How and why, roughly 2 million years ago, early human ancestors evolved large brains and began fashioning relatively advanced stone tools, is one of the great mysteries of evolution. Some researchers argue these changes were brought about by the invention of cooking. They point out that our bite weakened around the same time as our larger brains evolved, and that it takes less energy to 【小题1】 nutrients from cooked food. As a result, once they had learned the art, early chefs could invest less in their digestive systems and thus invest the 【小题2】 energy savings in building larger brains capable of complex thought. There is, however, a problem with the cooking theory. Most archaeologists believe the evidence of controlled fire 【小题3】 back no more than 790,000 years.

Roger Summons of the Massachusetts Institute of Technology has a solution. Together with his team, he analyzed 1.7 million-year-old sandstones that formed in an ancient river at Olduvai Gorge in Tanzania. The region is famous for the large number of human fossils (化石) that have been discovered there, alongside an impressive ‘assembly of stone tools. The sandstones themselves have 【小题4】 yielded some of the world’s earliest complex hand axes —large tear-drop-shaped stone tools that are associated with Homo erectus (直立人). Creating an ax e by repeatedly knocking thin pieces off a raw stone in order to create two sharp cutting edges requires a significant amount of planning. Their appearance is therefore thought to 【小题5】 an important moment in intellectual evolution. During the process, the researchers found distinctive but unusual biological molecules (分子) that are often 【小题6】 as biomarkers of heat-tolerant bacteria. Some of these live in water between 85℃ and 95℃. The molecules’ 【小题7】suggests that an ancient river within the Gorge was once fed by one or more hot springs.

Dr. Summons and his colleagues say the hot springs would have provided a convenient “pre-fire” 【小题8】 of cooking food. In New Zealand, the Maori have traditionally cooked food in hot springs, either by lowering it into the boiling water or fey digging a hole in the hot earth. Similar methods exist in Japan and Iceland, so it makes 【小题9】 sense, if difficult to prove, that early humans might have used hot springs to cook meat and roots. Richard Wrangham, who devised the cooking theory, is fascinated by the idea. Nonetheless, fire would have offered a distinct advantage to humans, once they had 【小题10】 the art of controlling it since, unlike a hot spring, it is a transportable resource.

The Origin of Trick-or-treat

On October 31, hordes of children armed with Jack-o’-lantern-shaped buckets and pillow cases will take to the streets in search of sugar. Trick-or-treating for candy is equivalent to Halloween, but the tradition had to go through a centuries-long 【小题1】 to arrive at the place it is today. So how did the holiday become an opportunity for kids to get free sweets? You can blame pagans (异教徒), Catholics, and candy companies.

Historians agree that a Celtic autumn festival called Samhain (萨温节) was the origin of modern Halloween. Samhain was a time to celebrate the last harvest of the year and the approach of the winter season. It was also a festival for 【小题2】 the dead. One way Celtics may have appeased the spirits they believed still walked the Earth was by leaving treats on their doorsteps. When Catholics invaded Ireland in the 1st century CE, they rebranded many pagan holidays to 【小题3】 their religion. November 1^st became the “feasts of All Saints and All Souls,” and the day before it was dubbed “All-Hallows’-Eve.” The new holidays looked a lot different from the original Celtic festival, but many traditions 【小题4】 around, including the practice of offering food to the dead. The food of choice for Christians became “soul cakes,” small pastries usually baked with expensive 【小题5】 and spices like currants and saffron.

Instead of leaving them outside for 【小题6】 ghosts, soul cakes were distributed to beggars who went door-to-door 【小题7】 to pray for souls of the deceased in exchange for something to eat. Sometimes they wore costumes to honour the saints—something pagans originally did to avoid being 【小题8】 by evil spirits. The ritual, known as “souling”, is believed to have planted the seeds for modern-day trick-or-treating.

It wasn’t until the 1950s that trick-or-treat gained popularity in the US. Following the Great Depression and World War II, the suburbs were booming, and people were looking for 【小题9】 to have fun and get to know their neighbours. The old 【小题10】 of souling made a comeback and gave kids a chance to dress up in costumes and roam their neighbourhoods. Common trick-or-treat offerings included nuts, coins, and homemade baked goods (“treats” that most kids would turn their noses up at today).

This Is Why Most Grocery Stores Lack Windows

When you’re grocery shopping, have you noticed that supermarkets often lack windows, and if they have them, they’re only at the front of the store? You may 【小题1】 pay attention to the architectural features of the building because you’re there to shop for food, not admire the layout.

But that’s the point. If grocery stores had windows, would it be easier to ignore your main shopping task? There are all sorts of supermarket 【小题2】 grocery stores have to keep you shopping longer. It’s no 【小题3】 that grocery stores often lack windows and there are a few reasons behind this trend.

One of them is a (n) 【小题4】 to keep people inside longer. Stores want to create a separate environment within their store where the outside world doesn’t exist. In spite of the rain or sunshine, your attention remains 【小题5】. The technique also prevents shoppers from noticing it’s getting dark out. It really 【小题6】 to an immersive (沉浸式的) shopping experience, for better or worse.

Keeping daylight out of stores can help preserve the products, as some fresh produce can go bad faster in direct sunlight. Too much sun exposure can even cause packaging 【小题7】 to fade. Having windows in stores would also reduce the space 【小题8】 to display products. Not to mention, 【小题9】 with strong structural supports, outside walls can hold the heavier items on the shelves of those walls.

Due to the high cost of constructing windows and storefronts, along with the potential security risks they probably 【小题10】, retailers (零售商) choose to minimize the number of entry points into their space in order to cut expenses and improve safety.