Height in the Honorverse

SWM wrote:

DarkEnigma wrote:Thanks for all the great info. The consensus seems to be that Honor's genetic mod is what accounts for her height. Of course the obvious follow up question is will little Raoul (and any future children of Honor's) HAVE to grow up on a heavy world then or risk being a giant?

No, I don't think so. The Meyerdahl mods increased strength and bone structure so that the recipients higher gravity would not tend to shrink. It did not give them a greater natural stature.

In any case, the entire idea of people on light-gravity worlds growing taller is speculative, mostly an invention of science fiction. There is some natural disadvantages to being tall on heavy-grav worlds which could plausibly lead to a higher death rate and an evolutionary pressure toward shorter people over very long periods of time. But there is no similar pressure the opposite direction on light-gravity worlds.

Absolutely. I think the "tall and skinny" light-grav aspects in SF have been around for so long primarily because the concept is part of the "Ooooooh, shiny!" aspect of the genre. And, of course, by now it's become so central a trope that people automatically give it continued credence when they write. For that matter, I've done it myself in a few cases, even in the Honorverse. I refer you to the prime minister of the Talbott Sector.

As for the Meyerdahl mods do, please, recall that Stephanie Harrington is repeatedly described as being small, not especially tall. As SWM (and others) have pointed out, the primary effect of the Mdeyerdahl mods when it comes to height and physique is to allow lower muscle and bone masses healthily support a human body in a heavy-grav environment. Because of that, most natural selectors for smaller size are effectively trumped so that (assuming the "short and squat" evolution of heavy-worlders beloved in science fiction actually would apply) those modified will grow up with something much closer to what we would think of as :normal" builds and physiques.

MaxxQ wrote:The San Martinos live in the mountain mesas because the high grav on SM concentrates all the CO2 at sea level, making the (sea level) atmosphere dangerous (CO2 is heavier than oxygen).

Not quite true.

See article:

http://ruc.noaa.gov/AMB_Publications_bj ... 19MS-1.pdf

Perhaps the gross atmospheric pressure and density becomes to high?

We might want to look up scuba diving air mixture tables?

You also addressed this in Best Laid Plans where Honor muses over being tall, but having several generations of ancestors (in the Harrington line) who where short.

Quote Beginnings, BLP: "Honor told herself that was a good thing and tried not to think about how . . . overgrown she was beginning to feel. No one was quite sure when so much altitude had crept into the family’s genes, although the majority opinion was that they could look all the way back to Great-Great-Great-Great-Whatever-Granddad Karl. There seemed to be a few holes in that theory, as far as she was concerned, though. Certainly her grandfather had been tall—almost as tall as her dad, in fact—as had his parents, but most of the previous generations had been of little more than average height, so where had Grandad Karl’s genes been then? Besides, there was her mom’s genetic contribution to consider, and all of the Beowulf side of the family was on the short side."

runsforcelery wrote:[snip]
As for the Meyerdahl mods do, please, recall that Stephanie Harrington is repeatedly described as being small, not especially tall. As SWM (and others) have pointed out, the primary effect of the Mdeyerdahl mods when it comes to height and physique is to allow lower muscle and bone masses healthily support a human body in a heavy-grav environment. Because of that, most natural selectors for smaller size are effectively trumped so that (assuming the "short and squat" evolution of heavy-worlders beloved in science fiction actually would apply) those modified will grow up with something much closer to what we would think of as :normal" builds and physiques.

runsforcelery wrote:
Absolutely. I think the "tall and skinny" light-grav aspects in SF have been around for so long primarily because the concept is part of the "Ooooooh, shiny!" aspect of the genre. And, of course, by now it's become so central a trope that people automatically give it continued credence when they write. For that matter, I've done it myself in a few cases, even in the Honorverse. I refer you to the prime minister of the Talbott Sector.

As for the Meyerdahl mods do, please, recall that Stephanie Harrington is repeatedly described as being small, not especially tall. As SWM (and others) have pointed out, the primary effect of the Mdeyerdahl mods when it comes to height and physique is to allow lower muscle and bone masses healthily support a human body in a heavy-grav environment. Because of that, most natural selectors for smaller size are effectively trumped so that (assuming the "short and squat" evolution of heavy-worlders beloved in science fiction actually would apply) those modified will grow up with something much closer to what we would think of as :normal" builds and physiques.

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I believe I am right in saying that, like most other parts of the body, bone growth is strongly influenced by and somewhat propotional to the load on the bones. Following that fact, persons with unmodified genetics would actually grow taller in high gravities and shorter in low gravity.

Similarly, in high gravity people would tend to grow larger muscles, and to some extent would be less likely to develop reserves of fatty tissues (because the continuous exercise needed just to walk around would work off the excess). The opposite would apply in low-gravity environments.

Over evolutionary timescales, very high gravity would select for people with good balance and with lesser distance to fall (ie, short athletic people), while very low gravity would not select against gigantism. Overall, this would probably lead to population heights similar to modern Earth... but only after many generations.