In the early 1960s Wilt Chamberlain was one of only three players in the National Basketball Association (NBA) listed at over seven feet.
在 20世纪 60年代早期，Wilt Chamberlain 是美国国家篮球协会中仅有的身高超过7英尺的三个人之一。
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.
虽然现在人们比 140 年前高了 2英寸，特别是那些出生在已移民美国很多代的那些人，但是明显的，在二十世纪60年代早期，已经到达了他们的身高的极限。
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.
Wright 州大学的人类学家 William Cameron Chumlea 说：“在这个基因和环境的条件下，现在整体的人们已经长到我们能够达到的范围了。”
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.
拿 NBA 球员来说，他们身高的增加主要由于从世界各地招募到了球员。
Growth, which rarely continues beyond the age of 20, demands calories and nutrients - notably, protein - to feed expanding tissues.
身高的增长一般在 20 岁以后就停止了，而发育是需要能量和营养的，其中的蛋白质用来供给组织的生长。
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.
西北大学的人类学家 William Leonard 说：“有一些限制是个体器官的基因结构导致的。”
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.
Mass州的Natick的军队研究中心的高级人类学家Claire C. Gordon确信百分之九十的入伍新兵不需要更换新的制服和工作站。
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. ”