Your mileage may vary

Published December 17, 2006

The Environmental Protection Agency rewrote one of the great fictions of American life last week by changing the formula for calculating miles-per-gallon numbers on the window stickers of new cars, to take into account higher speeds, more aggressive driving, more air-conditioning use and other factors not in the old system. In other words, it's more like the way people actually drive. The rules cover 2008 models, some of which will be on sale next month. The change cuts the estimate of highway mileage by 8 percent on average, and city mileage up to 25 percent.

Got milk? Got genes?

Human beings have continued to evolve as recently as within the last 3,000 years, a team of geneticists has found. The newly detected change concerns the ability to digest milk in adulthood, and the mutated genes that make it possible were found among the peoples of East Africa. When cattle were first domesticated 9,000 years ago and people later started to consume their milk as well as their meat, natural selection would have favored anyone with a mutation that kept the lactase gene switched on even after babies were weaned. Such a mutation arose among an early cattle-raising people in north-central Europe - almost all Dutch people and 99 percent of Swedes are lactose tolerant. Now scientists have found completely separate genes that serve the same purpose - making adults lactose tolerant - in cultures focused on cattle in East Africa. The principal mutation, found among Nilo-Saharan-speaking ethnic groups of Kenya and Tanzania, arose 2,700 to 6,800 years ago, according to genetic estimates reported in the journal Nature Genetics.

College: Pay for what you get

Ursinus College, a small liberal arts institution in the eastern Pennsylvania countryside, made a strange discovery a few years ago. The college was losing applicants because its tuition was too low. So early in 2000 the board voted to raise tuition and fees 17.6 percent, to $23,460 (and to include a laptop for every incoming student to help soften the blow). Then it received nearly 200 more applications than the year before. Within four years the size of the freshman class had risen 35 percent. Applicants had apparently concluded that if the college cost more, it must be better. "It's bizarre and it's embarrassing, but it's probably true," said Dr. John Strassburger, the president. With the race for rankings and choice students shaping college pricing, the University of Notre Dame, Bryn Mawr College, Rice University, the University of Richmond and Hendrix College, in Conway, Ark., are just a few that have sharply increased tuition to match colleges they consider their rivals, while also providing more financial assistance. Families associate price with quality, and a tuition rise, accompanied by discounts, can lure more applicants.

On Mars, don't drink the water

Okay, so water has flowed on Mars within the last few years. Images of Martian gullies show what appear to be the deposits left by little spurts of water as they trickled downhill. If an astronaut could bottle up some of this extraterrestrial water, could she drink it? Probably not. At this point, it's impossible to know exactly which minerals are dissolved in the water, and in what concentrations. But the evidence from salt deposits elsewhere on the surface suggests that a Martian aquifer isn't exactly Poland Spring. There's a reasonable chance that any liquid you might find on the surface of the planet would be an acidic sludge of minerals.

Look out, lawn guy

California lawn mowers and leaf blowers will have to have catalytic converters as of the new year. Last week, the Environmental Protection Agency granted California long-awaited permission to slash emissions from lawn mowers and other small-engine machines. The converters cut smog emissions by roughly 40 percent. Next year, the EPA plans to seek the same change across the nation. Lawn mower engines pollute more than you might imagine. Engines under 50 horsepower account for 7 percent of smog emissions in California from mobile sources, the equivalent of about 3-million cars. The California Air Resources Board has estimated that walk-behind mowers will cost between $37 and $52 more .