Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
Paul the Precognitive Octopus has picked Spain to win the World Cup.
And ignore that old curmudgeon PeeZee, who’s had his fill of Paul. He’s just smarting from having been caught in a tryst with philandering South Carolina gubernatorial candidate Nikki Haley. Here he is, surprised by photographers in Charleston while leaving a hotel with Haley. (The wig doesn’t fool anyone.)
One of the key innovations in the history of life—at least, looking back at it from the viewpoint of a complex species—was the origin of multicellularity. Having many cells that are differentiated, so that different cells can do different things, allows the specialization of tissues and organs that opens up many new ways of life. Kidneys, wings, legs, leaves, brains—all of these things require differentiation of cells. A single cell on its own has to do it all: reproduction, movement, excretion, and nutrition. Multicellularity and cell differentiation means some cells can change their function, becoming mouths or anuses or livers without disrupting, say, the other cells that are responsible for reproduction. It’s a way of overcoming pleiotropy by farming out tasks to specialized tissues. In their important book The Major Transitions in Evolution, John Maynard Smith and Eörs Szathmáry considered multicellularity one of the nine most critical evolutionary innovations.
So how did multicellularity come about? How much genetic change was needed to get those single cells on their own to form colonies, with some of them specializing in reproduction and the others in locomotion, nutrition, and the like? Did it take a wholesale restructuring of the genome?
That was the question that Simon Prochnik and his colleagues asked—and partially answered—in a new paper in Science. They had a clever approach: look at two species that were fairly similar, but one of which was multicellular, showing some differentiation among cells, and the other was not. Here are the species they used. The “simple” one was the unicellular alga Chlamydomonas reinhardtii, which has flagella, threadlike organelles that can be whipped about to move the cell though the water. This species has been used extensively in studies of movement and organelle differentiation. Its genome was sequenced in 2007. Here’s what it looks like (note the flagella):
Chlamydomonas reinhardtii
The “multicellular” species compared to C. reinhardtii was a multicellular green alga, the famous Volvox carterii. Here it is:
Volvox carteri
What you see is a spherical multicellular organism, but one that’s not very highly differentiated. Nevertheless, it has crucial features that differentiated uni- from multicellular species. There are two types of cells. First, there are about 2000 “somatic” cells with flagella that lie on the surface of a ball of jelly (or, as the authors call it, “glycoprotein-rich extracellular matric”). These somatic cells allow coordinated swimming so that the whole ball can swim in one direction (But there are also 16 large reproductive cells (“gonidia”) that can form sperm and eggs, which can cross-fertilize another Volvox and produce a zygote. These zygotes undergo meiosis (becoming haploid again, like their parents), and grow inside the “female”, eventually bursting free as the mother goes to her just reward. They can also reproduce asexually, produces little Volvoxes that are genetically identical to the parent (you can see some forming in the photo above).
The Joint Genome Institute website outlines why this relatively simple species is a good model for studying multicellularity:
The 48-hour life cycle allows easy laboratory culture and includes an embryogenesis program that features many of the hallmarks of animal and plant development. These features include embryonic axis formation, asymmetric cell division, a gastrulation-like inversion, and differentiation of germ and somatic cells.
In their new paper Prochnik et al. asked a simple question: if we sequence the whole genome of Volvox carteri, how much difference does it show from its fairly close unicellular relative C. reinhardtii? Does the initial evolution of multicellularity require many new types of genes, or will a few simple changes suffice?
The answer seems to be the latter. Comparing the V. carteri genome with the already-published C. reinhardtii genome, Prochnik et al. showed this:
The authors’ conclusion? Not many new genes have to change to turn a single cell into a multicellular, proto-differentiated species. In the Science news piece on this article, plant biologist Arthur Grossman comments: “The findings suggest that it doesn’t take very large changes in gene content to transition from a single-cell to a multicellular lifestyle.”
Is this surprising? Well, not really. I’m not sure most biologists would have suggested that multicellularity requires a wholesale restructuring of the types of proteins present in one-celled species. If that were true, it would be very difficult to go from one-cell to multi-cells in an adaptive, step-by-step fashion.. I would have thought that changes in protein sequence (not type) were important and, perhaps, changes in how genes are used—how they are turned on and off, and when. (This is a suggestion for which biologist Sean Carroll is famous. I once questioned it, but now am coming around to his point of view.)
Perhaps the transition from one cell to a Volvox-type species involves changes in gene expression or timing. Prochnik et al. didn’t look at “microRNAs” (miRNA), those bits of the genome that are involved in selectively silencing genes after they’re transcribed into messenger RNA but before they produce protein. Nor did they investigate expression patterns of genes (something that’s obviously going to happen soon, as it’s not too hard to do), or look at the regulatory regions of protein-coding genes. Finally, it’s still possible that although multicellularity here didn’t require new types of proteins, it did rest in a crucial way on changes in the sequences of those proteins. That would be a hard thing to study.
Prochnik et al. recognize this: as they say in the paper, “Further studies of gene regulation and the role of noncoding RNAs will be enabled by the Volvox genome sequence, allowing a more complete understanding of the transformation from a cellularly complex Chlamydomonas-like ancestor to a morphologically and developmentally complex ‘fierce roller.'”
It seems, then, that at least this critical step in the original of multicellular species may require not wholesale changes in the types of genes in the genome, but a few critical tweaks in how those genes are expressed.
And let us not forget that the building blocks for all of this rested on things that had already evolved in one-celled organisms, which in themselves are fantastically complex, with elaborate networks of genes for metabolism, excretion, protection, movement, DNA replication, DNA translation into protein, and cell division. Single cells may look simple, but Lord, they’re not!
As one my my colleagues commented after reading this paper, “Maybe all the hard work was done by bacteria.”
_________
Prochnik, S. E. et al. (28 authors) 2010. Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri. Science 329:223-226.
You know what’s coming. Yoga with Esther Ekhart:
When discussing the compatibility of faith and science, it behooves us to remember that religious folks who argue for compatibility are often of the very liberal stripe, and that there are many believers—and theologians—who disagree. This puts religious accommodationists in the uncomfortable position of having to claim that many Christian theologians are simply wrong.
I’ve just done a ten-minute video discussion with BioLogos’s Karl Giberson that will be online soon (stay tuned). Our topic was “Are science and faith compatible?” I took the “no” side, Giberson the “yes”. I won’t jump the gun here, but I did want to link to a post I mentioned in our discussion. Over at BioLogos, Albert Mohler, President of the Southern Baptist Theological Seminary in Louisville, Kentucky, has a rather long post (the transcript of a talk) on “Why does the universe look so old?”
He lays out all the possibilities (the universe is really old, though scripture seems to say it’s not; scripture is metaphorical: a “day” could be millions of years; the universe is young and God made it look old, etc.). And while chewing over the answers, he admits something that religious accommodationist try at all costs to hide: if you believe that the Bible really is the word of God, then you have a problem harmonizing it with science. Here’s what Mohler says (my emphasis):
In conclusion, there is a head-on collision here. There are those that claim there is no head-on collision [between science and faith]. Francisco Ayala, who just won the Templeton Award, says that science and religion cannot be in conflict because they’re answering two different questions. Science is answering the how, and religion is answering the who and the why. That is intellectual facile. The scripture is claiming far more than who and why and any honest reading of the modern scientific consensus knows that it too is speaking to the who and very clearly speaking to the why. Stephen J. Gould, the late paleontologist of Harvard University, spoke of what he called non-overlapping magisteria. He said science and religion are non-overlapping magisteria. Each has its own magisterial authority and its own sphere of knowledge and they never overlap. Well the problem is they overlap all the time. They overlap in Stephen J. Gould’s own writings. We cannot separate the who and the why and the what, as if those are intellectually separable questions. In his new book Why Evolution is True Jerry Coyne cites Michael Shermer at the very beginning who says this, “Darwin matters because evolution matters. Evolution matters because science matters. Science matters because it is the preeminent story of our age. An epic saga about who we are, where we came from, and where we are going.”
Now it sounds to me like he’s talking about the why, not just the when and the what. I want to suggest to you that when it comes to the confrontation between evolutionary theory and the Christian gospel we have a head-on collision. In the confrontation between secular science and the scripture we have a head-on collision. I want to suggest to you that it is our responsibility to give an answer when we are asked the question “Why does the universe look so old?” In the limitations of time, it is impossible that we walk through every alternative and answer every sub-question. But I want to suggest to you that the most natural understanding from the scripture of how to answer that question comes to this: The universe looks old because the creator made it whole. When he made Adam, Adam was not a fetus; Adam was a man; he had the appearance of a man. By our understanding that would’ve required time for Adam to get old but not by the sovereign creative power of God. He put Adam in the garden. The garden was not merely seeds; it was a fertile, fecund, mature garden. The Genesis account clearly claims that God creates and makes things whole.
Well, I’m not sure I meant “why” in the sense that Mohler did. I don’t think there’s a divine reason, much less an “ultimate reason” for anything—that is, any reason beyond the working out of the laws of physics and chemistry. We came from evolution, which was the result of primordial chemistry, and we’re going where evolution, and our own nongenetic social evolution, take us. But regardless, Mohler states clearly the problem confronted by those who think that the Bible is not just a big story, but God’s word.
The whole point of Mohler’s talk (read it at your peril) is to show that accepting Genesis as merely a metaphor yields far more theological difficulties than seeing the book as literal truth and then trying to understand what God actually did. Would that BioLogos, and other religious accommodationists, at least admit that there are theological difficulties here. Their solution is always to claim that Mohler’s form of theology is wrong, obsolete.
But what’s Mohler’s solution about the age of the universe? He punts, and in amusing way.
Secondly—and very quickly—if I’m asked why does the universe look so old, I have to say it looks old because it bears testimony to the affects of sin. And testimony of the judgment of God. It bears the effects of the catastrophe of the flood and catastrophes innumerable thereafter. I would suggest to you that the world looks old because as Paul says in Romans chapter 8 it is groaning. [Earth to God: OY VEY!] And in its groaning it does look old. It gives us empirical evidence of the reality of sin. And even as this cosmos is the theater of God’s glory, it is the theater of God’s glory for the drama of redemption that takes place here on this planet in telling the story of the redemptive love of God. Is this compatible with the claim that the universe is 4.5 billion years old in terms of earth, 13.5 billion years old in terms of the larger universe? Even though that may not be the first and central question it is an inescapable question and I would suggest to you that in our effort to be most faithful to the scriptures and most accountable to the grand narrative of the gospel an understanding of creation in terms of 24-hour calendar days and a young earth entails far fewer complications, far fewer theological problems and actually is the most straightforward and uncomplicated reading of the text as we come to understand God telling us how the universe came to be and what it means and why it matters.At the end of the day, if I’m asked the question “why does the universe look so old?” I’m simply left with the reality that the universe is telling the story of the glory of God. Why does it look so old? Well that, in terms of any more elaborate answer, is known only to the Ancient of Days. And that is where we are left.
How did Giberson deal with this frank avowal of incompatibility from a prominent Baptist minister? You’ll have to listen to our discussion.
The final on Sunday will be between Netherlands and Spain—Spain’s first entry ever to a World Cup final (or even a quarter final!) Indeed, maybe this game was the final, since I’m betting that Spain will (as Germany would hav ) walk over Netherlands. But what do I know, except that I’m for Spain.
I still don’t believe, though, that Paul is prescient. And now he’s receiving death threats from angry German fans. They want to eat him!
_____
A fair number of you in our World Cup contest guessed Spain and the Netherlands in the final. Most of the feasible scores are covered, too, so there should be a winner.
If you’re a soccer neophyte like me, you’ve undoubtedly asked yourself, “Why are those World Cup players swapping their sweaty jerseys after the game?”
Today’s New York Times explains, recounting the history of this odd practice and some anecdotes. A snippet:
The gentlemanly ritual is believed to have begun in 1931, when France beat England for the first time. The French players were so ecstatic they asked the English players if they could have their jerseys as keepsakes. The English obliged.
It was not until 1954 that exchanges took place at a World Cup, according to FIFA.com, but one of the more memorable moments in the ritual was an exchange that did not take place.
In 1966, England defeated Argentina, 1-0, in the quarterfinals, but the play was so vicious that when England’s manager, Alf Ramsey, who had referred to Argentina’s players as animals, spotted one of his players exchanging jerseys with an Argentine, he stepped in and yanked the jersey away.
That image remains as much a part of the rivalry between the countries as Diego Maradona’s Hand of God goal and David Beckham’s red card in 1998.
“Ramsey’s intervention was hugely symbolic,” said Ellis Cashmore, a professor of sociology, media and sport at England’s Staffordshire University. “Exchange rituals are freighted with cultural functions, such as reinforcing social solidarity, affirming friendships and perpetuating economic partnerships.”
Stay tuned here for the goal-by-goal scores of Germany vs. Spain.
One of the big differences between religion and science as “ways of knowing” is that in science we can almost always specify what observations or experiments would prove our theories wrong. In contrast, the faithful do not (and cannot) specify what observations would disprove their beliefs—or the whole basis of their religion. There are two reasons for this distinction. First, through judicious theological manipulation the faithful carefully insulate those beliefs from disproof, often in a hypocritical way. When evidence is found against them, like the medieval age of the shroud of Turin or observations showing that prayer doesn’t work, the faithful simply say, “No, you can’t test God.” No matter that if the Shroud of Turin did date to around 30 A. D., or if prayer did cure people in double-blind tests, those same believers would trumpet to the skies the proof of their faith. Evidence for religious beliefs is counted; evidence against them is dismissed. Needless to say, science doesn’t—and couldn’t—work that way.
Second, because religious belief is irrational, the faithful often won’t let themselves even consider counterevidence. The evidence for evolution is by now overwhelming (I wrote a book about it, and didn’t even scratch the surface), but still around 60% of Americans think that humans were created by God directly instead of having evolved—and a lot of the latter believe that our evolution was guided by God. Faith has immunized these people against the plain facts. I’ve always thought that the existence of horrible tragedy and evil, particularly that inflicted on innocent people and that produced by natural forces like earthquakes and tsunamis, were prime evidence against the more loving and omnipotent species of god. But there’s a whole branch of theology—theodicy—designed to explain those things away. Let’s put it this way: if the Holocaust didn’t make people abandon their belief in God, then nothing ever will.
Religion is not a way of knowing because it doesn’t have a way of knowing that it is wrong. And without that, you don’t know if you’re right. That’s why science makes progress in understanding the world while religion is still mired in medieval theology.
Granted, some of the faithful—and many of you readers—have abandoned religious belief because it either seemed irrational or was contradicted by empirical evidence. Dan Barker has chronicled this journey in his poignant book Godless. But the abandonment of faith is often a gradual process, so gradual that believers don’t even realize it’s happening. How many of you, when you were believers, were brave enough to lay out the kind of evidence that would make you bail on God?
But we atheists, being scientifically inclined, can do the converse: we can lay out what observations would turn us into believers. Over at AlterNet, Greta Christina describes six things that, if they happened or were observed, would convince her that God exists. These including magic writing in the sky, correct prophecies in sacred texts, accurate information gained during near-death experiences, followers of one religion being much more successful (in ways that couldn’t be explained by economic and social factors) than followers of other faiths. Go read it: she qualifies and explains all of these things in detail.
Darwin himself, in a letter to the botanist Asa Gray, laid out his criteria for believing in God:
Your question what would convince me of Design is a poser. If I saw an angel come down to teach us good, and I was convinced from others seeing him that I was not mad, I should believe in design. If I could be convinced thoroughly that life and mind was in an unknown way a function of other imponderable force, I should be convinced. If man was made of brass or iron and no way connected with any other organism which had ever lived, I should perhaps be convinced. But this is childish writing.
Making the same point, I provided my own list in a critique of the claim that science and faith are compatible:
There are so many phenomena that would raise the specter of God or other supernatural forces: faith healers could restore lost vision, the cancers of only good people could go into remission, the dead could return to life, we could find meaningful DNA sequences that could have been placed in our genome only by an intelligent agent, angels could appear in the sky. The fact that no such things have ever been scientifically documented gives us added confidence that we are right to stick with natural explanations for nature. And it explains why so many scientists, who have learned to disregard God as an explanation, have also discarded him as a possibility.
It’s your turn. If you’re one of the faithful reading this, feel free to post those observations that would convince you that God doesn‘t exist.
And, if you’re one of the more numerous atheists, agnostics, or skeptics who comment here, supplement my list and Greta’s with observations that would make you accept God’s existence. If you comment, don’t be facetious. This is a challenge to those believers who say that their way of knowing is equivalent to that practiced by science and rational investigation.
Mo needs his own octopus:
