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Rare 'goat-sheep' born on Irish farm

bbc.co.uk

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Re: Rare 'goat-sheep' born on Irish farm

#101

Post by Houshalter »

spullara wrote: post #79
Houshalter wrote: post #74

Earlier quoted context omitted.

I don't see why it's that implausible. You are descended from almost every single human being alive 1,000 years ago. Can you find any significant amount of DNA contributed from only a single one of your ancestors? What he is suggesting is that a single hybrid made it's way back into the hominid population. It had children with other hominids, and those children would have had half as much pig DNA. They had children w…

"You are descended from almost every single human being alive 1,000 years ago." Um. No.

Yes actually. Here is an explanation why. http://dgmweb.net/Ancillary/OnE/NumberAncestors.html

Re: Rare 'goat-sheep' born on Irish farm

#102

Post by dang »

001sky wrote: post #98
dang wrote: post #91

Earlier quoted context omitted.

It would be more appropriate to say that a comment is dead, because you can tell that by looking at it, than that an account is banned, because you can't tell that by looking at it, and when you get that wrong, it's misleading. I definitely should have communicated this more clearly above; I'm sorry I didn't. It's not just nitpicking. We've gotten many emails from distressed users asking why they were banned because…

@dang can you take a look at this as well. https://news.ycombinator.com/item?id=7537035

Sure. I read it, but didn't understand it precisely. If you'd like to take another crack at it, the best thing would be to make your suggestions as concrete as possible and send them to hn@ycombinator.com.

Re: Rare 'goat-sheep' born on Irish farm

#103

Post by bradleyjg »

Houshalter wrote: post #100
pcrh wrote: post #94

Earlier quoted context omitted.

"You are descended from almost every single human being alive 1,000 years ago." Not exactly 1,000 years, but more like 120-135,000 years for the male line [1], and 200,000 years for the female line [2]. [1] "Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females " dx.doi.org/10.1126/science.1237619 [2] https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Mitoch...

No it's much closer to 1,000 years. Every generation the number of possible ancestors you have doubles. 2 parents, 4 grandparents, 8 great grandparents. Within a few generations back, you have literally millions of ancestors.

Doesn't that assume no overlap? It seems like the odds of 2^n unique ancestors would be pretty low by the time you get to 10.

Re: Rare 'goat-sheep' born on Irish farm

#104

Post by maxerickson »

bradleyjg wrote: post #103
Houshalter wrote: post #100

Earlier quoted context omitted.

No it's much closer to 1,000 years. Every generation the number of possible ancestors you have doubles. 2 parents, 4 grandparents, 8 great grandparents. Within a few generations back, you have literally millions of ancestors.

Doesn't that assume no overlap? It seems like the odds of 2^n unique ancestors would be pretty low by the time you get to 10.

This seems like a reasonable discussion of the issue:

http://gcbias.org/2013/11/11/how-does-your-number-of-genetic...

After ~15 generations your genealogical ancestors aren't all that likely to have contributed much to your DNA.

Re: Rare 'goat-sheep' born on Irish farm

#105

Post by marshray »

saalweachter wrote: post #96
marshray wrote: post #71

Earlier quoted context omitted.

I think he's saying relatively modern chimps and pigs may have had a hybridization event. Another argument was that the morphological distance, or genetic differences besides chromosome number, are just too great. Most of us are familiar with the platypus. A paper published in Nature a few years ago demonstrated that the platypus genome contains both bird and mammal chromosomes, and therefore that the vastly differen…

No. The platypus is not a bird/reptile hybrid. That is a wild misinterpretation of a genome study which happened a few years back. http://scienceblogs.com/pharyngula/2008/05/10/the-platypus-g...

Should I take from this that phys.org is not a particularly reliable source?

Re: Rare 'goat-sheep' born on Irish farm

#106

Post by saalweachter »

marshray wrote: post #105
saalweachter wrote: post #96

Earlier quoted context omitted.

No. The platypus is not a bird/reptile hybrid. That is a wild misinterpretation of a genome study which happened a few years back. http://scienceblogs.com/pharyngula/2008/05/10/the-platypus-g...

Should I take from this that phys.org is not a particularly reliable source?

I am not particularly familiar with phys.org. Briefly scanning it, it looks pretty normal.

Most likely it's just someone stepping outside their wheelhouse. I mean, I trust PZ on biology, but I wouldn't incredulously accept legal advice from him. So, maybe reliable for physics/space, but unreliable for biology is my guess?

Re: Rare 'goat-sheep' born on Irish farm

#107

Post by eps »

dang wrote: post #91
eps wrote: post #90

Earlier quoted context omitted.

1. Emailing is not a viable option. I simply don't have email setup on all but one device that I use to browse HN. 2. You can nitpick on technicalities, but it doesn't matter to lacero if he was hell-banned or ip-blacklisted. All that matters is that his comments go in trash can and that's what I was trying to rectify. PS. A proper way to support these cases is to add "flag for mod review" option to dead comments and…

It would be more appropriate to say that a comment is dead, because you can tell that by looking at it, than that an account is banned, because you can't tell that by looking at it, and when you get that wrong, it's misleading. I definitely should have communicated this more clearly above; I'm sorry I didn't. It's not just nitpicking. We've gotten many emails from distressed users asking why they were banned because…

> I don't buy the thing about email not being accessible enough

There's nothing to buy. I will not email mods about false negatives. It's inconvenient.

Re: Rare 'goat-sheep' born on Irish farm

#108

Post by spullara »

Houshalter wrote: post #101
spullara wrote: post #79

Earlier quoted context omitted.

"You are descended from almost every single human being alive 1,000 years ago." Um. No.

Yes actually. Here is an explanation why. http://dgmweb.net/Ancillary/OnE/NumberAncestors.html

It is obviously false. There are many people that were alive 1000 years ago that you have no relation to due to geographic separation. Just because you can analyze something using statistics doesn't make it right. It even explains some of the discrepancy in the description of that chart — your ancestors are not unique and therefore the entire chart is just statistical hyperbole.

Re: Rare 'goat-sheep' born on Irish farm

#109

Post by Steuard »

ghkbrew wrote: post #67
Steuard wrote: post #60

Earlier quoted context omitted.

I saw that claim in the article, yes. I'll admit that I don't know enough about genetics to make strong claims here, but it doesn't sound remotely plausible to me. He wants to simultaneously claim that 1) hominids got so much porcine DNA that they have lots of substantial, recognizable anatomical features as a result, and 2) hominids have so little porcine DNA that it's all but invisible in our genetic code. I'm not…

In general I agree with you, it's an extraordinary claim with less than extraordinary proof to put it mildy. However I thought I'd make one small correction on your genetics. > most genetic inheritance happens one full chromosome at a time. is actually not true. Sperm and eggs have only one copy of each chromosome instead of two like most cells in the body. However, that one chromosome is a pretty good mixture of the…

Thanks! I didn't realize that recombination was so frequent. I'm glad to have a better sense of that now.

Re: Rare 'goat-sheep' born on Irish farm

#110

Post by Steuard »

Houshalter wrote: post #74
Steuard wrote: post #60

Earlier quoted context omitted.

I saw that claim in the article, yes. I'll admit that I don't know enough about genetics to make strong claims here, but it doesn't sound remotely plausible to me. He wants to simultaneously claim that 1) hominids got so much porcine DNA that they have lots of substantial, recognizable anatomical features as a result, and 2) hominids have so little porcine DNA that it's all but invisible in our genetic code. I'm not…

I don't see why it's that implausible. You are descended from almost every single human being alive 1,000 years ago. Can you find any significant amount of DNA contributed from only a single one of your ancestors? What he is suggesting is that a single hybrid made it's way back into the hominid population. It had children with other hominids, and those children would have had half as much pig DNA. They had children w…

Right, so he's claiming that the genes responsible for this really pretty random list of traits ("protruding, cartilaginous mucous noses"? "Prostate encircles urethra"? "Alcoholism"?) were so strongly selected for that they became 100% ubiquitous in the human genome. Meanwhile, every other trace of pig ancestry got diluted away to nothing.

I understand the idea of dilution, I just don't understand why he thinks that so many random things would survive it to become defining features of the human species. Remember, he's not just saying that 2% of living humans carry Genghis Khan's Y-chromosome or have red hair or something, he's saying that all of these traits became completely universal.

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