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Are you more like a bonobo (above) or a chimp? (via wikimedia commons)

Bonobos and chimpanzees may look alike, but behaviorally they are very different. Chimps are aggressive and warlike, and males dominate. Bonobos are more peaceful and tolerant and females rule. These two primate species are our closest living relatives (we share nearly 99 percent of our DNA), and humans share traits with both species. Some people are more like bonobos, and others more like chimpanzees.

A new study published this week in PNAS shows that most human males are hormonally similar to bonobos when in a competitive scenario, but those men striving for a high status are more like chimps.

The biologists conducting the study began by documenting changes in the levels of two hormones—cortisol and testosterone—in 12 pairs of bonobos and 24 pairs of chimpanzees presented with a situation in which they had to compete for food. The scientists used cotton swabs dipped in Sweet Tart dust (Sweet Tarts stimulate saliva production in primates) to collect saliva before and after the pairs were presented with a pile of food.

Previous research has shown that when human males are faced with a competition of some sort, your average guy will experience increases in levels of glucorticoids like cortisol. Men who are striving for a high status, however, exhibit increases in testosterone levels. And when the competition is over, winners (of either type) have an increase in testosterone and losers a decrease.

Bonobos are like the average guy, according to this new study. Prior to competition, they experience an increase in cortisol, which is associated with stress and a passive coping strategy. Chimps are like the men striving for power; their testosterone levels increase prior to competition and they react as if the situation is a threat to their status.

But humans are the only primate species out of the three to experience changes in hormone levels after the competition is over. ‘It’s exciting because we can see that in some ways we’re similar to bonobos, in others we’re similar to chimpanzees,” says Brian Hare of Duke University. “But then there’s also a part of our biology that seems to be entirely unique.”

Cover of July-August 2010 issue

First of all, go and check out Smithsonian‘s 40th anniversary issue, “40 Things You Need to Know about the Next 40 Years.” There’s lots of science, nature and technology stories, including ones about electric cars, how a wildlife refuge is dealing with rising sea levels, lab-grown body parts and how one scientist is building batteries with viruses. Want more? Here are eight books that have interesting lessons for our future:

Collapse: How Societies Choose to Fail or Succeed, by Jared Diamond: The human race is faced with many challenges in the coming decades—climate change, overuse of resources and a growing population, to name a few. How should we respond? In Collapse, Diamond looks at how human societies faced such problems in the past.

Death from the Skies! The Science Behind the End of the World, by Philip Plait: The Bad Astronomer examines the many ways the universe could end life here on Earth, from coronal mass ejections to the more likely scenario of the planet being devastated by an asteroid.

Hack the Planet: Science’s Best Hope—or Worst Nightmare—for Averting Climate Catastrophe, by Eli Kintisch: Some have proposed using geoengineering to manipulate the climate and prevent the worst potential outcomes of climate change. Kintisch examines the debate in this recently published book.

Eaarth: Making a Life on a Tough New Planet, by Bill McKibben: McKibben first warned of the effects of climate change two decades ago. In his most recent book, he argues that we’ve already changed the planet so much that we’ve lost the climatic stability that marked human development up until now, and he offers advice for how the human race could survive this new era.

The World Without Us, by Alan Weisman: What would happen if humans were suddenly wiped out, killed off by disease or abducted by aliens? How quickly, and how, would the planet recover from us?

The Department of Mad Scientists: How DARPA Is Remaking Our World, from the Internet to Artificial Limbs, Michael Belfiore: DARPA—the Defense Advanced Research Projects Agency—has been responsible for the invention of many of the technologies we depend on as a modern society, like the Internet and GPS. What else might they have in store for our future?

No Small Matter: Science on the Nanoscale, by Felice C. Frankel and George M. Whitesides: Whitesides is featured in our anniversary issue for his work making medical laboratories on chips the size of postage stamps. But nanotechnology can do so much more, as Whitesides and Frankel show in this book, which includes beautiful photos of nanoscale objects.

The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science, by Richard Holmes: The book delves into the scientific world at the end of the 18th century, so you may wonder why it’s on this list. Here’s why: “If there is a second Age of Wonder, I believe it will be driven by the United States of America, and that the Smithsonian will be at the heart of this new possibility.”

What are your predictions for the future? Are you optimistic, like President Obama, or do you think we’ll all be eating jellyfish?

Short-beaked common dolphin (credit: NOAA/NMFS Southwest Fisheries Science Center)

If you had to catch all of your food, would you go after anything and everything that came across your path? Or would you wait for the bigger payoff? Squirrels and bunnies or deer and bear?

Dolphins go for the marine version of option B, preferring to eat only high-energy fish, according to a new study in the Journal of Experimental Marine Biology and Ecology.

Short-beaked common dolphins (Delphinus delphis) are the most common cetacean species in warm Atlantic waters. Biologists in France studied these mammals’ diets by looking in the stomachs of dolphins that had been caught accidentally in tuna drift nets in the Bay of Biscay. The dolphins most frequently ate Kroyer’s lanternfish (Notoscopelus kroeyeri) and Glacier lanternfish (Benthosema glaciale), two relatively rare but high-calorie species. Although other fish, such as Bean’s sawtooth eel (Serrivomer beanii) and Boa dragonfish (Stomias boa ferox) are much more abundant, the dolphins tended not to eat these low-calorie meals.

Living in the sea requires a lot of energy—just think about how tired you get from swimming—so dolphins require high-energy fuel to keep going. They need to be discerning in their eating habits.

A rhinoceros drawn on the wall of a cave in Romania (Credit: Andrei Posmosanu/Romanian Federation of Speleology)

In modern times, rhinos are exotic creatures that inhabit faraway lands in Asia and Africa. There are only five living species; all but one is threatened with extinction. But rhinoceroses are an old lineage. They have been around for 50 million years or so, and they once roamed areas in North America and Europe, in temperate and even arctic regions (there was even a woolly rhino).

Some species in Europe survived past the end of the last Ice Age and didn’t become extinct until around 10,000 years ago. That made them perfect subjects for long ago cave artists, like the one who made the drawing above, which was found last year in a cave, Coliboaia, in northwestern Romania. Much of the cave is underwater, which explains why the drawings were only found recently though the cave itself was discovered 30 years ago. Spelunkers exploring the cave found about half a dozen images of animals, including two rhinos, a bison and a horse. There may have been other paintings but they were likely destroyed by the water that now fills the cave.

Jean Clottes, a cave art expert from France (where the most famous cave art can be found, in Lascaux), has estimated that the drawings are around 23,000 and 35,000 years old, based on their style and similarities to other prehistoric art. Radiocarbon dating of the drawings or nearby bear bones may provide a more accurate estimate of when these ancient artists lived.

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Apollo with his famous lyre is the Greek god of music. This son of Zeus was also closely associated with the Sun and is often assumed to be the Sun god Helios by a different name. In other polytheistic circles, none of the gods of music in Hindu, Norse, Japanese or Egyptian mythologies were associated with celestial bodies. But the Greeks, at least, made the connection between music and the cosmos.

Yesterday, part one of “Music of the Heavenly Spheres,” traversed the world of modern music honoring the planets, stars, novas, quasars and other astrophysical objects that make up our universe. Today we look at the music of centuries past and modern orchestral pieces that were inspired by the vast vacuum of space.

Richard Strauss’ “Also Sprach Zarathustra” (“Thus Spoke Zarathustra”) was an homage to Friedrich Nietzche’s famous book of the same name, which had nothing to do with astronomy. But it became one of the most recognized songs to be associated with the cosmos after its use as the opening theme for Stanley Kubrick’s 2001: A Space Odyssey.

“Zarathustra” is probably the soundtrack that first comes to mind when daydreaming whimsically of the Milky Way, perhaps mingled with Alexander Courage’s theme to Star Trek, or John Williams’ award-winning scores to the Star Wars films.

But these modern composers had nothing on their brethren from the last four centuries.

Gustav Holst’s gorgeous 1918 suite “The Planets” is likely the most compelling tribute to Earth’s stellar brethren of the last millennium. There is a caveat. Holst drew his inspiration less from the planets themselves than from the Roman deities for which they are named. But the suite does evoke a certain understanding of the dyadic nature of the cosmos, simultaneously filled with chaos and beauty.

From the clashing tumult of “Mars: The Bringer of War” (clearly influential in the scores by Hans Zimmer in countless historical action flicks from Gladiator to The Last Samurai) to the rich, flowing melodies of “Jupiter: The Bringer of Jollity.” From the light, lilting airs of “Venus: Bringer of Peace” to the boisterous crescendos of “Uranus: The Magician,” Holst scores the soundtrack to our solar system’s cosmic dance magnificently.

Only Pluto was left out. Perhaps Holst foresaw Pluto’s coming loss of status as a planet; more likely, he just didn’t have time. Even though it was discovered four years prior to his death, that was over a decade after he had completed “The Planets.”

Luckily for Pluto, in 2000 the Berlin Philharmonic commissioned British composer Colin Matthews to write a movement to round out the suite. Pluto was demoted from planet status soon after its completion. The Philharmonic also commissioned movements for four asteroids, including Ceres, the largest in the asteroid belt, and recently dubbed “dwarf planet” alongside Pluto.

But Holst wasn’t the first to include odes to the heavenly spheres in his oeuvre.

Franz Joseph Haydn’s 1777 opera “Il Mondo Della Luna” tells the story of a devious astronomer who cons a nobleman into believing there is a society on the moon. George Frideric Handel’s “Total Eclipse,” an aria from the opera “Samson,” compares a solar eclipse to the protagonist’s loss of sight.

The Jupiter Symphony, Mozart’s final work, was not named as such until after Mozart’s death and, in fact, it has nothing to do with the planet Jupiter at all. It is named such by those who thought that the final minutes of the symphony were so complex they could only be understood by the Roman god-king Jupiter.

Bach never wrote about his inspiration from the stars, but when some of his most famous pieces are blended with recordings of wind from Mars, as Kelvin Miller did in 1998, it becomes a cosmic hit. Miller transformed wind measurements from the Pathfinder probe into sounds and weaved them through some of Bach’s more memorable pieces in the album “Winds of Mars.”

Several other modern composers have built on the legacy of these giants of classical music in paying tribute to astronomy. Peter Eotvos composed the erratic and sinister, yet strangely compelling, symphony “The Cosmos.” And Cornell professor Roberto Sierra wrote a full-orchestral piece inspired by Saturn entitled “Anillos,” which means rings in Spanish.