Evolution--humans in a differing environment

[scifiwriter]

Hi folks. I'm hoping I can occupy a few minutes of your time. I'm not a student or scientist, I'm a writer doing research for my first novel. I know this post is broad and possibly confusing, and I apologize in advance for it.

 

I'll try to keep this brief. In my novel, in the distant future, a group of 5,000 to 10,000 colonists have settled a new planet and separated from Earth entirely. Over the next thousand years, they spend their time in an environment which is slightly different from ours, here and there--perhaps a bit more nitrogen in the atmosphere, perhaps a bit less ultraviolet light to contend with.

 

After that thousand years, they return to Earth looking and functioning with a notable difference in cultur eand physiology (the latter being the subject of my post), from adapting to a different environment over a relatively short amount oftime. They also have genetic engineering capabilities, and purposefully alter their physiological makeup to cope with the environment.

 

If we lived a thousand years on a planet with these small changes--and any other possible causes thatyou could imagine would effect humans so as to cause significant changes, including genetic engineering--what would you *speculate* both the causes and effects could be? I'm looking for a mechanism by which humans would return a thousand years later with altered--and advantageously so--physiology.

 

This is a brainstorm/ thought experiment, and your input would be very much appreciated. Let me know if and how I can improve my post. Thank you for your time and sorry for the possibly confusing question.

 

To summarize: I need a mechanism by which humans could be physiologically altered (mostly in an advantageous way) over a relatively short period of time. And I'm curious as to what the effects of small changes in environment could be after a thousand years.

Edited May 28, 2012 by scifiwriter

[Phi for All]

If the environment is only slightly different from Earth, there's not much much selective pressure for evolutionary change over such a short time. Are you assuming that these colonists have genetic engineering but Earth doesn't, or have the colonists developed more skills in that area than Earth?

 

You also need to take into account that any environmental adaptations from the new colony might leave them at a disadvantage when they come back to Earth.

[scifiwriter]

Thank you Phi for responding. Yes, the colonists have technology for genetic engineering that Earth does not, largely because in the novel Earth's economic and political systems collapse, and while the colonists continue to more or less thrive, science and society on Earth takes a huge backward plunge. The colonists develop themselves both to adapt to environment, and for other reasons--some wish to develop biological weapons, for instance, because there is a lot of political strife within the colony, and the weapons--well, it's complicated, but the weapons arise from the altering of human biology. The colony, by the way, is largely composed of scientists, for reasons I won't go into in the name of brevity.

 

I suppose the follow-up would be, how large a difference in environment would make a significant difference in physiological development? Perhaps the colonists were sent to a planet with the perfect temperature and presence of water, but a radically different composition of atmosphere for example.

 

I was thinking that many adaptations could be less advantageous here on Earth, for instance requiring them to use devices to breathe, or the need to avoid exposure to the sun, or any other of many possibilities. This aspect is intriguing. They would in this case be very reliant on technology for survival. It fits the needs of the story well.

 

 

Interestingly, the original working title for the book was "The Phi." I won't get into that though, long explanation.

[Phi for All]

Using evolution for that kind of time period might not be realistic. Any environment that's too different would require technology to overcome just to be there, so there's no pressure for selective adaptation. If you want a physiological change, your colonists have to actually deal physiologically with the environment. The differences would have to be small, and that means small selective pressures that would require a couple more orders of magnitude of time.

 

You mentioned less ultraviolet light to contend with, and darn it, that was the only thing I could think of that might make for a superior advantage for the colonists after only a thousand years. They might be able to adapt to higher UV radiation on the colony, thus making them capable of surviving longer/working in normally inaccessible places/being generally more productive back on Earth. I could see some kind of mutation being genetically engineered that would manipulate the UV radiation/vitamin D/calcium relationship to give you some interesting opportunities for physiological change.

[scifiwriter]

That does sound about right, considering that evolution occurs over vast amounts of time and I'm only working with a tiny sliver of that. It is interesting to consider that perhaps with a loss of ozone on Earth, if the colonists returned with a better suitability for withstanding solar radiation, that would be a tremendous advantage. Of course, what remains of civilization would have had to learn to adapt, but purposeful genetic intervention would make the colonists physically adapted and perhaps more so.

 

It is always possible that the intentional manipulation of the human genome had some unintended effects for the colonists, who may not have had the same stringent standards for experiments and ethics that we do. I'll keep mulling this over. Thanks a ton for your input.

[CCWilson]

The fewer the colonists, and the more closely related they are, the more likely you'd be to see changes. If the state controlled who was allowed to have babies, selecting only the brightest and most beautiful for the settlement's benefit, evolutionary changes could be rapid. Most importantly, if there occurred some natural disaster that killed a good percentage of the settlers or made them sterile, there could easily be significant changes in 1000 years; those with mutations, new or existing, that made survival or reproduction easier would come to predominate in the population. If there was a new mutation that spread, other characterstics of the individual who introduced the mutation, including those unrelated to survival, would spread as well.

 

 

The appearance of the subspecies after 1000 years might also be subtly different from those on Earth. The reason that you can easily distinguish Europeans from Africans from Asians from South Sea Islanders from American Indians by their appearance is that evolution occurred in each of those reproductively isolated groups, including changes in facial features that probably were the result of genetic drift and/or differences in the originators of the races rather than in anything related to survival or reproduction.