much identical in mammals ranging from chimpanzees to pigs. In humans, Varki and his colleagues discovered, the gene for CMAH is broken. It produces a stunted version of the enzyme which can’t manufacture Neu5Gc, and so our cells end up with none of these sugars on their surfaces.

The CMAH gene is broken the same way in every person that has been studied. That strongly suggests that all living humans inherited the mutation from a common ancestor. Since chimpanzees, our closest living relatives, have a working version of the gene, that ancestor must have lived less than six million years ago. Scientists can even say exactly how the gene mutated. A parasitic stretch of DNA known as an Alu element produced a copy of itself which got randomly inserted in the middle of the CMAH gene.

(Carl Zimmer, "Of Stem Cells and Neanderthals")

25 Comments

steve · 24 January 2005

Was it in that Chick tract, the line "But isn't losing something the opposite of evolution?"

Priceless.

btw

http://msnbc.msn.com/id/6859930/

Wayne Francis · 24 January 2005

Sadly its people like DaveScot and Behe that think all the genetic information was in the first life and its just slowly been lost over the last 3 billion years.

I'd agree with that only in that the first life, that we might recognise, had all the information needed for all life as we know it. It had adenine/thymine-uracil and guanine/cytosine. Recombine those and you can reproduce all the life forms we currently know about.

Chewie · 24 January 2005

There's a nice article by Richard Dawkins on this very issue, included in his book A Devil's Chaplain:

"The Information Challenge", http://www.skeptics.com.au/journal/dawkins1.htm

Steve Reuland · 24 January 2005

So does anyone want to claim that this Alu element, which is acting to disrupt a gene, isn't an example of "junk DNA"?

ruidh · 24 January 2005

DI hypothesis: Alu is God.

Matt Inlay · 24 January 2005

One could use that same logic to argue that Michaelangelo's David, carved from a slab of rock, represents a loss of information.

Joe P Guy · 24 January 2005

Matt Inlay's ironic comment is dead on.

I often work with 3D computer imaging. A cube (the slab of rock) has only eight major points of information: the eight vertices of the cube, along with the data determining how they relate to each other. This takes up next to no space on your hard drive. On the other hand, if you were to make a model of Michelangelo's David in Maya, that's a lot of vertices, not to mention bezier points and curves, to accommodate all of the detail and "natural" topography; that takes up an extraordinary amount of space on your hard drive.

The IDists can't seem to understand that material != information (because we humans tend to think of things, including information, in terms of "size" rather than "scope").

coturnix · 24 January 2005

There's a new one on loss of information:
http://dx.doi.org/10.1371/journal.pbio.0030042
and it is not just a loss of one molecule but a more generalized relaxed selection on 5' end, i.e., in regulatory domains in many genes. Can someone explain this in more detail?

Jari Anttila · 25 January 2005

I guess a sufficient reply to this "just a loss of information" -claim is:
"Maybe. But it's still an evolutionary change".

It's somewhat strange that this and other similar claims have become so common nowadays, because for most evolution-deniers it is quite irrelevant whether they descended from apes by losing or by gaining something.

The creationists like also to emphasize the distinction between micro- and macroevolution; claiming that the latter requires completely new structures and organs to evolve. Apparently everything else is just "microevolution", which they can safely allow to happen, because they think it's not a sufficient process for common descent.

But in human evolution it seems to be.
According to standard creationist definitions we have microevolved from apes.

Steve Reuland · 25 January 2005

If you are a creationist, then you cannot believe the results presented in the paper referred to by coturnix. The methodology requires assuming that common descent is true.

Modesitt · 25 January 2005

It's somewhat strange that this and other similar claims have become so common nowadays, because for most evolution-deniers it is quite irrelevant whether they descended from apes by losing or by gaining something.

To a degree, it does matter. A fairly fundamental tenent of some biblical interpretations is that it's all down hill after the Fall. It's why Adam lived to be 900 and the rest of us have no chance of that. We're all continuously degenerating, thus it's impossible for anything to evolve. Even if the bible didn't have the idea of God creating all life or the Earth being young in it, really hardline Christians would probably still attack evolution for being at odds with the idea of humanity being in a continuous state of degeneration. Following their logic, we could not have evolved from apes because obviously Apes < Humans(I've never seen a creationist suggest apes evolved from humans, although I'm sure at least one has made the argument that apes and humans are within the same kind and obviously apes are degenerate humans condemned by God). You can see this theme of degeneration in a lot of creationist arguments against evolution. The classic is "The 2nd law of thermodynamics proves evolution wrong". There's a reason you see it so often and it's not just because Dr. Dino is a workaholic. The reason is that it appeals to their belief that the universe is in continual decay since The Fall. They view it as "See, science agrees with the bible. We can't be evolving! We can only devolve!" You can certainly think of some others, like the old "It's been downhill since Darwin" or their disputes with the idea of fitness.

Great White Wonder · 25 January 2005

(I've never seen a creationist suggest apes evolved from humans, although I'm sure at least one has made the argument that apes and humans are within the same kind and obviously apes are degenerate humans condemned by God).

According to the Popol Vuh (a creation mythology I find vastly preferable to the boring one in the Bible), monkeys arose from a first generation of men created out of wood who were punished for refusing to honor their Creator aka Heart of Sky aka Huracan.

The desperate ones [the men of wood] ran as quickly as they could; they wanted to climb to the tops of the houses, and the houses fell down and threw them to the ground; they wanted to climb to the treetops, and the trees cast them far away; they wanted to enter the caverns, and the caverns repelled them. So was the ruin of the men who had been created and formed, the men made to be destroyed and annihilated; the mouths and faces of all of them were mangled. And it is said that their descendants are the monkeys which now live in the forests; these are all that remain of them because their flesh was made only of wood by the Creator and the Maker. And therefore the monkey looks like man, and is an example of a generation of men which were created and made but were only wooden figures.

Good stuff and, lest it be falsely claimed that I never said anything nice about Christians, we owe its earliest written transcription to a Dominican, Father Francisco Ximénez. http://www.earth-history.com/America/popvuh-preface.htm

EmmaPeel · 25 January 2005

One could use that same logic to argue that Michaelangelo's David, carved from a slab of rock, represents a loss of information.

LOL, good one! Anyway, granted that the first living organism had to have had a very small genome and very few genes (or some equivalent), there has indeed been a net increase of complexity or information - loosely defined. But have creationists (or evolutionists, for that matter) ever come up with an actual metric for talking about the quantity of information that makes sense in a biological sense? Or are all such debates going to necessarily be mired in a quagmire of ill-defined basic terms?

Don T. Know · 25 January 2005

A fairly fundamental tenent of some biblical interpretations is that it's all down hill after the Fall. It's why Adam lived to be 900 and the rest of us have no chance of that. We're all continuously degenerating, thus it's impossible for anything to evolve.

Yet, we are living longer today than we did fifty years ago. Of course, some would argue that increased longevity is "not natural." That it is human intervention that has made us live longer than the "continuous degeneration" would have allowed. Which means humanity has managed to overcome (if only partially) the consequences of the awful deed Adam and Eve committed in the Garden. Makes you wonder where we would be if biblical literalists were in charge of medical research.

thetruerobo · 25 January 2005

Heres a question, it requires a simple yes or no answer, no explanations. Above people have said that Michaelangelo's David, carved from a slab of rock, represents a loss of information. Is it true that Michaelangelo's David can never return to be the rock that it came from. Yes or no?

dog training information · 25 January 2005

Find out more about dog training information from http://www.dogtraining.mypetdogs.com

Ed Darrell · 26 January 2005

Do you really think truerobo needs more dog training?

Dr Yak · 26 January 2005

For a comentary on the paper on the degeneration of human regulatory regions (which was a very nice paper btw) see:
http://www.plosbiology.org/plosonline/?request=get-document&doi=10.1371/journal.pbio.0030073

On a vaguely related not a new study in this month's Genome Biology on a group of freeliving oceanic photosynthetic microorganisms shows that certain of the group members are shedding genomic information and genes and evolving at an accelerated rate (from ~2300 genes to ~1700). Quite an impressive "loss of information" for one of the most common (and important) organisms in the oceanic ecosystem.
http://genomebiology.com/2005/6/2/R14

What is the obssetion with "loss of information" anyway. Genes that are not useful in an organism's current lifestyle will be lost (look at all the psuedogenes for smell receptors in the human genome). That is basic natural selection. DNA is costly in terms of energy to make. I don't understand why this is supposed to be a weak point of Darwinian evolutionary theory?

chuckles · 26 January 2005

Hey Great White Wonder,

Your Norwich web page seems to be down. Do you still work there?

Great White Wonder · 26 January 2005

Chuckles --

Only when I'm not fighting my husband for alimony payments. ;)

Aggie Nostic · 26 January 2005

What is the obssetion with "loss of information" anyway. Genes that are not useful in an organism's current lifestyle will be lost. That is basic natural selection.

But is it? I've never quite understood why this HAS to be the case. As long as something isn't detrimental to survival, why does it have to go away? If something is neutral towards survivability, can it not just go on existing (assuming that it doesn't get clobbered by mutations)?

Great White Wonder · 26 January 2005

As long as something isn't detrimental to survival, why does it have to go away?

It doesn't have to go away. Last time I checked, the genes of most organisms are bound together in a more less linear chain in something called a "genome". Simple answer: a useless or detrimental allele will typically take a relatively long time to "go away" in a population unless the selection is really stringent, the detriment is severe, and the allele is dominant. The cost of having a "useless" allele floating around in a population or in an organism is evidently not a big deal for some life forms -- DNA replication is relatively cheap and size is not an issue unless being really really small and reproducing quickly is the key to not going extinct. There is a sort of sub-field of "minimal genomics" that is being explored currently that I find interesting. Scientists are asking questions like "What is the minimal genome for a living organism to reproduce independently?" Of course, the answer critically depends on what nutrients and other abiotic factors are provided to the organisms. But it's still interesting. I'm not aware of any Johnsonite Christians who are engaged in such research, although I'm sure they'll be happy to quote-mine anything the authors say anything about how "very little is known" about the first life forms on earth.

Dr Yak · 27 January 2005

But is it? I've never quite understood why this HAS to be the case. As long as something isn't detrimental to survival, why does it have to go away? If something is neutral towards survivability, can it not just go on existing (assuming that it doesn't get clobbered by mutations)?

It doesn't "have" to go away but, if not under selection then any mutations will not be cleared and hence will lead to an inactive gene. The problem is that making DNA, transcribing it into RNA and then making a protein is energetically very expensive. Thus making a protein that serves no purpose in a cost with no benefit and thus should be under negative selection. This is why there are so many survellance mechanisms that inhibit the transcription and translation of pseudogenes. In most multicellular organisms the cost of synthesising the extra DNA is not significant (hence the large amount of "junk" DNA in many genomes). However, in the particular case I refered to above, Prochlorococcus, is a free living bacteria that lives in very resource poor water. Hence it is under very strong selection to minimise its energy expenditure and nutrient usage - thus any DNA not serving a purpose will tend to be lost. Cheers, Yak

Vasha · 27 January 2005

On non-loss of information, see the new article by Whiting et al. in Nature. http://www.biomedcentral.com/news/20030116/04/

Molecular evidence indicates that the ancestors of modern stick insects were flightless, almost certainly completely wingless, and yet the genes involved in forming wings remained intact enough to be re-used when flight evolved again, in four different groups of stick insects, as much as 50 million years later.

This goes against Dembski's contention that genes involved in such modules as wings are so isolated in functionality that they would be very soon destroyed by mutation if they lost that function. (See PT thread "Promiscuity in Evolution" http://www.pandasthumb.org/pt-archives/000764.html)

Jari Anttila · 31 January 2005

Even if the bible didn’t have the idea of God creating all life or the Earth being young in it, really hardline Christians would probably still attack evolution for being at odds with the idea of humanity being in a continuous state of degeneration.

I suppose they would. But I think that for an average antievolutionist this is not a matter of theological correctness, but "I'm an image of God and not related to some filthy monkeys!"

Following their logic, we could not have evolved from apes because obviously Apes < Humans(I’ve never seen a creationist suggest apes evolved from humans, although I’m sure at least one has made the argument that apes and humans are within the same kind and obviously apes are degenerate humans condemned by God).

As a matter of fact, I did suggest that to some Finnish creationists some time ago. They didn't answer. If we didn't evolve/degenerate from apes, then it's logical to assume the opposite, if we want to explain the similarities between humans and apes. It is better than to try to separate two distinct "kinds" by using those miniscule differencies that humans and apes have. Does the Bible tell where apes came from? Had the Israelites known apes, the creationist attitude in this matter might be different. AFAIK, the native Africans have traditionally regarded chimps and gorillas as human beings.

You can see this theme of degeneration in a lot of creationist arguments against evolution. The classic is “The 2nd law of thermodynamics proves evolution wrong”. There’s a reason you see it so often and it’s not just because Dr. Dino is a workaholic. The reason is that it appeals to their belief that the universe is in continual decay since The Fall. They view it as “See, science agrees with the bible. We can’t be evolving! We can only devolve!”

That may well be the strongest point that creationism has. It tries to devise a really unified theory of everything: not only biology, geology and other natural sciences, but also history, culture, religion, politics, ethics...*everything*. It may be nonsense, but it's ambitious nonsense. I remember one creationist claimed that all other religions in the world are degenerated forms of Christianity. But I also find it as one of the most disturbing things in creationism, as viewed by a non-creationist theist, because it means that practically everything in this universe is run or even *created* by decay, corruption and other loathsome factors. A creationist God pretty much abandoned the world after the Fall and let the downfall handle almost everything (with the exception of the Christ) ever since. And this is supposed to be the worldview in which a loving and caring God has explanatory power...! It seems to me that a creationist "theory" can explain very little by God alone. Satan appears to be more important. I was wondering if this view is typical to the evangelical fundamentalist branch of creationism, which has (in the US, at least. Calvinist heritage?) defined the creationist movement in the 20th century? It may have been different in earlier centuries. Didn't the classical natural theology see the nature as perfect, so that it has been created in it's current form by a benevolent God?