How would zero gravity affect future generations

[TarkinLarson]

Hypothetically... if one were to have several generations of people living in micro/zero gravity, and they had children, in micro/zero gravity and so on and so on, how would this affect their biology.

Would our toes grow bigger so we can grasp onto the innards of space stations? would our legs shrink and be less powerful? would our heads and brains expand due to blood flowing out.

I assume we'd be all bloated and have terrible hearts and maybe never be able to return to a full 1G environment without breaking bones and suffering cardiac failure? Would there be any other aspects that might change?

[Nibb31]

We don't know. There haven't been any studies on the development of human children in micro-gravity.

[TarkinLarson]

Are there not any ideas or theories, not necessarily proof so far? Have there been any studies into other creatures reproducing in low/micro gravity situations?

[Steppanwolf]

I believe all first hand studies thus far have been on plant life and possibly microorganisms. Unless you want to count the Russian Space ... Geckos. #GoGetThoseGeckos

[crazyewok]

Personally I would say it would affect them very badly.

For any long duration space flights that may involve pregnancy some sort of centrifugal gravity would likely always be needed.

[K^2]

Hypothetically... if one were to have several generations of people living in micro/zero gravity, and they had children, in micro/zero gravity and so on and so on, how would this affect their biology.

Would our toes grow bigger so we can grasp onto the innards of space stations? would our legs shrink and be less powerful? would our heads and brains expand due to blood flowing out.

I assume we'd be all bloated and have terrible hearts and maybe never be able to return to a full 1G environment without breaking bones and suffering cardiac failure? Would there be any other aspects that might change?

You seem to be confusing evolutionary changes, which will take tens, if not hundreds of thousands of years, with changes that happen to a single individual due to the lack of stress on the body.

We don't know for sure how much zero gravity effects fetal development, but assuming there are no serious, irreversible problems there, a person who is born and lives in zero-G environment would be no different than the one who simply spent too much time there. Which does generally mean bone density loss and partial atrophy of some muscles. Without conditioning, such a person would not be able to survive in 1G environment. But this will be the case for the next generation, and the one after, with no difference. It won't matter if you have first generation of zero-G inhabitants or the tenth.

Over thousands of generations, you can start seeing evolutionary adaptations. But this assumes that there will be evolutionary pressure. If everyone is well cared for, and various zero-G discomforts don't result in mortality, then there will not be much change. If there are survival pressures, then that depends on exactly what they are.

[Lukaszenko]

Edited August 7, 2014 by Lukaszenko

[Godot]

I´d guess that their bones and skeletal musculature (as well as heart) would be weaker than that of children born and raised on earth, as they (and their heart) wouldn´t have to fight gravity.

It´s even questionable if they would ever learn to walk (after all the crawl/learn to walk stage would require gravity)

[KerbMav]

It is incorrect to assume that humans are born fully developed. And it seems very unlikely, that muscles and bones that were never developed to withstand and work in a planets gravity would be able to adept afterwards, let alone deformations of joints that were prone to happen due to the unfinished bone structure.

Could weighted clothing help in this respect at least on planets like Mars or the Moon even?

[Wanderfound]

It is very unlikely that a human could carry a child to term in microgravity.

[Wanderfound]

BTW, this book should be of interest to some folks here: http://www.amazon.com/Packing-Mars-Curious-Science-Life/dp/B00AR2BCLW

It's a lighthearted but well researched account of the more...biological aspects (to put it somewhat euphemistically) of space travel, and the history of the research that led to our current understanding. Worth the read.

[Seret]

It is very unlikely that a human could carry a child to term in microgravity.

We don't really know. It's one of the big red question marks about life in space.

[Wanderfound]

We don't really know. It's one of the big red question marks about life in space.

Yes, we don't know for sure (and possibly never will; it's an experiment that has some obvious ethical issues).

I doubt that you'd be able to find a doctor who wouldn't put his money on "almost certain miscarriage or worse", though. Microgravity messes with human biology in some rather profound ways.

[lajoswinkler]

It would end with extreme disability. Inner ear would not develop normally. Proprioception would fail. The brain would not receive these vital impulses from sensors around the body during the first few years of development so the brain itself would not develop normally.

Consider a baby born without eyes or with totally nonfunctional or missing optical nerve. It will grow up never experiencing any visual experience. There will be no data in the brain, and the brain's morphology which adapts to the data would be nonexistent.

We're talking about extreme problems here. Brains aren't premade data storage units which can be filled or empty. They are morphologically developed by the data input, too.

This is just the nervous system and locomotory system. Musculoskeletal system would be severely degraded. Immune system might suffer, too.

The brain stuff is a certain thing, even though no experimental data exists because it can be induced from previously known stuff.

It's much more difficult to predict whether embrionic development would be influenced. It would be great if experiments in zygotes and embrios (not fetal, that would be unethical because fetuses have nervous system) would be done on ISS, but I can imagine the rightwing and fanatical Christian nutters going crazy over it. It would never be approved with such dumbasses in USA and Russia.

[TarkinLarson]

Thanks for all the great responses.

I was perhaps a little flippant in my original remarks. I was not confusing evolutionary changes per se with individual changes. I understand that there will be profound changes to individuals which may eventually lead to them not being able to existing in a 1g environment again, at least without (I assume) lengthy and gradual rehabilitation.

Perhaps I also misclassified this as [biology] too. Being as there are many ethical dilemmas surrounding this and the lack of experimentation, I was looking for an estimation or even a slightly 'sci-fi' answers. I get that without actually doing this, we won't know.

From what I've seen and read there will be many consequences. The ones that stand out to me are ones including development as a child as an intergral part... things like the inability to actually walk. That is very interesting. I hadn't even thought of that. Even development of the inner ear too!

[Godot]

Yes, we don't know for sure (and possibly never will; it's an experiment that has some obvious ethical issues).

I doubt that you'd be able to find a doctor who wouldn't put his money on "almost certain miscarriage or worse", though. Microgravity messes with human biology in some rather profound ways.

While maybe not all too ethical, one could do experiments on the ISS.

Send a pregnant non human mammal to ISS and keep it there till the pregnancy comes to an end ... be it by one way or the other.

(or alternatively, keep several non human mammals of mixed genders on the ISS with the aim of getting one of them pregnant)

One could even go further and, in case of a successful pregnancy, keep the offspring there during its youth years in order to see how it grows up

(and maybe at one point, when it is grown up, geti it down to earth).

(as for the kind of mammals ... maybe dogs, cats, or even just gerbils or mice)

Would surely yield interesting results from which one could draw conclusions about larger animals (like humans, for example)

[TarkinLarson]

While maybe not all too ethical, one could do experiments on the ISS.

Send a pregnant non human mammal to ISS and keep it there till the pregnancy comes to an end ... be it by one way or the other.

(or alternatively, keep several non human mammals of mixed genders on the ISS with the aim of getting one of them pregnant)

One could even go further and, in case of a successful pregnancy, keep the offspring there during its youth years in order to see how it grows up

(and maybe at one point, when it is grown up, geti it down to earth).

(as for the kind of mammals ... maybe dogs, cats, or even just gerbils or mice)

Would surely yield interesting results from which one could draw conclusions about larger animals (like humans, for example)

Wait... didn't Russia sent that satellite up for a Gecko procreation experiment recently? I believe it also kept fruit flies and other things too? I believe they lost control of it and it's orbit would degrade in a few weeks.

[N_las]

While maybe not all too ethical, one could do experiments on the ISS.

Send a pregnant non human mammal to ISS and keep it there till the pregnancy comes to an end ... be it by one way or the other.

(or alternatively, keep several non human mammals of mixed genders on the ISS with the aim of getting one of them pregnant)

One could even go further and, in case of a successful pregnancy, keep the offspring there during its youth years in order to see how it grows up

(and maybe at one point, when it is grown up, geti it down to earth).

(as for the kind of mammals ... maybe dogs, cats, or even just gerbils or mice)

Would surely yield interesting results from which one could draw conclusions about larger animals (like humans, for example)

And it would give a giant blow to the public opinion on space travel. I can hear them:

- "They take our tax money to torture puppies in space!!!"

- "This picture shows how a deformed kitten on the iss is born!!! Like this picture to stop animal cruelty!!!"

- "I am against spending money on space related stuff. Because they use it to make bunnies retarted."

- "Astronauts are worse than Hitler!"

[Godot]

And it would give a giant blow to the public opinion on space travel. I can hear them:

- "They take our tax money to torture puppies in space!!!"

- "This picture shows how a deformed kitten on the iss is born!!! Like this picture to stop animal cruelty!!!"

- "I am against spending money on space related stuff. Because they use it to make bunnies retarted."

- "Astronauts are worse than Hitler!"

Unfortunately this is true ... which is why I mentioned ethics.

Today even mice or gerbils might cause a oublic uproar, if any fanatical animal protection groups are able to convince the public that the animals get tortured during the experiments (even if it isn´t true)

[lajoswinkler]

- "I am against spending money on space related stuff. Because they use it to make bunnies retarted."

This is seriously funny.

[ThinkOutsideTheHangar]

There is no such thing as 0 gravity. Gravity is everywhere, as long as matter is present. It's just that we're in free-fall sideways ( also known as an orbit.), so there are no G-forces.

[WestAir]

There is no such thing as 0 gravity. Gravity is everywhere, as long as matter is present. It's just that we're in free-fall sideways ( also known as an orbit.), so there are no G-forces.

I'm not quite sure biology cares about semantics.

[TarkinLarson]

I'm not quite sure biology cares about semantics.

I agree there will never be zero gravity, but also agree with the above quote.

There is no such thing as 0 gravity. Gravity is everywhere, as long as matter is present. It's just that we're in free-fall sideways ( also known as an orbit.), so there are no G-forces.

Zero G/Micro G... in this context you're maybe being pedantic? You will perhaps notice that I do use the phrase micro g, interchangeably with zero g in my OP. I understand the difference, but felt that this debate should be about the effects of it on how humanity would develop biologically if there were many generations in space, without getting bogged down in the detail of 0G of 0.00000001G

Edited August 8, 2014 by TarkinLarson

[Mr Shifty]

There is no such thing as 0 gravity. Gravity is everywhere, as long as matter is present. It's just that we're in free-fall sideways ( also known as an orbit.), so there are no G-forces.

As long as we're being semantic, G-force isn't a type of force, it's a unit of force. When an astronaut is in orbit, they're not in free-fall 'sideways'; they are in fact falling toward the center of the Earth. And free-fall is indistinguishable from rest without an external reference frame, i.e. in general relativity, an object in free-fall is travelling along the geodesic defined by local gravity and no forces are acting on it.