Americans' Height
In the early 1960s Wilt Chamberlain
was one of the only three players
in the National Basketball Association (NBA)
listed at over seven feet. If he had played last season,
however, he would have been one of 42.
The bodies playing major professional sports
have changed dramatically over the years,
and managers have been more than
willing to adjust team uniforms to fit
the growing numbers of bigger, longer frames
The trend in sports, though,
may be obscuring an unrecognized reality:
Americans have generally stopped growing.
Though typically about two inches taller
now than 140 years ago, today's people
---especially those born to families
who have lived in the U.S. for many generations
---apparently reached their limit in the early 1960s.
And they aren't likely to get any taller.
"In the general population today, at this genetic,
environmental level, we've pretty much gone
as far as we can go," says anthropologist
William Cameron Chumlea of Wright State University.
In the case of NBA players,
their increase in height appears to result
from the increasingly common practice of
recruiting players from all over the world.
Growth, which rarely continues beyond
the age of 20, demands calories and nutrients
---notably, protein---to feed expanding tissues.
At the start of the 20th century,
under-nutrition and childhood infections got in the way.
But as diet and health improved,
children and adolescents have, on average,
increased in height by about an inch
and a half every 20 years, a pattern
known as the secular trend in height.
Yet according to the Centers for Disease Control
and Prevention, average height---5′9″ for men,
5′4″ for women---hasn't really changed since 1960.
Genetically speaking, there are advantages
to avoiding substantial height. During childbirth,
larger babies have more difficulty passing through
the birth canal. Moreover, even though
humans have been upright for millions of years,
our feet and back continue to struggle with
bipedal posture and cannot easily withstand
repeated strain imposed by oversize limbs.
"There are some real constraints that are set by
the genetic architecture of the individual organism,"
says anthropologist William Leonard
of Northwestern University.
Genetic maximums can change,
but don't expect this to happen soon.
Claire C. Gordon, senior anthropologist
at the Army Research Center in Natick, Mass.,
ensures that 90 percent of the uniforms
and workstations fit recruits without alteration.
She says that, unlike those for basketball,
the length of military uniforms has not changed for some time.
And if you need to predict human height
in the near future to design a piece of equipment,
Gordon says that by and large,
"you could use today's data and feel fairly confident."