Inferring what the common ancestor of the great apes was
So to be clear once and for all, protein-coding changes have the largest known effect on phenotype, but changes outside of protein-coding sequences, such as in the regulatory sequences surrounding the exons and introns, are NOT epigenetics. They are non-protein coding genetic changes. Hope to have cleared up some confusion now
[edit added: Humans are apes. All humans are apes, but not all apes are human.]
Modern humans are a species of ape that is descended from earlier species of apes as shown by the fossil record, genetic evidence, and morphology. What are you trying to say, that evolution didn't happen? If so, then you are very misinformed.
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Last edited by TheBicyclingGuitarist on 28 Dec 2010, 6:42 am, edited 1 time in total.
Epi= outside, near, next to
gene= protein coding sequence
therefore 'epigenetics' can refer to both methylation and to sequence changes outside of protein-coding genes. I have a BSc in biology with an emphasis on evolutionary biology; I'm not just postulating at random, here.
LKL,
From your knowledge, is it possible that epigenetic changes can become genetic in nature? For example sickle cells are an evolutionary adaptation against malaria... could this have been at first an epigenetic adaptation that was constantly expressed over a thousand+ years and became genetic in nature?
I guess what im asking is if its possible for an epigenetic change to become genetic if the epigenetic change is present in every generation for a long period of time.
sickle cell was never epigenetic; it is a mutation in the gene for hemoglobin, resulting in a protein that denatures in low oxygen conditions (read: exercise or stress).
I think what you're asking is whether epigenetic changes can affect the germ line and become permanent, and the answer to that is whether or not the changes are in DNA methylation (ie, the attachment of a non-DNA molecule to a section of DNA that controls the transcription of a gene) or changes in the actual code of a regulatory section of DNA. The latter is generally a congenital mutation and can be passed down to future generations; the former can be passed to future generations, but we don't know yet how far it goes. For instance, mice who are exposed to pesticides will have grandchildren (grandpups?) which are negatively impacted, even if they were never exposed to the pesticides themselves, because they inherited the methylation changes of their parents and grandparents, which the grandparents acquired only on exposure to the pesticide. How far does it go? How do the mice revert to normal methylation patterns? I haven't heard any information about those questions. One would think that a section of DNA that has been methylated could be un-methylated, or vice-versa.
Thanks. That was my question.. I was wondering if a prolonged epigenetic change could over long periods of time become a mutation itself in the dna. Unfortunately I cannot wrap my head around biology so it will be up to you to make that discovery
"How do the mice revert to normal methylation patterns? I haven't heard any information about those questions. One would think that a section of DNA that has been methylated could be un-methylated, or vice-versa."
It can and has been un-methylated. You can watch a documentary called 'The Ghost in your Genes' (you can find it on youtube) .. they had a scientist there explaining how they did it. They even had some human cancer patients go into remission with an epigenetic treatment that re-set whatever genes they had switched off that fought off cancer. Fascinating stuff.
LKL : i remember reading that it's very simple for methylation to be completely reset in the germline in one generation, which is why i think this type of epigenetics is a very short-term change, non-sequence changes have most likely NO effect on evolution beyond a few generations. (like how cockroaches which become resistant to pesticide can be not-resistant again some generations later, suggesting a short-term epigenetic change)
The problem with completely resetting all methylation is that it is normal for some gene reglators to be methylated, and normal for other regulators to not be methylated (possibly dependent partly on the environment that the organism lives in). Just stripping off the methyl groups might not be the right answer.
Right. I think what they did was flush out all methylation from the mice and the mice on their own reset themselves back to what they should have working (factory default? lol) ... but not the abnormal ones they had inherited from their pesticide-choked ancestor.
Back to great apes. Humans diverge only five million years ago, and genetics shows bottlenecks when the species was recently between 5-10,000. They were outnumbered by the other apes, and pushed out into the grassland.
Bones converge going back, all apes have a common ancestor, so Orangs once lived in Africa. Others, Java Man, Austropithicus, also move from africa to southeast Asia, in some dim past, and are just as likely to have moved back, as some human genetics show. Modern human traits spread faster than the population moved. Sex at the edge, plus time, shows genetic traits moving where people did not.
Apes as a species go back another sixty million years, so there was time for branching long before the recent human split.
Due to the attached skin and fat layer, only found in sea mammals, a Swamp Ape has beem proposed. This aquatic ape was the ancestor of humans. Like other warn water sea mammals it lost it's fur, except the top of the head that stayed above water, and lubrication points in the pits. No direct evidence has been found.
Farther back, a quadaped with fangs and a high sex drive.
Animals that live in larger groups tend to stay the same, diverse genetics, loaners like humans live in groups of eight to twelve, who all had the same great grandparents going way back. Other humans were food, their family tree has no branches. A million years of close family will produce many things, most of which, if they do not die, should be killed.
Creationists say god created man a few thousand years ago, Evolutionists harp on man diverged from the apes five million years ago, I say they are still apes.
excuse me, but what? apes don't go back 60 million years, that's PRIMATES, and if you got your taxonomy right, apes are just the great apes + gibbons, the rest are monkeys or other primates.
*edit* re-reading Inventor's post, he sounds like a misanthropic pessimist who likes to use "we are apes" as a denigrating term instead of saying, we are classified as apes and descended from an ape, but we have some qualititative differences which seperate us.
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