Most People Carry Neanderthal Genes | Hacker News Reader

Most People Carry Neanderthal Genes

online.wsj.com

28 pointsjseliger14 comments

"I really think when you get up to 2%-to-5% genetic overlap, it is probably not wise to think of these as a separate species," said anthropologist Fred Smith at Illinois State University who studies Neanderthals.

By some other measurement, we have 96% overlap with chimpanzees, right? It's ridiculous for science journalists to use numbers without bothering explaining them.

Of course, the original article in the journal Science probably contains much more context, but (pet peeve alert) the newspaper doesn't provide a link, and even if they did it would probably cost a bunch of money to read it.

Non-free journals delenda est.

We have about 99% overlap with chimpanzees (not counting copy numbers & some types of rearrangements). Neanderthal shares 96% of the 1% Homo sapiens/chimp difference with humans and 4% with monkeys. According to Green's population model, the estimated fraction of Neanderthal ancestry for non-African populations today is between 1 and 4% (I guess these are the numbers Fred Smith refers to as 2 to 5%). By the way, 10% of all Americans can be traced back to the Mayflower.

The quote is misleading. The 2-5% figure refers to what percentage of the genes of modern non-Africans were inherited from Neanderthals, not merely common to both groups through a common ancestor. Most of these genes are inconsequential, as they exhibit very little variation even between species. The wide range in the estimate exists because it was determined by extrapolating from the small portion of the genes which do show variation.

The corresponding value for chimpanzees is 0%, as they are not our ancestors, though we share recent common ancestry.

Fun things they did:

(1) Tagging the DNA in a clean room. (2) Digesting CpG sites, which are more prevalent in microbes, to make the rest of their work easier. (3) Used allele frequencies to determine that all 3 source bones come from different individuals, though 2 likely share the same mother based on mtDNA analysis. (4) Determined that all bones were from women. (5) Determined that Neandertals are closer to non-Africans than to Africans.

Original article (Science magazine, free full-text): http://www.sciencemag.org/cgi/content/full/328/5979/710

I also share genes with bananas and fish.

But you are not a descendant of bananas or most fish.

We share a common ancestor

Yes. But that's not what the article was about. Modern humans and Neanderthalians share much more genetic material than the 4% the article talked about.

The 4% is the proportion of genetic material we inherited from them. And that's an interesting and non-trivial thing.

So Neanderthalians were some of our ancestors. But bananas weren't.

Speciation paradox

If your ancestors originated from an area of the world where there were bananas and fish, and shared more genes with them than people from other areas of the world, it would indeed raise interesting questions.

Life is a mess.

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