|Q:||Dear Dr. Scientist
I just watched Avatar, and my friend said that humans are gonna be that tall someday, because people have been getting taller for the past 500 years. Is my friend a retard?
Possibly - Down Syndrome, cerebral palsy and more impactful forms of autism, commonly known to teenage boys as "being a retard" are more prevalent these days than ever. But I think you meant: is your friend correct about humans continuing to get taller? I'll just go ahead and address that question.
True or False: are humans getting taller?Well, it's a bit of both, but there is certainly some truth to the idea that the heads of human beings are gradually getting higher.
Assuming you belief in evolution, you know that humans evolved from an ape-like ancestor. And assuming you've ever been to a zoo, you know that humans are generally taller than apes, except for King Kong, who if you'll remember was something of a genetic aberration (also, if you'll remember, King Kong lived sometime in the 20th Century, so perhaps apes have been doing a little evolving of their own). But yes, ever since 3 foot, 6 inch Lucy, the line of hominid species that has somehow cumulated with Perez Hilton has been getting slowly more vertical.
Why? Well, once upon a time it had something to do with running faster and throws spears, but most of that's not very applicable anymore unless you're competing in the summer Olympics. There's also a sexual selection component; studies show that greater height among humans is often a sought-after trait. Let me tell you, it's true: I'm 6'2", and I can't tell you how much strange I get. Also, being a Doctor named Scientist helps; females also seem to go nuts over that whole perceived success thing, another characteristic height is correlated with.
But girls wanting to bang guys tall enough to outrun mammoths isn't the whole story.Truth is, human height has actually been fairly cyclical, and may have already started to level out. Some evidence suggests that many early Homo Sapiens were nearly as tall as people today, and humans in the middle ages definitely were. During the 1600's-1800's, people actually got a little shorter, due to the harsh living conditions brought about by the Little Ice Age and proliferation of French Philosophy. And while it's true that people today are the tallest they've ever been, this is actually more due to better nutrition than to evolution. My brother just returned from India and reported that almost without exception, people from the wealthy classes were taller than those from the poorer classes. This would be true in America too except that in America, everybody eats too much.
So, to address your question:Are we going to turn into the vertically-gifted, nature-intuned Na'vi people potrayed by the movie Avatar? Not unless we all become tree-huggers, fly to a different planet, and start boning Smurfs.
Aside from the blue skin, tentacle pony-tails and lithe, zero-percent body fan bodies (which people have been unsuccessfully struggling after for years), humans simply will never get that tall. Genetics and nutrition aside, the structure of the human body just doesn't do well supporting heights much over the high-sixes/low-seven-feet levels. The likelihood of joint and bone problems shoot way up at this height, as do circulation issues related to pumping blood all the way up to the stratosphere of Gheorghe Muresan's head. So while humans will probably continue get a little taller for a while, there's a physical limit to how tall we can get in our current form, and we're probably almost there. Unless we also evolve stronger skeletal structures. Or move to another, lower-gravity planet. Or get Wolverine-style metal implanted in our bones. In which case all this goes out the window.