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22

Well, that's just it, we don't actually have much phenotypic variation. For example, compare this: to this: or this: Or this: to this: This is phenotypic variation: And of course, you can't beat the birds of paradise when it comes to variation (though, strictly speaking, these are different species): So, as I hope is clear from ...


13

Actually it is a very important question for laboratory animals (and, I imagine, endangered species) and was calculated to be 25 couples. With any number of animals (including humans), there is always some inbreeding happening, but you can reduce it with the number of breeding pairs and careful pairing. When you get to 25 pairs (50 animals) and have ...


13

There is ample genetic evidence for a population bottleneck following the out-of-Africa migration. This would account for the reduced genetic diversity found in non-African populations. There is further evidence for an earlier major bottleneck that reduced the human population to around 10,000 individuals. These kinds of studies are typically done now via ...


12

Firstly, it's not true that you can't tell racial background from DNA. You most certainly can; it's quite possible to give fairly accurate phenotypic reconstruction of the features we choose as racial markers from DNA samples alone and also possible to identify real geographic ancestral populations from suitable markers. The reason that human races aren't ...


11

Inbreeding depression, "the reduced survival and fertility of offspring of related individuals" (quoting the linked article), is a well-known and well-understood biological effect. It does, indeed, affect humans. The problem is that recessive mutations become more likely to affect the survival of the offspring of relatives. Imagine that you have a mutation ...


11

The first modern humans evolved about 200.000 years ago in Africa. When they lost their body hair (or at least most of it), they needed some other protection of their skin from the sun - otherwise they are prone to develop melanoma. Melanin is such a protection, and the rate of melanoma is much lower in dark skinned people. There is also a nice correlation ...


10

I thought it was just that the other aneuploidies were fatal. They occur as often but miscarry earlier in the term therefore you don't see them. So basically there are only three that are viable 21,18 and the sex chromosome with a number of combinations: XO, XXY, XYY and XXX. More information here: ...


10

"Blame" is a strong word. The human Y chromosome has only a few dozen protein-coding genes. One of the most important, for males anyway, is SRY, the sex-determining region. This is a transcription factor that is responsible for modulating the expression of other genes; those genes need not be on the Y chromosome. SOX9 for example is itself a ...


8

This difference would have the greatest impact on treatment for cancer, in which a treatment protocol is based on genes deleted, amplified, altered in the tumor vs the reference genome for that patient. In terms of health risks based on SNP genotypes, the data are far from complete. Sure, some level of risk can be assigned to a variant (SNP), say at certain ...


8

I very much agree with bitwise's answer. I just want to point out that even in terms of nucleotide sequence there are some extremely conserved genes. The most highly conserved are ribosomal RNA genes. The image below shows the conservation of 16S rRNAs from archaea, bacteria, and eukaryotes (eukaryotes do not have 16S in their cellular genome but the gene ...


8

The concept of a human/chimp hybrid is called a humanzee. No humanzees have ever been recorded despite the fact that sexual intercourse between humans and chimps has been recorded on several occasions. This suggests that male-human/female-chimpanzee is not capable of producing viable offspring, at the very least. As to why, several reasons will contribute: ...


8

Hair color is not so simple as that. Most traits, especially those as complex as color, are controlled by many alleles at many loci. That's why there are different kinds of brown, blond, and red hair in the population. There is no "hair color gene." A fascinating paper came out a few years ago, identifying dozens of SNPs playing a role in hair and eye ...


7

Depends on what you mean by unchanged. If you mean a gene that maintained the same nucleotide sequence, then the answer is no. If you meant a gene that descends from a very ancient gene, i.e. one can find orthologs in very distant species, then the answer is yes. Many of the basic molecular systems are relatively conserved, including several metabolic paths ...


7

That would be hard to say because really beneficial mutations become well distributed through the genome. Basically the differences between us and chimpanzees are a catalog of all the beneficial (or completely neutral) mutations since the ~4.7 M years since we diverged from each other. Separating them from changes which have no special effect would be ...


7

I'm not sure I buy your premise: firstly, the degree and form of male-female differentiation in social roles has varied widely across time and culture in human history so I doubt it forms a uniform evolutionary driver such as you describe. Secondly, the degree of male-female differentiation appears to me to be much greater in species such as gorillas, lions ...


7

"How come most animals never seem to evolve over millenia?" I guess the word "seem" in your question should not be disregarded. You seem to assume that cockroaches (or most animals as you say) did not change much the last tens or hundreds thousands of years. But what do you know about that? Have you actually reviewed many research that estimate the rate of ...


7

There are many different variants of O (all loss-of-function) indicating that this mutation has arisen many times in the human population. The prevalence of O is indeed taken as evidence of balancing selection. Various pathogens use the A or B antigens as receptors. The cited paper presents evidence about the phylogeny of the ABO gene in human populations ...


6

Just continue scrolling down wikipedia: there are also listed two examples of beneficial mutations: the one conferring HIV resistance, and the one conferring malaria resistance. Note that 'beneficial' is relative. The mutation associated to malaria resistance is actually causing sickle cell disease.


6

The processes that control the germline of metazoans (multicellular animals) are highly regulated compared to single cell bacteria and eukaryotes as well as plants. At this point there are no clear stories of gene transfer into a complex animal, though there are some for plants: "animals and fungi seem to be largely unaffected, with a few exceptions, ...


6

A major limiting factor in such an exercise is the complexity of the biological process under question (eye colour etc.,) and thus, our nascent understanding of these. What I mean is that there is not a single gene that determines a given characteristic, rather it is the complex interaction of a set of genes in different conditions responding to ...


6

Another list of simple human traits can be found on the Western Kentucky University site. I will ask also AB0 and Rh Blood Groups, you can use this also to check associations with other genotypes/phenotypes, see this stackexchange question If you are going to sequence also the mitochondrial DNA, you may want to reflect on questions to ask also about their ...


6

Bone Marrow transplants are extensively matched in order to prevent rejection. Current matching methodology is HLA matching: Stanford Children's Hospital Guidelines How are a donor and recipient matched? Matching involves typing human leukocyte antigen (HLA) tissue. The antigens on the surface of these special white blood cells determine the genetic ...


6

Dawkins is overgeneralizing. Genetic distance is a fairly new field, and a heated topic, since your answer depends upon which genes you are comparing. If you picked ONLY strongly-conserved genes for your genetic distance comparison, then you'd find that humans, bonobos, dogs, mice, mosquitos, shrimp, and bakers' yeast are all equally distant (and that the ...


6

According to wikipedia, "comparisons between known skin pigmentation genes in chimpanzees and modern Africans show that dark skin evolved along with the loss of body hair about 1.2 million years ago and is the ancestral state of all humans." This is several million years after after the time estimated for the last common human-chimpanzee ancestor, but at ...


6

Presumably this means that at least some grey haired humans have noticeable reproductive advantage, or maybe they had it in the recent past. No it doesn't. Natural selection is not that strong, it doesn't optimize every single possible physical trait towards maximum reproducing. And as others have mentioned, having lots of grey hair usually ...


5

Polyphasic sleep can allow people to sleep at multiple regular intervals throughout the day and allows people to get by with less total sleep. I don't know of any training that can help people reduce the amount of monophasic sleep they need without a negative impact.


5

Gene frequencies (frequencies of each allele at a given loci) in populations are affected by many things divided in to systematic and dispersive processes. Systematic process (migration, mutation, selection) affect gene frequencies in an often quite predictable manner and strength. Dispersive process (Random drift, differentiation between sub-populations, ...


5

23andMe is a company that provides sequencing. Before they sequence your genome, they ask you to fill in a couple of surveys, one of which is about your physical features. Here is a list of some of the questions they ask: How much hair do you have on your upper/lower back? When you walk, in what direction do your feet naturally face? Do you have ...


5

Meiosis is the type of cell division responsible for the diversification of genetic material among egg and sperm cells. The diversity comes primarily from crossing over (Prophase I) and the cell divisions (Telophase I & II) later on in the process. Meiosis begins with one diploid cell containing two copies of each chromosome—one from the organism's ...


5

Others have posted that the term beneficial in genetics is contextual - single mutations may be harmless, unless another mutation is co-inherited; this is called epistasis (where more than a single mutation/genotype/allele is required for the phenotype). I have not studied the list comprehensively, but there is a 'catalog' of all robust genome-wide ...



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