Chocolate is a very old treat, though it's changed over the years

Q. The food was first made some 5,500 years ago by the Mayo-Chinchipe culture in the upper Amazon basin area in what is now Ecuador. It started life as a beverage before morphing into its present form, getting much of its flavour from fermentation after harvest. Are you close to naming this “adored” product? A. Please pass the chocolate, though it will bear no resemblance to the Mesoamerican chocolate beverage made from “a paste of ground cocoa beans mixed with combinations of water, corn, fruit, chili peppers or honey,” says Gemma Tarlach in “Discover” magazine. Chocolate arrived in Europe in the 16th century as a warm drink made with “chocolate liquor,” today’s baking chocolate. The transition to eaten chocolate occurred in the mid-19th century, “when European confectioners added sugar and extra cocoa butter to chocolate liquor, creating what’s known as dark chocolate.” Milk chocolate followed in the 1870s, with milk powder added to the mix; white chocolate, a 20th-century product, is technically not chocolate at all since it contains no cocoa solids.

As to chocolate being a “feel-good” food, research doesn’t bear this out. But, chocoholics, “take heart,” says Tarlach: higher chocolate consumption is linked “with a lowered risk for coronary heart disease, stroke and other cardiovascular troubles." Q. The three-year-old squeals with almost unbearable joy as she flees from the terrible monster – in the form of her father or big brother. Why is fleeing so much fun? A. The description of the three-year-old comes from Boston College research professor Peter Gray (“Psychology Today” online). More than a century ago, naturalist Karl Groos noted that, when playing, the young of prey animals (monkeys, lambs, squirrels) prefer to be chased while the young of predators (wolves, lions) prefer to be the chasers. As Gray explains, “When an animal is running from a real predator, the motivating force is fear. When an animal is practicing, in play, how to get away from a play predator, the motivating force is joy.” Humans playing the game of “tag” want to be chased, not the chaser (“it”), suggesting an evolutionary heritage more of prey than predator. Indeed, Gray argues that even our major sports – football, soccer, baseball, basketball – are better understood as games of chase than of war.

Concludes Gray, “… your dog likes to play at chasing cars (big prey), balls (small prey), and all sorts of other moving objects. … in its ancestry, skill at running down game was more crucial to survival than was skill at fleeing, dodging, and hiding.” Q. “From guns and houses to prosthetic limbs and vehicle parts, if you can think it, you can print it, … as long as it is inanimate matter,” says “New Scientist” magazine. Can human organs be made with a 3D printer? A. The holy grail of bioprinting would be to engineer vital organs, such as the kidney, the heart, the liver, says bioprinting pioneer and team leader Jennifer Lewis at Harvard University, as interviewed by the magazine’s Sean O’Neill. The challenges are many: Not only does the team have to print an organ’s cells but these have to mimic the high densities of living tissue, replicating an organ’s many bodily functions and then putting the organ into the body without it being rejected. “We’re still decades away,” Lewis says.

Currently, the team is pursuing more immediate goals, such as aiding the pharmaceutical industry when it brings a new drug to market. While about $1 billion is spent doing that, “20 per cent of all drugs fail clinical trials because they are toxic to the kidney.” Hence, the ability to print kidney tissue would provide “physiologically authentic models of human tissue to test drugs on.”