What did the Neanderthals do for us? | Hacker News Reader

What did the Neanderthals do for us?

bbc.com

34 pointsJacobAldridge21 comments

The most interesting part of this article is how much of the Neanderthal genome is still present in the non African population. I would be really interested to see the same analysis applied to the Melanesian population who are 6% or so denosovian [1].

1. https://en.m.wikipedia.org/wiki/Denisovan

What advantages did the Neanderthal genes add (or take away)? The only way to really find out is to create a modern day living Neanderthal. There's probably decades of research to do before we can pull that off, but some day it will happen. We need more than just the genome, unfortunately.

We already know a surprising amount about Neanderthal humans. They were generally short, around 5'7"/170cm, but their bones and muscle attachment sites were larger, suggesting bigger and more powerful musculature.

Combine hereditary strength with a vigorous lifestyle during a brutal epoch, when both predators and prey were dangerous giants, and we are looking at a truly powerful breed of humans who are thought to have been many times stronger than modern Homo Sapiens humans.

It seems, though, that this great strength was not a useful enough trait to be passed on through interbreeding; the modern humans displaced H. Neanderthalensis after a few thousand years, and we definitely don't have the musculature they had, not even our Cro Magnon ancestors who were contemporary with them.

Their huge braincases are another mystery. They averaged 1600 cubic cm, versus 1400 for modern humans. Were the Neanderthals smarter? Or were their brains larger, as claims one scientist, to accommodate a larger optical center for their enhanced night vision?

Ah, what we would give to have a way to warp time and visit that bygone era!

They were generally short, around 5'7"/170cm

Looking at this[1] list, I would call them average. Specially when nutrition was probably less than ideal then.

[1] https://en.wikipedia.org/wiki/Human_height#Average_height_ar...

The other way to approach it is to create a modern human. If 3% out of 20% is Neanderthal per human it must mean that a perfect snapshot exists across multiple donors.

Both are interesting but unlikely experiments.

> What advantages did the Neanderthal genes add (or take away)? The only way to really find out is to create a modern day living Neanderthal. There's probably decades of research to do before we can pull that off, but some day it will happen

Do you want to create Khan? Because that is how you create Khan. If you're averaging a bunch of genomes to do this (e.g simple rank-based voting), and assuming most mutations are deleterious, you're probably going to end up with some sort of super-Neanderthal who is way smarter and stronger than the average human.

Fictional sources are not evidence in a debate or argument.

The Khan part is a joke but the rest is serious. Nearly all mutations are unique and deleterious. So if you average them all out, you'll end up with an organism that is significantly more fit than average.

fables parables and other tales are simplifications and analogies that make boring or hard logic easier to grasp.

The boy who cried wolf isn't about any particular real boy, but you don't need a real example to figure out that its not just possible but plausible.

Must we always have a previous real example to govern the future? Some futures aren't necessarily repeats of history.

It's possible these genes contributed no significant evolutionary advantage and their prevalence is just an accident of history. For instance, Genghis Khan's Y chromosome isn't found in a large percentage of Asian males because it confers a selective advantage, he just happened to be in a position to reproduce much more than most.

"It may seem strange that we inherited disease-causing genes at all. After all, only beneficial genes should survive, so surely over hundreds of generations we should have shaken off these unwanted contributions?"

Certainly not my field, but my understanding is that unless a mutation has a direct impact on survival and fertility... then there is no evolutionary drive for it to go away.

All animals have negative genes that just stick around as random "junk" which has accumulated over the years. It's not surprising that we have picked them up too.

Some genes exhibit pretty complex behaviour. For example, the gene for sickle cell anemia manifests as sickle cell disease only when an individual is homozygous in that gene (i.e. They have inherited a copy of this gene from both parents). Such individuals have a host of health problems, including being more susceptible to malaria. However, individuals who are heterozygous (i.e. they inherited just one copy from one parent) for the sickle cell gene do not typically have sickle cell disease, and being heterozygous in this gene actually confers resistance to malaria. In areas where malaria is a major cause of death, the gene for sickle cell anemia is much more common than it is elsewhere.

> Certainly not my field, but my understanding is that unless a mutation has a direct impact on survival and fertility... then there is no evolutionary drive for it to go away.

Well, genes get corrupted by random mutations, and if they have no survival value, there is no correcting force. So they drift out of the genome.

Are you referring to genetic drift? This is a statistical phenomenon by which alleles that are near neutral for viability change in frequency until one becomes fixed. This doesn't mean that neutral mutations will invariably push the wild type out of the genome. Actually, that would be improbable in the absence of a selective pressure or an accident of history.

I'm saying genes that have no survival-value will fade away due to accumulating random mutations.

That's probably different from whatever you're describing.

'Junk' DNA doesn't actually contain genes. By definition, a gene encodes a functional polypeptide or RNA. This is different from alleles that are neutral for viability. An example of such an allele might be connected earlobes -- this phenotype is genetically determined, but unless there's sexual selection I'm not aware of, you are correct that we wouldn't necessarily expect the alleles involved in this phenomenon to go away. However, they might as a result of an accident of history or genetic drift.

This is a very interesting topic, but the article is fluff: smoking, red hair, some diseases.

I am 2.5% Neanderthal.

Pffff. If you are < 3% are you even european? ;)

If she had over 3% she would have written a smarter article. ;)

We share a lot more than 20% of our DNA with Neanderthal's ~99%. So, it's not clear exactly what they mean by this article.

They factor out genes attributable to common ancestors we had with Neanderthals.

They're talking about genes that were specifically modified along the Neanderthal branch of evolution and then added back to us.

Considering we are the same species and would interbreed, I don't think it's that clear which line started a given mutation. Unless they had a lot of samples to work with.

IE, did a trait start with us and move to them. Or did it start with them and move to us.

The Tibetan adaptation to high altitudes is a good example of introgression from Denisovans: http://news.nationalgeographic.com/news/2014/07/140702-genet...

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