So I was wondering if new born babies on Mars would have any body changes rather than new born babies in Earth.
Example: Would the bone structure be different when they grow up?
If you like to read something "deep" about this problem: Kim Stanley Robinson Otherwise:
Will be exactly same as on Earth, but:
Mars has around 38% of Earth's gravity = less muscles need. = Problems when they do actually come back to Earth and experience 263% gravity.
Fluids in our inner ear - may cause disorientation, but most likely only for those, who were born and live in space.
In some time (centuries/millennia) bone structure will change for sure, because those with lighter bones will be higher in 'survival of the fittest'. Because it would make any job on Mars easier for them = more money = children have higher chance to have children. You may not see it now, but will you employ some slow "earth-like" individual, or 200% faster "mars-like" handyman?
In opposite of Fayth85 opinion:
There is still 'survival of the fittest' for example:
"If you solve food problem, ppl won't die and would have one more child"
"If you drive below limit, you won't have problems with law and/or won't have crash"
"If you live to very old age, you can teach children more and give them (most likely) more money. In opposite of you die right after they were born."
"If you win Mars olympic games (because of lighter bones) - your children would have (for sure) the biggest chance to survive"
"If you are attractive - you can be dumb, you still have higher chance to find partner than nonattractive+dumb person."
So yes, but not because baby is born on Mars would make it lighter bones = "magic" - i don't think this thing is already in genes. Maybe in some time human genes would develop into something like: "bigger gravity = bigger bones" but that will take 10000 years at least and frequent traveling between Earth/Mars etc. But I would not underestimate genes.
Evolution is a process of seeing what works best in the subject's environment. Though this is a process that takes thousands-to-millions of years, there are times when this process is sped up considerably: a population bottle-neck.
This is when it's easiest to see what little changes are the most beneficial. Then the fastest runner, or the longest runner, or the one that carries the most weight wins out--should any of those traits be seen as desirable to a mate. But you're talking about humans.
Humans no longer follow 'survival of the fittest'. Now it's the one with the cute backside, or the highest intellect. That creates a problem, because if you cannot predict what the 'desirable trait' is, you cannot saw how evolution will pan out. So, I guess it's anyone's guess--but I hope the first part helped somewhat 8-)
As they grow up, there will be differences in bone density and muscle mass and probably a host of other problems due to the low gravity environment.
But when born, they will be 100% pure human babies, the same as on earth. Things that happen during the organisms lifespan don't influence the next generation... jews have been cutting off foreskins for thousands of years, yet each generation stubbornly gets born with it again.
I disagree with the accepted answer. In the Mars case, the survival of the fittest would have a clearly winner: only those who make past childhood would reproduce. If loss of bone tissue, or harder radiation levels kill a lot of children, or leave them with sort of a glass-bone disease then surely the ones passing on their genes are the ones who can get laid without breaking their hips.
And secondly, maths suggest that mere "survival of the fittest" can't account for the incredible variability that we experience here on Earth. While this darwinian mechanism it's easily proven, evolution must use some other methods as well. Evolution hasn't stopped on humans; [sexual dimorphism] is on the wane, as well as our jaws as we don't need that many teeth now (we're getting rid of the third molar).