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Odysseus
03-07-17, 00:55
If Interbreeding between two different species causes sterile offspring , then why do humans still carry Neanderthal genes?

We all know that when two different species of animals Interbreed with each other they give birth to sterile offspring that are unable to reproduce.

We are told that Neanderthals & Homo-sapiens are classified as two different species yet they were able to have offspring together that could reproduce........what gives?


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Angela
03-07-17, 02:48
If Interbreeding between two different species causes sterile offspring , then why do humans still carry Neanderthal genes?

We all know that when two different species of animals Interbreed with each other they give birth to sterile offspring that are unable to reproduce.

We are told that Neanderthals & Homo-sapiens are classified as two different species yet they were able to have offspring together that could reproduce........what gives?


Sent from my WAS-LX1 using Eupedia Forum mobile app (http://r.tapatalk.com/byo?rid=89698)

This is how it was explained by Reich:

""The team showed that the areas with reduced Neanderthal ancestry tend to cluster in two parts of our genomes: genes that are most active in the male germline (the testes) and genes on the X chromosome. This pattern has been linked in many animals to a phenomenon known as hybrid infertility, where the offspring of a male from one subspecies and a female from another have low or no fertility.

'This suggests that when ancient humans met and mixed with Neanderthals, the two species were at the edge of biological incompatibility,' said Reich, who is also a senior associate member of the Broad Institute and an investigator at the Howard Hughes Medical Institute. Present-day human populations, which can be separated from one another by as much as 100,000 years (such as West Africans and Europeans), are fully compatible with no evidence of increased male infertility. In contrast, ancient human and Neanderthal populations apparently faced interbreeding challenges after 500,000 years of evolutionary separation.""

Other articles have highlighted that it was the male hybrids which were particularly affected.

https://www.quora.com/How-were-Neanderthal-human-hybrids-fertile

"The speculation and conjecture ends when analyzing the mitochondrial DNA of both species; which, upon extensive study, supports the premise that the Neanderthals werein fact a separate species from humans; with the genetic separation of the lineages originating between 800,000 and 400,000 years ago.The hybrids proved to be fertile for the simple reason that the two species shared sufficient genetic similarity for it to be possible, without genetic complications arising in the hybrid species that rendered it sterile. There is no deeper meaning behind how or why it was possible.
However, studies conducted from the Stanford University School of Medicine; and available in the April 7th 2016 edition of The American Journal of Human Genetics; suggests that the Y-chromosome of the Male Neanderthal proved to be unviable in hybrids; conceivably due to incompatibility with other human genes.
Thus, the question is only half right in its assumption, however as only the female hybrids proved to be fertile. This is due to a concept known as Haldane’s Rule; which states that if one of the genders in a hybrid species turns out to be sterile, that gender is most likely the one that is heterogametic, namely the gender with different sex chromosomes."

As for remaining Neanderthal ancestry, it's not the same 2% that is present in all humans. It varies. Another area where there is no Neanderthal ancestry in anyone, besides the X and the Y, is the speech center in the brain.

LeBrok
03-07-17, 03:16
Not all the Neanderthal genes were deleterious for people, some of them were very helpful instead. Adaptation to cold and new environment, resistance to new diseases and perhaps lighter skin,

Linda Raymond
19-01-18, 23:24
I know I have some Neanderthal genes. 286 variants according to 23 and me but I must not have gotten any to survive the cold environment. I'm sitting here in Florida dying from this cold weather. (just being slightly dramatic) lol.

bicicleur
20-01-18, 11:12
[/COLOR][/FONT][/SIZE]https://www.quora.com/How-were-Neanderthal-human-hybrids-fertile

"The speculation and conjecture ends when analyzing the mitochondrial DNA of both species; which, upon extensive study, supports the premise that the Neanderthals werein fact a separate species from humans; with the genetic separation of the lineages originating between 800,000 and 400,000 years ago.The hybrids proved to be fertile for the simple reason that the two species shared sufficient genetic similarity for it to be possible, without genetic complications arising in the hybrid species that rendered it sterile. There is no deeper meaning behind how or why it was possible.
However, studies conducted from the Stanford University School of Medicine; and available in the April 7th 2016 edition of The American Journal of Human Genetics; suggests that the Y-chromosome of the Male Neanderthal proved to be unviable in hybrids; conceivably due to incompatibility with other human genes.
Thus, the question is only half right in its assumption, however as only the female hybrids proved to be fertile. This is due to a concept known as Haldane’s Rule; which states that if one of the genders in a hybrid species turns out to be sterile, that gender is most likely the one that is heterogametic, namely the gender with different sex chromosomes."

so the Y-chromosome of the male Neanderthal is unviable, but the Y-chromosome of the male modern human is?
how do they know that? because Neanderthals Y-DNA went extinct and modern humans not?
or do they have a biological explanation?


As for remaining Neanderthal ancestry, it's not the same 2% that is present in all humans. It varies. Another area where there is no Neanderthal ancestry in anyone, besides the X and the Y, is the speech center in the brain.

yes, modern humans had some functions that made them able to survive in groups which Neanderthals lacked
that is not the reason why modern humans could outcompete Neanderthals though
modern humans lived side by side with Neanderthals for 30.000 years with only limited interaction and without one being able to outcompete the other
the blade stone tools invented by modern humans 50 ka did the job
within 10.000 years these tools spread all over Eurasia with modern humans causing the extinction of Neanderthals and all other archaïc species

Silesian
20-01-18, 16:25
If Interbreeding between two different species causes sterile offspring , then why do humans still carry Neanderthal genes?

We all know that when two different species of animals Interbreed with each other they give birth to sterile offspring that are unable to reproduce.

We are told that Neanderthals & Homo-sapiens are classified as two different species yet they were able to have offspring together that could reproduce........what gives?


Sent from my WAS-LX1 using Eupedia Forum mobile app (http://r.tapatalk.com/byo?rid=89698)
Good questions. From a European sample/data set here is what we know.
Some point form points of interest-
1)Many Europeans have Neanderthal admixture.
2)Europeans plot in specific regions on well defined worldwide pca plot.
https://d8v5jhqx5tv4l.cloudfront.net/wp-content/uploads/2017/09/pca_yamna.png
3)Oase1 is very old and is in same geographical region[80-90Km+/-]as very old genetic samples-Iron Gates.

​Peștera cu Oase (Romanian pronunciation: [ˈpeʃtera ku ˈo̯ase] (https://en.wikipedia.org/wiki/Help:IPA/Romanian), meaning "The Cave with Bones") is a system of 12 karstic (https://en.wikipedia.org/wiki/Karst_topography) galleries and chambers located near the city Anina (https://en.wikipedia.org/wiki/Anina), in the Caraș-Severin (https://en.wikipedia.org/wiki/Cara%C8%99-Severin) county, southwestern Romania (https://en.wikipedia.org/wiki/Romania), where some of the oldest early modern human (https://en.wikipedia.org/wiki/Early_modern_humans) remains in Europe (37,800 years old) have been discovered.[1] (https://en.wikipedia.org/wiki/Pe%C8%99tera_cu_Oase#cite_note-Wilford-1)

In 2015 genetics research revealed that the Oase 1 fossil (https://en.wikipedia.org/wiki/Fossil) had a recent Neanderthal ancestor, with an estimated 5-11% Neanderthal autosomal DNA. The specimen's 12th chromosome was also 50% Neanderthal.[2] (https://en.wikipedia.org/wiki/Pe%C8%99tera_cu_Oase#cite_note-2)[3] (https://en.wikipedia.org/wiki/Pe%C8%99tera_cu_Oase#cite_note-3)
https://en.wikipedia.org/wiki/Pe%C8%99tera_cu_Oase
http://images.devs-on.net/Image/wdtwPRQby4AZhlsj-Region.png
http://umap.openstreetmap.fr/en/map/ancient-human-dna_41837#9/44.8344/21.7722

https://kumbarov.com/ht35/R1b_xP312xU106_V.38.1.pdf

4)Some old Iron Gate samples are between [green triangle with red on above pca] specific R1b branches like L754+ and V88+

http://images.devs-on.net/Image/vGJjLSd7tvI1eJbt-Region.png
5)European Neaderthal habitat regions measured by different markers
http://rsos.royalsocietypublishing.org/content/2/4/140022
http://rsos.royalsocietypublishing.org/content/royopensci/2/4/140022/F1.large.jpg

6) Stage 4 evolution -Neaderthal description; larger cranial capacity,prominent nasal cavity[Dinarid ], receding chin, large eyes, occipital bun, stocky build,
https://thumbs-prod.si-cdn.com/KvuCnrHSnLS9l6KvUxxtsT8L1cM=/800x600/filters:no_upscale()/https://public-media.smithsonianmag.com/filer/60/61/6061c583-f904-475e-81a5-76983f312a8c/42-68873364.jpg

https://upload.wikimedia.org/wikipedia/commons/thumb/c/c5/Neanderthal_cranial_anatomy.jpg/400px-Neanderthal_cranial_anatomy.jpg

7) [NEAR]- Near African Regions[Africa + Near East cradle of evolution and or development] plot on various/different points on pca; and therefore might have different type of Neaderthal and or other types of admixture as of yet- unknown.
"​The genetic structure of the world's first farmers"
https://www.biorxiv.org/content/early/2016/06/16/059311

...........Neanderthal admixture and that separated .........

Angela
20-01-18, 17:35
so the Y-chromosome of the male Neanderthal is unviable, but the Y-chromosome of the male modern human is?
how do they know that? because Neanderthals Y-DNA went extinct and modern humans not?
or do they have a biological explanation?



yes, modern humans had some functions that made them able to survive in groups which Neanderthals lacked
that is not the reason why modern humans could outcompete Neanderthals though
modern humans lived side by side with Neanderthals for 30.000 years with only limited interaction and without one being able to outcompete the other
the blade stone tools invented by modern humans 50 ka did the job
within 10.000 years these tools spread all over Eurasia with modern humans causing the extinction of Neanderthals and all other archaïc species

I think what they meant, Bicicleur, is not that the Neanderthal y is unviable per se, but it was unviable in the hybrids " conceivably due to incompatibility with other human genes."

firetown
22-04-18, 00:16
so the Y-chromosome of the male Neanderthal is unviable, but the Y-chromosome of the male modern human is?
how do they know that? because Neanderthals Y-DNA went extinct and modern humans not?
or do they have a biological explanation?


It is actually far more simple than people are willing to acknowledge. Neanderthals lived in small populations isolated from one another. 30-40 individuals. When homo sapiens arrived in Europe en masse, they were defenseless. What do you think happened? The men were killed and the women were taken. The fertility issue was presented in a singular study as a possibility for the absence of Neanderthal y-DNA. A BBC article turned that possibility-opinion into a headline. And next thing you know... people run with it and present it as fact. Read the actual studies. Not just the articles about them.