The biology of Mauritius: part 2

July 2, 2011 • 9:09 am

Yesterday I presented some photographs and descriptions by biologist Dennis Hansen of his work on the isolated island of Mauritius.  That only scratched the surface of the amazing biology of the endemic species on this island, and I want to finish up this brief lesson with some more show-and-tell.

Dennis also sent me an reallly nice paper written by him and Christine Müller in The International Journal of Plant Science (reference below).  It describes how one species of very rare Mauritian plant seems to be both pollinated and have its seeds dispersed solely by a lovely endemic gecko. Maybe I’m wrong, but I think this is the only case of a plant that depends entirely on a lizard for reproduction.  But I’ll let Dennis tell the tale (his photographs are below, and I suspect that if you leave your email address in a comment, he’ll send you a pdf of the paper, which is well worth reading):

Anyway, here’s a handful of shots from the field—one of my favourite Mauritian endemic plants, Roussea simplex, being both pollinated (photo 1 &2) AND having its seeds dispersed (photo 3) by the same gecko species, the blue-tailed day-gecko, Phelsuma cepediana. It’s a cool system, but under threat from invasive ants that chase off the geckos (!), and invasive plants that outcompete Roussea simplex. There are likely less than 150 plants left of this species. Don’t worry. In Mauritius, that’s plenty (like Douglas Adams recounted for the Rodrigues fruit bat in ‘Last Chance to See‘ — “don’t worry, there are HUNDREDS of bats left!”). Yes, many species—and even more interactions—are in trouble indeed. The paper about this interaction even made it to the front cover of a journal from your university press (Int J Plant Sci). Who cares that this paper probably will pick up less than 10 citations in its lifetime—it made me feel immensely privileged to have studied this interaction. If nothing else, then because it means that it will not—unlike Quammen puts it for The Song of the Dodo—forever remain unbeknownst to us, because no one took the time to sit down in the forest and listen (or watch, in this case).

Photo 1:

Photo 2:

Photo 3:

Here’s a photo I’ve taken from Hansen and Müller’s paper showing the lizard with a smear of pollen on its head (arrow). The pollen is mixed with a sticky, viscid residue, and so is unsuitable for disperal by insects, but fits nicely on the lizard’s head.  And when the lizard goes to the next plant for nectar, the pollen is transferred to the stigma.


Curiously, though seed dispersal appears to rely entirely on the gecko, seeds that were recovered after passing through geckos, or taken directly from the plant, were never seen to germinate.  They were all attacked by a fungus that killed them. Perhaps the specific microclimate of the forest floor somehow facilitates seed germination.

But wait—there’s more.  Again, I defer to Dennis’s descriptions:

Colea colei: an amazing little understory plant from the rainforest in Mauritius, sort of like a thin, upright liana up to a few meters high, with a tuft of green leaves at the top. It is cauliflorous, with the gorgeous flowers emerging straight from the stem, all the way down to the ground (don’t get me started on the cool evolutionary ecology of that trait).

Telfair’s skink [Leiolopisma telfairii] with Pandanus fruit: from Round Island, north of Mauritius. Heaven on Earth, that island is. Home to many of the surviving endemic reptiles of Mauritius. I think of Churchill with a cigar whenever I look at this photo. [JAC: this island is the only place known to harbor this reptile.]

One of my favourite geckos, the Ornate Day Gecko, Phelsuma ornata:

Two of the huge orb-weaving spider Nephila inaurata & its gecko-victim: sometimes male geckos will jump off the surface they are on, if threatened by a larger male. In this case, the poor fella jumped right into the web of the spider! The second photo shows the gecko two hours after the spider’s injection of digestive enzymes (several points of injection). Kinda looks like it’s been hit by a flame thrower.


One of a Dombeya flower—notice the secondary pollen presentation on the tip of the petals, and the yellow nectar at the base of the petals.  Coloured nectar is an incredible subject on its own, but I will refrain from harping on at great length here.

One of Telfair’s skink, Leiolopisma telfairii, on a palm inflorescence. All the yellow spots in its face are pollen grains, too.

Some of the largest surviving Phelsuma [genus of “day geckos”] gecko, Guenther’s gecko [Phelsuma guentheri]:

Some more of the Blue-tailed Day Gecko, P. cepediana, pollinating flowers of Trochetia blackburniana (notice the size difference between the large male hanging off the flower, and the small female/juvenile almost disappearing into the flower)


THE END

Thanks to Dennis for sharing his work and photos with us.

_________

Hansen, D. M. and C. B. Müller.  2009.  Reproductive ecology of the endangered enigmatic Mauritian endemic Roussea simplex (Rousseaceae).  Int. J. Plant Sci 170:42-52.

Sam responds to the “transcendence” issue; I respond to him

July 2, 2011 • 4:51 am

Yesterday I highlighted Sam Harris’s Q&A session with Reddit readers, and posed my own question to him, one prompted by his drawing a distinction between the low-level “spiritual” experience of, say, watching a sunset, and the more powerful transcendent experiences of religious people, those who meditate, and mystics.  My question for Sam was this:

“So if we accept that people do have these seriously transcendent experiences, what follows from that—beyond our simple desire to study the neurobiology behind them?”

I’m chuffed that Sam has actually answered this question over on his site, in a new post called “What’s the point of transcendence?”

He has four answers, which I list below, but you’ll want to read his explanation in full, especially because he responds specifically to some of the comments that you readers made yesterday:

  1. It is possible to feel much better (in every sense of “better”) than one tends to feel.
  2. There is a connection between feeling transcendently good and being good.
  3. Certain patterns of thought and attention prevent us from accessing deeper (and wiser) states of well-being.
  4. Certain “spiritual” experiences can help us understand science.

I’ll be brief in response, taking up his points in order:

1.   Sam notes that transcendent experiences confirm religious people in their faith, and block their transit to nonbelief.  This is undoubtedly true for some people, but I do wonder how many of the religious really have felt “utterly at ease in the world—and such ease is synonymous with relaxing, or fully transcending, the apparent boundaries of the ‘self.’” Certainly many have, but I am curious how many religious people would tick a box on a survey saying that they’d had this experience.

Regardless, while I agree with Sam that “these states of mind act as a kind of filter: they get counted in support of ancient dogma by the faithful,” I strongly disagree with his claim that “their absence seems to give my fellow atheists yet another reason to reject religion.”  We already have plenty of reasons to reject religion, foremost among them the lack of any evidence for religious claims.  I doubt that there are any of us who question the “reality” of transcendent experiences among the faithful.  Just watch any video of fundamentalist congregations weeping or speaking in tongues, or of Orthodox Jews davening in the synagogue.  What we doubt is not the existence of these states, but the interpretation of what they mean.  They are not evidence for the truth of religious claims.  Period.  How much, really, has atheism been held back by our denial of such spiritual states?  Very little, I would think.

2.  Sam argues that these transcendental experiences make one more ethical: “There are states of consciousness for which phrases like 1boundless love and compassion’ do not seem overblown.”  I submit that here Sam may be projecting from his experiences with Buddhism, and that for other faiths the connection between transcendence and morality is tenuous.  How can we test his claim? By showing that religious people—who, after all, are supposed to experience these mental states quite frequently—behave more morally than do atheists.  I  submit that there’s no evidence for that assertion, and, in my opinion, it’s probably wrong. Are atheists really below par in in the morality department?  Look to many countries in Western Europe, where belief is low, for one answer.

3.  Sam claims that transcendent states can give us insights not available under normal experience, and convey a greater sense of well-being.  I agree with him on this.  Having briefly engaged in meditation for a while (and abandoned it simply because I was too impatient to sit without thinking), I know that it reduces stress, makes one realize the pettiness of one’s problems, probably makes one healthier in body as well as mind (though I’m not aware of evidence bearing on this), and, perhaps by enabling reflection, helps one solve problems.  Some of my drug experiences in college left me with a permanent and salubrious residue: most notably a sense of wonder about and appreciation of everyday things—things as simple as a rabbit or an ice cream cone.  I’m sure this has helped me maintain the sense of wonder that is vital fuel for an evolutionary biologist.

But I’d also claim that if every religious person gave up their faith and simply meditated instead, the world would be a much nicer place.  Validating the transcendent experiences of the faithful doesn’t move us towards this goal.

4.  Sam argues that some scientific progress is facilitated by having transcendent experiences:

There are insights that one can have through meditation (that is, very close observation of first-person data) that line up rather well with what we know must be true at the level of the brain. I’ll mention just two, which I have written about before and will return to in subsequent posts: (1) the ego/self is a construct and a cognitive illusion; (2) there is no such thing as free will.

Again, is the support for this claim anything other than personal experience?  I agree with both of Sam’s points, but was convinced of their veracity not through meditation, drugs, or religion, but simply through rational contemplation.  And I believe that others who agree also do so largely from thinking about these issues.

Now it’s true that secular (and Buddhist) meditation may help one gain these insights (particularly the first), but I also submit that transcendent experiences of the religious sort prevent one from arriving at these conclusions.  After all, religion—at least of the Abrahamic variety—tells us we have a soul, the antithesis of an illusory ego.  And the idea that we really do have free will is behind most Christian doctrine on sin; for your fate absolutely depends on exercising that will (unless, of course, you’re a Calvinist).   So while this may be an argument for meditation, it’s not an argument for transformative experiences of the religious kind.

In sum, I think Sam’s points constitute a compelling argument for secular, contemplative meditation, which might benefit many of us.  Whether that activity produces “transcendent” experiences more powerful than those gained from, say, contemplating the immensity of the universe, or the amazing accomplishments of natural selection, is a point up for grabs. But I’m not convinced that grasping the reality of even genuinely deep transcendent experiences will make us more understanding and more powerful opponents of religion.  We already have plenty of weapons in our arsenal against that form of delusion.

I’ve never seen an atheist reject religion because they didn’t apprehend that religious people often have powerful “spiritual” experiences.  But I’ve seen plenty of us reject religion because we see these experiences as purely subjective, and not proof of any divine realities.  In The End of Faith Sam argues that “moderate religions” are pernicious simply because they enable the more virulent forms.  By somehow “validating” the transcendent spiritual experiences of religious people, we are in danger of doing the same thing for religion in general.

Ancient bird pigments identified

July 1, 2011 • 2:11 pm

I’ve previously written about work identifying the colors of feathers in fossil dinosaurs (birds, of course, evolved from feathered dinosaurs).  These colors were assumed by looking at the shapes of melanosomes (pigment granules) in the fossils and judging the color from the shape of the granules—assuming granule shapes were conserved between fossil and modern birds.  Now, however, according to a new paper in Science by Wogelius et al., we can guess the colors more directly by a method (Synchrotron Rapid Scanning X-Ray Fluorescence, or SRS-XRF) that can detect trace metals that are attracted by some pigments.  Using this, the authors found that a fossil bird, Confuciusornis sanctus, appears to have had had the pigment eumelanin, which is blackish-brown.

C. sanctus is the first known bird that had a true beak, and lived about 120 million years ago. The fossil is to the left below (A, images from the paper) and the SRS-XRF scan, with false color, to the right (B).  Copper shows up as red, and is in especially high concentration in the neck feathers.  This, along with other analyses, suggested that those regions had high concentrations of the pigment eumelanin, which binds copper.

When they examined the copper-rich region of the neck feathers with scanning electron microscopy, they found the region full of bodies that looked like “eumelanosomes” (pigment granules containing eumelanin).  These granules were also found in some of the flight feathers.   Here’s one of the copper-rich granules.

To verify that these were not artifacts, they looked at a variety of material from other living or fossil species, including other animal parts known to be high in copper (fish eyes) and feathers of living birds, which also showed a correlation between eumelanin pigment density and high copper detected by SRS-XRF.

Conclusion:  C. sanctus had the pigment eumelanin in its neck feathers, so it probably had dark downy feathers, shading into lighter colors at the tips of the flight feathers, where copper concentration is lower.  The distal flight feathers had no trace metals, and so were probably white or another color.  Our best guess, then, is that this ancient bird was parti-colored.

_______

Wogelius, R. A. et al. 2011.  Trace metals as biomarkers for eumelanin pigment in the fossil record.  Science (early view): 10.1126/science.1205748

h/t: Greg Mayer

Ask Sam

July 1, 2011 • 7:17 am

Sam Harris has recorded a new video in which he answers questions from Reddit readers.  It’s nearly an hour long, so you might want to watch it while having lunch or doing some other light task, as there’s nothing heavyweight here that requires extreme concentration. However, it’s still worth watching, for Sam takes up a number of good questions, and some of his answers are provocative.  The questions include these (I’ve paraphrased them, and put asterisks and times for the ones that most interested me):

How do we best advance our agenda of rationality and atheism?

What’s up with all your meditation experiences?  What did it do for you, and what does that mean for the rest of us?

Should we be afraid of using the term “spirituality”?

There was a fair amount of criticism of your latest book, The Moral Landscape.  Did you think any of it had substantial merit?

**Why should atheists take seriously the “transcendent” experiences reported by the faithful and others? (starts 14:07).

You’ve admitted to the use of MDMA (Ecstasy).  What was your experience like, and did you consider it beneficial?

Can one ethically defend eating meat?

Why are you so concerned with personal security?

Why isn’t atheism to blame for Stalinism and Nazism?

**Is there anything said in defense of religion that has ever given you pause or made you think you were wrong in attacking it? (starts at 38:00)

How can we really measure “well-being”—your ultimate criterion for judging morality—given all the possible and unknowable consequences that could result from a given act (for example, even nuclear accidents might be “good” in the sense that they could make us more careful in the future and ultimately save more lives)?

What kind of research are you up to in neuroscience?

To me the most interesting part begins at about 14:07, when Sam talks about the non-equivalence of our “spiritual experiences of beauty and awe” with the real and much deeper transcendent experiences reported by religious people, mystics and those who meditate. Sam says this:

“There’s a spectrum of experience that we have to acknowledge that many, many millions of people have experienced that is a hell of a lot more interesting in the end—and transforming of the human personality—than just being in awe at the beauty of nature. So atheists deny this at their peril because people who have had these experiences know that they’re not being captured in this language of: “What a beautiful sunset.”

This discussion continues at 21:25, when Sam criticizes atheists, scientists and secularists for failing to “connect to the character of those experiences” and for failing to “give some alternate explanation for them that is not entirely deflationary and demeaning and gives some warrant to the legitimacy of those experiences.”  He implies that these experiences are somehow beyond the purview of science.  I find that strange given Sam’s repeated emphasis on the value of science in studying mental states.

I’m not quite sure what he’s getting at here, and he doesn’t elaborate, but I don’t see why giving credence to these über-transcendent experiences as experiences says anything about a reality behind them.  Yes, they might indeed change one’s personality and view of the world, but do any of us deny that?

I had similar experiences on various psychoactive substances when I was in college, and some of them were even transformative.  The problem is not with us realizing that people can feel at one with the universe or, especially, at one with God; the problem comes with us taking this as evidence for some supernatural reality.  What does it mean to say that an experience is legitimate?  If someone thinks that he saw Jesus, I am prepared to believe that he thought that he saw Jesus, but I am not prepared to say that he really did see Jesus, nor that that constitutes any evidence for the existence of Jesus.

So my question for Sam would be this:  “So if we accept that people do have these seriously transcendent experiences, what follows from that—beyond our simple desire to study the neurobiology behind them?”  (I’d also like to ask him why he always wears black!)

h/t: Grania Spingies for the video

Biology: a reader reports from Mauritius

July 1, 2011 • 6:07 am

Mauritius is a small volcanic island of about 2000 square kilometers, located 900 km east of Madagascar.   Because of its origin as an oceanic island that formed bereft of any life, it’s home to many rare and endemic species (some of which, like the dodo, are extinct).

When I asked readers to send photos of their biological research,  Dr. Dennis Hansen, who is based at the Institute of Evolutionary Biology and Environmental Studies of the University of Zurich, came though in spades.   He sent well over a dozen photos of his work on Mauritius, all of which were gorgeous. I’ll highlight some of them today and the rest tomorrow.  First, a map:


Then a view, described by Dennis thus:

 A morning view from the most famous mountain in Mauritius, Le Morne. It is like a miniature South American Tepuis; we went there by helicopter to study the national flower of Mauritius, whose last populations survives on the vertical cliffs of the mountain. Up there, looking across to the southwestern Black River Gorge mountains, one can almost forget that the island also houses a destructive human population of 1.3 million on a mere 1865 square kilometers. Almost.

The first involves one of the world’s rarest birds: the Echo parakeet (also called the “Mauritius parakeet”), Psittacula echo, found on the southwest part of the island. If you’ve read Last Chance to See, you’ll know about the extraordinary effort expended in saving this gorgeous bird. Once down to a mere 9 individuals, and about to become an ex-parakeet, captive breeding has brought the population back to about 290 individuals. It’s one of the great success stories of conservation.  Here are a couple of Dennis’s pictures; they are all of the same individual, named “Alpha” (note the band):

Some of these birds are so tame that they’ll do this:

Dennis described Alpha as “a sadly slightly too tame, hand-reared Echo parakeet. He hung around our field station in the rainforest & loved stealing my morning coffee.”  When I asked him if Alpha did this often, and if he really liked the coffee, Dennis replied, “Yes, Alpha the Echo had a beak for coffee. I never let him drink it on purpose, and tried to keep him off my cup (easier said than done). But just this once I thought I’d want a photo of him in flagrante delicto.”

There’s a good description of how work is going on this species at the Odyssey website.  Here are two photographs (by Genevieve and Chris Johnson, respectively) of a hand-reared Echo parakeet abandoned by its parents. Note the full crop in the first photo!

Here’s a chick being weighed.

The next species is endemic to the Seychelles, an archipelago whose location is on the map above. (By the way, both Mauritius and the Seychelles have endemic species of Drosophila in the D. melanogaster subgroup, D. mauritiana and D. sechellia respectively. I’ve spent years working on these species, and have published quite a bit on them, but, sadly, I’ve never had the privilege of visiting either island).

If you thought that the giant land tortoise was endemic only to the Galápagos, think again.  The Aldabra atoll (a series of island in the Seychelles) has its own (smaller) species of giant tortoise, Aldabrachelys (or Geochelone) gigantea.  And while there about 19,000 individuals in toto on the Galápagos, there are more than 150,000 individuals of the Aldabra species.   Some of them have been transplanted to Mauritius to replace its extinct endemic tortoise, and that’s where these photos come from.  First, a tortoise eating a fruit:

Look at those jaws!  Dennis reports that this, however, is a yawn:

And of course all of those tortoises have to come from somewhere.   Dennis describes the photo below:

Two giant Aldabra tortoises having fun at the La Vanille Tortoise Reserve in Mauritius (where we do a lot of our feeding experiments). You can’t spend more than 30 minutes around these behemoths before you hear/see it. Cracks me up every time.

Note the huge disparity in size between male and female (also seen in the video below):

Dennis also sent a link to a 26-second video of mating Aldabra tortoises (below). You’ll find it sad, touching, and hilarious.  I still wonder how insemination can really occur this way!

Tomorrow: gorgeous geckos that pollinate flowers.

Oh, and heeeere’s Dennis:

The weevil with screws in its legs

June 30, 2011 • 1:49 pm

by Matthew Cobb

One of the things that natural selection hasn’t created is the wheel (and don’t give me all that stuff about the golden wheel spider rolling up and bowling down Namibian sand-dunes to escape from a predatory wasp! That doesn’t count and you know it. I mean a wheel and an axle). It also hasn’t created the screw. Or rather, it hadn’t. In a brief article that has just appeared in Science (subscription needed to get past abstract—grrr), Thomas van der Kamp, Patrik Vagovic, Tilo Baumback and Alexander Riedel from Karlsruhe and Berlin describe how the leg joints in the weevil Trigonopterus oblongus “work as a biological screw-and-nut system”. And it might just be related to why there are no wheels in nature, or at least in weevils.

Here’s the only figure in the article. It shows reconstructions of the ‘coxa’ (the first leg joint, where the leg joins the thorax) in green, and the trochanter, the first leg segment, in yellow. The coxa is the thread, the trochanter the screw. There’s also a nice scanning electron microscope image of the trochanter. The system works pretty much like your hip does – except the knobbly bit at the end of your hip has turned into a screw shape. (All the nerves and stuff run down the centre of the trochanter.) Most insect joints work like hinges.

The 3D reconstruction [(A) to (E)] of coxa (green) and trochanter (yellow) of left hind leg of T. oblongus. (A) Depressed position. (B) Elevated position. (C) Coxa cut horizontally along rotation axis; dorsal aspect of trochanter while leg depressed. (D). Isolated trochanter showing external spiral thread and tendon (t). (E) Dorsal portion of coxa corresponding to ventral portion of (C). (F) Scanning electron microscope photograph of the right metatrochanter showing posterior condyle (c) and external spiral thread (e).
So why doesn’t the leg unscrew itself? Most of the weevil’s leg motion will not involve a 360 degree rotation, or the hapless insect would get stuck after a couple of paces. Instead it will simply swing back and forth. Doesn’t the leg get blocked when it’s screwed in to the max? Presumably so, in which case careful observation should show weevils back-pedalling to unwind their legs. And conversely – why doesn’t the leg come unscrewed? The muscles appear to hold it in place. Phew!
The Science website has a little article about this and a nice image showing SEMs of both screw (r) and thread (l), and of the weevil itself:
Credit: Science/AAAS
Now why does the weevil have this odd arrangement? The obvious advantage is that you can rotate the leg right round. But in that case, why not evolve the axle/wheel combination? The authors speculate that the screw might be better:
We suggest that an advantage of this construction is that the leg comes to a stable resting position, preventing passive straining of leg muscles, which would not be accomplished by an axle construction.
Above all, they think that it might be the weevil’s unique feeding posture, where it shoves its rostrum (its ‘snout’) into its food, that holds the key. Substantial forces will be generated on the weevil’s legs as it tries to grip the substrate; having a screw would effectively block the rotating joint, stopping the weevil from ending up with its head smashed in the food.
If you don’t understand what I mean – try it; put your palms flat on the table, your arms braced, then put your face down onto the table; flex your arm muscles (the equivalent of the screw-lock) and you’ll be fine –  let them go (the equivalent of having an axle) and you’ll end up with your head on the table… Most undignified – even for a weevil.
[EDIT – various points clarified after a hasty first draft! h/t Jerry and Adam M. You can sort the rest of it out yourselves in the comments…]

Another accommodationist book on evolution

June 30, 2011 • 5:34 am

Why do accommodationists have to spoil a perfectly good book on evolution by dragging in a lot of stuff about God? I barely touched on the subject in WEIT, merely stating that “elightened faith” (what I meant was deism) had no problem with evolution; and if I had it to write again, I’d leave that sentence out.  You can tell people about evolution, and give them the evidence, without dragging in theology.

Unless, that is, you’ve won the Templeton Prize.  Last year’s winner, evolutionist Francisco Ayala, has a new book, Am I a Monkey? Six Big Questions About Evolution,  published by Johns Hopkins University Press.

Here are the six big questions:

• Am I a Monkey?
• Why Is Evolution a Theory?
• What Is DNA?
• Do All Scientists Accept Evolution?
• How Did Life Begin?
• Can One Believe in Evolution and God?

Lest you have any doubt about how Ayala answers the last question, here’s the Press’s blurb:

This to-the-point book answers each of these questions with force. Ayala’s occasionally biting essays refuse to lend credence to disingenuous ideas and arguments. He lays out the basic science that underlies evolutionary theory, explains how the process works, and soundly makes the case for why evolution is not a threat to religion.

Now if you take the last question literally, the answer is “Of course you can believe in evolution and God—lots of people do.”  But that’s not how Ayala construes the question, as you can see from the blurb above: he’s asking whether evolution is a threat to religion.  And the answer to that is “Yes, of course it is, for millions of religious people see it that way, and for very good reason.”

Obviously, in a book about evolution, Ayala is going to propose a form of religion in which evolution isn’t seen as a threat. But that’s not evolution, it’s theology.

I could easily write a similar book, but with a final chapter that answers that same question in a completely different way. But of course that book wouldn’t be promoted by the National Center for Science Education.