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Short answer, we don't know. There are several competing hypotheses but they are all nearly impossible to test. Behavior often suffer the same problem with testing, we can come up with a hypothetical reason but since we are the only organism that does it we have no good testing options. Secondary sexual characteristics in general have problems with testing....


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Thalassemia is a genetic disease, in which either the alpha- or the beta-globins are missing or mutated. The hemoglobin of the blood is a protein complex which in adults consists of 2 alpha- and 2 beta-globin subunits. The ratio of these proteins needs to be exactly right, if one of them isn't produced enough or even missing, this leads to non-functional ...


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Is it possible to change the DNA of all the cells of an adult human? In development? Yes. Changes in the DNA prior to S-phase in the zygote will result in all the cells inheriting the changed DNA. Before or during the 1-cell stage in embryology, any changes will be ubiquitous in the developing adult and all their cells. In the adult? No. No technologies ...


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3% and 99.9% are from different calculation method. 20% (a rough estimation, might be wrong) of neanderthal DNA survived in the modern human genome, but it is 'diluted' by the human population, which lead to 2 percent of neanderthal DNA in each human genome. This is the number 3%. But how can we know it's neanderthal DNA? If DNA fragment contains ...


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This is a good opportunity to correct some major misconceptions. I'll be brief and avoid being technical because this is introductory biology. First, genes are present on DNA, and "store instructions" on building proteins, among other things. Poor diet, lifestyle and sleeplessness do not primarily affect the DNA itself, but rather the reading of it and the ...


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is it necessary that a given species must have at least one common ancestor? You could imagine a species divided into groups, each group having a single common ancestor. In that case, you might ask, do the common ancestors themselves have a common ancestor, somewhere further back? Our current hypothesis is that, if you go back far enough you can find a ...


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any giving individual alive today will be either an ancestor to ALL of the humans (in that future time) or none of them. What is the rationale behind this? It's a simple mathematical observation nothing more than that. One that doesn't actually require doing any math to understand. Take a few billion people, let them mix & breed freely within the ...


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