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.
Today we have a grab-bag of diverse photos from several readers, some sans wildlife. The first is from Brandon Cooper, who collaborates with my ex-student Daniel Matute collecting Drosophila flies in Africa:
I recently returned from Zambia, Malawi, and Namibia where Matute and I collected a nice transect of melanogaster and simulans. While collecting in the South Luangwa area of Zambia, I took these two pictures that I think you will enjoy. Needless to say it was a lot of fun collecting flies in areas where big cats randomly walk past. [Leopard: Panthera pardus.]
Reader Charleen Adams sent in two birds:
Belted kingfisher (Megaceryle alcyon). This (?) female was being mobbed by crows on an otherwise serene Seattle day. After landing next to this pillar at the Fred Hutchinson Cancer Research Center, she shut her eyes for about a minute. I kept the crows away until she came to. In a burst, which relieved me tremendously, she flew off.
I had a little too much lens for this Red-tailed Hawk (Buteo jamaicensis):
And some stellar stunners from reader Tim Anderson in Oz:
I have attached two star photos taken last weekend.
The first shows the Small Magellanic Cloud and the Large Magellanic Cloud. These are two irregular galaxies visible to the naked eye in the southern hemisphere close to the South Celestial Pole.
These objects are among the closest galaxies to the Milky Way and are both areas of vigorous new star formation. The prominent star at the top of the picture is Beta Hydri, which appears to be similar to the sun, though much later in its evolution, being a red giant.
The second picture shows gas and dust clouds in part of the Milky Way visible at this time of year in Australia.
Each picture was compiled from a set of about thirty 8-secondphotographs taken with a 15mm focal length lens on a Canon 70D camera. The details of the LMC and SMC is borrowed from the commentary in the Sky Safari program (whic I recommend for stargazers).
Current Biology is a fortnightly scientific journal published by Elsevier, one of the main publishing companies that people have got very cross about because of their financial model, and the fact that its most recent research articles are kept behind an expensive paywall. However, to celebrate the 25th anniversary of the magazine, Current Biology have published a series of reviews and ‘Primer’ articles about the history of life on Earth, and they are all Open Access, so everyone, anywhere in the world can read them.
This excellent initiative will provide many WEIT readers with the opportunity to update their knowledge, or to gain new understanding. The articles are written for an academic audience, but you can skip over the bits you don’t understand, or simply look at the figures showing, for example, the evolution of animals:
Figure 4 from Briggs (2015) The Cambrian explosion — ranges and relationships. Fossil evidence for the diversification of major animal groups based on first appearances of taxa during the Cambrian explosion, overlain by a metazoan phylogeny with branch lengths calibrated using a molecular clock approach (after Erwin et al. 2011).
Here are the contents of the special issue – the links should take you straight to the abstract, and you can then choose to read the full text on line, or download a PDF of the article. If you know these fields, you’ll see that these articles have been written by some of the top people in the area.
I haven’t read them all yet (they were only published last night!), but those I have looked at seem excellent. They cover everything from the RNA world, through the origin of eukaryotes (organisms with a cell nucleus and mitochondria), the Cambrian explosion, the origin of terrestrial flora, right up to the evolutionary history of birds.
UPDATE: I’ve just learned that Elsevier’s Open Access generosity has limits – two weeks, in fact. These articles will all disappear behind a paywall in two weeks. Poor show, Elsevier! So, folks – download those PDFs ASAP! Don’t delay!
UPDATE UPDATE: The two week figure is incorrect. The articles will be open access for *four weeks* before disappearing behind the paywall. They will then be available again in a year’s time. Apologies for the confusion.
A week from today I’ll be flying from Stockholm to Atlanta via Newark, a flight I’m not looking forward to, for it’s over nine hours before I even get to the hell that is Newark Airport. Meanwhile in Dobrzyn, Hili deviated from her usual trick of coming into the house by jumping on the window, triggering Andrzej or Malgorzata to go outside, pick her up, and carry her inside. Now she can come in if the window is simply opened, for she destroyed the screen last summer by constant scratching (cats are jerks). Now the screen is scheduled for replacement, so, with this rare exception, Hili still comes inside by the “carry me” route. (Letting her learn that the window can open is a sure route to damaging future screens.)
A: Come in all the way here right now, because I want to close the window.
Hili: I can’t, because something is chirping out there.
In Polish:
Ja: Wejdź wreszcie, bo chcę okno zamknąć.
Hili: Nie mogę, bo tam coś ćwierka.
There are no “laws” in evolutionary biology comparable to those in physics, except perhaps that “all species evolve”. But that’s not very exciting. What we have in my field are not unbreakable “laws,” but patterns or generalizations. When these become sufficiently general and impressive (i.e. 80-90% of species obey them, often across diverse taxa), then we have an area of research where explanations can be general. A lot of good evolutionary biology consists of case studies that don’t elucidate a previously understood pattern, and lots of those studies good, or even iconic —Peter and Rosemary Grants’ paper on the evolutionary increase in beak size of Geospiza fortis due to a drought is one example. It serves as an iconic example of natural selection, but doesn’t shed light on how natural selection works in other cases—and it’s no worse for that.
In my own work I’ve often tried to elucidate the genetic/evolutionary basis of these broad patterns, hoping that a simple and general explanation could at one stroke explain many “anecdotes.” I’ll simply describe below what I see as “laws of evolutionary biology”: those generalizations which hold sufficiently strongly that explaining them in one group might also give explanations for all groups. And I think we now know at least the partial biological basis for each of these “laws”?
If only one of the two sexes of a species is brightly colored, ornamented, or advertises itself to the other, that sex is usually the male. The explanation, first given by Darwin but subject to much recent work, is sexual selection, and we have a good understanding of how it works, but not necessarily why females in a population prefer one type of male over another. The evolutionary basis and mechanics of female preference is an active area of research.
If there is only one trait that can be used to distinguish members of different species, that trait is very often the shape or behavior of the male genitalia. This is the subject of William Eberhard’s excellent but underappreciated book,Sexual Selection and Male Genitalia, a must-read for evolutionary biologists. (It’s out of print now, I think, but you can get it from your library.) The answer appears to be sexual selection on those genitalia, implying that females can detect the differences in shapes as they evolve within a species—leading to differences between species. The fact that such characters are often diagnostic means that sexual selection on male genitals must be a potent and ongoing evolutionary force within species. (It’s interesting that in those groups where sperm is not transferred via the genitalia but by organs like spider pedipalps, it is the sperm transferring organs that are diagnostic, supporting the sexual-selection explanation.)
If in crosses between two closely-related species, only one sex among the hybrids is inviable or sterile, it is almost invariably the heterogametic sex (the one that has two unlike sex chromosomes). I spent much of my career working on this phenomenon, which holds widely: in insects, mammals, birds, worms, and so on. The generalization is called “Haldane’s rule” after its publication by the evolutionary geneticist J.B.S. Haldane in 1922. In the last 90 years the rule has been strengthened, holding widely across animals. And it holds regardless of which sex is heterogametic. In mammals and many insects, for instance, in which males are XY and females XX, the males are sterile or inviable in species crosses. But in birds and butterflies, in which females are heterogametic and males homogametic (having similar sex chromosomes), it is the females who are preferentially sterile or inviable in species crosses. This suggests that the cause of Haldane’s rule isn’t connected so much with one gender evolving faster than the other, but with the sex chromosomes themselves.
In crosses between species, the genetic cause of the preferential sterility/inviability of the heterogametic sex resides on the sex chromosomes. I worked a lot on this problem too, and it’s deeply connected with “law” #3. If genes for inviability or sterility act as recessives in hybrids, for instance, then every such gene in a hybrid’s heterogametic X chromosome will be expressed, and that individual will be sterile or inviable. (Males in XY species, for instance, will express every single gene on the X chromosome in hybrids: usually the Y has few genes. But females, being XX, will have every deleterious recessive masked by a dominant allele on the other sex chromosome, and so will be more fit.) This is called the “dominance theory,” and there’s a lot of evidence supporting it. Recessive genes that debilitate hybrids are also found on the autosomes, but are not expressed in first-generation species hybrids and so don’t cause Haldane’s rule. The other explanation for the “X-effect” is that the X chromosome evolves faster than the autosomes (non-sex chromosomes), and so deleterious interactions in hybrids will involve that chromosome more often. That, too, appears to play a role in Haldane’s rule, but probably not as large a role as the “dominance hypothesis.”
Readers are welcome to add to this list of evolutionary biology “laws,” for these are the only ones I can think of that hold so widely.
“If it’s on my money and it’s on the state flag, I can put it on a patrol car,” said [Polk County] Sheriff Moats, who wrote to Georgia’s sheriffs this year to promote the motto’s placement on law enforcement vehicles. “Just about every single day, I have another sheriff calling and saying, ‘I’ve done it’ or ‘Can you send me a picture of your patrol car?’ ”
Some officials contend that their display of the motto is elementary patriotism, a four-word way of “standing up for America, standing up for our country,” Sheriff Moats said. Others in law enforcement say the stickers are a response to the battering their profession’s reputation has taken after more than a year of high-profile killings and extraordinary scrutiny.
“With the dark cloud that law enforcement has been under recently, I think that we need to have a human persona on law enforcement,” said Sheriff Brian Duke of Henderson County, Tenn. “It gave us an opportunity to put something on our cars that said: ‘We are you. We’re not the big, bad police.’ ”
So that’s why we have this:
Sheriff Johnny Moats’s department vehicle in Cedartown, Ga., the seat of Polk County. He bought the “In God We Trust” sticker with his own money after he heard that Missouri sheriffs had begun displaying them. Credit Kevin D. Liles for The New York Times
And the only sensible response, from Annie Laurie Gaylor of the Freedom from Religion Foundation:
“This motto has nothing to do with the problem of police forces’ shooting people, but it’s a great way to divert attention away from that and wrap yourself in a mantle of piety so that you’re above criticism,” said Annie Laurie Gaylor, a co-president of the Freedom From Religion Foundation, a Wisconsin-based group that has demanded that law enforcement officials stop exhibiting the motto. “The idea of aligning the police force with God is kind of scary. That’s the first thing you’d expect to see in a theocracy.”
The cops respond:
“I don’t know why an atheist is so upset about us putting up ‘In God We Trust,’ ” Sheriff Moats said. “I’m not saying that they trust God. I’m saying that we, as the guys in this department who put this on our cars, we trust in God. And why is that a bad thing? Even if you don’t believe, you know God’s all about good.”
Does that mean that every cop who rides in those cars is a believer? And how do they know that “God’s all about good”? If that were the case, why would the cops have to deal with (and sometimes commit) the murder of innocent people?
The problem, of course, is that this motto has been repeatedly deemed Constitutional by the courts, and so the cops can use it with impunity. But it’s still a prima facie violation of the First Amendment.
I am growing weary of pointing out the stupid things said by Republicans and creationists (there’s considerable overlap), which is like crying, “Look, that lion ate a gazelle!” One gets to a point where it’s neither new nor interesting. But in the interest of documenting the scientific missteps of Presidential candidates, especially when it comes to evolution, I submit for your disapproval this three-minute video of GOP candidate Ben Carson speaking on September 30 at the University of New Hampshire. There’s also a transcript below the video.
Carson’s comments are indented; my gloss flush left. Emphasis (bold) is mine.
Well first of all, you have to hear what I actually believe because the media distorts it enormously for their own purposes. Is there climate change? Of course there’s climate change. Any point in time temperatures are going up or temperatures are going down. When that stops happening, that’s when we’re in big trouble.
Ummm. . . can you get any dumber than that? In fact, we’re in big trouble when average temperatures keep going up, as we know is happening now.
What is important is that we recognize that we have an obligation to take care of our environment. I don’t care whether you are a Democrat or a Republican, a liberal or a conservative, if you have any thread of decency in you, you want to take care of the environment because you know you have to pass it on to the next generation.
There is no reason to make it into a political issue. As far as evolution is concerned I do believe in micro-evolution, or natural selection, but I believe that God gave the creatures he made the ability to adapt to their surroundings. Because he’s very smart he didn’t want to start over every fifty years.
Well, cut off my legs and call me Shorty: Carson’s admitting some (micro)evolution here! But once he does that, he’s given away the game, for there’s no essential difference between microevolution and macroevolution. If microevolution goes on long enough, it produces major evolutionary change: for existence, the transformation of ancestral, terrestrial artiodactyls into whales, or early amphibians into reptiles. There’s no given point, though creationists claim there is, where microevolution has to stop because otherwise the changes are trespassing into the bailiwick of macroevolution. And if you look at the fossil record of, say, the evolution of early mammals from reptiles, you see precisely that: there is a continuous and gradual change, with no one point at which you can say, “This is where mammals began.” We see, in fact, fossils that are so intermediate that they are classifiable only as “mammal-like reptiles.” (One could just as easily call them “reptilian mammals”.)
Now clearly Carson doesn’t believe this, because in an earlier speech he said evolution producing adapted organisms made as much sense as a tornado blowing through a junkyard producing some useful object. But if you admit the possibility of microevolution, you admit of a gentle wind that, over time, has the same effects as that hurricane!
Carson further admitted in that talk that God produced organisms in one bout of creation, though he was unclear whether it took six literal days or six metaphorical days. In either case he’s backtracking on what he said before. Now it’s up to reporters to ask Carson what he sees as the difference between microevolution and macroevolution, and why the former is possible but the latter is not.
And as for God being “very smart,” well, if he was really smart he wouldn’t use the tortuous process of evolution, which involves the suffering of millions of animals and the extinction of millions of species that die without leaving descendants. He’d just give organisms the ability to instantly change their morphology and physiology in response to environmental change, or make that change by waving his hand. After all, God can do anything, and it takes Him no effort.
Carson continues:
So I say people who want to believe other than that they are welcome to do that. I known there are some people who say “you know it all just happened.” Well where did it all come from in the first place? “I don’t know but it’s there somewhere.” So I give them that it’s there. They say there was a big explosion and it all became perfectly organized to the point where we can predict seventy years hence when a comet is coming. Um, that requires more faith than I have. You know, that’s a complex set of things. Just the way the earth rotates on its axis, how far away it is from the sun. These are all very complex things. Uh, gravity. Where did it come from? I mean, there are so many things. So I don’t denigrate the people who say “Eh, eh, whatever, somehow it happened.” I don’t denigrate them, I just don’t have that much faith. But they are welcome to believe whatever they want to believe. I’m welcome to believe what I want to believe. They say I can’t be a scientist and yet somehow I became a neurosurgeon and did pretty well.
Shades of Bill O’Reilly and the tides! The record of predicting the arrival of comets, and the occurrence of solar and lunar eclipses, is pretty close to perfect. And we have plenty of evidence for the Big Bang, including the expanding universe and the microwave radiation that is the persisting echo of that bang. These are not matters of faith, but of fact.
Carson continues to insist that both science and religion are based on “faith,” playing on the different meanings that word has when applied to science (where it means “confidence based on observation, experiments, and experience”) versus religion (where it means something like “firm belief in something without the need for evidence strong enough to convince most rational people”). I recommend he read my piece in Slate on this difference.
As for gravity, it comes from the distortion of space-time by objects with mass.
Carson’s last statement, “They say I can’t be a scientist and yet somehow I became a neurosurgeon and did pretty well,” is telling. It shows that one can indeed be a competent physician, applying principles of science to one’s work, as Carson surely did, without extending those same principles to one’s beliefs—or even to areas like cosmology and biology. Carson’s inability to distinguish faith from fact makes him completely unsuitable to be President of the United States. Finally, I think he’s beginning to recognize that his antiscientific stand on evolution makes him look pretty dumb, so he’s moving away from straight creationism to the intelligent-design variety (“microevolution but not macroevolution”).
If it were Valentine’s Day, this would serve as a special post, but I’ll just celebrate the Act of Love itself (taken from five orders of insects) with these photos from reader Jacques Hausser of Switzerland. His note was simply this: “I send you here some pictures of insects caught in the act or just before.”
