Science, Technology & Health: June 2004 Archives
I can't even count the number of times people have repeated to me the myth that eating beef raised with hormones for added meat has contributed to modern children hitting puberty younger than children did in the past. (Here's an earlier post on a related topic: "Marriage and Pregnancy").
The truth of the matter is a bit more mundane. There are several factors that lead to earlier puberty among modern first-world humans, and the major ones are:
1. More food. There's plenty of food to go around, and studies show over and over that heavier kids reach puberty sooner. Why? The several-years-long process requires around 400 extra calories per day for boys and around 300 for girls, and that's quite a lot of energy.
2. Better nutrition. Related to number 1, the body requires a sufficient supply of various vitamins and minerals, and American kids today eat better than kids ever have before.
(Incidentally, 1 and 2 also explain why people are taller now than they were in the past.)
3. Television. Television? Maybe. More specifically, kids who watch more television tend to be heavier and have less exposure to natural light.
Children who watch a lot of television produce less melatonin, new research suggests - the "sleep hormone" has been linked to timing of puberty.The article also notes that other studies have shown correlation between watching TV and earlier sexual experiences.Scientists at the University of Florence in Italy found that when youngsters were deprived of their TV sets, computers and video games, their melatonin production increased by an average 30 per cent.
“Girls are reaching puberty much earlier than in the 1950s. One reason is due to their average increase in weight; but another may be due to reduced levels of melatonin,” suggests Roberto Salti, who led the study. “Animal studies have shown that low melatonin levels have an important role in promoting an early onset of puberty.”
Commenting on the research, Alessandra Graziottin, director of the Centre for Gynaecology and Medical Sexology in Milan, said the results were very interesting and plausible. She told La Repubblica newspaper: “US studies have shown that the greater the exposure to television, the earlier the age of sexual experience, including teenage pregnancies.”Perhaps the effect isn't merely the result of the sexually-charged programs on TV, but is also related to our biochemistry.
(HT: GeekPress.)
I love huge pieces of equipment. Prompted by a story about Canada's "Trillion Dollar Tar-Pit" (HT: Newsfeed), here's a link to a site about Extreme Machines, like shovels, trucks, and bulldozers.
Almost every adult in the world can speak and comprehend speech, but most of us have no understanding of or appreciation for quite how amazing and complex this capability is. I'm not a linguist, but I've studied a lot of linguistics as part of my AI research and I'm constantly impressed by how intractable the problem is. Some people have made completely incredible and impossible claims regarding computers and language, but for the most part we really have no idea how the human brain does what it does.
Much of the difficulty in language stems from the need to disambiguate words and phrases that can have multiple meanings. Human language is incredibly redundant; there are a hundred ways to say the same thing, and any given word or sentence can have a hundred different meanings. Our brains learn (over the course of years, but still at a startling rate) how to perform these tasks, but we're still not able to teach (program) our computers to do the same things. (And I doubt we ever will be.)
Neal Whitman, who apparently is a linguist, presents an excellent example of just how confusing language can be. AI is a long way from being able to learn/generate/comprehend this type of result (other than with a rule-based approach, which is impractical), and we need more than an accumulation of baby steps to get there -- we need some dramatic breakthroughs that will radically change the way we think about natural language processing, because I think we're on an entirely wrong track.
