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Post by rialvestro on Nov 14, 2010 6:06:39 GMT -5
I just thought of this. In other topic some stated that reproduction in family members can cause deformations. Such as brother and sister having a kid together.
However there are several stories in which a species has to be repopulated with only one male and one female left of that species so how would that be possible?
If the first is true then the second could only reproduce for one last generation sense the next generation can't reproduce with each other as they're all brothers and sisters. Their kids, the 3rd generation would end up being deformed and the population of that species would not be saved from these deformed decedents.
So lets say there's only 2 humans left on Earth. They have a kid together. Now there are 3 humans left on Earth. They keep having kids at least till one of their children is the opposite gender of the first. The kids eventually have children of their own but their children end up coming out with malformed limbs and faces. How would this save the human race if this were to happen?
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Post by nicolii on Nov 14, 2010 16:41:30 GMT -5
That is a very good question. I cannot answer it.
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Post by Ryan on Nov 14, 2010 23:58:45 GMT -5
Deformations that occur are genetic mutations based on similar genetic coding. These malformations are actually rarer than you might think. Royal families for hundreds of years went through inbreeding. While this did lead to genetic mutations, and even illnesses, it did not prevent these families from dying out. Also, with each generation there would be slight variations in DNA due to the genetics of parenting. Given enough time, and provided that many children were birthed, eventually, the genetic variation would be great enough so that mutations that lead to deformations because of inbreeding would go away.
Mom + Dad = 3 girls + 4 boys
(Bro+sis) * 3 = (2 girls +3 boys) + (3 girls + 4 boys) + (2 girls + 2 boys - 1 boy) {the - 1 boy would be due to genetic mutation that lead to death}
Now, instead of bro and sis mating, cousins would mate. This slightly increases genetic variation.
There are 5 couples - this could lead to maybe 13 girls and 17 boys (just some random numbers I picked) with possibly 3 deaths due to genetic malformations.
Now cousins mate again, but this time they would be second cousins, much higher genetic variation. 13 couples leads to 30 girls, 28 boys, 2 deaths
28 couples of 3rd cousins leads to 55 more couples with only a few deaths
By the time we've reached 4th cousins, the genetic variation from the original parents would be roughly the equivalent variation between you and your great great great great great grand uncle. You would hardly be able to recognize them.
The reason this works is because while we carry the genes that make us who we are, we also carry many of the genes of our ancestors. These recessive genes, are basically genetic fail safes in the case that inbreeding must occur.
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Post by Rogers91 on Nov 16, 2010 1:56:32 GMT -5
^that... however a more healthy genetic combination would be the least geneticly common mates.. people from accross the globe would be the best parents due to a wide variety of differences between the two. now lets say beings from another planet where to reach us and where compatible then that would actualy produce extreamly healthy childeren and possible as even super human in comparison if the genetic codes where compatible. however as ryan said as long as the mateing of the family was more and more distant it would lead to more variety and eventualy better genetic lines that would support less mutations. now if brother and sister where to reproduce every single generation the gene pool would shrink and the likely hood of deformation would rise expanentialy. that situation could lead to still birth and eventualy sterilization of the off spring after several generations.
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Post by rialvestro on Nov 16, 2010 8:16:05 GMT -5
^that... however a more healthy genetic combination would be the least geneticly common mates.. people from accross the globe would be the best parents due to a wide variety of differences between the two. now lets say beings from another planet where to reach us and where compatible then that would actualy produce extreamly healthy childeren and possible as even super human in comparison if the genetic codes where compatible. however as ryan said as long as the mateing of the family was more and more distant it would lead to more variety and eventualy better genetic lines that would support less mutations. now if brother and sister where to reproduce every single generation the gene pool would shrink and the likely hood of deformation would rise expanentialy. that situation could lead to still birth and eventualy sterilization of the off spring after several generations. You know a new generation doesn't start till the previous generation starts having kids. Brother and sister could only start one single generation not multiple generations unless parent and child started having kids together then they would still be technically part of the new generation but also part of the last. Also about inter-species reproduction as you mentioned alien life forms. How would mating with an alien be any different from say, a dog mating with a cat? You don't really see inter-species breeding even on Earth though I'm not sure why it wouldn't be possible. We all got sperm and we all got eggs, why can't we mix them for creation of new species? Maybe it's already been done. *Points to duck billed platypus.* Hello part duck, part beaver, egg laying mammal where did you come from?
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Post by Ryan on Nov 16, 2010 9:40:20 GMT -5
Mating with an alien life form, might be like a dog mating with a cat, but if the two forms of life were similar enough, it could potentially be like a dog mating with a wolf.
Inter-species breeding is not possible due to different number of mating chromosomes. Humans have 22 genetic factors + 1 sex factor passed on in our reproductive cells. Other animals have a different number. Dogs for instance have 37 + 1 sex. Unless the pairs of chromosomes match up, then there cannot be breeding.
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Post by rialvestro on Nov 16, 2010 10:30:29 GMT -5
Mating with an alien life form, might be like a dog mating with a cat, but if the two forms of life were similar enough, it could potentially be like a dog mating with a wolf. Dogs and Wolves are both part of the K-9 species. They aren't just similar, they're exactly the same. That's like the difference between white and black in humans.
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Post by Ryan on Nov 16, 2010 11:51:12 GMT -5
Actually the difference between dogs and wolves is the same as the difference between a human and orangutan. The point is, dogs and cats can't mix because they are completely genetically incompatible. You cannot say that aliens are genetically incompatible, it is possible that they might be as genetically compatible as dogs and wolves.
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Post by low on Nov 16, 2010 12:09:48 GMT -5
Mating with an alien life form, might be like a dog mating with a cat, but if the two forms of life were similar enough, it could potentially be like a dog mating with a wolf. Dogs and Wolves are both part of the K-9 species. They aren't just similar, they're exactly the same. That's like the difference between white and black in humans. Not exactly. "Canine" isn't a species, Canis is a family and lupis is the species. Dogs as a whole make up a subspecies of wolves ( Canis lupis familiaris) and are still different "breeds" apart from each other. To say that humans of different skin colors are like different kinds of dogs is a bit closer, but still not entirely accurate. Dogs were "artificially selected" (that is chosen by humans rather than naturally being survivors in the wild) for docile behavior and tranquility around humans starting as early as 100,000 years ago. Humans all have common ancestry as recent at 60,000 years ago and some might say 45,000 years ago. Nonetheless, humans were selected more naturally than dogs and the difference between white people and other groups actually occurred as recent as 4-7 thousand years ago. (The lack of pigmentation has to do with agriculture and human migration. All caucasians are descended from Iraq, where barley, rye, and wheat were all cultivated between 10 and 13 thousand years ago. However, as people migrated northward toward the baltic region--around Estonia--, their food supply in harsh weather was limited exclusively to grain, which is an inadequate source of vitamin D, thus causing only those who could best metabolize vitamin D directly from sunlight to survive and later populate all over Europe when the weather improved. Melanin, the pigment which makes skin darker, absorbs UV rays and blocks some vitamin D metabolization from sunlight. That's why native americans--who lived in a climate barely different from northern Europe--are dark skinned: They had more fish and deer, which have vitamin D.) Now I think Ryan did a reasonably good job explaining what would likely happen. You would end up with a much more narrow gene pool that would eventually level itself out. Humans are all very inbred at many points on the evolutionary line. We all have 60,000 years of common ancestry (Y-chromosome Adam) and yet 160-200,000 years as a species (Mitochondrial Eve). Some of our deformities have actually proven beneficial. For example, we have a mutation in the primate gene for jawbone formation. All other primates have a hefty jawbone and our jawbone is very weak. Other primates also have chewing cause the skull plates to fuse at an earlier age (3 years old) because the bone rubs up against the temples harder. Our brain mass can continue to increase until around age 30 instead of age 3 because of a defective gene. With inbreeding, any advantages or disadvantages...or disadvantages that turn out advantageous...or advantages that turn out disadvantageous...or just completely neutral traits...are more likely to show up early on. Look at the Founder Effect, for example, which is just a microcosm of what you described. An example of this in people is Ellis Van Creveld syndrome in the Amish. Let's say two people, one of whom had 3 nipples, populated a small island. Its reasonable to conclude that 3 nipples would be a fairly common feature among those people.
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Post by low on Nov 16, 2010 12:25:22 GMT -5
Actually the difference between dogs and wolves is the same as the difference between a human and orangutan. *Human ( Homo sapiens) and Neanderthal ( Homo sapiens neanderthalensis) is a much better comparison, actually. As it turns out, Neanderthals didn't die out so much as we overpopulated and bred with them. The point is, dogs and cats can't mix because they are completely genetically incompatible. Just to clarify for everyone, compatibility is based primarily on chromosome number as well as very obvious fertilization issues (i.e., a penis has to fit into a vagina, and a stamen and vagina won't work--there aren't any known animal-plant hybrids).
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Post by rialvestro on Nov 16, 2010 13:30:40 GMT -5
*Human ( Homo sapiens) and Neanderthal ( Homo sapiens neanderthalensis) is a much better comparison, actually. As it turns out, Neanderthals didn't die out so much as we overpopulated and bred with them. Neanderthals are humans and they did die out. Neanderthal is just what we call our cave dwelling ancestors. So in a way yes we did breed with them because we are them. Of course you can't breed an animal with a plant. Plants don't even breed. They have a form of reproduction however there's no act of sex between plants. There are some animals however who reproduce differently than humans or pets. Allot of people know about how some Lizards are able to regrow their limbs if they should ever loose one. (This was the basis for one of Spider-man's villains and while the rest of the series is fiction that lit bit was the basis of reality) What you may not know is that some other animals have even more amazing regeneration capabilities. A star fish for example, if you cut off any of it's limbs not only will the original star fish grow a new limb but the severed limb will also grow a new star fish. As far as I can remember only Star Fish and some worms are able to reproduce this way. Not all worms, most will just die if you cut them in half but some types of worms will grow into two worms if you cut them in half. Going back to the more common form of reproduction, sex, given that Cats and Dogs both breed the same way and provided you used breeds that were the same size, there's no reason they couldn't have sex. However even though breeds we use as pets seem very similar their wild counterparts are not so much. Funny thing is domestic dogs can grow to be bigger than domestic cats but in the wild it's exactly the opposite. Also dogs in the wild aren't any bigger than their domestic counterparts or at least not noticeably bigger just by looking at them. (Unless you want to compare a wolf with a mini poodle but I was thinking biggest domestic compared to biggest wild.) Cats on the other hand, no domestic cat is ever going to be the size of a full grown lion. Basically which domestic and wild dogs are roughly the same size. Domestic Cats, full grown, are roughly the same size as a wild cat's babies. That being said. Wolves literally are Dogs. Their features are exactly the same, some people actually have domestic wolves as pets. It's just another breed. Domestic Cats however have about as much in common with lions as humans have with apes. Just like there's no such thing as a domestic lion there is also no such thing as an ape that lives like a human. I've never seen a house cat that could take down an elk and I've never seen a human with thumbs on their feet.
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Post by Ryan on Nov 16, 2010 13:34:00 GMT -5
Thank you low for bring some genetic history and experience to the debate, it is quite helpful.
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Post by low on Nov 17, 2010 13:57:34 GMT -5
Neanderthals are humans and they did die out. Neanderthal is just what we call our cave dwelling ancestors. So in a way yes we did breed with them because we are them. No, this is incorrect. Neanderthals were a select group of hominids who left africa prior to the rest of the homo sapiens population and developed their own adaptations. After a more developed homo sapiens left Africa around 60,000 years ago, they overpopulated neanderthals and bred with them in parts of Europe, the Middle East, and Western and Central Asia. It sounds like you're confusing Homo sapiens neanderthalis with earlier hominids, which include Homo erectus and Homo habilis, among other. Of course you can't breed an animal with a plant. Plants don't even breed. They have a form of reproduction however there's no act of sex between plants. Most plant reproduction is still called "sexual reproduction" even if there's nothing that would be called an act of sexual intercourse by a human being. However, if you were to use a scientific definition instead of a non-colloquial definition, then plant reproduction is almost always sexual reproduction, in that it involves male and female gametes, haploid cells, forming zygotes, or diploid cells. Going back to the more common form of reproduction, sex, given that Cats and Dogs both breed the same way and provided you used breeds that were the same size, there's no reason they couldn't have sex. This is true, however, in order to produce offspring, which would have varying degrees of fertility themselves based on genetic differences, the chromosome number has to match. Two haploid cells can't combine into a diploid cell capable of growing without the same chromosome number. It would be an extremely rare (albeit vaguely possible) anomaly if that were the case. Refer to this chart to assess breeding capability. As you'll notice, dogs and cats are nowhere close in chromosome number. Dogs and wolves have exactly the same number. Lions and cats also have the exact same number. And yes--you can breed a lion and a cat, provided you can make the lion hungry for sex instead of food.
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Post by rialvestro on Nov 17, 2010 15:49:21 GMT -5
And yes--you can breed a lion and a cat, provided you can make the lion hungry for sex instead of food. You know this kind of contradicts your previous statement. A lion is obviously allot bigger than your house cat and getting their parts to fit would be rather difficult even if you could prevent the lion from eating the cat. It might work if the male was the house cat but if the male is the lion then getting reproduction to work would be something like trying to fit an entire water melon into a child's lunch box.
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Post by low on Nov 17, 2010 21:00:14 GMT -5
You know this kind of contradicts your previous statement. A lion is obviously allot bigger than your house cat and getting their parts to fit would be rather difficult even if you could prevent the lion from eating the cat. It might work if the male was the house cat but if the male is the lion then getting reproduction to work would be something like trying to fit an entire water melon into a child's lunch box. Oh, I know. It's unlikely, but, technically, it's genetically possible.
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Post by qooqǝɯɐƃ on Nov 17, 2010 21:21:47 GMT -5
No, this is incorrect. Neanderthals were a select group of hominids who left africa prior to the rest of the homo sapiens population and developed their own adaptations. After a more developed homo sapiens left Africa around 60,000 years ago, they overpopulated neanderthals and bred with them in parts of Europe, the Middle East, and Western and Central Asia. I thought the Homo sapiens actually fought with them and drove them to extinction rather than breeding with them. Where did you learn all this, btw? I've only heard things on Discovery, maybe a little from school and the occasional article.
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Post by Flags_Forever on Nov 18, 2010 17:54:44 GMT -5
*Human ( Homo sapiens) and Neanderthal ( Homo sapiens neanderthalensis) is a much better comparison, actually. As it turns out, Neanderthals didn't die out so much as we overpopulated and bred with them. Actually, Homo sapiens neanderthalensis is not a valid taxon. Neanderthals were not a sub-species of Homo sapiens, but rather a separate, distinct species, Homo neanderthalensis. The latest research indicates that the two did not interbreed on a large enough scale to have any long-term effect on either population.
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Post by low on Nov 19, 2010 3:06:00 GMT -5
Actually, Homo sapiens neanderthalensis is not a valid taxon. Neanderthals were not a sub-species of Homo sapiens, but rather a separate, distinct species, Homo neanderthalensis. The latest research indicates that the two did not interbreed on a large enough scale to have any long-term effect on either population. Aye, it's a highly controversial topic which seems to be shifting around every few months. I've seen Homo neanderthalensis and Homo sapiens neanderthalensis used before and both relatively recently, though the more recent documents (especially from in the summer, when this what a hot topic) indicate a separate, yet very similar species (closer than chimps and humans. I checked a paper called "A Draft Sequence of the Neanderthal Genome" from May, which, in the paragraph entitled "Average DNA divergence between Neandertals and humans" seems to indicate a (rough) estimate of 825,000 years. This definitely would make them a separate species instead of subspecies, so I stand corrected. The level of breeding which occurred is also a controversial topic, though there's good reason to believe that breeding did occur. The extent, I don't believe, is agreed on by most scientists, yet. The paragraph "Implications for modern human origins" says there wasn't very much interbreeding and that Neanderthal DNA made its way intro the human genome, but that human DNA did not make its way into the neanderthal genome. Quite a tangent for a topic about inbreeding and deformities. I thought the Homo sapiens actually fought with them and drove them to extinction rather than breeding with them. Where did you learn all this, btw? I've only heard things on Discovery, maybe a little from school and the occasional article. That, too. There were more of us, we had better tools, we worked better with each other than they did.
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Skwiggs
Moon
[AWD:1902181c]
Look Deeper.
Posts: 201
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Post by Skwiggs on Dec 9, 2010 5:56:13 GMT -5
The problem with what Ryan said here is there are no cousins to add, there are only the mom and dad
I'd liek to point out that inbred labratory rats should give you the answer about how the deformity takes place but also how it can keep going.
i'll simplify this as much as possible.
We are buit by our genes. We get 1/2 of our genes from mom and half from dad. If your parents have different genetic traits (liek eye color) one of the traits has to be "more powerful" than the other, i'll call this the dominent trait. (if that wasn't so we'd all have the same color eyes, since 2 differeing dominent traits try to both take over and a "half-breed" happens)
the Deformity your talkign about is when 2 "not powerful" traits (i'll call recessive traits) are the only ones there. in some cases (like eye color) it's no big deal that recessive traits dominate the organ (Brown eyes are Dominent and Blue eyes are recessive for example) In some organs both traits beign recessive can cause alot of harm (like stomaches that produce to little/to much acid can make you prone to ulcers and malnutrition)
When you mate with someoen that has the same recessive genes that you do there is a 1 in 4 chance both recessives will meet (your dominent+ recessive and thier dominent+recessive) the other 3 choices are 1 in 4 both dominents will meet and 2 in 4 that 1 dom and 1 rec will meet.
When you mate with someoen of an entirely different set of traits it's far less likely that they will have the matching recessive trait that can meet up with yours to cause the "deformity"
So how do inbred mice not all deform and die off? well the ones that do die don't reproduce, makeing the recessive trait less available. Remember some of the offspring will have both dominate traits. This is the basis of the "Darwin Awards" where people are recognized for contributing to the health of the gene pool by removing themselves from it.
Eventually the only ones that live have (quite literally) purged themselves of all the recessive traits. The offspring are all (more or less) clones. There is downsides to clones even WITH all the dominent traits.. but that's a whole new topic.
Future genetic varity IS possbile in these instances.. but that's a whole new topic as well.. LOL i'll stop here before it gets more complicated
Due to my laziness and short attention span, I have decided not to read your lengthy post. Morals aside, if you have to inbred something, do it a lot, kill off undesirable offspring, and you can repopulate just fine. (this was Hitlers plan for the "master race"
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Post by Ryan on Dec 9, 2010 7:22:27 GMT -5
I'm sorry, where was I wrong in all of this? You basically just gave a genetics 101 lecture - but it didn't really add anything that wasn't already said.
Also, mice have a gene that allow them to survive multiple inbreeding generations without significant change to their genetic structure, which is something humans do not have (because we have had no need to develop an evolutionary need for it, unlike mice). This is why mice often mate with siblings or cousins in early generations when their population is limited (caged mice, and mice colonies start this way)
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