TOP Discovery 2009 - 3. Gene Therapy Cures Color Blindness

Modern science already offers ways to enhance your mood, sex drive, athletic performance, concentration levels and overall health, but a discovery in September suggests that truly revolutionary human enhancement may soon move from science fiction to reality. A study in Nature reported that a team of ophthalmologists had injected genes that produce color-detecting proteins into the eyes of two color-blind monkeys, allowing the animals to see red and green for the first time. The results were shocking to most — "We said it was possible, but every single person I talked to said, 'Absolutely not,' " said study co-author Jay Neitz of the University of Washington — and raised the possibility that a range of vision defects could someday be cured. That's a transformative prospect in itself, but the discovery further suggests that it may be possible to enhance senses in "healthy" people too, truly revolutionizing the way we see the world.

TOP Discovery 2009 - 2. The Human Epigenome, Decoded

The decoding of the human genome nearly a decade ago fueled expectations that an understanding of all human hereditary influences was within sight. But the connections between genes and, say, disease turned out to be far more complicated than imagined. What has since emerged is a new frontier in the study of genetic signaling known as epigenetics, which holds that the behavior of genes can be modified by environmental influences and that those changes can be passed down through generations. So people who smoke cigarettes in their youth, for example, sustain certain epigenetic changes, which may then increase the risk that their children's children will reach puberty early. In October, a team led by Joseph Ecker at the Salk Institute in La Jolla, Calif., studied human skin and stem cells to produce the first detailed map of the human epigenome. By comparing this with the epigenomes of diseased cells, scientists will be able to work out how glitches in the epigenome may lead to cancers and other diseases. The study, which was published in the journal Nature, is a giant leap in geneticists' quest to better understand the strange witches' brew of nature and nurture that makes us who we are.

TOP Discovery 2009 - 1. Our Oldest Ancestor, "Ardi"

With her long, elegant fingers, 4-ft. frame and a head no larger than a bonobo's, it's hard not to feel a certain fondness for little Ardi, the oldest skeleton of a prehuman hominid ever found. Painstakingly pieced together from more than 100 crushed fossil fragments unearthed in Ethiopia, this female specimen of Ardipithecus ramidus (Ardi, for short) lived 4.4 million years ago and had remained anonymous until 1992, when her fragments were first discovered. After 17 years of research, a team of scientists led by Tim D. White from the University of California, Berkeley, published a comprehensive analysis of Ardi in October, in a series of articles in the journal Science. Among the team's revelations: Ardi was surprisingly unchimplike despite being the earliest known descendant of the last common ancestor shared by humans and chimps. Also, she was capable of walking on two feet despite living in an area of woodland and forest — a finding that downplays the importance of open grasslands to the evolution of human bipedalism