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Hairiness -- allowing adaptation to warmer environments -- was among gains

Roughly 500,000 year ago, the breeding populations that would evolve into humans (Homo sapiens) and Neanderthals (Homo neanderthalensis) separated.  Neanderthals came to dominate the mountainous, forest terrain of Europe, while humans spread out across the warm grasslands of Africa and the Middle East.
 
But the long estranged relatives would come into contact in an intimate way once more when mankind thrust its way into Europe roughly 80,000 years ago.  And by intimate, yes, we mean there was sex.
 
I. Understanding Our Shared Family Secret -- Neanderthal Sex
 
Ever since researcher and entrepreneur J. Craig Venter, Ph.D. became the first human to have his or her genome sequenced in 2007, the race was on to sequence the Neanderthal genome and find what secrets it might hold.
 
Led by led by the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and its top ancient-DNA expert, Svante Pääbo, the project yielded a draft genome in May 2010, followed by a "finished" Neanderthal genome in March 2013. 
 
With the initial 2010 announcement, definitive proof of our ancestors' steamy romance with European Neanderthals was laid bare for the first time.  Today researchers are still worker to chronicle that mysterious engagement and what impacts it has on modern human genetics.
 
Harvard Medical School (HMS) geneticist Professor David Reich's lab -- working with collaborators at the Max Planck Institute -- is the latest to offer new insight into this relationship.

Professor David Reich
Professor David Reich, Harvard Medical School [Image Source: Harvard]

To hunt down Neanderthal genes, the researchers first sequenced 846 people of non-African heritage (who likely contained Neanderthal genes) and 176 people from sub-Saharan Africa (who likely did not receive Neanderthal genetics).  These sequences were then used to pinpoint the genes that the non-African humans (e.g. Europeans) shared with Neanderthals, but which weren't found in people of sub-Saharan African origin.
 
In total Professor Reich's team located 100,000 genes that originally belonged to the Neanderthal genome but penetrated the human genome, thanks to our frisky ancestors.

DNA
Roughly 2 percent of Europeans' DNA comes from Neanderthals. [Image Source: Mashable]

The researchers next examined individuals to look at how much Neanderthal DNA they had and what holes in the genome that DNA crammed into.  They found that on average non-Africans had roughly 2 percent Neanderthal-inherited DNA, but that these genes were not uniformly laid out.  Some stretches of the participants' DNA were rich in Neanderthal genes, while others were more like "deserts", devoid of Neanderthal genes.
 
II. Breeding With Neanderthals Had Genetic Downsides
 
HMS Professor Sriram Sankararaman, the first author of a new study on the work, comments:

It suggests the introduction of some of these Neanderthal mutations was harmful to the ancestors of non-Africans and that these mutations were later removed by the action of natural selection.

The location of the barren stretches -- mostly in the female "X" sex chromosome, and in genes on other chromosomes most-expressed in male testes germ cells -- show that it was likely difficult for the Neanderthals and their hopeful human mates to conceive children.  This is a common problem in genetics called "hybrid infertility" that occurs between species related closely enough to be sexually compatible, but different enough to suffer fertility issues.

Geico Caveman
Humans and Neanderthals are believed to have struggled with fertility issues.
[Image Source: Terez Owens]

The way the human genome stretched to accommodate genetics from the members of the Neanderthal species could lead not only to breakthroughs in understanding human evolution, but also in human health studies and finding ways to prevent infertility in crossbred livestock.
 
Professor David Reich, senior author of the study, comments:

Now that we can estimate the probability that a particular genetic variant arose from Neanderthals, we can begin to understand how that inherited DNA affects us.  We may also learn more about what Neanderthals themselves were like.  [The barren DNA stretches] suggest that when ancient humans met and mixed with Neanderthals, the two species were at the edge of biological incompatibility.  It is fascinating that these types of problems could arise over that short a time scale.

While past studies have suggested that interbreeding improved immunity and genetics related to disease resistance, it turns out that Neanderthals might have actually passed along some harmful genes, as well.  Studies suggested that genes associated with increased risk of lupus, biliary cirrhosis, Crohn’s disease, and smoking addiction were all inherited from the Neanderthals.

Lupus Harvard
Neanderthals also contributed genes that caused diseases such as Lupus
[Image Source: DermNet]

Likewise, Asians with some Neanderthal DNA saw an increased risk of type 2 diabetes versus Europeans or Africans.
 
III. Benefits, New Look Also Came With the Territory
 
But the study also looked at how the Neanderthal genes influenced genes affecting keratin, a fibrous protein found in hair, skin, and nails.  It indicated the Neanderthal donations might have made the human European colonists more hairy, allowing them survive harsh winters.
 
And while Neanderthals have traditionally been portrayed as dark haired, darker skinned primates, recent research indicates that quite the opposite may be the case.

Neanderthals
Hairiness, blonde hair, and thick body hair are all thought to have been inherited from Neanderthals. [Image Source: OurPRG]

Researchers believe that darker skin and hair color came from the human gene lines, where as genes yielding red or blonde hair and lighter skin complexion came from Neanderthals.  Perhaps that explains like regions such as Scotland and Scandinavia where Neanderthals are believed to have survived the longest have the highest rates of red or blond hair and fair skin.

Neanderthal Red haired
Red hair and fair skin are also thought to have been inherited from Neanderthals.
[Image Source: BBC News]

A study on the work has been published in the prestigious peer-reviewed journal Nature.  A second paper has been published in the prestigious peer-reviewed journal Science.

The researchers next goals include making tests for the Neanderthal genes identified available to the public, enhancing the hunt for Neanderthal genomes by sequencing other Neanderthals' full gene sequences, and sequencing the DNA of Denisovans (Denisova hominins) -- another close relative of man that bread with early humans in Oceania.

The ongoing research is funded by the Max Planck Institute, the Howard Hughes Medical Institute (HHMI), the National Science Foundation, and the National Institutes of Health (NIH).

Sources: Nature, Science, Harvard Medical School



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Fertile hybrids are uncommon
By Amedean on 1/31/2014 5:46:50 PM , Rating: 2
From what I understand most hybrids of dissimilar species are sterile. The odds of producing a hybrid that can procreate is very small. I think this might help to explain one reason why so little neanderthal DNA is in the human gene pool.

I am no specialist on the matter, I am just communicating some knowledge of animal husbandry.




RE: Fertile hybrids are uncommon
By Divide Overflow on 1/31/2014 8:18:28 PM , Rating: 3
Perhaps the two species are not as dissimilar as commonly believed.


RE: Fertile hybrids are uncommon
By drycrust3 on 2/1/2014 1:03:47 PM , Rating: 3
And perhaps these two "species" are actually the same species!
As I recall, there was some research done quite a while back now that compared the mitochondrial DNA of some people from all around the world, and it was found they all descended from the same original mother, who was given the name "Eve". This couldn't happen if the origin of mankind came from two different species, so lets put it plainly out there: these two species are the same species!
The problem here is these scientists don't have any standard genetic based definition which states where a species starts and finishes.
We have people in jail because their DNA put them there, so scientists can, if they want, find such a level of uniqueness in DNA that they can say "That DNA sample came from that person there!". However, scientists still haven't come up with a boundary that says "The level of difference between this DNA sample (say from a chicken) and that DNA sample (say from a duck) indicates they are different species" or "The level of similarity between this sample (say a Doberman) and that sample (say an Alsatian) indicates they are the same species".


RE: Fertile hybrids are uncommon
By futrtrubl on 2/2/2014 1:12:16 AM , Rating: 3
Actually having a single "Eve" mother and being descended from two "species" is not mutually exclusive. Eve is just a lot older, ie from before Neanderthals and modern humans split.

However, I agree that the problem here is the definition of the word "species". Given the hard definition that a species is different if it can not produce viable offspring the neanderthals and modern humans are not the same species, but maybe subspecies. But even that is a relative definition. If you had say a human, Neanderthal and a Denisovan and the human could breed with the Neanderthal and the Denisovan but the Neanderthal and Denisovan couldn't breed together... is that one species or two? Add a hypothetical 4th hominid that could only breed with the Denisovan but not the others, is that 1, 2, or 3 species?

The problem with using some level of difference in DNA is that 2 species might not be able to breed and be 1% different while another might have 2% variability within its own species.


RE: Fertile hybrids are uncommon
By drycrust3 on 2/2/2014 5:30:59 AM , Rating: 2
quote:
Eve is just a lot older, ie from before Neanderthals and modern humans split.

Wait ... wait ... so you're saying that Neanderthals were human, so why aren't they now? Humans had their common origin in "Eve", and you're saying that Neanderthals had "Eve" as their common origin too, so that tells you something: they and us are the same species!
quote:
Given the hard definition that a species is different if it can not produce viable offspring the neanderthals and modern humans are not the same species, but maybe subspecies.

Incorrect, the evidence is that humans have Neanderthal DNA in them, i.e. we are the result of viable offspring. Thus we can conclude they and us are the same species.


RE: Fertile hybrids are uncommon
By boobo on 2/2/2014 9:07:05 PM , Rating: 2
It's a bit more complicated than that. There are entire branches of Neanderthal DNA that are incompatible with human DNA. If we were really one species, the entire genome should be compatible. Maybe they were already well into the process of splitting into a separate species but had not completed the process yet. Maybe nobody taught mother nature proper classification systems.


By drycrust3 on 2/3/2014 4:46:26 AM , Rating: 3
There is a possible reason for the incompatible with human Neanderthal DNA, which is that for some reason there were Neanderthal populations that were isolated from the general larger gene pool, e.g. an ice age, possible rising sea levels, migration to an isolated area, etc, stopped communication for a long period of time.
If a gene pool is too small at the start of a time of separation, then the lack of diversity increases the amount of mutations compared to those in the larger gene pool, so after a while, the population stops growing (assuming food isn't a problem) and starts to drop.
It is highly likely that in the course of human history this has happened. If this did happen to Neanderthals, where they were isolated for an extended period of time, and their starting population was too small, this would result in them being incompatible with not just humans, not just Neanderthals who are outside of their group, but at the same time they were becoming increasing incompatible with themselves too. They were almost in a mutation feedback loop, where the mutations shortened life, so the diversity within the population reduced, and because it reduced mutations perpetuated and spread within the group, and thus the life expectancy shortened even more.
As far as I can tell, this doesn't mean those in that isolated gene pool are a different species, they are the same species, but suffering from more mutations than those in the larger gene pool.
Of course, there are lots of assumptions here. For example, we don't know where this "incompatible" Neanderthal DNA was obtained from, although it probably wasn't from humans, so maybe it was from archaeological excavations, but from where? An isolated region or along a main trade route? If it was obtained from an archaeological excavation, then why wasn't it what the Max Planck Institute used instead of having to sift through tons of DNA to get a few ounces of gold?


RE: Fertile hybrids are uncommon
By seraphim1982 on 2/3/2014 11:24:37 AM , Rating: 2
I think people are forgetting the fact that is there about estimated 60-70,000 years of homo sapiens breeding with homo sapiens. That 2% of neanderthal DNA may have been much higher in non-modern day humans.


RE: Fertile hybrids are uncommon
By drycrust3 on 2/3/2014 2:22:02 PM , Rating: 2
Our world wide population is far far far too low for us to have been here even 50,000 years. Our current growth rate is around 1.2% per year, and with that sort of growth rate we would exceeded one person per square millimeter long ago.
Even if our growth rate was 0.1% per annum, our population would have exceeded 1 person per sq metre on the earth's surface (land and water) 25,000 years ago (starting population = 10,000. If it was less then we might have become extinct from too many genetic mutations), meaning we cannot have been here more that 25000 years!
Formula used is: N=No*exp(rt), where N= final population, No=starting population, r=rate of population increase, and t=time period in years.


RE: Fertile hybrids are uncommon
By japlha on 2/3/2014 5:25:59 PM , Rating: 3
Why do you assume a constant growth rate?
Ever heard the carrying capacity of an ecosystem? As a population grows the capacity to obtain resources to reproduce and sustain that growth becomes more and more difficult. So you cannot have infinite growth.

By your argument our entire universe should be populated with bacteria because of their high growth rate.


RE: Fertile hybrids are uncommon
By Reclaimer77 on 2/3/2014 5:46:14 PM , Rating: 2
Is that some creationist BS?

Are you aware how many mass slaughters have taken place throuought history? Plagues? Famine? Genocide? Wars?

How many children would have been born if not for this?

Did you take all this into account?

I would ask how do you explain the carbon dating, geologic, and DNA evidence. But I hear you guys have ways to explain all that away too...


RE: Fertile hybrids are uncommon
By drycrust3 on 2/4/2014 7:17:52 AM , Rating: 2
As far as I know what I wrote isn't on any Creationist website, or at least it wasn't when I wrote it, if you do find the general ideas what I've written on any Creationist site then what I did was independent, and if you find what I wrote exactly the same then they copied me. I very seldom frequent Creationist sites, mainly because I don't have time, they are going in the wrong direction for my liking, or because this is a forum where Creationist references would not be welcome, so if I do give a reference it is almost always a non-Creationist one anyway. I did have some URLs where people could go and check what I said, but the website wouldn't accept my post, so I removed the URLs.
My recollection is I did, in the course of the research here, read one Creationist blog, but as far as I'm aware I didn't quote from it. A small part of what I said may have come from it, but my recollection is if I did then it wasn't significant part. I think I did use the text to look for key words to Google (or Bing or DuckDuckGo or Yahoo or Ask or Dog Pile) and to follow the citations they provided, which were peer reviewed non-Creationist journals.
In regards to the things like famines and wars and pestilence, etc, yes, I am aware of those things, they reduce the rate of population growth, but don't stop the population from growing. According to one paper if you watch a population over time it can expand ... expand ... expand ... plateau ... contract ... contract ... contract. Assuming food isn't the issue, why does this happen? Genetic mutations! See, each generation passes on mutations, mostly these aren't so serious as to affect the overall population, but if you have a population which is restricted or prevented from accessing the general gene pool, then the mutations aren't lost, they are passed on and cumulate, and with each generation the cumulations increase and new mutations are added, and these reduce life expectancy, so the population starts to contract, and eventually the replication rate is exceeded by the rate of dying.
The only way to prevent this from happening is by having a large enough gene pool at the start of the period of isolation. In the paper I read they gave the example of needing at least a population of 1000 to 10,000 if you were going to go beyond several hundred generations, which is why I stated the size of the 500,000 year time frame as needing a starting population of 10,000, because there are something like 20,000 generations, so you needed a large gene pool to start with. The problem with this time frame is that even with much lower than 1% rate of expansion you still end up with a massive world wide population at the end of 500,000 years.
Really, when you look at this time frame, there are just so many problems that it really makes you wonder why it was even mentioned. For example, you end up with such large world wide populations that your spread sheet can't calculate them, and that is before you add in the genetic mutations. It isn't very hard to make up a spreadsheet where you just put in the figures and up pops the answers, so you can easily try things like having 1/10th of the rate of population expansion or 50,000 years or a starting population of 100, etc.
In all these things, the whole point of science is to test what others have done.


RE: Fertile hybrids are uncommon
By Reclaimer77 on 2/4/2014 8:17:08 AM , Rating: 2
Well my apologies. However the only people who think there is still a debate about how old Earth is are Creationists.

Your population theory is old and tired, and it's on very shaky ground. Just because we don't know every variable that might have contributed, or detracted, from the worlds population doesn't mean you can just throw out all the hardcore proof of the Earth's age!

It's impossible for a planet to form in the ridiculously short time-frame the Creationists cling to. I know they believe a deity just magic'd it all up, but come on.


RE: Fertile hybrids are uncommon
By ammaross on 2/4/2014 10:51:21 AM , Rating: 2
It would be a lot easier for creationists to claim that $deity 'formed' Earth over billions of years (intelligent design theory perhaps?) rather than poofed it into existence.

Also, the population growth formula cited doesn't have factors for early-death, but merely uses bacterial-growth models. You would need to reduce population-expansion-drivers (breeders) for periods of plague (Black Death wiped out 1/3 of Europe), wars (how many men who didn't breed, let alone women [think civilians and those of Jewish decent in particular] were wiped out in World War 2?). Wars were even more frequent, but on smaller scales, in earlier tribal periods, but just as devastating to an overall population growth model. This doesn't even take into account other factors yet.


By drycrust3 on 2/5/2014 6:33:53 AM , Rating: 2
quote:
It would be a lot easier for creationists to claim that $deity 'formed' Earth over billions of years (intelligent design theory perhaps?) rather than poofed it into existence.

You obviously haven't read the primary historical text used by Creationists. The main gist of it is exactly "poof" and "there it is". For example "no universe" then "poof" and then "there it is", "no stars" then "almost poof" then "there they are", "no plants" then "poof" then "there they are", "no animals" then "poof" then "there they are", "no humans" then "extra special poof" then "there he is", etc.
"Well," you say, "that just can't happen. It is impossible for that sort of thing to happen." So can you describe Big Bang? "Well, it was like there was nothing, not even space, then poof there was the universe and space and stars and stuff like that". So, science now says that "poof" is acceptable in some cases? "Well ... sort of ... ummm ... in special cases ... like when things just pop into existence." Okay, so does that means science recognises it might actually be possible for things to "poof" and then "there it is" to happen?


By drycrust3 on 2/7/2014 8:06:45 AM , Rating: 2
quote:
However the only people who think there is still a debate about how old Earth is are Creationists.

No, the only people who debate how old the earth is are those who don't believe it isn't young. The facts all point to a young Earth. For example, we now know that it just isn't possible for humans to have lived here millions of years because we know that each generation passes on between one and three genetic mutations per generation, but with even just one genetic mutation per generation we'd have gone extinct long ago if we'd been here millions of years. We also know that our world wide population is also too low compared to what we'd expect if we had been here 100,000s of years. After 50,000 years there would be more people here than square millimetres on the earth's surface.
We also know that there is Carbon 14 in the oil we extract from the ground, and Carbon 14 has fairly short half life, meaning it would be almost undetectable after 65000 years, yet there it is in your gas and petrol. How can that be? Only by the original hydro-carbon based deposits being buried less than 65000 years. So how does that affect the "millions of years" theories? It shows them wanting! Those theories don't fit the facts.
So to sumarise: cross out "millions of years", it hasn't happened; cross out "100,000's of years", we haven't been here long enough; cross out anything longer than 65,000 years because the amount of Carbon 14 in the oil, gas, and coal all show it can't have happened.
Finally, the onus is on the advocates of the "millions of years" to prove they are right. I can't see how they can do this as all the evidence is stacked against them, but that isn't my problem, the onus is on them to prove they are right.


RE: Fertile hybrids are uncommon
By talonvor on 2/8/2014 12:31:49 AM , Rating: 2
That's incorrect, what the mitochondrial DNA shows us is that at some point in the past, there was a bottleneck that squeezed the human population down to near extinction levels. They have pinned this event to the eruption of the Toba super Volcano some 74+ thousand years ago.


By drycrust3 on 2/9/2014 10:35:45 AM , Rating: 2
The problem with "a bottleneck" is scientists still don't seem to know what is and isn't "a species", so how can they know whether there was or wasn't a bottleneck.
For example, does a Neanderthal have the mDNA "Eve" gene? Since we have Neanderthal genes in us then of course they have the mDNA "Eve" gene in them, so they are the same species as us, so we can cross them off the list of "different species" and add them to "Prehistoric Races".
One of the issues that arises over many generations is the effects of cumulative genetic mutations, and this apparently happens when part of a group is restricted from accessing the general gene pool, e.g. geographic isolation on an island, cut off by an ice age, to big a difference in physique between breeds to allow natural breeding, etc. Does this mean that cut off group becomes a different species or not?
As I said before, there needs to be a boundaries placed that define what is and isn't a species, because "a bottleneck" could have arisen as a consequence of isolation from the main gene pool, although I think it was real (as per the Creationist's Primary Historical Text).
I gave them a method of defining a species (check the mitochondrial DNA to see if has the "Eve" gene, but does that work for every species? Do cats and rats and elephants all have their own mDNA "Eve"? I'm guessing they do, but I will have to do some research to confirm that.


RE: Fertile hybrids are uncommon
By Totally on 1/31/2014 11:21:38 PM , Rating: 2
That is due to mismatched number of alleles, or gene groups.

If species are similar enough to over come all the reproduction barriers(e.g. incompatible hardware), there is the genetic one.

Species A has 42(21 of which get passed on to offspring)
Species B has 40(20 of which get passed on to offspring)

Species A mates with B results in an offspring(if it survives) with mismatched alleles (40+1), since it is an odd number the resultant offspring is sterile.

TL;DR

Neanderthals had the same number of alleles as we do.


RE: Fertile hybrids are uncommon
By Fritzr on 2/3/2014 9:59:55 PM , Rating: 2
Present day example
Species: Timber Wolf/Gray Wolf
Species: Domesticated Dog
Species: Coyote

Coyote+Gray Wolf=Red Wolf (a 4th species with a stable breeding population)
Dog+Coyote=fertile hybrid dog
Dog+Wolf=fertile hybrid dog
The German Shepherd breed descends from sheep dog-wolf crosses. Herd defense dogs rather than the common sheep driving dogs.

Wolf-Dog hybrids are fairly common and are not recommended for casual ownership as they tend to inherit wolf behavior to greater or lesser degree without predictability. Breeding the hybrids with desirable traits leads to the wolf descended breeds that can be safely owned.

Based on instinctive behaviors that wolves, dogs & coyotes do NOT share but are always found within each type, they are 3 distinct species that have no problem with producing fertile hybrid descendants.


So..
By aurareturn on 1/31/2014 8:07:03 PM , Rating: 1
This article is saying white people have more Neanderthal genes than Africans and Asians? Cause I actually believe that.




RE: So..
By Jeffk464 on 1/31/2014 8:37:55 PM , Rating: 4
This is not new, previous articles have shown that there is about zero Neanderthal DNA in sub Saharan black populations.


RE: So..
By retrospooty on 2/1/2014 7:40:08 AM , Rating: 4
That is kind of a well known point now. This article is just mentioning what has already been proven by the human genome project. The highest neanderthal gene content of any group of humans is in Europe... The highest among Europeans is in northern Italy. Being that my family is from northern Italy this makes me neanderthaler than you! :P So what? I dont get sick often and I scratch myself alot. Big deal.


RE: So..
By daar on 2/1/2014 10:34:03 AM , Rating: 2
Source?

The Nature research articles indicate East Asians as having the highest Neanderthal DNA, interestingly enough, as it doesn't really match what the pictures indicate.


RE: So..
By retrospooty on 2/1/2014 3:24:29 PM , Rating: 2
I saw it on a National Geographic special on the human genome last year. It looks like there are variances in the studies... Or possibly this one included Denovisans as Neanderthal therefore its highest in Asians.


RE: So..
By Jeffk464 on 2/1/2014 8:37:39 PM , Rating: 2
And you probably have a natural sweater during the winter time. :)


RE: So..
By just4U on 2/3/2014 11:04:29 AM , Rating: 2
Ron Jeremy ... is that you?


RE: So..
By phxfreddy on 2/1/2014 12:55:41 PM , Rating: 2
Information set #1 + Information set #2 => Information Set #1

Yes indeed. It explains much.


RE: So..
By JediJeb on 2/3/2014 1:52:30 PM , Rating: 2
quote:
This article is saying white people have more Neanderthal genes than Africans and Asians? Cause I actually believe that.


I guess that means Hitler had it wrong, the pure humans would have come from mid Africa not Central Europe.


Off Topic
By Cypherdude1 on 1/31/2014 9:10:15 PM , Rating: 2
What the hell does this have to do with high tech?

DailyTech hasn't even covered half of the Snowden leaks. BBC online has covered more Snowden leaks than DailyTech:
1. Snowden leaks: Canada 'spied on airport travelers'
http://www.bbc.co.uk/news/world-us-canada-25977620

2. Snowden leaks: GCHQ 'spied on Facebook and YouTube'
http://www.bbc.co.uk/news/technology-25927844

3. NSA 'engaged in industrial espionage' - Snowden
http://www.bbc.co.uk/news/25907502

Try covering more high tech subjects, lest ye become irrelevant .




RE: Off Topic
By StormyKnight on 1/31/2014 10:56:43 PM , Rating: 5
quote:
What the hell does this have to do with high tech?

Clearly sorcery was used for genome sequencing, not <cough> technology <cough> high or otherwise.


RE: Off Topic
By wordsworm on 2/2/2014 9:41:14 PM , Rating: 2
Who told you that DT was ever relevant? DT is 60% tabloid, 38% political right-wing, with a menage making up the last 2%.


RE: Off Topic
By purerice on 2/3/2014 11:39:14 PM , Rating: 2
You forgot the sarcasm note.

Otherwise you appear as a self righteous troll sacrificing your valuable time to not only read an article you find irrelevant but also the comments. Not only that but then you are compelled to post your own. That would make you quite a prick which is obviously not the case.

So please don't forget "/sarcasm" next time.


Typical
By cactusdog on 2/1/2014 2:42:56 AM , Rating: 2
It just proves that some men will f*ck anything......




RE: Typical
By sorry dog on 2/3/2014 10:29:34 AM , Rating: 2
...and does a lot to explain the hairy chested 70's....


RE: Typical
By Dorkyman on 2/6/2014 5:43:15 PM , Rating: 2
This is why man invented alcohol. And bars.


Cumulative errors add up.
By drycrust3 on 2/2/2014 4:34:05 PM , Rating: 2
quote:
Roughly 500,000 year ago, the breeding populations that would evolve into humans (Homo sapiens) and Neanderthals (Homo neanderthalensis) separated. ...
But the long estranged relatives would come into contact ...roughly 80,000 years ago.

Eighty thousand years seems to be far to long a time frame to get from sitting around a fire at night, drinking soup, and chatting about how much seed to sow in spring to the technology we have now. My guess is we are looking at a time frame of maybe a few thousand years.
The amount of detrimental mutations passed from one generation to the next has been determined to be between one and three (URL removed). Since we are talking about something that happened over a time frame of 500,000 years, with 25 years per generation, we'd expect there to be 20000 generations in that period of time, thus there would between 20,000 and 60,000 detrimental mutations passed to our population after 500,000 years. Since we have around 22,000 genes, that suggests an average of at least one detrimental mutation per gene in each person in our current population. I tried to find out at what point humans should go extinct, but I couldn't find a definitive answer that didn't entail complex maths.
According to one paper:
quote:
These population sizes are effective sizes and so are likely to be an order of magnitude lower than the census size, which implies that for populations to be sustainable over more than a few hundred generations they must number in the thousands or tens of thousands.

URL removed.
In this case we are looking at 20,000 generations, so we'd have had to start the time frame with a population greater than 10,000, meaning our current world population should be ...
Population growth formula: N= N0*exp(kt) where N0 is the population at the start of a time frame (in this case it would have to be a minimum of 10,000 for us to survive 500,000 years), k=population growth rate (1.36% per year), and t= time frame (50,000 ... yes, but 500,000 won't work in my spreadsheet, so I'm using 50,000). The answer is our world wide population would be 2 E 299 (2 x 10^299) meaning our population would exceed the entire square metres on the planet's surface.




RE: Cumulative errors add up.
By JediJeb on 2/3/2014 2:06:24 PM , Rating: 2
quote:
In this case we are looking at 20,000 generations, so we'd have had to start the time frame with a population greater than 10,000, meaning our current world population should be ... Population growth formula: N= N0*exp(kt) where N0 is the population at the start of a time frame (in this case it would have to be a minimum of 10,000 for us to survive 500,000 years), k=population growth rate (1.36% per year), and t= time frame (50,000 ... yes, but 500,000 won't work in my spreadsheet, so I'm using 50,000). The answer is our world wide population would be 2 E 299 (2 x 10^299) meaning our population would exceed the entire square metres on the planet's surface.


What this doesn't take into account is mass death eras such as what happened when the Black Death hit us.

quote:
All in all, the plague reduced the world population from an estimated 450 million down to 350–375 million in the 14th century.


Losing nearly 20% of world population within a few years would have quite an effect on the population growth. Even the Spanish Flu pandemic lowered the world population nearly 3-5% in a few years. It wouldn't take many setbacks like that to drastically reduce that total population calculation results. Also what infant mortality rate does that calculation take into account? If 0% then it is drastically overstimated for any period of time before the last few centuries.


RE: Cumulative errors add up.
By drycrust3 on 2/4/2014 4:31:30 PM , Rating: 2
If I used an absolutely correct mathematical formula would I get something substantially different from what I got? Say my results were out by 50%, that amount of people is still wildly different from what we see today.
Anyway, the whole point of an average growth rate is it takes into account things like the Black Plagues, infant mortality, dying during child birth for mothers, poor hygiene, mortality from genetic mutations, genocides, wars, etc. I tried lower growth rates, e.g. 0.0012 (0.12%) and while the end numbers were different, the meaning was still the same: the population we see around the world is not large enough. You need to go to almost nil growth rate to get through 50,000 years without flooding the world with people, but then that conflicts with my understanding of archaeological evidence and my reading of history, which is that humans have been expanding at a fairly good growth rate their whole time.
Science is all about making theories fit facts.
One of the other main points is that science says each generation passes on between one and three genetic mutations to the next generation, so after 500,000 years the cumulative effect of genetic mutations would be, at a minimum, an average of almost one mutation per gene per person. This would be making us extinct right now (i.e. our life expectancy would be dropping, our deaths from "natural causes" in childhood would be increasing, etc), if not have made us extinct by now.


Where have all the copy editors gone?
By typicalGeek on 1/31/2014 11:26:39 PM , Rating: 3
I know that for some reason most on-line news sites seem to be lacking even the most basic editorial oversight. But this article is so rife with errors it really distracts from the content:
"Roughly 500,000 year ago..."
"Led by led by the Max Plank Institute..."
"Today researchers are still worker to chronical..."
etc.




By geekman1024 on 1/31/2014 11:51:15 PM , Rating: 2
Read the sign:

Warning! Neanderthals at work.


Questioning methology
By wallijonn on 2/7/2014 10:34:22 AM , Rating: 2
quote:
To hunt down Neanderthal genes, the researchers first sequenced 846 people of non-African heritage (who likely contained Neanderthal genes) and 176 people from sub-Saharan Africa (who likely did not receive Neanderthal genetics). These sequences were then used to pinpoint the genes that the non-African humans (e.g. Europeans) shared with Neanderthals, but which weren't found in people of sub-Saharan African origin.


Exactly how does one discriminate what isn't of non-African heritage and what is? Exactly how does one guarantee that the sub-Saharan pool sample weren't tainted by the hundreds of years of European rule (British, French, German, Italian, Portuguese, Spanish).

It may have been better to use samples from some unknown and undiscovered tribe deep inside the Amazonian Jungle (which may better represent an African heritage due to their isolation and less likelihood to have been contaminated by colonists' DNA) and from an isolated Fennoscandian village to better represent viable genetic differnces.

846 and 176 represent a very small pool, imo. To think that there is little possibility of interbreeding between African natives and their colonists is to also believe that there are no "Italian" genes within the British DNA pool of today.




speculation in fiction
By PaulLev on 1/31/2014 6:55:31 PM , Rating: 1
Fascinating. For more speculation on Neanderthal-modern human relations - in a science fiction novel published in 1999 - see The Silk Code http://www.nytimes.com/books/99/11/28/reviews/9911...




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