April 24th, 2012, 08:32 PM
According to Richard Dawkins I share 50% of my genes with siblings. According to my Biological Anthro professor, I share 1/4th of my genes with the daffodil. According to Richard Wrangham and Dawkins, I share 98% of my genes with chimpanzees. Now I share 4% with Neanderthals? How can all of these figures be correct without contradicting one another? I've always wanted someone to explain this to me...preferrably a Geneticist...
First, be aware that those figures are not exact. There is a good margin of error. The chimp share may be as low as 95%.
In addition, they overlap.
For example : some of the 4% you share with Neanderthals are also part of the 95% to 98% you share with chimps.
Re the 25% shared with plants.
Think about this : life evolved for more than 2 billion years, developing a whole heap of genes to do specific jobs, before it split into animal and plant. The common ancestor has passed on a bunch of those genes down to us, and to daffodils both. The 1000 million years roughly that have passed, since the common ancestor, is a small amount of time compared to the more than 2 billion that happened before, in which most of life's genes were developed.
The 25% of genes you share with daffodils are also shared with chimps.
Thanks. Guess it was more common sense than I thought.
Yet it still dosn't explain the 50% shared with siblings and 95% shared with chimps. Makes it sound like we are more closely related to chimps than our own kin. The 95% we share with chimps are perhaps simply homologous, not simple allele variations?
Remember that it's the same thing. Your siblings also share 95/98/x% of their genes with chimps.Yet it still dosn't explain the 50% shared with siblings and 95% shared with chimps.
Genes replicate. It's not like it's a jar of jelly beans where it's possible for the red/yellow/green ones to run out.
Yes but if I only share 50% of my genes with my siblings it must be due to different alleles of the same genes (meaning we share all of our genes but just have half that are different versions of the same genes), correct?
Shouldn't we share even more genes with Neanderthals than Chimps? We had a more recent common ancestor...some of the 4% you share with Neanderthals are also part of the 95% to 98% you share with chimps.
i think the percentage referred to is genetic information specifically attributed to neanderthals - it leaves out all the similarities that are due to common descent prior to the H.sapiens / H.neandertalensis split
in cladistic terms you tend to leave out the plesiomorphies and concentrate on the synapomorphies, which the 4% refers to
the commonality referred to when comparing humans with chimps or daffodils is just the overall similarity at the level of the gene, codon or nucleotide, and will include all the very basic development stuff for building cells and guiding the development - things that are pretty conservative, since if they go wrong the effect is often disastrous
Yes, it is registered on a different quota. the 50% means that you own 50% of the chromosomes of both of your parents. With siblings, you can differ 100% or 0%, depending on the amount of chromosomes from eiter parent.Originally Posted by gottspieler
the 98% difference from chimps comes from the 98% accordance in the genetic code, so intronic data is let out. You have 98% the same proteins, or they only differ slightly. The neandertal were evolved on a separate branch. They are NOT our ancestors. But they evolved around the same time. During that time an average of 2% of the polymorphisms in DNA can shift. Which is an extra 2% on top of the 98% we already differed from the chimps.
Try reading some articles on fylogeneticism. It's pretty interesting, and hopefully on topic.
You should be a little more clear. They aren't our direct ancestors. We do however, share a common ancestor and are closely related genetically.They are NOT our ancestors
still, neandertals are not ancestors even if related
after all, your uncle isn't your ancestor, your dad is
Can't be more clear then that, i mean you said what you understood, and that was correct. Neanderthals would have the higher intelligence of someone with down syndrome, capable, sociable, but does lack the capacity to improve himself.
Still there are traces of viral DNA in the human code, that can explain the sudden explosion of the human brain. Usually in evolution, a bigger brain isn't the answer. Couldn't find any references to this piece of DNA though, but i would love to find proof of this mutated viral piece that promotes the growth of the brain, stalls childbirth, and makes growth slower. This all makes us different from monkeys. And gives our brain time to fully develop.
No need to postulate viral DNA. The human brain evolved gradually. We can see the progression in fossil craniums, from Australopithecus 3 million years ago, brain size 400 cc, to Homo habilis 2 million years ago, with a brain 600 cc. Homo erectus, about 1 million years ago, had a brain size of about 900 cc. Homo sapiens, 200,000 years ago, had a brain size of 1200 cc.
In other words, no dramatic changes. Just a slow gradual evolution of larger and larger brain.
I know there is an explanation without taking viral DNA into the equation. But i felt something was missing. Virusses do change evolution, and even accellerate.
Why else would mainly (only) primates evolve with bigger cranial capacity? And why would only the human branch continue this? Possible viral interference would make it a little more conceivable to me.
Well I guess I don't mean "ancestor" then. I should say "relatives".
I guess I was just afraid that Creationists would read "they are NOT our ancestors" and take it the wrong way. But they take everything the wrong way...lol...so I guess it's ok...
The use of tools, is probably the result of bigger brains, not the cause.My personal explanation is that only the human lineage developed tool use beyond its most basic level. When pre-humans start wielding tools and weapons, and needing the skill to make and use them, brain size will evolve. No other great ape lineage ever developed tools and weapons beyond the most basic form.
Though i understand your point, that the need would be to have bigger brains to be able to improve the weapons/tools. Still, a bigger brain is not the evolutionary most logical choice. In my eyes.
To Zwolver
My hypothesis is slightly more complex than that. The first pre-humans to make shaped stone tools were Homo habilis, several million years back, and their tools were pretty damn crude. However, it seems very likely to me that other tools were in widespread use before that. Unshaped rocks, sharp lengths of wood, unshaped bones etc. I think this because chimps use very simple tools, and our ancestors had bigger brains than chimps, and more upright stance - better for wielding crude tools.
Australopithecus, 3 million years ago, was only 1 metre tall, and had arched feet plus upright stance and a 400 cc brain (about a third again bigger than chimp brains). The foot arches are an adaptation for upright walking and running. Their skeletons are not of a sort suited well for tree climbing, and their bones have been found on what was grasslands. Thus, they must have spent a lot of time foraging or hunting in Africa's grasslands. The question arises, how could a frail, 1 metre high ape have avoided predation on Africa's grasslands?
My view is that it would take a combination of weapon use, and cooperative operation. Even a pride of lions might be reluctant to tackle a tribe of Australopithecus armed with wooden spears, and huddling together with all those sharp ends pointing at the lions. However, such cooperation and weapon use would demand some degree of intelligence. This would be a stimulus to development of both brains and language.
I have moved some posts from this thread which were veering off into some kind of religious or philosophical direction.
We do not share 98.8% of our base pairs with chimps. It has already been revised down to 95% and new research is pushing that percentage down even further. Concerning the actual number of genes we have in common with chimps, it is said to be between 25-29% ("Even with all of this information the two genomes are close to 96% identical, and 29% of the genes found in the two genomes are completely identical").
The comparisons between Neandertal Genomes and genes with that of AMH is in its infancy/beginning stages but, we know that 99.7%+ of the base pairs between Neandertals and Anatomically Modern Humans (AMH) (Eurasians) are identical. One has to keep in mind that the Neandertal genome sequencing is not yet complete, only about 60% of it is done, and the genes within that genome, have just started to be studied.
Speech, hair and immune genes are what scientist are looking at now concerning Neandertals, and they are finding that all AMH have Neandertal genes (in the immune system, so far, as high as 85%).
One can be assured that the genes Neandertals and AMH share are far higher than what we share with chimps, and it is also much higher than 1-4%. The 1-4% does not represent the total % of the genome or the total % of genes that are common or identical between Neandertals and AMH. For Eurasians the genome base pair is 99.7%+ identical to neandertals. For Africans the genome base pair is between 95.7-98.7% identical to neandertals. The 1-4% is a % difference in base pairs between some eurasians and africans and it is not the % of total genes or total base pairs shared with or derived from neandertals.
Do not let people fool you.. Neandertals are our direct ancestors. Every person on this planet can trace their direct family line (from parent to parent - mother and father) back to parents in our ancestry that were Neandertals. For fun, lets say you went back in time and killed the first neandertals to ever exist..... You would have just prevented every modern human alive today from ever existing. That is ancestry... No neandertals, no you.
Sorry Gonzales.
It just aint so.
Humans evolved in Africa. There is almost an entire family tree in pre-human fossils found in Africa, including 200,000 year old human bones found in South Africa. The earliest human bones out of Africa were 100,000 years old. Neanderthal bones in Europe, though, go back 300,000 years.
The fossil record shows very, very clearly, that we are not descended from neanderthals. However, it is probable, again from the fossil record, that both neanderthals and humans are descended from Homo erectus.
That is not what the fossil record shows but, that is a completely different topic than the one here..
The DNA shows that modern humans have neandertal DNA due to breeding/being our ancestors (a parent of our parents etc.) .. This cannot be denied.
Every person on the planet has DNA derived from neandertals, not just the ancestors of neandertals. Again, this means that you have multiple neandertals in your direct line. Without the neandertals, you do not exist. It is just undeniable. At some point in your direct line, you will run into a neandertal. They are your ancestors.
Again, not true.
People of 100% African descent have no neanderthal DNA at all. It is mostly Europeans who have that.
Conclusion : interbreeding with neanderthals happened to a degree by humans that had left Africa behind. So Neanderthals are a small fraction of the ancestors of humans from Europe, Asia etc., but not Africans. Even for Europeans, the contribution of Neanderthal genes is very small, meaning most of our ancestors were Homo sapiens, not Homo neanderthalensis.
http://en.wikipedia.org/wiki/Neander...ing_hypotheses
I quote from my reference.
"Genetic research has confirmed that some admixture took place. The genomes of non-Africans include portions that are of Neanderthal origin,[82][83] due to interbreeding between Neanderthals and the ancestors of Eurasians in Northern Africa or the Middle East prior to their spread. Rather than absorption of the Neanderthal population, this gene flow appears to have been of limited duration and limited extent. An estimated 1 to 4 percent of the DNA in Europeans and Asians (French, Chinese and Papua probands) is non-modern, and shared with ancient Neanderthal DNA."
I see what the problem is.. You read wikipedia, believe wikipedia and then quote it. I have no problem with you believing whatever you want, you are free to do so but, even africans have DNA/genes that are derived from Neandertals (we do not know how much in total yet but, we will in time), and it does not matter how much, it still makes one of their direct hominid ancestors the neandertals too.
Link
"These alleles, of which several encode unique or strong ligands for natural killer cell receptors, now represent more than half the HLA alleles of modern Eurasians and also appear to have been later introduced into Africans. Thus, adaptive introgression of archaic alleles has significantly shaped modern human immune systems."
This means that africans, yes, even africans, have great grand-pappies and great-grand-mammies somewhere in their ancestry that are neandertals.
Concerning the speculation as to how or why this is, well, it is just that, speculation, not fact. The total % of genome and genes we have derived from Neandertals is also unknown at this time. The study of those genes will tell Us. However, our base pairs are 99.7%+ identical and so I am comfortable in suggesting that we are going to have a lot of genes that have been derived from neandertals. The 1-4% is an estimation, a guess, at the derived differences in base pairs between some eurasians and africans but, it is not the exact % of total genes or total base pairs derived from neandertals within all AMH. Again, we will learn more as time goes on but, the one thing we do know is that our ancestors include neandertals. With out them, you and I do not exist.
Gonzales
It is not just Wiki that tells this story. Here is sciencedaily.
Non-Africans are part Neanderthal, genetic research shows
I quote :
Some of the human X chromosome originates from Neanderthals and is found exclusively in people outside Africa.
And
"Dr. Labuda and his team almost a decade ago had identified a piece of DNA (called a haplotype) in the human X chromosome that seemed different and whose origins they questioned. When the Neanderthal genome was sequenced in 2010, they quickly compared 6000 chromosomes from all parts of the world to the Neanderthal haplotype. The Neanderthal sequence was present in peoples across all continents, except for sub-Saharan Africa, and including Australia."
I have also seen this information in New Scientist, and I could do a quick google and find it in numerous other sources.
Yes, but this doesn't really prove this. I have compared neanderthal and human dna, together with hobilis, erectus, and sapiens, and while most are in line, neanderthal dna seems to diverge from that tree.
Simply try it, go to National Center for Biotechnology Information and check out for yourself. Some knowledge is required though.
If that's not enough. Simply check timelines. And that neanderthals have lived more secluded (isolated) from humans. Only later they actually met face 2 face.
Didn't I read some where that we get all our genes from a genetic 'Eve' of about 80,000 years ago after some apocaliptic event wiped out most of the worlds human population.
If this is indeed true then surely Neanderthals & hobilis etc.. could have still been evolving up until this point independantly of homosapiens and we might not actually be directly descended from any of them. Maybe even if this event hadn't taken place they might still exist to this day, just like monkeys and apes etc....
Good question. Why were they extinct in the first place. The ice age? And their lack for higher brain capacity, working in teams and controlling fire. That would be my guess..
Neanderthal survived 300,000 years, and became extinct 'soon' after meeting Homo sapiens. Fairly obvious that our ancestors were responsible. My own view is that it was direct murder. If we look at primitive human tribal societies, we see inter-tribal warfare is often rife. Some tribes have from 20% to 60% of the males killed off in inter-tribal battles pretty much every generation. If such warfare is so bad between tribes of humans, how bad would they have been between human and neanderthal?
I don't think it was murder, as neanderthal were pretty much fysically stronger then humans, and actually more conservative with energy, so they would need less food. I don't know how big they were though, maybe humans towered above them.
Zwolver
Success in battle depends on more than strength. The technology of the weapons you use is vital, as is the skill of the fighters, and the cunning of the tactics used. I could easily see massacres of neanderthals, when humans are sneaky in ambush, and use projectile weapons that the neanderthal would not have. Neanderthals lacked projectile weapons - Technology & science - Science - DiscoveryNews.com - msnbc.com
let's face it : we don't really know whether the decline of neandertals was due to active confrontation or merely because of differential survival rates
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