Health care in the Inca empire probably wasn't anything to envy, but a skull surgeon was around if you needed one. Researchers studying over 400 skulls exhumed near the Inca capital city of Cuzco observed that several dozen had been bored, cut, or scraped completely through the skull wall, usually on the front or left side. The reason? It's possible the openings were made to relieve fluid pressure from head injuries, perhaps from the blow of a right-handed opponent's weapon. The procedure, called trepanation, was similar to a modern-day craniotomy.

The researchers found trepanation to be a surprisingly common practice among the Incas, and sometimes the surgery was repeated. One skull had been operated on in seven different locations.

Older skulls were less likely to show signs of healing after being perforated-which indicates the earliest surgical attempts were often fatal to patients. But by the 15th century, success rates seem to have risen to almost 90 percent, and surgeons had agreed on a technique: They carefully scraped away bone material with a sharp tool, avoiding damage to the brain beneath.

Global warming silver lining

Although meteorologists from the U.S. National Oceanic and Atmospheric Administration (NOAA) are forecasting a "normal or above normal" Atlantic hurricane season this year, they've also released a study suggesting the long-term effect of global warming will be to produce fewer Atlantic hurricanes annually, if slightly stronger and wetter ones. A climate model used by the scientists predicted an 18 percent decrease in hurricane numbers by the last decades of this century. Currently, an average season (running from June to November) produces about 11 tropical storms, roughly half of which reach hurricane status when winds rise to 75 mph.

Like global warming itself, the NOAA study is provoking controversy within the scientific community since it contradicts earlier studies that predicted an overall increase in hurricanes as global temperatures rise. Upper-level winds over the Atlantic, known as wind shear, are thought to interfere with hurricane formation and were factored into the new model.

Wind shear was largely blamed for the 2006 and 2007 hurricane seasons, which produced few storms in spite of dire NOAA forecasts. The record-breaking and devastating 2005 season-which produced 28 tropical storms and hurricanes, including Katrina-has now been attributed to the local warming of the Atlantic tropics.

Lab notes

Hindsight is 20/20. A study published in the journal Tectonics by U.S., European, and Chinese geologists warned of a "significant seismic hazard" in China's Sichuan Province only 10 months before the province's May 12 earthquake that left over 55,000 dead. Chinese officials may have been unaware of the study. Sadly, earthquakes cannot yet be forecast with any certainty or precision.

Scientists at a recent United Nations meeting offered warnings that "second-generation biofuels"-made from non-food crops such as reeds and grasses-could be disastrous if introduced in the wrong areas. Certain plants are admired for their robustness and biofuel potential-such as jatropha, a toxic oilseed plant-but may harbor the potential to become invasive species, crowding out native plants and crops and ultimately costing some nations more than they'd otherwise save in gas.