Such data are consistent with recent research indicating that slow growth induced by temporary malnourishment can usually be reversed. Chronic underfeeding during childhood, however, permanently affects stature and other traits, including intelligence.
Second, the trend toward increasing height has largely leveled off, suggesting that there is an upper limit to height beyond which our genes are not equipped to take us, regardless of environmental improvements. Interestingly, the age of menarche, which is also influenced by nutrition, has shown a corresponding decrease over this same time period. Some scientists believe that the increase in teenage and out-of-wedlock pregnancies in the developed world may be an unanticipated consequence of improved nutrition.
Third, conditions of poor nutrition are well correlated to smaller stature. For example, the heights of all classes of people, from factory workers to the rich, increased as food quality, production and distribution became more reliable, although class differences still remain. Even more dramatic, the heights of vagrant London boys declined from 1780 to1800 and then rose three inches in just 30 years--an increase that paralleled improving conditions for the poor. Even today, height is used in some countries as an indicator of socioeconomic division, and differences can reveal discrimination within social, ethnic, economic, occupational and geographic groups.
For those hoping that humans might someday shoot basketballs through 15-foot high hoops, the fact that the increase in human height is leveling off no doubt will be disappointing. For those who understand, however, that our genes are merely a blueprint that specifies what is possible given an optimal environment, a limit on height is just one of many limitations in life, and certainly not the most constraining.
With environmental variables perhaps near their optimum, what are the prospects for evolutionary increases in height as a consequence of changes to our genetic blueprints? Apply the methods of the thought experiment above and see.
See what we're tweeting about
8 Comments
Add CommentRich = better nourished = taller = predjudice towards taller people. If women from all socioeconomic backgrounds prefer taller mates, then all other things being equal the species actually will become taller genetically. A bizzare case of phenotype causing a change in genotype.
Reply | Report Abuse | Link to thisThe issue with that theory is that, according to this article at least, the genes of those who are taller because of better nutrition are no different from the genes of those with poor nutrition and shorter stature. There should be no change in the genetics of their children, which is why height increase is beginning to level off.
Reply | Report Abuse | Link to thisAh, the great feeling of being right! I received an eyeroll and a scoff from my wife when suggesting that nutrition was a determining factor in height at dinner tonight. She said "You think I'm short because my parents didn't feed me properly?" I hadn't meant it as a personal attack, but now I feel like I can hold me head a little higher :)
Reply | Report Abuse | Link to thisThis explains it for me, have researched a lot in this area
Reply | Report Abuse | Link to thishttp://www.angelfire.com/space2/noah/
I think this is so interesting. We are a mixed family. I grew up in a very large household, and I topped out at 5'4". My mother was a naturalist (nice way of saying hippie.) We didn't eat meat if it wasn't raised on our own land, and we our own eggs. Our milk we often traded our grown vegetable with dairy farmers nearby. I have three brothers that are very tall, and two that are my height (or a little taller). All of my sisters with the exception of one are considered to be short. Considering that we all grew up eating the same things, it isn't nutrition. It is also a very interesting preconception that taller people are healthier. My mother is 5'1", is 83 years old, never goes to the doctor and still goes horseback riding (no joke). She still has the same lifestyle as when we were growing up. My sister works in a convalescent home and she tells me that rarely are any of her charges that are above 5'6" and over 75 years old very active or physically healthy compared with those that are of smaller stature. (Of course this is only one home with about 200 residents, and not a scientifically controlled observation). However, my father was 6'2" and was also very active. Sadly he passed away at the age of 65 of a heart attack. (These are only personal experiences mind you.) This is what spawned my interest because I've noticed that most of the taller people on my fathers and mothers side of the family tended to have shorter healthy lifespans.
Reply | Report Abuse | Link to thisIt sounds strange, but rarely have I seen any very tall people who are also very old?
Height Prediction Calculator for Children
Reply | Report Abuse | Link to thishttp://www.etoolsage.com/calculator/Height_Prediction_Calculator.asp?toolsort=1500
People shrink with age. You can lose several inches by the time you are elderly. Older people tend to be a bit hunched also, which will make them look shorter. I see few with good posture who stand fully upright.
Reply | Report Abuse | Link to thisPlus, older people are from older generations...the peak in tall people are not the elderly people now. I suspect it's the boomer generation that was tallest....studies I've seen show the US peak in height around 1960 (people born in that year). Those people would only be in their early 50s now, not in nursing homes....
Okay nutrition might have a factor but what about those in 3rd world countries who are taller than some who have had a healthy upbringing in the States?
Reply | Report Abuse | Link to thisI think height's solely based on genes. And since most prefer a taller mate the height averages have been slowly increasing over centuries. I heard back when Napoleon was Emperor the average height for a male was 5'6. Now it's about 5'9-5'10. Once your daughters start getting taller and aim for taller mates obviously there is going to be an increase in the overall height, it just takes time. I'm sure one day 6'0 will be average height for males.