Will humans keep getting taller? | Hacker News Reader

Will humans keep getting taller?

bbc.com

32 pointsdavnn48 comments

As an extremely "average" height guy, height has been one "human variable" that has always confused me - anecdote after anecdote after anecdote from both proclamations from women, professional sports, and more importantly, our(Western) culture in general have made height seem to be the most important physical trait in a male; yet this article, along with actual research have time and time again either demonstrated this to not be the case[0] or relatively mixed [1] in preference.

Anecdotally, the answer to the article seems to be "yes" due to selective pressures, but the data suggests otherwise.

[0] (meta study) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3277695/

[1] http://psycnet.apa.org/journals/ebs/7/2/121.pdf&productCode=...

Being tall is highly advantageous in the right circumstances, terrible in the wrong ones. It just varies based on environment, resources, etc. Athletes know this too, but it does so happen that the sports which make the most money right now thrive on big, tall men. Basketball and American football thrive on giant guys, but it's not the only model.

The best rock climber isn't going to be an NBA forward, it's going to be someone with a better power-to-weight ratio. That doesn't have to be short, but it can't be too tall without wasting weight on long bones that are going to have to support smaller muscles.

Cramped airlines seats aren't great for tall people either.

Japanese housing is terrible for tall people too.

Honestly, not a lot in Japan is ideal for tall people, including the reactions of the average person when you're walking around...

One of those circumstances is in combat. Historically that has been extremely important.

It wouldn't surprise me that under more violent circumstances, mate preferences shift toward those of greater size, strength, and overall physical ability.

Well mate preference tends to shift towards living mates.

You only have to compare the recent ancestors of the Maori with current Maori to see the effects of constant warfare in an environment which is not food constrained.

Sure, unless you need to be in a tunnel system, or survive on a small island with minimal resources. It doesn't help to be a giant viking if you can't eat like one.

There is pretty conclusive evidence that taller men are on average more attractive than shorter men. However being more attractive does not necessarily mean you will have more kids. My theory is that people want to marry people of similar attractiveness, so if for very attractive people the pool of potential matches could actually be smaller, in part because attractive people are more choosy. Also in terms of evolution, if you have sex it doesn't matter how attractive your partner was.

> Also in terms of evolution, if you have sex it doesn't matter how attractive your partner was.

It does, because your partner's attractiveness affects your child's attractiveness, and thereby their mating ability.

From the article: In fact, from a pure Darwinian perspective of fitter organisms producing more offspring, the opposite is happening with modern Homo sapiens. Impoverished, less healthy, and thus typically shorter families tend to have more children than prosperous families.

Everybody knows it, but it's pretty crazy when you think about it. However with a generally increasing standard of living that factor should still get smaller and smaller and the people thus taller and taller.

I think the confusion comes from defining what is a "fitter" organism?

and if we keep to trend, its quite likely we will bring Idiocracy[1] to fruition

[1] http://www.imdb.com/title/tt0387808/

I'm not sure what you mean by "the most important physical trait in a male". Women prefer taller men. They say so and studies back this up. Taller men have more mating options and more attractive partners. Taller men make more money, and they are more likely to be selected as leaders. They are perceived as more dominant and more attractive. It is utterly indisputable that in western societies at least, being above average in height is a huge benefit societally for men.

Do taller men have more children? Apparently not, but that's kind of a horrible metric for success in a modern society, because people are actively choosing not to have as many children. More interesting questions might be how height affects frequency of sexual encounters, or number of sexual partners, or any of a number of other measures that most men might want to increase, vs number of children, which is a number that most men do not want to increase significantly beyond the average.

Actually, an interesting question might be too ask how many children a man wanted compared to how many he had. Do taller men end up with more, less, or the same control over their reproduction?

I would say that women have a bias towards socially dominant/powerful men which probably goes back to favouring the chief of a tribe in paleoithic time.

As humans tend to reduce the problem down with stereotyping people probably associate tall with socially dominant even if isn't very accurate. Thus you get a feedback loop where taller people are expected to act a certain way and then start acting that way.

I know a guy who is a dwarf who also has a very successful business, is a funny and charming guy and also has a beautiful and kind girlfriend. So height is neither a ticket or a penalty to success in life.

As a 200cm/6'6" man, I think the optimum height is 6'4" - you get all the benefits of being tall (social prestige, being able to breathe in crowds) and fewer of the disadvantages (clothes still fit, beds still fit, buses and planes still fit, don't hit your head on doorframes or light fittings anywhere near as much).

If only I could go back in time and tell young vacri to stop growing at 6'4" :)

At 6'2", I wish I had either gone up to my projected 6'8" (I think based on the double at two metric) or stayed down at a mere 5-10"or 6'. Everything is too small for me... Long airline flights are excuciating, and even the height of common kitchen fixtures is really too low

what country do you live in? I'm your same height and I don't really have these issues.

US. I also have the difficulty of broad shoulders and something like a 50" chest, which makes airline seats even more fun - if I'm in an aisle seat, I constantly get one shoulder run over by the drink cart because it's sticking out beyond...

At least around here, anything household is designed for the height of a typical 5'5" woman. Counters and tables are low enough that I have to half bend over to use them.

US as well -- I'm going to start paying more attention to sinks. Maybe I do have to stoop and I've just grown accustomed to it.

> broad shoulders and something like a 50" chest

That explains the rest.. I'm a toothpick.

> As an extremely "average" height guy,

Out of curiosity, what do you consider an extremely "average" height?

Interestingly, the article fails to mention the strong correlation between height and longevity - not in the positive direction.[0]

If you want to live longer, shorter is better when controlled for other factors like nutrition.

[0]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1071721/

Body size and cancer rates is correlated within a species (bigger individuals get cancer at a great rate than smaller individuals).

  2004 study found that for 
  each extra inch of height 
  above average, someone could 
  expect to earn per working 
  year of his or her life up 
  to $789 more (about $976 in
  today's money)

The disturbing statistic there is that in 2004, whatever you could get with $789, now you need $976 to do the same thing.

Kind of terrifying.

Height can also be a pain. I'm 6'5" and have lower back and sciatica pain, probably since most of my height is in my torso. Fitting into some cars is horrible. Airline seats are hell. My son is short for his age; go figure.

I would imagine as the average height increases, from a product design point of view, cars, planes, etc. will become more accommodating for people who would be considered very tall today's standards

This assumes that average height continues increasing, which is not a given. The Dutch might represent the peak. They might not ever get taller. Americans might never reach that height.

I would also not assume that airplanes would become more accommodating to taller people. They certainly have not become more accommodating of fatter people despite a lot of movement in that direction.

Cars have become worse, probably due to safety standards. The lower ceiling height, thicker pillars, and cab-forward massive dash boards with highly sloped windshields. I'm thinking about getting a Mercedes commercial van; that ought to fit, and I can sit upright.

This is the main reason I will only consider full-size pickups for my primary driver going forward. I cannot accept the limited visibility and poor ergonomics of sedans. I'm not exceptionally tall, at only 6'2".

No.

A human being 4.12E+12 meters tall, standing on the equator, would have their head moving at the speed of light due to the rotation of the earth. At that point, their experience of time would essentially stop, and reproduction would cease. Also, cosmic rays and lack of O2 would begin to distract the subject from reproduction with cumulative effects from suffocation and radiation burns long before evolution could raise humans to the aforementioned 4 billion km height.

There are other considerations (viz. angular momentum, occasionally passing the human through the Sun at roughly knee height, lunar collisions, &c.) So, anyway, no, we can't keep getting taller.

You assume they would be standing up.

Damn you.

Technically if they weren't standing up, wouldn't that be getting longer?

Another problem: ultra-tall humans competing for space at the poles. I think that the height limit (due to c) works out to be 4.12E+12m / cos(latitude).

We can indeed keep getting taller if the human height series converges

You ignore that it's entirely possible to have an infinite, monotonically increasing sequence with a fixed upper bound. Yes, people could keep getting taller without ever exceeding some defined limit.

However we would begin to encounter problems as the sequence of heights approached said limit. The deltas would become smaller than the precision of our equipment, and later would become smaller than physically meaningful scales (i.e. length scale of an atom). In this limit, I think it would be reasonable to generalise "keep getting taller" to "probabilistically grow by the smallest physically meaningful amount on an arbitrarily long timescale", in which case this continues to be well defined as t→∞ even if it would be difficult to physically observe.

I omitted reference to convergence on a limit from my brief note because it's self-evidently obvious to even the most casual observer that the argument is no less specious than saying that one cannot simply walk into Mordor. There is a practical limit to human height, and rather than simply converging upon it while remaining less than that limit by some nonzero amount, humans will actually reach that height in a finite duration of time and then stop evolving altogether, at least along that particular dimension.

You would be right if humans are made of numbers and not atoms.

But humans are made of many atoms, and the measurement is averaged over some time period in which molecules vibrate many times, so there is no limit to the precision with which they can be measured.

Forgive me if I've misunderstood, but isn't your proposed problem akin to Zeno's paradox of infinite distance, where we never reach anywhere because first we need to go 1/2 the distance, then 1/2 of that, etc.?

Which, of course, is resolved in math by limits, and in the real world by discrete units (i.e. atoms).

Zeno's paradox also conveniently ignores that the time chunks are getting smaller alongside the distance chunks.

An item going at 1m/s will cover half a meter in half a second, and still have half a meter to go. Then after another quarter of a meter, it still has a quarter of a meter to go... but now only a quarter of a second has passed. If you keep on making the time units smaller, then of course it will 'never arrive'. It's not much of a paradox if you take a time-based characteristic and then don't give it enough time to occur :)

Also, there is a finite limit to the signal delay that can be reasonably endured. Neuron signals travel at around 50 M/s. The giraffe probably represents the evolutionary limit of how far the brain can be from the feet before you start stumbling and falling over. This is a rather interesting post on some of the potential mechanisms of giraffe balance.

http://psychsciencenotes.blogspot.com/2013/08/why-dont-giraf...

Can I replace your "studies" with [[citation needed]]

No. The first link from the parent already provided citations for all of the factual claims I made.

Fair enough, thanks.

No problem. It's legitimate to ask for citations in the face of "common knowledge" claims. I should have initially called out that the parent's own citation supported and provided deeper citations for my claims.

6'2" here. attractive females regularly select me for mating purposes and I make a large sum of money annually.

Where are your [citations]?

We detached this subthread from https://news.ycombinator.com/item?id=11951165 and marked it off-topic.

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