No one is sure how the ancient Egyptians built the pyramids near Cairo. But a new study suggests they used a little rock ‘n’ roll. Long-ago builders could have attached wooden poles (木杆) to the stones and rolled then across the sand, the scientists say.

"Technically, I think what they’re proposing (提议、建议) is possible," physicist Daniel Bonn said.

People have long puzzled over how the Egyptians moved such huge rocks. And there’s no obvious answer. On average, each of the two million big stones weighed about as much as a large pickup truck. The Egyptians somehow moved the stone blocks to the pyramid site from about one kilometer away.

The most popular view is that Egyptian workers slid the blocks along smooth paths. Many scientists suspect (推测) workers first would have put the blocks on sleds(滑板). Then they would have dragged them along paths. To make the work easier, workers may have lubricated the paths either with wet clay or with the fat from cattle. Bonn has now tested this idea by building small sleds and dragging heavy objects over sand.

Evidence from the sand supports this idea. Researchers found small amounts of fat, as well as a large amount of stone and the remains of paths.

However, physicist Joseph West thinks there might have been a simpler way, who led the new study. West said, "I was inspired while watching a television program showing how sleds might have helped with pyramid construction (建造). I thought, ‘Why don’t they just try rolling the things?’" A square could be turned into a rough sort of wheel by attaching wooden poles (杆、竿) to its sides, he realized. That, he notes, should make a block of stone "a lot easier to roll than a square".

So he tried it.

He and his students tied some poles to each of four sides of a 30-kilogram stone block. That action turned the block into somewhat a wheel. Then they placed the block on the ground.

They wrapped one end of a rope around the block and pulled. The researchers found they could easily roll the block along different kinds of paths. They calculated that rolling the block required about as much force as moving it along a slippery (滑的) path.

West hasn’t tested his idea on larger blocks, but he thinks rolling has clear advantages over sliding. At least, workers wouldn’t have needed to carry cattle fat or water to smooth the paths.

A Personal Budget

If you want to control your spending and work towards your financial goals, you need a budget. 【小题1】 While linked to restricted expenses, a budget needn’t be restrictive to be effective.

A budget will show you how much money you expect to bring in, then compare that to your required expenses-such as rent-and your discretionary (自由决定的) spending, such as entertainment or eating out. 【小题2】

A written, monthly budget is a financial planning tool that allows you to plan how much you will spend or save each month. 【小题3】

Though making a budget may not sound like the most exciting activity, it’s an important part of keeping your financial house in order. 【小题4】 If you spend less in one area, you can spend more in another, save that money for a large purchase, build a “rainy day” fund, increase your savings, or invest in building wealth.

【小题5】 To make an effective budget, you must be willing to work with detailed and accurate information about your earning and spending habits.

Ultimately, the result of your new budget will show you where your money is coming from, how much there is, and where it all goes each month.

Parrots have long been known for their remarkable cognitive (认知的) ability and exceptionally long lives. Nevertheless, it remains a secret whether the two features have impact on each other. “The problem has led to good quality data,” says Simeon Smeele, a doctoral student at the Max Planck Institute of Animal Behavior, who leads the study with the intention of solving the mystery and gaining a better understanding of parrots.

To generate a sufficient amount of sample size, Simeon Smeele teamed up with Species360, a zoological information management organization. Together, they gathered data from over 130,000 individual parrots sourced from over 1,000 zoos. This database allowed the team to gain the first reliable statistics of average life span of 217 parrots species — representing over half of all known species.

The analysis revealed that the average life expectancy of parrots is up to 30 years, which is extremely rare in birds of this size. “Some parrot species have a maximum lifespan of over80 years, which is a respectable age even for humans. This is really spectacular if you consider that a human male weights about 100 times more,” says Smeele.

Next, the team combined the data and ran models to determine whether or not parrots’ cognition had an influence on their long lives. The results showed the link between increased brain size and longer lifespans in parrots. Because brain size can be an indicator for intelligence, the findings suggest that parrots with relatively large brains had cognitive capabilities that allowed them to deal with threats in the wild that could otherwise kill them, resulting in a longer longevity.

In the future, the team plans to explore if sociability and cultural learning in parrots might contribute to long life expectancy as well. Smeele says,   “Large-brained birds might spend more time socially learning food-searching techniques that have been around for multiple generations. This increased learning period could potentially explain the longer life spans, as it takes more time but also makes the food-searching techniques more adaptive.”