1: How Dinosaurs Grew So Large and So Small
Until recently, paleontologists had no way to measure the age of dinosaurs or to figure out how they grew. So, we assumed dinosaurs had a physiology similar to modern reptiles. But it turns out that the clues we needed were locked in the animals’ bones all along—in growth lines similar to the annual growth rings in trees. John R. Horner, Kevin Padian, and Armand de Ricqlès, who have studied dinosaur bones together for more than 20 years, break down how they helped to determine the growth rates of many dinosaur species.
2: Are We the Only Intelligent Life in the Galaxy?
With so many exoplanets out there in the galaxy, it seems reasonable to hope that life may be prevalent. On our planet, it took a series of unusual coincidences to give rise to our intelligent civilization, and it’s quite unlikely such serendipity has taken place elsewhere. Science writer and astrophysicist John R. Gribbin examines how everything had to go just right. Perhaps most unlikely of all, he argues, was the development of our technological species—a feat that is probably unique in the Milky Way.
3: Decoding the Puzzle of Human Consciousness
Physiological and behavioral evidence indicates that humans are fundamentally similar to many other animals in terms of their responses to painful and pleasurable stimuli. Even so, scientists disagree on whether other creatures have consciousness or can suffer. Dr. Susan Blackmore, a psychologist researching consciousness and memetics, and author of The Meme Machine, explains the arguments on each side of this great debate and introduces her own concept of the “selfplex.”
4: Why Your Brain Needs Exercise
Everyone knows that exercise is good for the body. But it’s also been well-established that exercise has positive effects on the brain, especially as we age. Less clear has been why physical activity affects the brain. Doctors David A. Raichlen and Gene E. Alexander explain how key events in the evolutionary history of humans may have forged the link between exercise and brain function. And they show how cognitively challenging exercise may benefit the brain more so than physical activity, which makes fewer cognitive demands.
5: The First Monster Black Holes
In the very distant, ancient universe, astronomers can see quasars—extremely bright objects powered by enormous black holes. Yet it is unclear how black holes this large could have formed so quickly after the big bang. Dr. Priyamvada Natarajan, a theoretical astrophysicist focusing on cosmology, gravitational lensing, and black hole physics, explains how she and her colleagues have tried to solve this mystery by proposing a novel mechanism for black hole formation. Rather than being born in the deaths of massive stars, the seeds of the most ancient, supermassive black holes might have collapsed directly from gas clouds.
6: Pets: Why Do We Have Them?
For over 50 years, psychologists have been trying to understand the appeal of animal companionship. Two out of three American households keep an animal primarily for companionship and we spent an estimated $95.7 billion on our pets. Examine how scientists are finding some common threads that tie people to their household pets. From goldfish to Golden Retrievers, our attraction to animals may be driven by biological and social forces that we don’t consciously acknowledge.
7: The Mysteries of Neandertal Art
Until recently, we believed there was still at least one important distinction between Homo sapiens and Neandertals, but then some simple cave paintings changed everything. Kate Wong, a senior editor for evolution and ecology at Scientific American, explains how images dating back 65,000 years have settled a long-running debate over Neandertal cognition.