And Yes, Who We Pick As Mates = Natural Selection


As far as I know (and I’m going by my layman’s (or woman’s) understanding of things) three things cause / contribute to the process of evolution.  Natural selection, climate change and TIME.

Interracial marriage is not an example of evolution, it is an example of natural selection which, over time, contributes to changes to a species, and that process of change over time is called evolution.

A hundred years ago the percentage of people who had to wear corrective lenses was less.  The further back in time you go, very likely the less people you find with impaired vision.  Why?    Because visually impaired humans living more closely with nature are a lot more likely to become bear fodder and never reproduce.   Because before we invented our way to the top of the food-chain, we needed our senses a lot more to survive; our ability to hear, and see, and RUN.  So, just like it is still in nature, survival of the fittest.

Of course this doesn’t apply today.  People like myself who get laughed out of the building when we try to enlist in the Navy (for being too blind) still manage to cope quite well thanks to corrective lenses.  We hold down jobs, we raise children–who likely will also inherit our weak vision.  Over time we have more and more people needing corrective lenses because it no longer happens that the weak sighted humans are killed off by bears, or by accidentally falling off cliffs or, whatever perils our ancestors had to face who didn’t have the benefit of corrective lenses, seeing eye dogs or white canes.

This is an example of natural selection working against a species.  Because those of us with weak vision are able to live and procreate we are creating more visually impaired people.  Usually the opposite effect comes from natural selection.   Weaker traits do not get passed on because the individual with that weaker trait doesn’t get to survive.  Not in the natural world.  Anyone who knows anything about wolves or lions or any of the big predators knows–it is the sick or the aged or the weak that predators target and go after.  Why?  Because predators naturally do not want to have their rib cages kicked in or their skulls crushed, and the bigger stronger younger prey are more likely to cause serious harm–assuming they can catch them at all.

So natural selection, over time, does change a species.  If you go to Europe and check out the doorways of those cool old castles, I hear the doorways are very short.  Like….people over 5 feet tall have to stoop over to walk through them.  Why?   Because people were shorter back then.

Even in my lifetime…I was the tallest girl in my school growing up.  That was back in the day when there weren’t any professional women sports teams and girls were just beginning to have the same kind of physical education/fitness programs in schools as boys.   in the 30 years since I graduated I have seen more and more taller young women.  Girls that make me look short.   My guess is because women are finally “allowed” and even encouraged to use their bodies more–push themselves like boys to discover what they can do–they are getting stronger.   Or maybe it’s just that the human race is still just getting a little bigger with each passing generation.  This is evolution.  Environmental changes or natural selection over time causes species to adapt physically.  That changing process is evolution.  If human beings survived another million years (highly doubtful) or more, those humans of the future might look a lot different than we do now.   Especially as we replace what we used to do physically to survive, with machines to do it for us.

Another thing that creates change–diet.  In the horse example I gave in my previous blog, what I copied for that from Wikipedia describes how horses teeth changed as the horse’s diet changed.

If only brown haired, brown eyed people were allowed to have children, eventually blue or green eyed people would disappear–with maybe the occasional throw back now and then.  If interracial marriage became more and more accepted and popular, over time it is very possible the races now existing on this planet might be effected.  There might not be white people one day.  Because the more interracial couplings that happen, the more mixing of the races occurs, over a short amount of time, like 50 years or 100 years or 200 years, the face of humanity will change.  If all tall people were forbidden to procreate and only short people had children, the human race would likely start to get shorter again.

If the climate changes and the sun becomes more intense, again, white people might find it harder to survive than people with more pigment in their skin.  This would be a case where environment change is reshaping a species.   If the gravity on this planet were to change and become stronger…very likely many species would die out altogether, while other species might have a few individuals with stronger thicker bones, survive.  Those individuals with the stockier bone structure would mate with other individuals with stockier bone structure and that species would slowly adapt more and more to the new gravity, producing stockier offspring–and any offspring born without the thicker bone structure would die and not pro-create, until one day a stockier thicker boned version would exist, completely replacing the lighter framed earlier version of that same species that could not survive.

This is evolution or what causes evolution, as I understand it.  When you have the conditions of survival change and the life in that environment must adapt to the changes or die.

Another example–river dolphins.  Copied from Wikipedia:

Differences between marine and river dolphins

Both river dolphins and marine dolphins belong to a group of mammals called cetaceans, but they differ somewhat in appearance. For example, the snout of a river dolphin measures about 58 centimeters (2 ft) long, approximately four times as long as that of most marine dolphins. River dolphins have smaller eyes than marine dolphins, and their vision is poorly developed because they live in dark, muddy water. This environment also makes river dolphins less active than marine dolphins. River dolphins feed primarily on fish.[1

 
So….dolphins who do not use their vision very much because their environment doesn’t let them see, develop smaller eyes and weaker eye sight than dolphins in clear water who need and use their vision to survive.   Two examples of marine mammals very different from each other because of their environment.  And yet, both are dolphins.

Another example of animals who have adapted to suit their environment–Siberian tigers.  Gorgeous cats.  The largest of the big cats.  He has feet the size of platters–great big huge feet, why?  Because he travels on snow–needs to be able to run on snow.  So his feet have adapted.  Where humans have to wear snow shoes to walk on snow, the Siberian Tiger has his larger paws to achieve the same result.

An interesting animal to watch is the polar bear.  Either he will become extinct in the next 50 years, or he will adapt to his radically changing environment.  If he adapts he will physically change.   His diet will have to change.  How he gets fresh water to survive will have to change.  How well he can endure warmer temperatures will have to change.  If he can’t adapt fast enough, he will die and there will no longer be polar bears.

But there will be other bears.

Just like once upon a time there were Neanderthals and now there are not, while other species of humans who lived alongside Neanderthals did not die but endured.  Neanderthals didn’t become us…but they did leave their genetic signature behind and contributed to what has made humans what we are today.

I don’t know how to end this.  I hope this makes some kind of point. I guess what I’m trying to describe is, the ingredient Creationists don’t want to take into account is time.  Creationists are used to thinking a deity said “let there be–” and there it suddenly was.  They apply that same kind of thinking to evolution.  They think one species just suddenly becomes something else. That’s not how it happens.  It takes time–millions of years.   Over time creatures that looked rather like wolves started hunting more and more in the water, started feeding more on fish than prey animals on land.  Over time these animals adapted to hunting in water, and came out onto dry land less and less.  Over time these animals developed limbs more like paddles instead of legs, and longer leaner bodies to make them cut through the water more swiftly.   And over a really long period of time these animals became cetaceans–dolphins, Orcas, whales.  Warm blooded mammals that live like fish in the sea.

Given enough time, a species will adapt itself to its changing environment.   Because if it doesn’t, or if the change happens too soon, it goes the other route.  It becomes extinct.  Or changes to the point that it hits a roadblock and cannot change or adapt anymore, which is what they guess happened to the Neanderthal.

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3 comments on “And Yes, Who We Pick As Mates = Natural Selection

  1. just a small note;
    one thing many people misunderstand is the definition of the word ‘fitness’ or ‘fittest’ in context of natural selection. people always think ‘fittest’ necessarily means biggest/strongest/fastest/etc. but fitness refers only simply to the ability to pass on your genes. the more offsrping you have, the ‘fitter’ you are. and so what is ‘fit’ changes depending on the environment.

    so while in normal everyday language it makes sense for us to think that ‘natural selection’ isn’t working as it normally would anymore, since we’re interfering and saving the weak with corrective lenses or medication, so those ‘weak’ genes that would normally not get passed on are being passed on…. i don’t think that’s quite right if you’re using looking at is from a scientific perspective. natural selection is still happening, but the selection pressures have changed because the environment has changed. who are the people (what are their traits?) who are more likely to have kids, more likely to have more kids? that’s what our environment is ‘selecting’ for now…

    • Agreed. However I was trying to come up with simplistic modern day examples for people who have difficulty thinking back beyond 2000 years.

      Fittest. Strongest. Whatever…I agree it’s not really about that. But natural selection does take that into account. If the foliage is changing (as in the case of horses) and leaves on trees are getting less but their necks are too short for them to graze grass, all the short-necked horses would likely starve, or figure out a way to perhaps kneel or splay their legs to get at the grass. By doing this they are adapting new feeding habits to compensate. But they are also making it more difficult for themselves to run from the sudden appearance of a predator–thus the individuals who have to kneel or contort their bodies more to get at the grass would be perhaps a little slower to get their feet under them to run, while the individuals with longer necks who don’t have to crouch over so much to eat, would already be running. So which would likely be the horse caught by predators and who would be the ones to survive? Also they are eating grass not leaves so this will change the job their teeth have to do. Over time their bodies will change to make it easier for them to chew and easier for them to lower their heads to graze, simply because (I think) the individuals most successful at survival will be the ones with slightly longer necks, slightly stronger teeth…

      I’m making this up of course. I am not a scientist just an amateur paleontologist. Without reading it all again I’m not exactly sure what the climate changes were that caused changes for the horse. But I’m trying to explain in my way how I think the fittest survive. In the case I’m coming up with above, the horses that were “fittest” were the ones able to adapt to compensate and over time they physically changed to make eating grass easier and reaching down for grass easier.

      Some people speculate that if humans stop using their fingers so much because we have machines and computers to do so much for us, one day human hands might not look the same as they do now. Or say, right now people get carpal tunnel syndrome or tendonitis in their wrists or elbows from repetitious work like checking or word processing… If we continued as is without making machines to do the work for us, continued demanding more from our hands and lower arms than they are currently able to take, perhaps in the future humans would have stronger lower arms and wrists.

      Anyway, this is about as far as a non-scientist just trying to explain my understanding of how evolution / natural selection and changing environment works. I would welcome any scientist reading this blog to explain it for me. I do try to read about evolution. I have a huge fascination with prehistoric and ice age animals and animals in general. But a lot of science neep is over my head too. All I can write about here is how I understand what I’ve read rather like how a Christian might try to explain their interpretation of some verse in the bible.

      • well, i’m no scientist either, but I did study biology up to university, if that helps haha. I think your understanding is mostly right. But again i’d just like the stress that it’s not in about ‘better’ or stronger, it’s about what allows the organism pass on its genes. so ‘better’ is better ONLY in that specific environment and context. if having a weaker jaw or weaker teeth helps you survive your environment, then that’s ‘better’ in the eyes of natural selection. for example, I was reading about the narwhale yesterday and it has no teeth in it’s mouth! it looks so strange. or actually, they found that it has vestigial teeth, useless and hidden. we normally wouldn’t think of having no teeth as ‘better’, but more narwhales with smaller teeth must have survived than narhwhales with bigger teeth, and more narwhales with no teeth survived than narwhales with small teeth…

        as for human hands/arms/wrist, all those would only make a difference if it affects a) survivability to mating age and b) ability to get a mate and c) ability to bear children. if it doesnt affect these (and i don’t think it would have much effect?), then we wouldn’t see different hands or strong arms because of it.

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