Granpappy was a Neandertal

Fascinating stuff…read this paper in PNAS, Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage, or this short summary, or John Hawks’ excellent explanation of the concepts, it’s all good. It’s strong evidence for selection in human ancestry for a gene, and just to make it especially provocative, it’s all about a gene known to be involved in brain growth, and it’s also showing evidence for interbreeding between Homo sapiens and Neandertal man.

The short short explanation: a population genetics study of a gene called microcephalin shows that a) it arose and spread through human populations starting about 37,000 years ago, b) this particular form of the gene (well, a small cluster of genes in a particular neighborhood) arose approximately 1.1 million years ago in a lineage distinct from that of modern humans, and c) the likeliest explanation for this difference is that that distinct lineage interbred with modern humans 37,000 years ago, passing on this particular gene variant that was then specifically selected for, a process called introgression.

The work looks sound to me, and I’m convinced. The one thing to watch for, though, is that there will be attempts to overreach and couple possession of this gene to some kind of intellectual superiority. We don’t know what this particular variant of the gene does yet! All we can say at this point is that some abstract data shows that a particular allele spread through the human population at a rate greater than chance would predict, that the gene itself has as one of its functions the regulation of brain growth, but that it is highly unlikely that that particular function is affected by the variant. Whatever it does, I expect the role is more along the lines of subtle fine-tuning rather than simply making people smart.

Hands off those genes

Here’s an annoying case of political correctness run amuck.

…the Human Genome Organisation (HUGO) Gene Nomenclature Committee…is renaming a number of genes that have potentially offensive or embarrassing names.

The shortlist of 10 genes - including radical fringe, lunatic fringe and, bizarrely, Indian hedgehog – was compiled in response to physicians’ worries about “inappropriate, demeaning and pejorative” names.

The problem arose because most of the genes were initially discovered in fruitflies, and their names were then transferred to the human versions of the genes, which were discovered later…when applied to the human versions of the genes, many of these names become uncomfortable.

While no one wants to curtail the creativity of fruitfly geneticists, it will be important to ensure that, in the future, no joky names are adopted for human genes where they might cause offence. Other quirky names in the fruitfly genome include headcase and mothers against decapentaplegia (MAD).

Darn prissy physicians. They’ve got no sense of humor. Will they try to rename one-eyed pinhead next? How about half baked? The zebrafish geneticists are just as amusing, you know.

I’d like to know what the physicians are concerned about, anyway. It’s not as if they’re going to be informing patients that their illness is caused by a broken frizzled gene, nor is it going to be somehow better or easier if they rename it “Wnt Receptor X-17” or something similarly dry and empty. I hope whoever started this knows a good proctologist who can do a stick-ectomy.

And seriously, there ought to be something like the priority rules of taxonomy to prevent random gomers from running around changing names just because they don’t like them.

Join us, Minnesota teachers!

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A while back, I mentioned this new group that had formed here in Minnesota to sponsor better science teaching, the Minnesota Citizens for Science Education. Our first big public meeting is happening this Saturday at the Bell Museum in Minneapolis, at Science Education Saturday:

Some of the most popular and dynamic professors involved with evolutionary biology at the University of Minnesota – Mark Borrello, Randy Moore, PZ Myers and others – will join a panel of public school K-12 educators to present practical suggestions for the classroom, useful resources for teachers and ideas for working with students and your community.

This event is primarily aimed at educators and education students, with talks about precisely what the Minnesota state science standards require of our teachers, but I don’t think they’d turn away other interested parties. I’m not actually going to be speaking (I’m still going to insist that I be regarded as “popular and dynamic”, however, and I may have to put that on my business cards)—I’m moderating a panel discussion with the real deal, teachers who are actually on the front lines of the struggle against creationism—but Randy Moore and Mark Borello will be giving talks in the morning, and I’m sure they’re going to be excellent.

Strange worm, Xenoturbella

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This odd marine worm, Xenoturbella bocki, is in the news right now, and I had to look it up in Pechenik’s Biology of the Invertebrates(amzn/b&n/abe/pwll) to remind myself of what it was. Here’s the complete entry:

Xenoturbella bocki

This marine worm, first described in 1949 as an acoel flatworm and later claimed as either an early metazoan offshoot or a primitive deuterostome, has recently been affiliated with primitive bivalve molluscs, based upon a study of gamete development (oogenesis) and an analysis of sequence data from both 18S rRNA and mitochondrial genes. Little is known about its reproductive mode, and developmental studies that might help to resolve the phylogenetic issues are just starting to be reported. A second species was described in 1999.

The animals are up to 4 cm long, vermiform (worm-shaped), and covered by locomotory cilia. They have no digestive tract, and indeed no organs at all. Their only conspicuous morphological feature, other than their cilia, is a statocyst for determining orientation. To date, they have been collected only off the coasts of Sweden and Scotland, in sediments at depths of 20 m to 100 m.

That’s it. Part of that is now known to be wrong: the data showing an affinity to the molluscs is an artifact, caused by the fact that it somehow eats bivalves, and partly digested clam material contaminated the samples. Otherwise, not much is known; I’ve found papers describing the presence of oocytes inside the animal, but no one as far as I know has actually observed its development. It’s a strange, mysterious blob of a worm.

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The Halloween Cafe Scientifique: an evening of Mad Scientists

On Halloween, I gave a short presentation as our first Cafe Scientifique of the year. The main intent was to introduce our schedule for the year and to give an amusing introduction to the media image of scientists by showing a few movie clips…and to say a few things about how we really ought to be seen.

I’ve put most of the clips on youtube, so you can see what I was talking about below the fold.

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Gum disintegration syndrome

Here’s a weird and trivial phenomenon to consider: gum disintegration syndrome.

I’m not much of a gum-chewer, and never have been…but I remember gum from when I was a kid, and you could chew and chew and maintain a flavorless wad for a long time. Recently, I thought I’d try gum as an appetite suppressant, and I got some of the sugarless stuff. To my surprise, I’d chew on it for a few minutes, and shortly I’d feel it losing its texture and getting runny, and then it would dissolve into small fragments that I’d just swallow. I thought it was those dang cheap confectionery companies, that the formulas for gum base had changed since I was a kid, or maybe it was the sugarless kind that was just different. I tried a couple of different brands—same result. I would have abandoned it there and chalked it up to yet another example of the evils of creeping capitalism and Things Were Better in the Good Old Days, but I mentioned it to my wife, who thought I was nuts. She’s been dipping into my gum, and noticed no difference—it lasts as long as she wants to chew it.

Weird. My wife sent me this Straight Dope article on it, but it’s not very helpful. There’s some speculation that it’s a result of secretions during arousal (unlikely in my case; I can be reading, or driving the car, and it happens…unless perhaps I have a remarkable libido) or temperature (I tried taking the gum out every once in a while to cool, but no difference, it still breaks down. Besides, my body temperature isn’t unusual enough that my doctor has noticed.) At this point it’s simply a mystery. Maybe I’ve acquired some novel new digestive enzymes, but I don’t think I’ve been in any teleporter accidents—if I graduate from dissolving Wrigley’s to novel ways of eating donuts, I’ll let you know.

I’m not concerned about it*—maybe it’s just as well this is a vice I won’t be pursuing—but now I’m curious. Anyone else have the power to reduce gum to soup? Does it only happen in moments of passion? Details!

*Although…if everyone gets a mutant superpower in their life, and mine is the ability to digest gum instead of acquiring laser eyeballs or telepathy or super-regeneration, I’m going to feel ripped off.

A Devonian lamprey, Priscomyzon

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Reconstruction of Priscomyzon in dorsal (top) and left lateral (bottom) views. b, Macropthalmia stage of Lampetra showing anterior location of orbit and smaller oral disc, both positioned in front of the branchial region. The total length of the specimen is 116 mm. Drawings in a and b are scaled to show equivalent head lengths: from anterior limit of the oral disc to rear of the branchial region. Horizontal bars indicate the anterior–posterior span of the oral disc in each species.

The life of a parasite must be a good one, and often successful; the creature at the top of the drawing above is a primitive lamprey from the Devonian, 360 million years ago, and the similarities with the modern lamprey (at the bottom) are amazing. It’s less eel-like and more tadpole-like than modern forms, but it has the same disc-shaped mouth specialized for latching on to the flank of its host, it has similar circumoral teeth for rasping through scales and skin for its blood meal, the same pharyngeal adaptations for a life spent clamped to a fish.

I’ve put a photo of the fossil and a cladogram below the fold.

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Lucy is going on tour

The remains of Lucy, the famous fossil australopithecine, are going to be touring the US for the next few years. Start lining up. It’s opening in Houston.

The six-year tour will also go to Washington, New York, Denver and Chicago. Officials said six other U.S. cities may be on the tour. But they would not release the names, saying all the details had not yet been ironed out.

Minneapolis, maybe? I hope? Otherwise I’m going to have to make a trip to Chicago.

No word yet on whether the Answers in Genesis museum near Cincinnati will be bidding on the exhibit.