The Deflated Ego Problem refers to the fact that many scientists were very disappointed to learn we had less than 30,000 genes. Those scientists were expecting that the human genome would contain many more genes in line with their belief that humans must be genetically more complex than the "lower" animals. They should have known better since knowledgeable experts were predicting fewer than 30,000 genes and these same experts knew that humans don't need many more genes than other animals [see: Revisiting the deflated ego problem].
Disappointed scientists don't use the term "deflated ego;" instead they refer to their problem as the G-value paradox. This makes it seem like a real problem instead of just a mistaken view of evolution.
I just read the original paper on the G-value paradox and I think it's worth quoting some of it because it clearly states the issues. The paper is by Matthew Hahn and Gregory Wray when they were both at Duke University in Durham, North Carolina, USA. (Hahn was a graduate student in Wray's lab, he is now a professor at Indiana University.) (Hahn and Wray, 2002). It's important to note that these are respected scientists and their views are still very popular.
They begin their brief review by expressing surprise that the human genome had "a surprisingly modest 31,000 genes." Then they explain why this is a problem.
That's not what happened in most cases. What usually happened is that disappointed scientists attempted to justify their naive expectations and then propose solutions that still make humans more genetically complex even though they have the same number of genes as other animals.
Here's what the justification looks like.
What they did not do in their paper was to mention that many knowledgeable scientists were predicting fewer genes and their predictions were backed up by solid evidence (e.g. Ewing and Green, 2000; Roest Collius et al., 2000). Nor did did they mention the idea coming from evo-devo that complexity doesn't correlate with the number of genes but with differential control of a core set of genes. I'm struggling to understand why there's so much resistance to this key concept that's strongly supported by data from a number of model organisms.
Here's what the "solution" to the G-value paradox looks like.
We now know that neither process causes a significant increase in the number of gene products but, even in 2018, it's still widely believed that this is the answer to the G-value paradox.
As I mentioned above, I'm having difficulty understanding why the G-value paradox was created in the first place but that difficulty pales in comparison to my difficulty in understanding why it remains so popular in 2018. Perhaps my readers can help me out. Do you have a problem accepting that humans have about the same number of genes as other mammals, fish, or insects? If so, can you explain to me why you think this is a problem that demands a solution?
Disappointed scientists don't use the term "deflated ego;" instead they refer to their problem as the G-value paradox. This makes it seem like a real problem instead of just a mistaken view of evolution.
I just read the original paper on the G-value paradox and I think it's worth quoting some of it because it clearly states the issues. The paper is by Matthew Hahn and Gregory Wray when they were both at Duke University in Durham, North Carolina, USA. (Hahn was a graduate student in Wray's lab, he is now a professor at Indiana University.) (Hahn and Wray, 2002). It's important to note that these are respected scientists and their views are still very popular.
They begin their brief review by expressing surprise that the human genome had "a surprisingly modest 31,000 genes." Then they explain why this is a problem.
Even though sequencing the human genome may be merely a first pass at a deeper understanding of our biology, one fact stands out as demanding an immediate explanation: Why do humans have so few genes?The is a perfect description of the Deflated Ego Problem—the number of genes did not match their naive expectation. Normally when a scientific result doesn't match your expectations—and you recognize that your expectations were "naive"—that would cause you to reevaluate your expectations, especially when you learn that other scientists did not share them.
The assumptions and chauvinism implicit in this question—that humans are vastly more complex than the other fully sequenced eukaryotes and should therefore have a commensurately larger suite of genes—are difficult to argue clearly and may be even more difficult to justify biologically. Still, it is hard to deny our intuitive perception that the number of genes in a genome should be roughly correlated with complexity and that organismal complexity can be ranked as yeast Arabidopsis). However, the number of genes in the genomes of these organisms does not match our naive expectation.
That's not what happened in most cases. What usually happened is that disappointed scientists attempted to justify their naive expectations and then propose solutions that still make humans more genetically complex even though they have the same number of genes as other animals.
Here's what the justification looks like.
This disjunction between the number of genes and organismal complexity, what we call the “G‐value paradox,” parallels the finding during the 1950s that the physical size of genomes does not correlate with organismal complexity, a relationship known as the C‐value paradox. The finding that much of the genome contains noncoding repeats and “junk” DNA seemed to resolve the C‐value paradox. Implicitly, this resolution rested on the assumption that once noncoding DNA was taken into account, the total number of genes would then correlate with organismal complexity (Cavalier‐Smith 1985). However, the published G values of the completely sequenced eukaryotes make it clear that we have not yet resolved the C‐value paradox—it has merely given way to the G‐value paradox.Do you see what they just did? They tried to convince you that other scientists were also expecting there to be more genes because humans are more complex. This "problem" even has a name: it's called the G-value paradox.
What they did not do in their paper was to mention that many knowledgeable scientists were predicting fewer genes and their predictions were backed up by solid evidence (e.g. Ewing and Green, 2000; Roest Collius et al., 2000). Nor did did they mention the idea coming from evo-devo that complexity doesn't correlate with the number of genes but with differential control of a core set of genes. I'm struggling to understand why there's so much resistance to this key concept that's strongly supported by data from a number of model organisms.
Here's what the "solution" to the G-value paradox looks like.
Just as the discovery of noncoding DNA seemed to resolve the C‐value paradox, so a few simple observations may in time resolve the G‐value paradox. These observations all attempt to give more value to each of our genes and thus to give us a more accurate genomic predictor of organismal complexity by identifying the true measure of information encoded by a genome, the "I‐value." Some of the observations we discuss here have been offered as the answer to explaining our modest number of genes, whereas some have been invoked in combination. These observations indicate that the evolution of organismal complexity will typically involve changes in the genome that are subtler than simply adding genes. The C‐value paradox was resolved by a plea to the G value; a resolution of the G‐value paradox may be offered by a plea to the I value.The most common ways of giving "more value" to existing genes, according to Han and Wray, are alternative splicing, and posttranslational modifications. Both of these possibilities give you more bang for the buck with the same number of genes because each gene can produce multiple products.
We now know that neither process causes a significant increase in the number of gene products but, even in 2018, it's still widely believed that this is the answer to the G-value paradox.
As I mentioned above, I'm having difficulty understanding why the G-value paradox was created in the first place but that difficulty pales in comparison to my difficulty in understanding why it remains so popular in 2018. Perhaps my readers can help me out. Do you have a problem accepting that humans have about the same number of genes as other mammals, fish, or insects? If so, can you explain to me why you think this is a problem that demands a solution?
Ewing, B., and Green, P. (2000) Analysis of expressed sequence tags indicates 35,000 human genes. Nat Genet, 25:232-234. [doi:10.1038/76115]
Hahn, M.W., and Wray, G.A. (2002) The g-value paradox. Evolution and Development, 4:73-75. [doi: 10.1046/j.1525-142X.2002.01069.x]
Roest Crollius, H., Jaillon, O., Bernot, A., Dasilva, C., Bouneau, L., Fischer, C., Fizames, C., Wincker, P., Brottier, P., Quetier, F., Saurin, W., and Weissenbach, J. (2000) Estimate of human gene number provided by genome-wide analysis using Tetraodon nigroviridis DNA sequence. Nat Genet, 25:235-238. [doi:10.1038/76118]
