The Naked Scientists

The Naked Scientists Forum

Author Topic: Human Bats  (Read 4275 times)

Offline OldMan

  • Sr. Member
  • ****
  • Posts: 222
    • View Profile
Human Bats
« on: 06/08/2004 04:44:27 »
If we took a bunch of people and locked them in the earth or basically a zero light situation, then opened it up again in say a few hundred million years do you think they would have developed a form of sonar?
Would they still have eyes after that long or would they simply be exceptionally weak/non-functional?

Tim


 

Offline MooseHole

  • Full Member
  • ***
  • Posts: 73
    • View Profile
Re: Human Bats
« Reply #1 on: 09/08/2004 17:18:19 »
I don't think there's any reason not to have eyes, except maybe some extra energy is needed to grow them and maintain them.  If they were to evolve away, it would probably be because the people aren't able to get much food and stuff.

If food was scarce, people whose genes didn't devote much energy to eye production would probably live longer, and would be more likely to reproduce.  So it really depends more on the entire environment, not just lack of light.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Re: Human Bats
« Reply #2 on: 09/08/2004 17:42:01 »
Surely the fact that there's no light is reason enough to not have any eyes !!..seems reasonable to me that if the circumstances allowed, that they would then indeed have no choice but to develop sonar to navigate their way around....and probably an extreme sensitivity to smell, sound and vibration/touch too......and that's what I have to say about that.

'Men are the same as women...just inside out !'
 

Offline bezoar

  • Hero Member
  • *****
  • Posts: 950
    • View Profile
Re: Human Bats
« Reply #3 on: 10/08/2004 01:33:35 »
There are some fish that live in the bottom of caves, that over time have evolved to not having eyes.  I read that in the National Geographic once.  Oliver Sacks wrote a book about a man whose sight was restored after havin been blind from early childhood.  It's a fascination story.  It seems that other parts of the brain sort of over develop to compensate for the lack of sight.  When his sight was restored, it was very disorienting to him, and he had difficulty adjusting to seeing again.  Eventually, he went blind again, and you get the feeling from the story that it was almost a relief for him.
 

Offline MooseHole

  • Full Member
  • ***
  • Posts: 73
    • View Profile
Re: Human Bats
« Reply #4 on: 10/08/2004 18:03:23 »
In order for people to be born without eyes, there has to exist within the species the possibility of not having eyes.  I don't know if any humans have ever been born without eyes, but if they have, then this is a probable occurance if the energy to produce and maintain eyes is needed elsewhere.

Think of it this way (I didn't come up with this):
There's a world completely covered in Daisies.  When its sun is very hot (because of planetary rotation, orbital distance from the sun, solar cycles, etc.), the bright white daisies thrive, because they reflect the unneeded sunlight.  This makes most of the daisies bright.  When the sun is cold (for the above reasons), the darker colored daisies thrive because they absorb the heat and hold it for a longer period of time.  This makes most of the daisies dark.

The point of this is that at least some light and dark daisies have to exist at all times, or else the species will be unable to adapt to the changing conditions.  Therefore, there have to be people born without eyes, or at least people who have genes with the proclivity to be born without eyes for this to happen.
 

Offline neilep

  • Withdrawnmist
  • Naked Science Forum GOD!
  • *******
  • Posts: 20602
  • Thanked: 8 times
    • View Profile
Re: Human Bats
« Reply #5 on: 10/08/2004 19:28:34 »
Ok...thanks Moosehole... understood..... but, are not humans born with eyes because we do live in an illuminated world ?..............if, for instance we could survive without light in the first place then would there still have not been the chance for humans to not have eyes ? ie: the possibility to not require sight would then exist eh ?.....I appreciate you explaining it to me...cheers.


'Men are the same as women...just inside out !'
 

Offline tweener

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 1144
    • View Profile
Re: Human Bats
« Reply #6 on: 11/08/2004 03:37:33 »
This thread brings to mind a question I've pondered in the past.  If a species finds itself in an environment that is survivable but different from what is ideal, such as people in complete darkness, is there some sort of internal feedback mechanism that will adapt the genes to the new environment? Using this example, while people in complete darkness would, in the first few generations, certainly be born with eyes, the eyes would not work because they never were used during development.  This is well proven and stems from the fact that the brain would not develop to support functionality that is not exercised.  The eyes are still there and would certainly work if the child had developed in a normal lighted situation.

However, it appears from many cave dwelling species that eyes will cease to develop after many generations.  If this were purely chance, it would seem that many species would still have eyes even if they were non-functional from dis-use.

----
John - The Eternal Pessimist.
 

Offline MooseHole

  • Full Member
  • ***
  • Posts: 73
    • View Profile
Re: Human Bats
« Reply #7 on: 11/08/2004 21:49:37 »
Our genes have developed in such a way as to make us seek out the most healthy people and reproduce with them.  This is why in the 1700s fat people were considered sexy (skinny people were the ones dying of hunger).  In today's society, we think of skinny people as being healthy (even though some people are too skinny for their own good).

In a completely dark situation, those who don't devote a lot of energy to eyesight development can rechannel it to other things.  This, in general, makes them more healthy for the environment they live in.  Therefore, those people with bad eyesight will be more likely to reproduce and create children with bad eyesight, until eventually the entire population will be blind or near blind.  If a mutation happens where someone is born completely without eyes, that person will in general be more healthy than the others, and therefore will get more action.
 

The Naked Scientists Forum

Re: Human Bats
« Reply #7 on: 11/08/2004 21:49:37 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums