The Loom » The Tangled Bank

Animal Friendships: My cover story for Time magazine

Carl Zimmer — Thu, 09 Feb 2012 15:42:33 +0000

I’ve got a story on the cover of the latest issue of Time. It’s about the evolutionary origins of friendship. For a number of scientists, friendship–in a deep sense of the word–is not limited to our own species. The fact that friendship may be a widespread biological phenomenon could help us better understand why it has such a positive effect on our own health.

If you’re interested in the scientific literature, the best way in–and the way I first started to get familiar with it–is this review in the latest issue of Annual Review of Psychology by Dorothy Cheney and Robert Seyfarth, two of the world’s leading primatologists.

One thing that I delve into in the story is the question of just how widespread animal friendship really is. We don’t know, in large part because scientists haven’t done that many long-term field studies on wild animals. When scientists do watch dolphins or baboons for decades, they can see some bonds between unrelated individuals that last for long stretches. (Yet another value that comes from slow-cooked science.) On the other hand, what may look like friendship may just be anthropomorphic ...

Evolving Bodies: A Storify follow-up

Carl Zimmer — Wed, 18 Jan 2012 17:51:57 +0000

In yesterday’s New York Times, I wrote about a new paper in which scientists report the evolution of single-celled yeast into multicellular snowflake-like “bodies.” Most (but not all) of the experts I contacted for the story had high praise for the study. (It also won an award when it was presented as a talk over the summer at the Society for the Study of Evolution.) Once the story appeared, however, some scientists took to Twitter to express their skepticism. As much as I like Twitter, this is one of the situations where it fails. You can’t have a conversation about genetics, lab strains versus wild types, etc., in 140 character chunks. At least not very satisfying ones.

So here’s what I decided to do last night. I used Storify to collect the comments of Leonid Kruglyak of Princeton and Michael Eisen of Berkeley, and then passed them on to Will Ratcliff, the lead author of the new study. He then responded. Below you’ll find the Storify tweets, and then Ratcliff’s response. Please continue the conversation in the comment thread. (And be sure to download the paper–it’s open access.)

[View the story "Yeast evolving" on Storify]

Will Ratcliff responds:

Well, I ...

Evolving Bodies: My new story in tomorrow’s New York Times

Carl Zimmer — Tue, 17 Jan 2012 01:25:18 +0000

In the history of life, single-celled microbes have evolved into multicellular bodies at least 25 times. In our own lineage, our ancestors crossed over some 700 million years ago. In tomorrow’s New York Times, I write about a new study in which single-celled yeast evolved into multicellular forms–completely with juvenile and adult forms, different cell types, and the ability to split off propagules like plant cuttings. All this in a matter of weeks. Check it out.

(The paper is not yet online yet, but here’s the reference: “Experimental evolution of multicellularity,” William C. Ratcliff, R. Ford Denison, Mark Borrello, and Michael Travisano. Proceedings of the National Academy of Sciences. http://www.pnas.org/cgi/doi/10.1073/pnas.1115323109 )

Update: Here’s a Twitter-Storify-blog follow up on some reactions to the study.

A Hot Young Earth: My Answer to the Annual Edge Question

Carl Zimmer — Sun, 15 Jan 2012 17:47:28 +0000

Each year, literary agent and science salonista John Brockman poses a question about science and gets a slew of answers from scientists, writers, and other folks. This year’s question is

WHAT IS YOUR FAVORITE DEEP, ELEGANT, OR BEAUTIFUL EXPLANATION?

Brockman got 187 responses, totaling some 126,700 words. A book, you say! Well, if this year is like previous ones, this year’s answers will indeed become a book. But in the meantime, you can browse the answers for yourself, perhaps plucking out those of your favorite people. (Fellow Discover blogger cosmologist Sean Carroll chooses Einstein’s explanation of gravity, for example.)

I found this year’s question particularly thought-provoking. Why is it that we call an equation or a theory “beautiful”? They don’t have pretty hazel eyes. They aren’t desert landscapes. I’m not sure of the answer. Scientific explanations seem to be beautiful if they give sense to confusing complexity in a very short space. Or maybe we just like the feeling we get when we consider how our puny human brains can interpret the universe.

For a lot of physicists, the beauty of an equation seems to be a good hint that it’s ...

Inside Darwin’s Tumor

Carl Zimmer — Thu, 12 Jan 2012 17:04:34 +0000

Cancer evolves. Those two words may sound strange together. Sure, birds evolve. Bacteria evolve. But cancer? The trouble arises from the fact that cancers, unlike birds and bacteria, are not free-living organisms. They start out as cells inside a person’s body and stay there, until they’re either wiped out or the person dies.*

Yet the same forces that drive the evolution of free-living organisms can also drive cancer cells to become more aggressive and dangerous. Evolution becomes our inner foe if mutations disable a cell’s self-restraint. The cell multiplies. Sometimes a new mutation arises in its descendants. If the mutations allow the cancer to grow faster, the cells carrying it will take over the population of cancerous cells. Natural selection and other processes that drive evolution on the outside start driving it on the inside.

Like so many other scientists, researchers who study cancer evolution have jumped on new technology for sequencing genomes on the cheap. They’re now starting to publish fine-grained histories of the disease, tracking individual mutations as they arise and spread. Nature has just published a fine example of this new research. I particularly appreciated the informative pictures they came up with to accompany ...

Resurrecting Evolution to Solve an 800-Million-Year-Old Puzzle

Carl Zimmer — Tue, 10 Jan 2012 19:17:45 +0000

This is a story of about how the parts of a puzzle locked into place 800 million years ago. The puzzle is an ion pump that you can find in any mushroom, mold, or yeast. I’ve reproduced a picture of it here.

Fungus cells, like our own cells, have lots of little pouches inside of them for carrying out special kinds of chemical reactions. In order for those reactions to work, there have to be a lot of positively-charged protons inside the pouches. To get those protons into the pouches, ion pumps like this one force them through membranes.

This pump (which is is offically known as a vacuolar ATPase complex) is a wonderfully complex collection of proteins. They fit together elegantly, and they cooperate to get this vital job done. One particularly cool feature of this pump is the ring lodged in the pouch’s membrane, where it spins around like a wheel. The ring is made up of six proteins–four copies of a protein called Vma3, and a single copy of two other proteins called Vma11 and Vma16–that lock together. If a mushroom can’t make all three types of proteins, ...

The French Disease, the Italian Disease, the Christian Disease–the New World Disease?

Carl Zimmer — Mon, 19 Dec 2011 22:35:13 +0000

In 1494, King Charles VIII of France invaded Italy. Within months, his army collapsed and fled. It was routed not by the Italian army but by a microbe. A mysterious new disease spread through sex killed many of Charles’s soldiers and left survivors weak and disfigured. French soldiers spread the disease across much of Europe, and then it moved into Africa and Asia. Many called it the French disease. The French called it the Italian disease. Arabs called it the Christian disease. Today, it is called syphilis.

I’ve been intrigued by the murky history of syphilis for a few years now. The text above is from the start of an article I wrote for Science in 2008. At the time, scientists were split between two explanations for sudden appearance of syphilis at the end of the fifteenth century. According to one, it was caused by bacteria that had evolved in the New World and were brought back to Europe by Columbus’s crew. But other researchers found many skeletons with signs of syphilis in Europe, Africa, and Asia that appeared to have been from long before Columbus’s voyage. They argued that it must ...

A Long Walk To Land

Carl Zimmer — Mon, 12 Dec 2011 21:33:52 +0000

Long before Darwin published The Origin of Species, there was talk of evolution. The more acquainted naturalists became with the major groups of animals, the gaps between them grew smaller. Once it seemed as if mammals were profoundly different than other vertebrates, for example. And then European explorers encountered the platypus, a mammal that laid eggs. Perhaps the major groups of animals had not been separately created, some naturalists suggested. Perhaps life had changed over time.

In 1837, a profoundly paradoxical creature was shipped from West Africa to London, packed in clay. It was destined for Richard Owen, the greatest British anatomist of his age. He picked away the clay, to reveal a creature that looked like a fish. It has a knife-shaped body, gills, and fins. “If indeed the species had been known only by its skeleton,” Owen wrote, “no one could have hesitated in referring it to the class of Fishes.”

But inside its body, Owen found what he could only call lungs. Its whisker-like fins had a chains of bones that faintly resembled arms. Owen was a fierce opponent of all the transformationists of his day, and ...

Peace, war, and evolution: My profile of Steven Pinker in tomorrow’s New York Times

Carl Zimmer — Mon, 28 Nov 2011 18:49:41 +0000

The New York Times has launched a series called Profiles in Science. When I was invited to join the undertaking, I proposed writing about the Harvard psychologist Steven Pinker. I had run into Pinker at the World Science Festival in June, and he had told me about his next book, The Better Angels of Our Nature, which was due out in the fall. In the 800+ page tome, Pinker argues that rates of human violence have been crashing for millennia, and he offers psychological explanations for the fall.

I’ve followed Pinker’s work since I first came across his 1994 book, The Language Instinct. In the wake of the book’s success, he quickly became a leading exponent of evolutionary psychology, coming out swinging against its critics such as Stephen Jay Gould. When Pinker described his book to me, I was intrigued. I wondered how someone who argued that human nature was shaped long ago by natural selection would end up arguing that human nature–or at least human experience–is now changing rapidly for the better. But there were other things I was wondering–how, for example, does a writer of massive books about human nature live inside the ...

Are we the teachable species?

Carl Zimmer — Tue, 22 Nov 2011 15:14:07 +0000

We know that our species is unique, but it can be surprisingly hard to pinpoint what exactly makes us so. The fact that we have DNA is not much of a mark of distinction. Several million other species have it too. Hair sets us apart from plants and mushrooms and reptiles, but several thousand other mammals are hairy, too. Walking upright is certainly unusual, but it doesn’t sever us from the animal kingdom. Birds can walk on two legs, after all, and their dinosaur ancestors were walking bipedally 200 million years ago. Our own bipedalism–like much of the rest of our biology–has deep roots. Chimpanzees, whose ancestors diverged from our own some seven million years ago, can walk upright, at least for short distances.

If looking for human uniqueness on the outside is difficult, is it any easier to look on the inside–in particular, at our mental lives? There’s no doubt that our minds allow us to do things that even our great ape relatives cannot. For one thing, we can represent the world symbolically in our heads, and we can use words to communicate that symbolic thought to one another. ...

Neanderthal Neuroscience

Carl Zimmer — Mon, 14 Nov 2011 21:18:28 +0000

When the Society for Neuroscience gets together for their annual meeting each year, a city of scientists suddenly forms for a week. This year’s meeting has drawn 31,000 people to the Washington DC Convention Center. The subjects of their presentations range from brain scans of memories to the molecular details of disorders such as Parkinson’s and autism. This morning, a scientist named Svante Paabo delivered a talk. Its subject might make you think that he had stumbled into the wrong conference altogether. He delivered a lecture about Neanderthals.

Yet Paabo did not speak to an empty room. He stood before thousands of researchers in the main hall. His face was projected onto a dozen giant screens, as if he were opening for the Rolling Stones. When Paabo was done, the audience released a surging crest of applause. One neuroscientist I know, who was sitting somewhere in that huge room, sent me a one-word email as Paabo finished: “Amazing.”

You may well know about Paabo’s work. In August, Elizabeth Kolbert published a long profile in the New Yorker. But he’s been in the news for over fifteen years. Like many other ...

Dinosaurs in flight: the movie

Carl Zimmer — Mon, 24 Oct 2011 20:15:39 +0000

Earlier this year in National Geographic, I wrote about how feathers evolved long before flight. This timing naturally raises the question, how did feathered dinosaurs take to the air? My article was accompanied by a picture from the University of Montana lab of Ken Dial, who argues that before dinosaurs flew, they flapped their wings to help them travel up and down inclines. While not all experts accept Dial’s hypothesis, it has the undeniable strength that he can gather evidence for it in living birds, rather than just inferring behavior from fossils alone.

This video shows some of the astonishing climbs birds can make with the help of some wing flapping. It’s a mix of lab climbs and footage from the wild, with an evolutionary tree of birds.

This is a skill that takes time for birds to develop, as shown in this video below. Dinosaurs might have gradually acquired the skill as well, as their arms evolved into more bird-like wings.

Dial argues that this flapping would also help on the way down, too. Here’s a young bird leaping to the ground, and flapping its wings to control its fall.

By the time dinosaurs had evolved the ability to use feathers ...

The Verge of Human

Carl Zimmer — Thu, 08 Sep 2011 14:49:00 +0000

If you were this man, you’d be smiling too.

The man is Lee Berger, a paleoanthropologist at the University of Witwatersrand in South Africa. He’s holding the skull of Australopithecus sediba, a 1.98 million year old relative of humans, otherwise known as a hominin. In April 2010 Berger and his colleagues first unveiled the fossil in the journal Science. As I wrote in Slate, Berger argued that A. sediba was the closest known cousin to our genus Homo. Hominins branched off from other apes about 7 million years ago, but aside from becoming bipedal, they were remarkably like other apes for about five million years. Among other things, they were short, had long arms, and had small brains. Berger and his colleagues saw in A. sediba what biologists often find in transitional forms–a mix of ancestral and newer traits. It has Homo-like hands, a projecting nose, and relatively long legs. It was intermediate in heigh between earlier hominins and the tall Homo. And it still had a small brain and long arms. (In August, Josh Fishman wrote a feature for National Geographic on A. sediba, complete with excellent ...

The Kindness of Strangers, Chimpanzee Edition

Carl Zimmer — Mon, 08 Aug 2011 21:31:18 +0000

In tomorrow’s New York Times, I take a look at a new study on the generosity of chimpanzees. Check it out. (And also check out Ed Yong’s take at Not Exactly Rocket Science.)

[Image courtesy of Frans de Waal]

What Home Looked Like For Seven Million Years

Carl Zimmer — Wed, 03 Aug 2011 17:01:03 +0000

To understand how we evolved, we have to understand where we evolved. Natural selection exists because the environment is kinder to some individuals than others. Depending on the species, that environment may be a lake miles underneath Antarctic ice, an alpine meadow near the top of a mountain, or an oxygen-free swamp in the sweltering tropics. Each habitat creates its own set of conditions in which individuals thrive or die. We humans are no different. We are the product of where we have lived.

A century ago, paleontologists thought humans evolved in Central Asia. At the time the only known fossils of an ancient human relative (what we now call a hominin) came from Indonesia. The idea of humans evolving in dank rain forests did not appeal to Western scientists who lived in temperate climes. They looked to Central Asia’s windswept plains. In 1926, the American paleontologist Henry Fairfield Osborn laid out this line of thinking in an essay called “Why Central Asia?”

“In that environment, the struggle for existence was severe and evoked all the inventive and resourceful faculties of man,” he wrote. “While the anthropoid apes were luxuriating ...

The ocean microbe within us

Carl Zimmer — Thu, 28 Jul 2011 23:58:06 +0000

Our cells are packed with various protein-stuffed sacs, each dedicated to carrying out essential tasks. One kind of organelle is peculiar, though. Mitochondria are jellybean-shaped structures whose jobs include making the fuel that our cells use to power everything they do. What makes mitochondria strange is that they carry their own DNA. It’s not a lot of DNA–just 37 genes–but mitochondria can make extra copies of it as they grow and divide. In other words, they act an awful lot like bacteria.

About a century ago, Russian biologists proposed that mitochondria actually started out as bacteria, which set up house in our single-celled ancestors. In the 1960s, University of Massachusetts biologist Lynn Margulis resurrected the idea, pointing to certain features in mitochondria, like their double membrane, found in bacteria but not in other organelles. In the 1970s, biologists began to invent the tools that allowed them to look at the DNA in mitochondria. As predicted, that DNA matched DNA from bacteria, not from animals.

Acquiring mitochondria over 2 billion years ago was a pivotal moment in our evolution. We are eukaryotes, as are trees, mushrooms, and amoebae. We all carry mitochondria (or ...

The Evolution of New York: My new story for the New York Times

Carl Zimmer — Mon, 25 Jul 2011 16:51:16 +0000

In tomorrow’s New York Times, I’ve got a story about evolutionary biologists who make New York their Galapagos Islands. Working on this story was great fun–I traipsed around Manhattan parks and medians, checking out mice and ants and salamanders. I spoke to other researchers who study plants, fish, and bacteria in and around the city. All of them observe evolution unfolding in what might seem like a very unnatural place. But after four billion years, nothing can stop evolution. Not even New York.

The Times has posted some of Damon Winter’s wonderful photographs for the story along with some audio from some of the scientists I describe. You can also listen to the new podcast, which features the story too (link to come).

[ Photo: Creative Commons: NatalieTracy on Flickr ]

Why is there sex? To fight the parasite army

Carl Zimmer — Thu, 07 Jul 2011 18:02:02 +0000

For several decades now, biologists have been puzzling over sex. In some ways, it seems like a huge waste of effort.

Sexual reproduction requires splitting a species into two sexes, only one of which will be able to produce offspring. There are some species of animals that do without males; the females simply trigger their eggs to develop into embryos without any need for sperm. All the offspring of an asexual animal can produce offspring of their own, instead of just half. So it would make sense that genes that gave rise to asexual reproduction would win out in the evolutionary race.

Clearly that hasn’t happened. The world is rife with sex. Animals do it. Plants do it. Even mushrooms do it. So evolutionary biologists have carried out a number of studies to get an answer to the question, “Why sex?”

In 2009, I wrote an essay for Science about this research. If I had been writing that essay today, I’d have focused some attention on an elegant experiment on the sex life of a humble worm. It gives a big boost to the long-floated idea that ...

A Beautiful Web of Poison Extends A New Strand

Carl Zimmer — Tue, 21 Jun 2011 16:51:05 +0000

I just got back yesterday from the annual meeting of the Society for the Study of Evolution. It took place in a big hotel on the outskirts of Norman, Oklahoma, during a windy heat wave that felt like the Hair Dryer of the Gods. It had been a few years since I had last been to an SSE meeting, and I was struck by how genomic everything has gotten. No matter how obscure the species scientists are studying, they seem to have outrageous heaps of DNA sequence to analyze. A few years ago, they would have been content with a few scraps. Fortunately, SSE hasn’t turned its back on good old natural history. There were lots of fascinating discoveries on offer, about species that I had assumed had been studied to death. My favorite was a talk about the rough-skinned newt, the most ridiculously poisonous animal in America.

The scientific tale of the rough-skinned newt begins five decades ago, with a story about three dead hunters in Oregon. Reportedly, the bodies of the hunters were discovered around a camp fire. They showed no signs of injury, and nothing had ...

Dr. Kiki’s Science Hour video is up. Jackalopes, zombie ants, evolution’s odometer, and more!

Carl Zimmer — Fri, 01 Apr 2011 19:51:59 +0000

Brian Malow and I talked yesterday about some of my favorite things on the latest episode of Dr. Kiki’s Science Hour–including the evolution odometer. You can watch it on Youtube, or you can head over to Dr. Kiki’s Science Hour site to download the video or audio. (The Skype goes berserk briefly, but we get back on track.)

The Tangled Bank is “spectacularly successful”–Quarterly Review of Biology

Carl Zimmer — Wed, 30 Mar 2011 22:28:31 +0000

The Quarterly Review of Biology delivers a rave for The Tangled Bank: An Introduction to Evolution. Daniel McShea of Duke University writes:

This is the first textbook I have seen by a professional science writer. If this is a sort of experiment in textbook publishing, it is a spectacularly successful one…The result is an introduction to the field that is not only accurate and up to date, but—of course—well written. How important is the prose in a textbook? For students, lively versus leaden, or clear versus cryptic, can be the difference between understanding and not, between being turned on to a field and being turned off. For what it is worth, I solicited help for this review from a biologically inclined high school student, who read a few chapters and reported it to be both clear and engaging….In summary, this is an excellent textbook, one that ought to be—and will be, I predict—widely adopted.

Inclusive Fitness: Return to the Wrestling Ring

Carl Zimmer — Wed, 23 Mar 2011 19:31:31 +0000

Last summer I wrote in the New York Times about a controversy over one of the most influential concepts in the recent history of evolutionary biology. Known as inclusive fitness, it basically says that helping relatives can be a good way to pass on your genes, because they’ve got your genes too.

In August, Nature published a lengthy paper by Martin Nowak, E.O. Wilson, and Corina E. Tarnita in which they argued that inclusive fitness was mathematically flawed and basically superfluous. I had no trouble finding other scientists who were ready to say all sorts of scathing things about Nowak et al. I’m no fan of ginning up fake debates, but when somebody says, “This paper, far from showing shortcomings in inclusive fitness theory, shows the shortcomings of the authors,” the story writes itself.

Seven months later, Nature has finally published some “Brief Communication Arising” letters from some of these critics. The first letter alone has 137 co-signers.

Their ranks include plenty of major players in the field of evolution (including John Alcock, Tim Clutton-Brock, Stephen Emlen, Paul Sherman, Mary-Jane West Eberhard, and Richard Wrangham). The tenor of the letters is more dignified than the comments I ...

Crowd-sourcing the swimming eyeball

Carl Zimmer — Tue, 15 Mar 2011 14:26:09 +0000

Last week I wrote in the New York Times about a fascinating new paper in which scientists described a lamp shell embryo that is, in effect, a swimming eyeball. The paper itself, however, comes in two parts. Along with the part on the swimming eyeball, the scientists also described a later stage of the lamp shell embryo in which it developed simple eyes connected to neurons. It’s primitive version of our own eyes that reveals some interesting things about evolution–particularly about the different photoreceptors that evolved over half a billion years ago for sensing light. At the time, I was struck by the fact that this one paper had two newsworthy insights. So I was glad to see PZ Myer takes up the other half of the story in excellent detail over at Pharyngula. Check it out.

The birth of the animal kingdom: My new piece for the New York Times

Carl Zimmer — Mon, 14 Mar 2011 22:12:26 +0000

Tomorrow’s Science Times section of the New York Times has a special package of articles all about animals–the relationship between humans and the animals we raise, what makes us separate from animals, and so on. I took the opportunity to take a big step back and look at how animals came to be in the first place. The answer–or at least part of it–lies among some weird creatures, such as this tentacled creature that dwells inside snails. Check it out.

Darwin lecture now on Youtube

Carl Zimmer — Thu, 17 Feb 2011 18:24:53 +0000

Here’s the video of the lecture I gave last week at Stony Brook University, which was the basis of my recent blog post. I’ve uploaded the slides as a pdf here. (You can read the slides online or download them by going to the File drop-down menu.) I’m not sure what the ideal combination of video and slides would be…if anyone has any suggestions, let me know.

[Update--the video url got switched around. This should work now...]