Too many stories came in too fast at the end of March. Here are some we would have liked to explore in more detail. They’re all interesting and some have amazing facts and quotes.
- DNA vs. Evolution: A paper in the Royal Society Biology Proceedings1 warned that pleiotropy, the antagonistic effect of genes that need to mutate together, inhibits natural selection more than is usually realized. Sarah P. Otto writes,
Pleiotropy is one of the most commonly observed attributes of genes. Yet the extent and influence of pleiotropy have been underexplored in population genetics models. … Under the assumption that pleiotropic effects are extensive and deleterious, the fraction of alleles that are beneficial overall is severely limited by pleiotropy and rises nearly linearly with the strength of directional selection on the focal trait. Over a broad class of distribution of pleiotropic effects, the mean selective effect of those alleles that are beneficial overall is halved, on average, by pleiotropy.
Thus the simplistic notion that a beneficial mutation will be acted on by natural selection is “severely limited” by the effect of pleiotropy.
- Starbirth: In an article in the 19 March issue of Science.2 Robert Irion puzzles over why recent surveys of the heavens seem to indicate star formation was rapid in the early universe yet so slow today:
As findings from these surveys cascade into the literature, they are shaking up notions about the evolution of star birth in the young cosmos. Observers have found that some galaxies matured quickly after the big bang and then flamed out, forming giant blobs of stars that may have barely changed in at least 10 billion years. Another population of galaxies kept evolving, churning out new stars for eons and gradually settling into mature but mildly fertile galaxies such as our Milky Way.
But these claims seem to belie the uncertainty in the minds of modelers. The following admissions of ignorance are startling, considering the ease with which the textbooks present the story of starbirth and galaxy evolution:
Current theories of galaxy formation can’t explain why concussive waves of star birth swept through some early galaxies but not others–and why some of those fierce stellar fires got snuffed after a few billion years. Startled by their own data, a few observers have implied that modelers of the cosmos need new ideas to describe our universe’s combustive childhood (Science, 23 January, p. 460).
Theorists aren’t yet ready to revise equations on their cluttered whiteboards, but they agree that the surveys illuminate serious flaws. “We’re starting from a shaky foundation,” says cosmologist Carlos Frenk of the University of Durham, U.K. “We don’t understand how a single star forms, yet we want to understand how 10 billion stars form.” Fellow theorist Simon White of the Max Planck Institute for Astrophysics in Garching, Germany, concurs: “The simple recipes in published models do not reproduce the star formation we see. Theorists are now having to grow up.”
Irion doesn’t contradict the predicament; he just hopes that new sky surveys will clear up the mess.
- Alfred Russell Wallace: Nigel Williams reviews Michael Shermer’s bio of the man who independently “discovered” the “law” of natural selection.
Wallace was a colorful but tragic character. He went on some legendary adventures in Malaysia and elsewhere, and graciously played second fiddle to Charlie, but was also suckered by spiritualism and the fallacies of his own beliefs. He was another victim of loss of faith in the credibility of the Bible during his youth. Janet Browne, in Charles Darwin: The Power of Place (Princeton, 2002) has many interesting insights into the Wallace-Darwin relationship, practically accusing Charlie of intrigue to prevent him getting glory for the discovery of natural selection. Whether either of them deserved any credit is debatable. In the March-May 2004 issue of Creation Ex Nihilo magazine, Russell Grigg argues that Charlie knew about and plagiarized the idea of natural selection from half a dozen predecessors and peers.
- Charlie Worship: In the 23 March issue of Current Biology,4 interviewee Hugo J. Bellen (Baylor College of Medicine) is asked if he has a scientific hero:
Yes: Charles Darwin. His ‘Origin of Species’ is in my opinion the most important text in biology that has been published so far. I have read The Origin three times and every time I am in awe at Darwin’s ability to integrate so many different facts in a simple coherent theory. The principle of natural selection has stood for over 150 years now. Its implications for biology and genetics are far reaching, and the theory still hugely dominates our thinking as biologists.
Follow the chain links on “Darwin” for differing views about this hero.
- Another Thing You Can’t Live Without: David Carling (Imperial College) provides a quick review of AMPK in the 23 March issue of Current Biology.5 If you don’t know what AMPK is (AMP-activated protein kinase), just be glad you (and everything else alive) has it:
AMPK has been dubbed the cellular fuel gauge, because it is activated by a drop in the energy status of the cell. If ATP is used up faster than it can be re-synthesized, ATP levels fall and this leads to a rise in AMP. The increase in the AMP:ATP ratio triggers the activation of AMPK and leads to the phosphorylation of a large number of downstream targets. The overall effect of AMPK activation is to switch off energy-using pathways and switch on energy-generating pathways, thus helping to restore the energy balance within the cell. The conservation of AMPK throughout evolution emphasises its importance: homologs have been identified in all eukaryotic species examined to date, including plants.
Other recent articles have focused on this cellular “fuel gauge” as a means of controlling appetite and obesity (see, for instance, Nature April 1, 2004). When asked “Can we live without it,” Carlin answers immediately, “Almost certainly not.” Mice without it die in embryo, and it cannot be mutated much: “Although a complete loss of AMPK activity is lethal, subtle changes in AMPK activity can lead to serious clinical consequences.” You don’t say. How the first organisms got about without it, he doesn’t say.
- Genome Size: Also in Current Biology,6 Brian Charlesworth and Nick Barton examine the question of why genome sizes differ so much between organisms, and offer a suggestion:
Genome sizes vary enormously. This variation in DNA content correlates with effective population size, suggesting that deleterious additions to the genome can accumulate in small populations. On this view, the increased complexity of biological functions associated with large genomes partly reflects evolutionary degeneration.
But judging from the many puzzles, contradictory evidences and lack of observations mentioned in the article, it doesn’t appear that evolutionists or creationists quite have a handle on this one yet.
- Intron Origins: Another paper in the same issue of Current Biology7 attempts to put forward a hypothesis about intron origin and evolution (see 09/23/2003 headline). Phylogenetic evidence indicates that these sequences have been targeted by numerous intron insertions during evolution , but little is known about this process. Here, we test the prediction that exon junction sequences were functional splice sites that existed in the coding sequence of genes prior to the insertion of introns. Again, neither side seems to have scored a touchdown on this question. What are introns there for? If they evolved, why doesn’t the cell get rid of them, instead of using such complicated machinery to process them? As to “phylogenetic evidence,” it is subject to evolutionary presuppositions. Until we know more, we should not rule out the possibility that introns have a function.
- Integrating Your Eyes and Ears: Martin S. Banks (psychologist, Berkeley), explores the interaction of eyes and ears to help us make decisions. In Current Biology,8, he gives an example of this complex process we take for granted:
You enter a crowded room and someone calls your name. You turn to see who it is. You now see several people in the general direction the voice came from. Many are talking. Which one called your name? You hear it again and now the sound seems to come from straight ahead or nearly so. There are still a handful of candidates in your field of view, so you look from one to the other. Finally, you see one whose lips move as you hear your name once more. Sound and sight have come together and you identify the speaker as your college roommate. How does this work? That is, how does the brain find the appropriate auditory-visual correspondence to determine that a sound and sight have come from the same source?
He points to a recent study by Alais and Burr that produces an “important and seemingly pervasive rule for the combination of visual and auditory cues to spatial location.” Whatever it is, it’s amazing.
- Thank God for Our Moon: Lastly, an article in New Scientist argues that without a moon like earth has, life could not exist.
1Sarah P. Otto, “Two steps forward, one step back: the pleiotropic effects of favoured alleles,” Proceedings: Biological Sciences, The Royal Society, Issue: Volume 271, Number 1540, April 07, 2004 Pages: 705 – 714 DOI: 10.1098/rspb.2003.2635 (published online before print).
2Robert Irion, “Surveys Scour the Cosmic Deep,” Science Vol 303, Issue 5665, 1750-1752 , 19 March 2004, [DOI: 10.126/science.303.5665.1750]
3Nigel Williams, “In Darwin’s Shadow,” Current Biology, Vol 14, R216-R217, 23 March 2004.
4Q&A: Hugo J. Bellen, Current Biology, Vol 14, R218, 23 March 2004.
5David Carling, “:Magazine: AMPK,” Current Biology, Vol 14, R220, 23 March 2004.
6Brian Charlesworth and Nick Barton, “Genome Size: Does Bigger Mean Worse?” Current Biology, Vol 14, R233-R235, 23 March 2004.
7Sadusky et al., “Exon Junction Sequences as Cryptic Splice Sites: Implications for Intron Origin,” Current Biology Vol 14, 505-509, 23 March 2004.
8Martin S. Banks, “Neuroscience: What You See and Hear Is What You Get,” Current BiologyVol 14, R236-R238, 23 March 2004.
Plenty of research material above for the curious. We hope Creation-Evolution Headlines demonstrates to young people that there are still many scientific puzzles to solve and will stimulate a few to become scientists. Despite their bluff and bravado, the Darwin Party clearly doesn’t have answers to some of the most basic questions about stars, life, cells, and genes. Let’s roll.