Our chocolate addiction depends perilously on a coy reproductive system
Q. News reports on air and water pollution are relatively common but not so for light pollution. What can be said about this almost ubiquitous form of pollution? A. Let’s start by noting that “electricity’s eclipse of the nightly firmament is a distinctively modern phenomenon,” says Heather Smith in “Sierra” magazine. Public lighting was first introduced in the early 20th century in urban areas concerned about crimes committed after dark: Oil lamps gave way to gaslights, which were replaced by “moon towers,” illuminated when there was no full moon. Lit by arcs of raw electricity, they were “built as high as possible, both because they were so bright and because shorter versions had a history of electrocuting people who used them to light cigars.” Finally, the towers gave way to lightbulbs and, according to one scientific paper, “the United States, on average, became 6% brighter each year between 1947 and 2000.”
Other illuminating stats from the magazine: 99% of people in Europe and the U.S. experience some form of light pollution; 88% of North Americans can’t see the Milky Way from their home region; and Los Angeles’s glow on a clear night can be seen from 270 miles away. Finally, countries with the greatest levels of light pollution are Kuwait, Singapore and Qatar; those with the most pristine night skies are Chad, Central African Republic and Madagascar. Q. We think of BFF (“Best Friends Forever”) as a human thing but perhaps it’s not exclusively so. Do you know another animal that might also have a BFF? A. “Bovine Friends Forever” may also be true, says Dan Lewis on his “Now I Know” web site. One study found that cows, being naturally social, may even “pair off — platonically speaking,” finding themselves a bestie to hang out with. According to University of Northampton, England, researcher Krista McLennan, for a cow, a good friend may be a good thing to have around. First, she isolated some cows for 30 minutes, measuring their heartbeats throughout, then paired each of them with an unfamiliar cow and again took readings. Finally, the cows were measured after being put with their “best friends.” As McLennan told the BBC, “When heifers have their preferred partner with them…, their stress levels in terms of their heart rates are reduced compared with if they were with a random individual.”
Extrapolating from this, Lewis says, it’s likely that “happier, less stressed cows make more milk.” Farmers and cow lovers, take note. Q. It’s a wonder we have chocolate at all, given the cacao tree’s “coy reproductive system.” What’s the story here? A. “Arguably some of the most important seeds on the planet — they give us candy bars and hot cocoa, after all — come from pods created by dime-sized flowers on cacao trees,” says Susan Milius in “Science News” magazine. With Emily Kearney of the University of California, Berkeley, as our guide, imagine a blooming cacao tree with most of the flowers coming not from branches but directly out of the trunk. The male, pollen-making structure is fitted with a tiny hood and curving petals. Tiny midges no bigger than a poppy seed crawl into the hood, but what happens next is unclear. But here’s what is clear: The pollinator needs to extract 100-250 pollen grains to fertilize the 40-60 seeds of a cacao pod, then fly some distance away and deposit the pollen into the female part growing on unrelated trees. This offers a better chance of crosspollination.
To Kearney, it’s unlikely that the frail midges are up to the task. Perhaps, she muses, there could be “a clandestine, strong-flying native pollinator species that scientists just haven’t noticed.”