Why are there no insects in the sea?

June 19, 2011 • 3:05 am

by Matthew Cobb

One of my favourite questions relating to evolution is ‘Why are there no insects in the sea?’ Arthropods came onto the land around 380 MY ago, and crustaceans and insects separated soon afterwards, probably because of that ecological shift. More or less, you get crustaceans in the sea, and insects on land. So why didn’t the insects go back into the sea? It’s very hard to be certain of the answer to this – doing an experiment would be pretty tricky, after all. But we can get towards what might be the answer by thinking about some of the possible answers we might give:

– Insects can’t live in water. Although no insect species lives its whole life-cycle in water without access to air, many insect species pass their nymphal stage in freshwater, breathing with gills. Mayflies (more on this in an upcoming post) and dragonflies are two obvious examples. Last year Daniel Rubinoff, an entomologist at the University of Hawaii, discovered a number of moth species that have caterpillars (= larvae) that are equally at home on land or in freshwater. You can see a great video of one of these caterpillars moving between water and land here.

– Insects can’t cope physiologically with salt water. Not true. There are a large number of species of insect that have a larval stage that lives in brackish salt water, so living in the sea is not impossible. (Indeed, this fact shows that the real question should be ‘Why are there no insects that have their full life-cycle in the sea?’)

– The sea is full. I think this is probably the right answer – the niches that insects would occupy in the sea are already full. The insects’ cousins, the crustaceans, are already there. This is what ecologists call ‘competitive exclusion’. Any insect that started going back into the sea would either starve or be eaten, I reckon. Proving this, however, is tricky.

One implication of this is that evolution finds it difficult to go ‘backwards’ because life shapes and changes the ecosystem over time. When environmental conditions changed to make it possible for terrestrial life to evolve, crustacean-like arthropods moved onto the land and rapidly made a series of adaptations that led to their incredible success as insects (reducing the number of appendages, evolving first wings and then highly specialized larval stages, and so on). Retracing their steps back into the sea is no longer possible, for ecological reasons. Were something terrible to happen to some or all of the crustaceans, however, it seems pretty likely that those adaptable insects would be back in the sea in the blink of a geological eye.

The Guardian’s 100 greatest nonfiction books

June 18, 2011 • 8:02 am

For some reason, the Brits do “best book lists” much better than Americans.  The Guardian just published its list of the “100 greatest non-fiction books,” and it actually looks pretty good.

Sadly, only 5 of them are science books, but these choices aren’t too bad. I would have left off Hawking, but for general readers it’s a decent list.

On the Origin of Species by Charles Darwin (1859)
Darwin’s account of the evolution of species by natural selection transformed biology and our place in the universe

The Character of Physical Law by Richard Feynmann (1965)
An elegant exploration of physical theories from one of the 20th century’s greatest theoreticians

The Double Helix by James Watson (1968)
James Watson’s personal account of how he and Francis Crick cracked the structure of DNA

The Selfish Gene by Richard Dawkins (1976)
Dawkins launches a revolution in biology with the suggestion that evolution is best seen from the perspective of the gene, rather than the organism

A Brief History of Time by Stephen Hawking (1988)
A book owned by 10 million people, if understood by fewer, Hawking’s account of the origins of the universe became a publishing sensation

Here are some contenders I thought of:

The Eighth Day of Creation by Horace Freeland Judson.  An underrated and underappreciated book.  As I’ve said, this is the best history of molecular genetics around.

The Peregrine by J. A. Baker.  Still the greatest natural history book I’ve ever read.

The Blind Watchmaker by Richard Dawkins. Perhaps not as “scholarly” as The Selfish Gene, but maybe a better read for the layperson.

The Collected Essays of Stephen Jay Gould. This book doesn’t exist, but stands for his entire output of 300 essays for Natural History. It’s very hard to pick just one collection.

The First Three Minutes by Steven Weinberg.  I try to read popular physics books, but I’m often defeated. Maybe I’m just attuned to evolution.  This one, however, did engage me.

The Language Instinct by Steven Pinker. Still his best, and a classic.

Coincidentally, my own pick of the five best evolution books, accompanied by a long interview in which I wax eloquent about them, will appear in a few days on Five Books. (That site is rapidly becoming a must-bookmark for bibliophiles; check out the latest picks of other scientists in the “interview” section.)

Free free, as always, to weigh in.  I’d especially appreciate hearing about some good physics books for the inquiring biologist.

h/t: Matthew Cobb

Caturday Felid: A-Kat-Aten

June 18, 2011 • 6:30 am

by Greg Mayer

The ancient Egyptians would give anyone a run for their money when it comes to the care they lavished on their cats. Here’s a ca. 2000 year old cat mummy from the British Museum.

Egyptian cat mummy, ca. 50 BC, at the British Museum, by Mario Sanchez, Flickr.

Cats, miw or mau in Egyptian, were frequently mummified, along with other animals, and the cat Goddess was Bast. A traveling exhibit of mummies of all sorts, Mummies of the World, is touring the US; it is now in Philadelphia.

Update. Some readers wondered if the cats died natural deaths. From Reflections of Greatness, the catalogue of the Carnegie Museum of Natural History’s Egyptian collection, by Diana Craig Patch:

These animals were attended by priests and lived out their lives in relative comfort.  After an animal’s death, the priests mummified it so that it too could have eternal existence alongside its protector. … At some point, the priests realized that they could increase a temple’s income by selling mummified sacred animals as votive offerings… Since large numbers of animals were required, priests did not allow them to die of old age; instead most were slaughtered when they reached adulthood.

Tough times for Grayling

June 18, 2011 • 6:23 am

Anthony Grayling has had some rough sledding over the past few weeks. His new book, The Good Book: A Humanist Bible, failed to draw universal approbation. And his idea of founding The New College of the Humanities, an elite university that would bring in famous lecturers like Richard Dawkins and Steve Pinker, has met with a lot of scorn, mainly because the tuition would be £18,000 per year.

It also didn’t help that, as the Guardian revealed yesterday, the college is being underwritten to the tune of £200,000 by Peter Hall, a conservative who has donated nearly half a million pounds to the Tories.  Hall was approached for this donation by Grayling himself.

The rancor towards Grayling, whom I’ve always liked, is driven by charges of hypocrisy. As the Independent notes,

The author of more than 30 books has set himself up as a champion of fairness and equality. His humanist principles include the notion that religious groups “have no greater right than anybody else, any political party or Women’s Institute or trade union”. Writing in The Guardian in 2009, he complained of the “overweening privilege” accorded to religious lobbies and said it was easy to show that “the mindset which looks for and tests the facts rather than shores up ancient edifices of authority is likely to make the world a fairer one economically and in power relations too”. He is seen as a liberal and, until this week, a supporter of the public education system.

Just yesterday, the controversy impelled Grayling to resign as the incoming president of the British Humanist Association. He was due to take over on July 1, but issued this statement:

It was an honour to be named President of the British Humanist Association and I very much looked forward to working alongside the staff and trustees over the next two years to promote Humanism – a vitally important task in today’s world. Unfortunately, I believe that controversy generated by activities in another area of my public life will make it difficult in the next two years for me to be the sort of President that I would like to be for the BHA and all its members and supporters. In deciding to stand down and let the Trustees of the BHA appoint an alternative President, I wish them all the best in their important task.

I haven’t had strong feelings about New College, but I confess to some disappointment that champions of rationality and, presumably, of the “common man” would take part in such a high-priced venture.  I’d like to hear readers’ opinions.

But one thing is clear: Grayling, charismatic as he is, hasn’t handled public relations about New College at all well.  For one thing, he needs to put away the hairspray when the journalists visit:

Even his crowning glory is held in place only by “a bit of sticky stuff just to hold it up there”, he protested to interviewer Decca Aitkenhead in April. When another journalist visited the philosopher’s home last week, he discovered nine cans of hairspray in the toilet on the “his” side of the sink, mostly Pantene’s Ice Hold brand. Even for AC Grayling, some things are sacred.

And his hair was perfect

Ophelia channels Stedman

June 18, 2011 • 5:50 am

Go read why the left and the Tea Party must work together:

This is my healing work that I plan to do. I believe in love and reaching out and bridges and unity. I hope you all wish me luck and every success with my work, which I will be working on in many ways for many weeks to come, and which I will be reporting on via Twitter, Facebook, the New York Times, the Washington Post, People, USA Today, the Huffington Post, Tikkun, First Things, Christianity Today, my seven blogs, some of my friends’ blogs which I haven’t counted yet, and CBS News. In spite of all this fame and exposure I remain impressively humble and kind of bashfully surprised by all the success and approval I report daily via Twitter, Facebook, the New York Times, the Washington Post, People, USA Today, the Huffington Post, Tikkun, First Things, Christianity Today, my seven blogs, and some of my friends’ blogs which I haven’t counted yet.

Bachmann: teach both sides, no matter how stupid

June 17, 2011 • 5:50 pm

O Ceiling Cat, if you make Michele Bachmann the Republican presidential candidate in 2012, I’ll never doubt your existence again.  Surely somebody that looney, someone who so vociferously favors the teaching of intelligent design, could never be president of our great nation.

From CNN (today):

“I support intelligent design,” Bachmann told reporters in New Orleans following her speech to the Republican Leadership Conference. “What I support is putting all science on the table and then letting students decide. I don’t think it’s a good idea for government to come down on one side of scientific issue or another, when there is reasonable doubt on both sides.”

Intelligent design suggests that the complexity of the universe cannot be explained by evolution alone, and must also be attributed to a creator or supernatural being.

“I would prefer that students have the ability to learn all aspects of an issue,” Bachmann said. “And that’s why I believe the federal government should not be involved in local education to the most minimal possible process.”

Or, better yet, make Bachmann vice president on a Palin-Bachmann ticket.

Four crazy eyes

UPDATE: from the horse’s mouth, via Zack Kopplin:

And if you go to this page, you’ll hear her answer when she’s asked to identify those Nobel Laureates who “believe in intelligent design.”  Guess how many she can name?

Chris Stedman stole our word

June 17, 2011 • 8:54 am

Chris Stedman, who works for the Humanist Chaplaincy at Harvard, is an interfaith activist well known for his coddling of faith, his passive-aggressive hatred of all things Gnu, and his patronizing essays on how atheists must behave.  His new book, coming out next year, has a title purloined from our own dialogue:

The one good thing about this: accommodationists can no longer kvetch that “faitheist” has pejorative connotations (it didn’t start out that way anyway).  After all, Stedman wears the label proudly!

h/t: Sigmund