Humans: superb sweaters

Question: In sheer aerobic endurance, the human (trained) is hard to beat, says Indiana University kinesiologist John S. Raglin. Animals may easily outpace us, but if the "race" is stretched out for hours or days, most researchers agree that humans would win the gold. Upright humans are also extremely good at dissipating heat while animals trap it with all their hair, explains biologist and anthropologist James Carrier. "We are the best sweaters on the planet." Hence we become endurance walkers, bikers, marathoners.

Our easy bipedal locomotion serves another end, freeing our hands to do daily tasks even as we're on the go. Our fine motor control and coordination permit us to thread a needle and perform a whole array of extraordinary artistic and building tasks, adds Purdue kinesiologist Michael G. Flynn. We humans are without equals in tracking and catching objects, says Georgia State University sports scientist L. Jerome Brandon. "How many animals could hit a baseball coming at 100 mph and send it 300 feet in the air? How many could strike a golf ball 270 yards down a fairway?"

Question: From a reader in South Africa: "What happens if you let a helium balloon float up into the sky? Will it (a) reach outer space; (b) burst as the air thins; or (c) descend back to Earth after reaching a certain altitude?"

Answer: A kid's birthday balloon might go up a mile or so before it starts to descend as the helium leaks out. Some research balloons have a strong outer shell that allows them to rise to a certain level and stay there, says University of Hawaii meteorologist Steven Businger. Others that are made of stretchy material like polyurethane will expand as they rise and eventually burst. Weather balloons — a k a radiosondes — and their payload of instruments descend by parachute after the balloons burst. Some larger ones stay in the stratosphere for long periods to collect data, with commercial applications like communications. "No balloon will escape the Earth's atmosphere because they can't reach escape velocity of approximately 25,000 mph!"

Question: What are the absolute best and absolute worst "buys" out there in the global marketplace these days?

Answer: By far the best buys — in terms of bang per buck — are personal contributions to organizations that aid the poor in the poorest countries, such as Project Hope, Save the Children, CARE, etc., says Stanford University economist Roger Noll.