The Neanderthal--a comprehensive introduction to the fossil record

reply to post by poet1b


Just curious how this is relevant? I'm not complaining. I love poetry and have studied it in college a lot. I am a bit of a writer myself.

But who wrote it? How do you think it is relevant? You gotta include that kind of stuff in your post Thanks.

reply to post by Byrd


holy crap dude. I didnt even know about that.

Apparently the hybrids are FERTILE too!

third generation hybrids have been produced for both combos.....they too were fertile!

You sir, just blew my mind.

This calls for a more in depth review of how their genome was expressed.

Imagine if the chromosome fusing we see in humans and neanderthal is a product of second generation hybrid mating!

Originally posted by conspiracy nut
do ligers and tiglons happen in the wild or is that just man made breeding? what about zebras and horses?

edit on 6-3-2013 by conspiracy nut because: (no reason given)

Since lions and tigers do not exist in the same areas, this is not something that happens in the wild. It is done in captivity by disreputable carnies to produce a freak that ignorant people will pay to see. These cats suffer from many birth defects and usually die young.

bigcatrescue.org...

Looks like it only happens in captivity. What stuns me here is that these two animals are geographically separated and would never normally cross paths, but can still mate. However, they cannot produce fertile, viable, or even healthy offspring, and that's really what's essential here. [Edit: Actually, that statement is partially wrong concerning the fertility of the offspring, as you'll see below. Sorry]

So, the question becomes "Could the human and Neandertal produce fertile, healthy offspring?"

And...I've seen some ligers in our local zoo. They're pretty neat, but I'm wondering if they were moved to the zoo for rescue or bred there It was a long time ago though, and it was just a small petting zoo mostly; with a few exotic animals. I will have to go find out what they're up to.

reply to post by tadaman


It looks like we both had a piece of half-truth here. There's a neat chart in the link too, to show the possible mixes.

No fertile male ligers have yet been found and it is assumed all are sterile. This is not the case with females and a 15-year-old ligeress at Munich Zoo produced a li-liger after mating with a lion.

www.lairweb.org.nz...

I found this interesting article about chromosome fusion and hybridization of neanderthal / Homo-sapiens

It basically says that the fusion of our chromosomes wouldnt have prevented us from pairing with neanderthal, and that the actual fused genes are not that special. Actually BOTH groups may have had the fusion present already from a common ancestor, maybe.

It doesnt touch upon the possibility that the fused genes were a consequence of hybrid offspring, BUT it does say that it would be possible for such a trait from a hybrid to have isolated him from other "pure blood" populations as it further mixed and "corrected" its genome. Both ancestral histories contribute to the new hybrid but with each successive generation a more stable / particular selection of genes arises, and that is why the hybrid might not produce a fertile second generation hybrid. SO the more mixed the genetics from a similar genius, the better the chances for a fertile offspring hybrid to be produced. If the parents are TOO similar they will just come to a dead end.

Also such changes of genetic isolation occur rapidly, and so might account for the sudden appearance of cro-magnon in Europe and as he spread and lost his more primitive features, neanderthal died out by becoming genetically isolated from the hybrid populations....since neanderthal died out slowly. The process of becoming genetically unviable due to limited numbers would take some time.

People often ask me when this chromosome fusion happened in ancient hominins. I think they attribute excessive importance to this event, reasoning that chromosome fusion may have been the cause of some reproductive isolation. For example, they often ask specifically about Neandertals and modern humans, figuring that when we show Neandertals had 48 chromosomes, it will at last explain why they are extinct.
In reality, the fusion must have happened within a population.

The first person who carried it, and his immediate descendants, must have been able to mate and reproduce successfully with people who didn't carry it. This outcome is not uncommon for chromosomal rearrangements. Many create reproductive incompatibility, and those that do are very unlikely to become common within a population. Some become moderately common but create problems for homozygotes who carry two copies of them. Others seem to be neutral and do not cause noticeable problems.
So why do related species with different chromosome numbers often have trouble producing fertile offspring, even if they can mate successfully? This is likely because many chromosomal rearrangements and other genetic changes have accumulated in each lineage after a long period of reproductive isolation. Each may have been near selectively neutral within the population where it first occurred.

A few may start out deleterious in homozygotes, and later may become fixed in the population only after other genetic changes ameliorate (or "rescue") these deleterious effects. Sometimes, positive natural selection can favor changes within one population that decrease carriers' ability to reproduce with members of another population, and in these cases reproductive isolation can appear very rapidly. In other words, the evolutionary constraints on chromosome structure aren't simple.

Whether fast or slow, as each of the emerging species becomes different from the ancestral genetic background, the potential for reproductive incompatibility increases. This evolution is not a single jump, but a series of steps that may result in gametic incompatibility, hybrid inviability, or hybrid sterility.

The series of events leading to the fusion of human chromosome 2 are genetically very interesting, as are the repeated instances of rearrangement that Ventura and colleagues illustrate in chimpanzees. But chromosome fusion has no special magical power, and whether it was connected to ancient speciations or other events in our evolution will take a lot of creative hypothesis testing.

johnhawks.net...

So I went through the sources for that little article I mentioned before and I thought I would share, as it is that I am going through a learning process with genetics. I thought it would be cool to share some of the data with a little more meat.

To do that I broke down the source snippet and included some vocabulary you might need to understand it.

An inversion is a chromosome rearrangement in which a segment of a chromosome is reversed end to end. An inversion occurs when a single chromosome undergoes breakage and rearrangement within itself. Inversions are of two types: paracentric and pericentric.
Paracentric inversions do not include the centromere and both breaks occur in one arm of the chromosome. Pericentric inversions include the centromere and there is a break point in each arm.

en.wikipedia.org...

Cytogenetics is a branch of genetics that is concerned with the study of the structure and function of the cell, especially the chromosomes.

en.wikipedia.org...

subterminal Satellite

subterminal
Positioned near an end

Satellite DNA
Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin.[1][2]
The name "satellite DNA" refers to how repetitions of a short DNA sequence tend to produce a different frequency of the nucleotides adenine, cytosine, guanine and thymine, and thus have a different density from bulk DNA - such that they form a second or 'satellite' band when genomic DNA is separated on a density gradient.

Polymorphism
The existence of two or more different phenotypes resulting from two or more alleles, each with an appreciable frequency. Most blood group systems are polymorphic.

Phylogenetics
In biology, phylogenetics (pron.: /faɪlɵdʒɪˈnɛtɪks/) is the study of evolutionary relationships among groups of organisms (e.g. species, populations), which are discovered through molecular sequencing data and morphological data matrices.

subtelomeric heterochromatin

A telomere is a region of repetitive nucleotide sequences at each end of a chromatid, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Its name is derived from the Greek nouns telos (τέλος) 'end' and merοs (μέρος, root: μερ-) 'part.' Telomere regions deter the degradation of genes near the ends of chromosomes by allowing chromosome ends to shorten,
en.wikipedia.org...

Heterochromatin
Heterochromatin is a tightly packed form of DNA, which comes in different varieties. These varieties lie on a continuum between the two extremes of constitutive and facultative heterochromatin. Both play a role in the expression of genes, where constitutive heterochromatin can affect the genes near them (position-effect variegation)

en.wikipedia.org...

www.ualberta.ca...

Chimpanzee and gorilla chromosomes differ from human chromosomes by the presence of large blocks of subterminal heterochromatin thought to be composed primarily of arrays of tandem satellite sequence. We explore their sequence composition and organization and show a complex organization composed of specific sets of segmental duplications that have hyperexpanded in concert with the formation of subterminal satellites.

These regions are highly copy number polymorphic between and within species, and copy number differences involving hundreds of copies can be accurately estimated by assaying read-depth of next-generation sequencing data sets. Phylogenetic and comparative genomic analyses suggest that the structures have arisen largely independently in the two lineages with the exception of a few seed sequences present in the common ancestor of humans and African apes.

We propose a model where an ancestral human-chimpanzee pericentric inversion and the ancestral chromosome 2 fusion both predisposed and protected the chimpanzee and human genomes, respectively, to the formation of subtelomeric heterochromatin. Our findings highlight the complex interplay between duplicated sequences and chromosomal rearrangements that rapidly alter the cytogenetic landscape in a short period of evolutionary time.

johnhawks.net...

This MIGHT explain how we get the fused chromosomes in humans with 46 pairs, instead of 48. It was the best explenation I found so far so I thought I would include it here as well. This could explain why neanderthal stopped reproducing. He couldnt after everyone was walking around with a genome that left his incompatible with the rest. So that may be why he slowly died out while everyone else´s population quickly shot up.

Don;'t know if this was already posted or not..

African-American's Y chromosome sparks shift in evolutionary timetable.

Scientists say an African-American male's odd genetic signature suggests that the human Y chromosome's lineage goes back further in time than they thought — perhaps due to interbreeding with other populations such as Neanderthals.

"This really upsets a lot of ideas, but at the same time, it's understandable if we accept that human populations were structured in the past so that there were little pockets of diversity," said Michael Hammer, an evolutionary biologist at the University of Arizona who is one of the authors of a study published in the American Journal of Human Genetics.

The study focuses on the analysis of a DNA sample that was obtained from an African-American living in South Carolina and submitted to the Genographic Project, a National Geographic effort aimed at mapping human origins and migration. The funny thing about this sample is that it didn't match up with any of the previously known genetic signatures for the Y chromosome, which is passed down from father to son.

"Nobody expected to find anything like this," Hammer said in a news release.

A team led by Fernando Mendez, a researcher in Hammer's lab, analyzed more than 240,000 DNA base pairs on the African-American's Y chromosome. A comparison of the differences between the mystery genetic signature and previously known signatures led the team to conclude that the most recent common ancestor for the entire group lived about 338,000 years ago.

That goes further back than the fossil record goes for anatomically modern humans, Hammer said. "The fossil record speaks to 195,000 years or 200,000 years," he said. It also goes further back than the previous date for the most recent common ancestor based on Y-chromosome analysis, which is in the range of 142,000 years.

The researchers followed up on their discovery by searching through a genetic database for African populations, and turned up 11 men from western Cameroon who had virtually the same genetic signature.

Hammer said there could be two explanations for the previously unidentified Y-chromosome type: Either the genetic heritage of anatomically correct humans really does go back much further than what's reflected in the fossil record — or other populations, such as Neanderthals or the more recently identified Denisovans, interbred with modern humans. Anthropologists refer to that pattern of divergence followed by renewed interbreeding as introgression.

The results are "more consistent with introgression of an odd lineage," Hammer told NBC News. Over the past few years, scientists have been coming around to the view that such interbreeding did take place early in the history of our species. Recent analysis of Neanderthal and Denisovan DNA has indicated that a part of their genetic heritage survives in modern-day humans.

cosmiclog.nbcnews.com...

reply to post by NarcolepticBuddha



Seems some of the Ligers babies were getting some form of "parkinsons".

Since 1999 the park has bred its male lion and female tiger many times, producing about 24 cubs.

Not all of them have been healthy, though.

"We've had 3 out of 24 that, for all practical purposes, were normal but developed as they grew older some kind of neurological disorder," Hutcherson said.

Autopsies didn't reveal what caused the cubs to develop "head shakes," so park staff "chalked it up to a genetic defect," Hutcherson said.

news.nationalgeographic.com...

Originally posted by tadaman
reply to post by Byrd

 

holy crap dude. I didnt even know about that.

No biggie. I have graduate degrees in a couple of relevant fields here. This is all part of the stuff that I had to learn.

This calls for a more in depth review of how their genome was expressed.

Oh, they're doing that and a lot more that you're not finding (because it's in university only access journals and being discussed at conferences. It's not impossible to find, but if you're not in the loop, it's not likely that you'd ever hear of it.)

Imagine if the chromosome fusing we see in humans and neanderthal is a product of second generation hybrid mating!

As I said, that's one possibility. At this point, the evidence for anything is still fairly sparse, and those working on the project are trying to NOT make conclusions that will get them laughed at when better evidence comes up (after all, they'd like their names in the science books as "people who found this stuff out" instead of forgotten as "people who got the wrong idea.")

Originally posted by WaterBottle
Don;'t know if this was already posted or not..

African-American's Y chromosome sparks shift in evolutionary timetable.

Scientists say an African-American male's odd genetic signature suggests that the human Y chromosome's lineage goes back further in time than they thought — perhaps due to interbreeding with other populations such as Neanderthals.
(etc)

cosmiclog.nbcnews.com...

An intriguing read!

I did some checking to see what tribal groups were represented but didn't get far with that one. There are some fairly isolated tribal groups in Africa, but the coastlines tended to be more of a melting pot in recent times (and therefore, undoubtedly, far back into history since they're resource rich.)

From the abstract of the original paper:

Remarkably, this exceeds current estimates of the mtDNA TMRCA, as well as those of the age of the oldest anatomically modern human fossils. The extremely ancient age combined with the rarity of the A00 lineage, which we also find at very low frequency in central Africa, point to the importance of considering more complex models for the origin of Y chromosome diversity. These models include ancient population structure and the possibility of archaic introgression of Y chromosomes into anatomically modern humans. The A00 lineage was discovered in a large database of consumer samples of African Americans and has not been identified in traditional hunter-gatherer populations from sub-Saharan Africa. This underscores how the stochastic nature of the genealogical process can affect inference from a single locus and warrants caution during the interpretation of the geographic location of divergent branches of the Y chromosome phylogenetic tree for the elucidation of human origins.

source article link

As they say, the database is pretty thin, so making wild conclusions isn't warranted. What was interesting is that this wasn't found in any of the sub-Saharan material (which would imply a "northern African" source for these features of this Y chromosome.

reply to post by NarcolepticBuddha


It is a poem I wrote about a decade ago. It's about the animal insides frustration with civilization, and critique of what passes as high civilization.

I thought it was an appropriate response to the posters comments.

reply to post by NarcolepticBuddha


From what I have read and watched about Neanderthal's was that their hunting technique was pretty physical to say the least. They hunted in the thick forests and hunted large game with basically stabbing spears that they would thrust into their prey. Try sticking a spear into a wild boar or elk and see how often you don't break a bone. Imagine what would happen to a hunting group if they tried to take out woolly mammoth or rhino. Broken bones were par for the course, the way they hunted.

I have to wonder what happened when HS first encountered HN. They found themselves up against another great ape with the strength of a gorilla, but the intelligence of HS, armed with fairly even weapons technology.

One on one, toe to toe, HS is would have been more outmatched than a poodle against a pit bull. The female HN probably could have thrown around HS males like a rag doll.

What would it have been like to encounter such a competitor, and how did HS come to dominate?

reply to post by poet1b


The answer is very simple. Unintelligent people group together, arm themselves and dominate the intelligent ones, or simply exterminate them. Intelligent people never do that. You can call that kind of domination a success, but is it really? A successful domination of idiocracy. Perhaps, Neanderthals and other people who were destroyed that way moved to a better world, of which only they knew? I mean, what can a man with limited or no cognitive ability at all see in this Universe? What if this, physical, world is just a dungeon, a place where conditioning rules, ruled by Pavlov's dogs? If you ask me, I'm digging my tunnel out of there. And, perhaps. Neanderthals did the same.

Originally posted by poet1b
I have to wonder what happened when HS first encountered HN. They found themselves up against another great ape with the strength of a gorilla, but the intelligence of HS, armed with fairly even weapons technology.

One on one, toe to toe, HS is would have been more outmatched than a poodle against a pit bull. The female HN probably could have thrown around HS males like a rag doll.

What would it have been like to encounter such a competitor, and how did HS come to dominate?

edit on 7-3-2013 by poet1b because: Missing a point

Lets assume the Neandertaler didn't had a language and weren't organized + that the HS had dogs (dogs are good guards), if so then strenght wasn't much of an issue.
But pretty sure HS saw them as a threat (if they did meet) so like any big animals in Europe (we had tigers, eliphants, bizons and you name it they just all terminated this threat.

And you know we males do anything the females want, and they surely would wanted the Neandertaler dead

Interesting how that rendering of a "Primitive Predator HN" looks suspiciously like the photos and renderings of bigfoot etal......Could there be more to this? Did Neanderthal really disappear, or just relocate, like other humans?

here's a new article some of you will find interesting, and maybe want to write a thread on.

www.bbc.co.uk...

A study of Neanderthal skulls suggests that they became extinct because they had larger eyes than our species.

As a result, more of their brain was devoted to seeing in the long, dark nights in Europe, at the expense of high-level processing.

This ability enabled our species, Homo Sapiens, to fashion warmer clothes and develop larger social networks, helping us to survive the ice age in Europe.

The study is published in Proceedings of the Royal Society B Journal.

Neanderthals are a closely related species of human that lived in Europe from around 250,000 years ago. They coexisted and interacted briefly with our species until they went extinct about 28,000 years ago, in part due to an ice age.

reply to post by goou111


I'm thinking that (as we say in Texas) "this dog won't hunt."

The authors are citing their own previous work as proof of concept (the article is at this link) and they start from a "would probably have" to a sudden "it's completely true" stance.

Going on their logic, chimps would have much larger eyeballs than humans and polar bears would have the largest eyes and visual processing areas of all the bears on the planet.

It needs stronger proof than what they've presented. And yes, I know it got past peer review -- bad papers make it through peer reviews if the topic is esoteric enough.

reply to post by Byrd


Yeah when I was reading the article I have to say my bs meter was goin off. But I dont know alot about this stuff so it could be true lol

reply to post by goou111


Hi,
Just glanced over the snippet of the eye article,
They might be on to something,physiologically speaking. First off Hn was so adapted to its environment, that its development was an evolutionary dead end. It's robust body is not only an adaptation to the cooler forest environment of Europe, it was also superbly constructed for his hunting strategy. As an ambush hunter, he had to get in close and physically subdue his prey, not chase it down till it collapses, like modern humans.
There is a journal of some Roman general, who led a campaign into the wilderness of Germany, that noted once they left the main road, it was three weeks of marching in the darkness under the canopy of the forest, before they saw the sun again.
Maybe, Hn's larger brain volume was partially in response to a need for more visual processing power. If Hn was adapted to better low light visibility, he was likely colorblind. Could this be the source of color blindness in modern men?, whit h has its highest frequency in men of northern European ancestry.

Color blindness affects a large number of individuals, with protanopia and deuteranopia being the most common types of color blindness. [6] Individuals of Northern European ancestry, as many as 8 percent of men and 0.5 percent of women experience the common form of red-green color blindness. [7] The typical human retina contains two kinds of light cells: the rod cells (active in low light) and the cone cells (active in normal daylight). Normally, there are three kinds of cones, each containing a different pigment, which are activated when the pigments absorb light.

r

en.m.wikipedia.org...

Ok, so now as the ice ages take hold over the northern hemisphere, the forests recceded south, and in many areas disappeared completely, leaving Hn to change his habits and lifestyle.
I'm now thinking that Hn and Hs didn't actually share a niche. As Hn was pushed into the non forested areas he was likely semi-nocturnal, preceding to hunt in the dim light hrs before dawn and at dusk, as compared to Hs who is migrating into Europe from Africa or eurasia, depending on which school of thought you belong to, he would have been a daytime hunter , and the two could have coexisted for quite some time with only limited contact.
I think Hn's demise is more about an evolutionary dead end than about us being smarter than them.
Also intangible things such as social structure and inter group behavior are very seldom postulated on in such a discussion.
After reading a paper on severe injuries among Hn skeletons, I noticed that many of them were of the type you would get fighting. And I've recently learned that the very pronounced brow ridges found in archaic homo are hollow, and in other primates are primarily a gender specific,male, physical signaling device, such as the brilliant plumage of a peacock.
In higher primates competition for mates between males starts with eye contact between the males and inany cases is decided by menacing scowls andittle meaningful physical combat.
It has been posited that the large browridges of archaic homo were the manifestaion of a
mating display physiology.
What if Hn had an extremely matriarchal society, and the strongest males had to compete for the right to.breed with an available female.
Over the course of time this behavior could have become so ingrained that it kept their population levels very low and pair bonded, cooperatively breeding modern humans out paced them.