Harvard University Press Blog

Consider the Cuttlefish

In the following excerpt from Concealing Coloration in Animals, new this month, Judy Diamond and Alan B. Bond describe the amazingly adaptive camouflage of the cuttlefish.

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Concealment is often at least as much an effect of pattern as of color. Animal coloration usually appears as distinctive markings like the narrow stripes on grassland birds and insects, the spots on jungle cats, the leaf-sized patches of muted color on animals of the forest floor, or the fine mottled speckles on sandpipers and bottom-dwelling fishes. Such patterns echo the texture of the environment, matching the animal’s surroundings in the size and shape of color patches, as well as in the particular hues and intensities of coloration. To envision how pattern contributes to concealment, think of a digital image of an animal against its background. The image is composed of pixels of specified colors, and adjacent pixels that are similar in color will appear to the eye as patches of varying size. How well the animal blends into its surroundings is a function of the match between the color of the patches in the background and those on the animal, but blending in is also affected by the relative sizes of the patches, regardless of their color. Animals process these two kinds of visual information, color and patch size, in separate parts of their nervous system, and the information is subsequently integrated to assess the degree of resemblance to the background.

How animals integrate the information about color and patch size is most impressively illustrated by cuttlefish. Cuttlefish, which are free-swimming relatives of octopus and squid, are masters at generating patterns to match their environment. They have large, complex, sensitive eyes and a sophisticated control system that allows them to rapidly modify the patterns they display. When they detect changes in their surroundings, they can change the arrangement of light and dark patches on their body accordingly. At the Marine Biological Laboratory at Woods Hole in Massachusetts, Roger Hanlon studied how cuttlefish create their remarkable patterns. In one experiment, Hanlon and his colleagues placed cuttlefish in transparent aquaria on top of complex backgrounds, such as checkerboards, stripes, or spots. They photographed the cuttlefish to determine how well they matched the background patterns, and they timed how rapidly the animals could change from one pattern to another.

The change was immediate. Hanlon and his team found that cuttlefish use three major body pattern types for camouflage: uniform patterns on backgrounds with little or no contrast; mottled patterns on substrates with small, highly contrasting patches like small checkerboards; and disruptive patterns that break up their outline on substrates with high contrast and long, defined edges, like large checkerboards. In the lab, cuttlefish will camouflage on any substrate, natural or artificial, regardless of whether or not there is a predator in the tank.

In Loving Memory of Lonesome George

Upon learning of the death of Lonesome George, the last Pinta Island tortoise, we invited comment from Craig Stanford, Professor of Biological Sciences and Anthropology at USC and author of The Last Tortoise. His post is below.

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If Lonesome George had been human, his obituary would have read:

George passed away peacefully on June 24, 2012, at the age of approximately 100. He was born on Pinta Island around 1912 and lived there until 1971, when he moved to the Charles Darwin Research Station on Santa Cruz Island, Ecuador. He served his country for decades as the greatest tourist attraction in the Galapagos Islands, and was visited by tens of thousands of tourists each year. He dies leaving no surviving descendants.

That last sentence is the one that matters. Jorge Solitario, or Lonesome George, was the last surviving member of his race, the subspecies of giant Galapagos tortoise known as Chelonoidis nigra abingdoni, the Pinta Island tortoise. The main islands of the Galapagos archipelago each have or had their own distinctive giant tortoise, molded by natural selection to be adapted to the terrain and the foods of its island. George’s subspecies inhabited a small northerly island that is fairly barren, rocky, and forbidding, but which once had a large tortoise population. The whaling ships of the 18th century made short work of the islands, collecting hundreds of thousands of the animals to be stored alive in the cargo hold and butchered as needed for fresh meat during their long voyages. We estimate the pre-whaling tortoise population of the entire Galapagos chain to have been 250,000-300,000 tortoises. Perhaps 15,000 live on the islands today; at least three islands have now lost their tortoises altogether.

In 1971, seventy years after the last tortoise on Pinta was thought to have died, a biologist visiting the island spotted Lonesome George ambling across the dry landscape. Not realizing the significance of the sighting, a year passed before another biologist learned that the Pinta race was not quite extinct. Expeditions were mounted to Pinta to search for George. A large tortoise on a small island might not seem a difficult target, but only through much luck was George found. He was transported to the Darwin Station by boat, and remained there for more than forty years. All subsequent attempts to find more Pinta Island tortoises failed. For years he shared his pen with two females from the slopes of Wolf Volcano in the northernmost part of Isabela Island. But George showed no interest in having sex with them. Later, he was paired with females of other, similar subspecies from the islands, and in recent years three clutches of eggs were produced that he had fathered. But none of the clutches hatched. George was likely infertile, either through age, or just very bad luck.

The story of the Pinta Island tortoise does not quite end there. Recent genotyping of tortoises from around the Galapagos has turned up at least one tortoise, from Wolf Volcano on Isabela Island, that is fifty percent Pinta. It is likely the progeny of a Wolf tortoise and a Pinta tortoise that ended up on Isabela. Perhaps ocean currents carried it there, or more likely, he or his mother was dropped overboard by an inept crew of whalers. Only a tiny fraction of the tortoises of the islands have been genotyped, and there lies some faint hope that another male and female of the Pinta Island tortoises live still.

It is always sad and disturbing when humans drive a species into extinction. But extinction is rarely so clear-cut as with the tortoises of Pinta. One last surviving member lived on and on, reminding us of our past sins to his race and beckoning us to try one more time to save them. In the case of Lonesome George, it was too little, too late.

Lonesome George

Food and Memory

John S. Allen’s The Omnivorous Mind is an examination of the cultural and biological truths revealed by our evolving relationship with food. From the diets of our earliest ancestors, to cooking’s role in the evolution of the human brain, to the preoccupations of contemporary foodies, Allen’s take on how and what we eat is consistently revelatory. Below, Allen looks at the powerful role food plays in human memory. Also below, listen to a conversation with Allen on a recent episode of our podcast. 

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Not that long ago, at the counter of a gas station out in the country, something yellow and red caught my eye—it was a Bit-O-Honey candy bar wrapper. I had not had a Bit-O-Honey bar for nearly 40 years, having moved as a child from Bit-O-Honey’s midwest base to California. So I bought one. As I unwrapped and ate it, certain memories quickly came back to me: the difficulty of getting the inside wrapping paper off the sticky taffy, the little rectangles meant to be broken off one by one, the initial hard chewiness that always made me wonder if it was stale, and finally, the honeyed flavor of the taffy itself, offset by little bits of nut. The memories did not stop there, however: in an instant, I was transported back in time to the back seat of my parents’ car, looking out the window at the apparently endless rows of corn stalks that passed by for hour after hour as we drove down highways and interstates. I thought about AM radio and the backs of my parents’ heads. I finished my chunk of Bit-O-Honey, got in my car, and drove back to the present.

We all have our food memories, some good and some bad. The taste, smell, and texture of food can be extraordinarily evocative, bringing back memories not just of eating food itself but also of place and setting. Food is an effective trigger of deeper memories of feelings and emotions, internal states of the mind and body. So my Bit-O-Honey experience is not all that unusual. Search for websites with the word candy combined with vintage, retro, or nostalgia, and it becomes readily apparent that many people use candy as a pathway to the past. But why should this be the case?

 

There are several reasons. First, evolution has seen to it that food in general may be a privileged target of memory in the brain. There is a part of the brain called the hippocampus (one in each hemisphere) that is critical for memory. The hippocampus is particularly important for forming long-term, declarative memories—those that can be consciously recalled and which contribute to the autobiographies that we all carry around in our heads. The hippocampus is also important for spatial memories, which may be its primary role for animals that do not possess language. The hippocampus has strong connections with parts of the brain that are important for emotion and for smell. This may explain why emotional memories can be so vivid or why certain smells trigger a sense of recall in us even before we consciously remember an event.

The Stephen Jay Gould Mosaic

We’ve just released new paperback editions of a collection of Stephen Jay Gould’s most fascinating and introspective essays, with cover designs that reflect the unity of science to which Gould devoted his life and writing. By themselves, each cover contains an element out of context, tough to understand on its own. Together, the covers form an image that makes sense.

Here they are, arranged in order at our warehouse, ready to ship:

And then here, on display at Reiter’s Books in DC:

The books in this collection are some of Gould’s finest, all displaying his typical erudition, warmth, and whimsy. They include Dinosaur in a Haystack, Full House, Questioning the Millennium, Leonardo’s Mountain of Clams and Diet of Worms, The Hedgehog, the Fox, and the Magister’s Pox, The Lying Stones of Marrakech, and I Have Landed.

So much of Gould’s work was dedicated to showing why a more accurate way of understanding our world is to look at a given subject within its own context, and not as the progress of an average value or single thing. These new covers, then, are intended to highlight the complexity of context, to demonstrate how much more we understand when we stop trying to look at things in isolation.

Our thanks to Sam Potts for the great design. And, if you all see a little room to grow in that mosaic, you’re not wrong. More to come!

Anti-Intellectual Populism and Evangelical Self-Understanding

We’re soon to publish The Anointed: Evangelical Truth in a Secular Age, by Randall J. Stephens and Karl W. Giberson. The book is an exploration of intellectual authority within evangelicalism, a seemingly insular world in which, according to Stephens and Giberson, the teachings of dubiously credentialed leaders are favored over the word of secular experts in the arts and sciences. We invited Stephens and Giberson, who each have roots in evangelicalism, to answer a few questions about evangelical truth and its place in American life. 

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Q: Recent observers, including Ryan Lizza in The New Yorker, regard statements like Michele Bachmann’s endorsement of evangelical historian and philosopher Francis Schaeffer as anomalous or bizarre. But you argue that huge numbers of Americans embrace ideas like these. Can you explain how beliefs that appear extreme to outside observers can seem mainstream to their Evangelical adherents?

Many of the extreme and puzzling beliefs of evangelicals—like dinosaurs being contemporary with humans—are beliefs that they are raised with. Trusted but uninformed authorities in evangelical churches and religious schools present these ideas to laypeople and ministers so often and so convincingly that many grow up accepting them as obviously true.

Q: In The Anointed, you discuss knowledge authorities in diverse fields—history, evolutionary science, and psychology, among other domains. What threads connect these figures?

There are two threads that run through our Anointed authorities. The first is an appealing “Christianizing” of the ideas. David Barton “Christianizes” American history; Ken Ham “Christianizes” the science of our origins; James Dobson “Christianizes” social science, including the definition of the family. The “Christianizing” of these ideas, by default, undermines the credibility of secular ideas that might challenge the positions promoted by the Anointed leaders.

The second thread is old-fashioned American anti-intellectual populism. Barton, Ham, Dobson, and other Anointed leaders tend to make no effort to engage the fields they claim to represent. Barton never subjects his claims about American history to peer review in a journal. Ken Ham and James Dobson do no scientific research. In the secular world ideas get vetted in the academy through peer review in technical journals; then they appear in serious but more popular outlets; and then finally they might get discussed on the radio. The ideas of the Anointed cut out all these middlemen and appear immediately on the radio or television.

Daniel Lieberman on The Fastest Human Ever

We publish books on such a wide variety of topics that it can often feel like experts on everything are just an email away. We’ll see news stories and wonder, by reflex, what this or that author might have to say about them. “Oh, that’s an interesting take. Let’s get Dr. X on the line for some context.” Or, “That story makes no sense, let’s see if Professor Y can explain.”

That’s exactly what happened the other day when I saw this Chuck Klosterman story on Grantland asking “Is The Fastest Human Ever Already Alive?” The story begins with Usain Bolt, the dominating Jamaican sprinter, Olympic gold medalist, and holder of multiple world records. Klosterman notes the incredible downward trend of sprint times over the last two decades and speculates that, superhuman as they seem now, Bolt’s times could look pedestrian in as few as ten years.

These downward trends can’t continue forever though, because, as Klosterman notes, we can’t expect that a human will eventually run 100 meters in 0 seconds flat. So, working from the assumption that we’ll eventually hit the limit of what’s possible for human speed, Klosterman tries to figure out how close we’ve gotten to the limit, and whether the fastest human ever could possibly already be alive. Not quite as Klostermany as a few weeks back when he tried to apply the sports metric “value over replacement player” to rock musicians, but still pretty Klostermany.

So, anyway, three paragraphs into the article I’m wondering what Daniel Lieberman would have to say about this line of inquiry. Lieberman is Professor of Evolutionary Biology at Harvard, and author of The Evolution of the Human Head, which we published earlier this year. This is right up his alley, let’s send him an email.

But then I kept reading and—look at that—Lieberman pops up towards the end of the story. Way to go, media! And, unsurprisingly to people familiar with his work, Lieberman seems to demur on the question of the upper limits of human speed, because speed just isn’t what we’re built for:

“It’s useful to keep in mind that we should not be too impressed by Bolt and other speedsters. By mammalian standards, they are comparatively slow. Most decent quadrupeds out there—dogs, horses, zebra, lions—can run about 20 meters per second, twice as fast as Bolt, and they can do so for much longer (up to a few minutes). No Olympic sprinter could ever outrun a lion. We humans gave up the ability to run fast by mammalian standards many millions of years ago when we became bipeds and lost the ability to gallop. Instead, what humans excel at is endurance, especially on a hot day.”

In other words: “Think you’re fast? Go race a lion.” Sobering perspective from an expert.

And Lieberman’s very much the expert. We somehow seem to have not shared this video here before, so take a look now. Daniel Lieberman on barefoot running: