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.
Don’t forget to keep those photos coming in, folks! I’ll be here all year.
We have more greenery today, as reader/naturalist/photographer Lou Jost sent some photos from Ecuador. His notes:
In honor of your recent post on lichen symbioses, here are some photos of lichens and bryophytes, groups that don’t get much attention otherwise.These are all from cloud forest at 2100m elevation in the Banos area in Ecuador, except for the last one which is from 1200m. They remind me of coral reefs…
I can’t tell you anything about their biology, but readers may like to know how they were photographed. These are taken with an Olympus 60mm macro lens and PEN-F body (small micro-4/3 sensor). The interesting thing about this camera and lens is that it solves the macro photographer’s constant dilemma: at higher magnifications there is very little depth of field, but if he or she uses a smaller aperture to increase the depth of field, diffraction (unavoidable due to the wave nature of light) makes everything slightly unsharp. This camera does “focus bracketing”: when I press the shutter button the camera automatically takes a stack of up to 999 photos, each focused a bit farther away than the previous one. So I can use the lens’ best aperture, f/4.5. The depth of field for any one picture at this aperture is grossly inadequate, but there is software (I use Zerene) which takes the sharp parts of all the photos in the stack and combines them into one completely sharp picture. That’s what I’ve done here. Each image is merged from between twenty and eighty individual photos. Though this is best done with a tripod, several of the ones I am sharing here were taken hand-held.
Most of these pictures are dominated by lichens, with some liverworts. The last picture is of a new species of liverwort —see this post. It is special to me since the discoverer is going to name it after me!
Yesterday was World Hijab Day, a slick piece of public relations that manages to push a religious agenda, including the second-class status of females under Islam, by appealing to liberal sentiments of Westerners. By donning this repressive garment, liberal Western women are said to empower not only themselves, but their Muslim sisters.
Of course I support a woman’s right to wear a hijab, and understand that the intent of this day is to dispel bigotry against Muslims; but I don’t support the coercion of some Muslim countries in which women don’t have a choice to cover, nor do I support social pressure in other places (including the US) for Muslim girls to start wearing the headscarf. After all, this is a garment worn as a nod to the supposedly uncontrollable lust of men, which Islam sees as a women’s duty to repress by covering their hair. (As we all know well, a few wisps of hair can lead to horrible things!) Celebrating Hijab Day is like celebrating a woman’s wearing of a ball and chain.
When I asked a friend their opinion of Hijab Day, I got this response:
I think the same as I would always think. It is a well-intentioned but pig-ignorant mush-brained gesture fetishizing a symbol of female oppression.
The site’s slideshow has these pictures. The first is the site’s header, and note that it speaks of “rights to cover” but doesn’t say something far more important: “Stand for a woman’s right NOT to cover.”
What about those countries that require the wearing of a hijab, and in which you can be beaten for not wearing one? What “rights” do those women have? But that’s ignored in the slides below:
“Modesty is a part of faith”. Well, modesty is the part of faith that’s been inserted by men.
The conflation of modesty and liberation is demonstrated by the woman below.
But look at Kabul, Cairo, or Tehran 40 years ago. Women didn’t veil nearly as much then, for it wasn’t required. THEN they had a choice, and their choice was, by and large, not to cover (see my posts with photos here and here). That, of course, is ignored on World Hijab Day. And, as I’ve heard repeatedly, even women in Western countries are often forced to veil by social pressure—pressure imposed by their mosques, their family, and their peers. I seriously doubt that even a majority of hijabis in Europe or the Americans can be said to have “chosen” a veil in the sense of having worn it in the absence of any social pressure.
Good morning on a chilly (in Chicago) February 2, 2017; it’s 17° F (-8° C) here, with wind on top of that. It’s National Tater Tot Day in America, and in case you don’t know what these reconstitution nuggets of potato mush are, they look like this:
Actually, they’re not THAT bad. . .
It’s also Groundhog Day in the US: if Punxsutawney Phil doesn’t see his shadow (i.e., if it’s cloudy), we’ll have an early spring.
On this day in 1653, New Amsterdam, now known as New York, was incorporated as a town, and in 1874 the first Groundhog Day was celebrated in Punxsutawney, Pennsylvania. In 1901, this was the day of Queen Victoria’s funeral, and in 1922 James Joyce’s Ulysses was published. Can anyone remember what noise the cat made in the fourth chapter? Finally, on this day in 1990, significant steps were taken toward ending apartheid and restoring democracy to South Africa, as President F. W. de Klerk announced the unbanning of the African National Congress and promised to release Nelson Mandela from prison.
Notables born on this day include James Joyce (1882, so his great work was published on his 40th birthday), Jascha Heifetz (1901), Ayn Rand (1905), Stan Getz (1927), Graham Nash (1942) and Christie Brinkley, the Uptown Girl (1954). Those who died on this day include Dmitri Mendeleev (1907), Boris Karloff(1969), Bertrand Russell (1970), Sid Vicious (1979) and Gene Kelly (1996). Meanwhile in Dobrzyn, Cyrus the Kind once again makes a great sacrifice at the behest of the Princess.
Hili: Admit that you are not especially comfortable with me here.
Cyrus: I admit it.
In Polish:
Hili: Przyznaj, że nie jest ci tu ze mną specjalnie wygodnie.
Cyrus: Przyznaję.
Leon is still hiking in Southern Poland, but apparently became alarmed when he heard a cat meowing plaintively (you can see it in the second and third photos):
I was going to do an anti-Trump post about how Republicans are trying to sell 3.3 million acres of public land, but screw it: let’s have some music. There’s plenty of malfeasance to come, and I don’t want to devote too many posts to what you can read in the newspapers.
“Oh Shenandoah”, an old American folk song, is said to have come from the fur traders on the Missouri River; as Wikipedia notes:
The canoe-going fur-trading voyageurs were great singers, and songs were an important part of their culture. Also in the early 19th century, flatboatmen who plied the Missouri River were known for their shanties, including “Oh Shenandoah”. Sailors heading down the Mississippi River picked up the song and made it a capstan shanty that they sang while hauling in the anchor. This boatmen’s song found its way down the Mississippi River to American clipper ships, and thus around the world.
I find it ineffably beautiful in almost all versions, but here are three great ones. The oldest version is first, by the wonderful Paul Robeson, one of the greatest bass singers I’ve ever heard, and of course a political activist and polymath. He recorded “Oh Shenandoah” several times.
This version, by Van Morrison accompanied by The Chieftains, is very different but sends a chill up my spine. This version was recorded in 1998, and I have a hard time saying it’s not my favorite.
Let’s not forget Tennessee Ernie Ford, often seen as a cornpone singer, but that’s unfair. Here’s his version from 1959:
Matthew Cobb sent me this lovely video showing a camera pulling out from a view of a person at the Google complex to the limits of the Universe, and then reversing that. But it goes even farther in, going into the person on ever-smaller scales winding up with a quark. This should be a cause for awe, or, if you’re an accommodationist, “spirituality.” The YouTubes notes are below:
App for “Cosmic Eye”
This movie was generated using the iOS App “Cosmic Eye”, written by Danail Obreschkow at the International Centre for Radio Astronomy Research at the University of Western Australia. Cosmic Eye drew inspiration from a progression of increasingly accurate graphical representations of the scales of our Universe, including the classical essay “Cosmic View” (1957), the short movie “Cosmic Zoom” (1968), directed by Eva Szasz, and “Powers of Ten” (1977), directed by Charles and Ray Eames. Where possible, it displays real photographs obtained with modern objectives, telescopes, and microscopes. Other views are phenomenal renderings of state-of-the-art computer models. All scientists and sources have given permission and are fully credited in the app.
This transcript was tw**ted by Daniel Dale, Washington correspondent for the Toronto Star, as “the full transcript of President Trump’s speech to his Black History Month event.”
This is the unhinged ravings of a narcissist, ranting about fake news, Omarosa (one of the people on The Apprentice), etc. What an insult to black Americans—and to the world. What have we done?
A new paper in Nature by Jian Han et al. (reference and free link below; one of the coauthors is Simon Conway Morris, of Burgess Shale fame) describes the earliest known deuterostome: that superphylum of animals in which the blastopore (the first opening into the central part of the embryo) becomes the anus, and the second the mouth. (“Deuterostome” means “mouth second”). This is in contrast to the group of protostomes, in nearly all of which (there are exceptions) the first opening becomes the mouth, and the anus develops later at the other end.
Deuterostomes include all chordates (including vertebrates like us), echinoderms, and “hemichordates” (acorn worms and graptolites). Protostomes include everything else, including segmented and unsegmented worms, molluscs, insects, rotifers, and so on. Here’s a diagram showing the developmental difference, and a second diagram showing the big divisions of life.
The first deuterostomes, previously dated at 510-520 million years ago, have now been supplanted by Han et al.’s finding of a tiny creature (about 1.2 mm across) in central China, with the sediments dated to 540 million years ago. Although it has a huge mouth and no anus, it still shows features suggesting it was an early deuterostome, one that lived among the sand grains of the sea floor. The authors named it Saccorhytus coronarius, part of a new group called the Saccorhytida.
But first, some journalistic errors. If this creature was an early deuterostome, it would be one of the first creatures from the lineage that led to humans (and other chordates as well as echinoderms) after that lineage split from the lineage leading to protostomes. But that does not make it “humans’ oldest known ancestor,” as is blatantly (and erroneously) indicated by the title below.
That title is bogus! For all living and extinct species, including humans, had an ancestor that was much older than 540 million years—the “last universal common ancestor” (LUCA) of all creatures, which probably lived a bit over 4 billion years ago. The title above (click screenshot to go to link) was in fact from a press release by St John’s College in Cambridge, where Conway Morris works. How could they get it so wrong?
At any rate, that error seems to have been picked up by several other journalists. Here are two examples:
and this:
I like this one from LiveScience; it’s not only a bit more accurate, but funny. Actually, it’s not completely true, for this species didn’t have to be a human ancestor itself, for it could have gone extinct without descendants, like some of the early robust hominins. All its deuterostome ancestry shows is that it evolved after the split between the protostomes and the deuterostomes.
But on the paper, which I’ll summarize briefly. Han et al. report finding 45 of these creatures, with the reconstruction in color a couple of photos down. Here’s a scan of the anterior (front) part of the fossil itself, showing its big gob:
The most prominent feature of these fossils is the large mouth opening, clearly seen above, which is surrounded by several rows of papillae that may represent sensory organs. Each side of the body also bears four cones (8 total; you can see four above the mouth in the photo above). Han et al. suppose that the cones could have been used to expel water and waste, though they’re not sure.
These creatures were tiny, as I said, and were examined by both electron microscopy and CT scanning. Here are some photos; note the scale bars (a μm, or one micron, is one millionth of a meter, or one one-thousandth of a millimeter):
(from paper): a–c, Holotype XX45-20. a, Right side. The mouth (M) arched dorsally along the anterior–posterior axis. b, Chevron pattern (Ch) on the inner surface of the integument. c, A spine (Sp) close to the mouth. d–f, XX45-56. d, Left side. e, Detail of the dorsally arched and folded mouth with radial folds (Rf) and oral protrusions (Op) in d. f, Circular pores (Cp) on the dorsal, right side. g–i, XX48-64 with limited compression. g, Ventral view, showing body cones (Bc) bilaterally arranged around the anterior, including the mouth. Two circular pores are adjacent to the first body cones (Bc1) and a small circular pore is on the mid-ventral line of the body. h, Oral protrusions lacking distal ends and appearing as a circle of pores. i, Left view reconstructed by microcomputerized tomography data. Lbc1–Lbc4, left body cones; Nr, nodular rugae; Rbc1–Rbc4, right body cones; Rf, radial folds; Sc, sub-layer of cuticle; arrowed AP, anterior–posterior axis.
But if these are deuterostomes, with the mouth forming after the anus, where’s the anus on these things? They don’t have one! The authors explain its absence this way:
Early deuterostomes have a through gut, so the apparent absence of an anus in Saccorhytus could be secondary, as in brachiopods and ophiuroids. [That is, its ancestors could have had an anus but lost it.] It remains possible, however, that this feature was inherited from more primitive bilaterians, possibly linked to the acoels and xenoturbellids.
But if there’s no anus, how can they call this an early deuterostome? It turns out that the small creature has other features that link it with the deuterostomes, as shown in the phylogeny below derived from several characters (the bootstrap support isn’t all that high). In particular, they show that Saccorhytus bears resemblances to “vestulocystids,” or early echinoderms, which are clearly deuterostomes. These features, also studied by Conway Morris and his colleagues, include truncated cones on the body, a convoluted anterior part of the body, and “well developed radial ribs.”
Here’s the phylogeny showing the new species (in red) falling out with the deuterostomes:
(from paper): a, Lateral, hind and ventral views. b, The most parsimonious tree (tree length, 96; consistency index, 0.6771; retention index, 0.8394; rescaled consistency index, 0.5683) arising from a matrix of 25 taxa and 61 characteristics. The values at nodes indicate bootstrap support greater than 50% (see Supplementary Information for details).
Here’s a figure from a 2004 Nature paper showing the truncated cones (A and C) in some vestulocystids:
Finally, where the fossil was found and the appearance of the sediments (it must have been hard to spot these!):
Caption from paper: Geographical location of horizon and its petrography. (836 KB) a, Locality map of the Zhangjiagou section, Xixiang, Shaanxi Province, China. In addition to Saccorhytus, the phosphatic limestone of Bed 2 of the Kuanchuanpu Formation in the Zhangjiagou section (see ref. 16) contains numerous small shelly fossils. b, c, Petrographic sections (plane-polarized light) of Bed 2 showing the phosphatic bioclastic grains, carbonate matrix and cements.
The authors conclude that our earliest deuterostome ancestosr might well have been tiny and lived among sand grains of the sea floor; they were “meiofaunal”, meaning small bottom-dwelling animals that inhabit the sediments. They also conclude that since these species could have been very tiny, we may have missed even earlier appearances of deuterostomes in the fossil record. Finally, they conclude that respiration occurred through the body surface, and the presence of pharyngeal arches (structures bearing gill slits), which are present in all modern deuterostomes at some developmental stage, could have evolved later.
