The past year has been both tempestuous and exciting—from pet food, E. coli and toy poisoning scares to political fireworks over embryonic stem cell research to forest fires ravaging California. A controversial Nobel scientist (James Watson) went down in a blaze of infamy, tumbling from grace after putting his foot in his mouth one time too many, whereas a former vice president and defeated presidential candidate (Al Gore) rose from the ashes to become a Nobel Peace prize (and Oscar) winner for raising awareness on the urgency of global warming. The honor came on the heels of official worldwide recognition that climate change is not only a pressing problem, but one that was almost completely caused by humans—and one, too, that humans must fix.

On a related note, we discovered that the North Pole is melting, beloved freshwater dolphins are practically extinct and nuclear power—feared since the 1979 near-meltdown of the Three Mile Island nuke plant in Middletown, Pa.—has become the clean-energy alternative du jour that even has the backing of some enviros. For the first time, too, we enjoyed (depending on how you look at it) an extra month of daylight saving time, thanks to Congress, which made the move to save energy and, lawmakers said, to cut down on traffic accidents—and, perhaps most important, to make Halloween more special and safe.

Alas, 2007 was the year in which hopes were dashed that human growth hormone might be the key to eternal youth. It was also when parents everywhere became alarmed as school kids began contracting an antibiotic-resistant superbug (MRSA), and air travelers found themselves wondering whether their fellow passengers harbored serious contagious illnesses after it was revealed that a man with a virulent form of tuberculosis flouted official warnings to stay home, instead flying to Italy to get married. It was the year, too, when an American pastime became an American tragedy—a report on steroid use by pro baseball players revealed that even sports heroes are flawed.

The past year was one filled with mysteries as well, such as disappearing honeybees and the fate of famed computer scientist James Gray, who departed one fine day from San Francisco on a sailing trip never to be seen again, despite a massive, high-tech all-out search by friends and colleagues. There were ethical dilemmas that came to light, too, such as the decision by the parents of a severely disabled girl dubbed "Pillow Angel," who, after consulting a panel of doctors and ethicists, decided to have their daughter undergo surgery to stunt her growth, thereby keeping her small so that they could continue to care for her themselves.

But there were also some exciting new developments and discoveries: human skin cells were transformed to stem cells; primates came within a hair of being successfully cloned; scientists found that if they killed the virus behind some cancers, they might also kill the cancer; the discovery of a new planet with the most Earth-like characteristics yet observed; and, the unveiling of the first quantum computer. On the political science front, Libya finally freed five Bulgarian nurses and a Palestinian doctor, each of whom had served eight years of life sentences for allegedly deliberately infecting hundreds of Libyan children with HIV, despite evidence of their innocence. And who could forget the long-awaited debut of the Apple iPhone—and the dramatic price cut for the nifty new device that soon followed, angering early purchasers? Or robots sent in to help in the fruitless search for trapped miners after a deadly Utah mine collapse? Or the first wireless power transmission?

There was some promising genetic news on autism, Parkinson's and other elusive disorders, not to mention the discovery that Neandertals may well have spoken and, what's more, may have been redheads. Plus, 2007 is the year that getting parts of one's own genome mapped became as simple as plunking down a few hundred bucks (closer to $1,000, but still…).

The editors and reporters of SciAm.com have listed our top 25 science and health news picks of 2007 below (in no particular order), with the understanding that these are but a small sampling of the many notable stories of the year.—Lisa Stein, news editor, online