Why is increasing homozygosity in a population detrimental?
438204
the tendency towards a totally homozygotic population is a bad thing as the gene pool will shrink. this means that the population will not have certain members able to deal with the disease and so will therefore die out. A good example of this is banana plantations, where sexual reproduction has been greatly reduced in favour of the banana we all enjoy, and so there is no great genetic variation, and thus if a banana disease were to strike- the plants would most likely all die out.
201401
A few reasons...one is because, statisticaly, random flucuations are more likely in a small population, kind of like if you flip a coin twice, you might get 2 heads or 2 tails, but if you flip a coin 100 times, you'll probaly get something close to 50-50. \n\nAnother is that rare genetic types are easily 'diluted' in a large population, but can become significant in a small population. Think about why family members shouldn't marry: most of us have some harmful recessive genes, but it's unlikely that our spouse will have the same one, so it's not a problem. But, if we marry within our family, there's a much greater chance that our spouse also carries the recessive gene.  In small populations, more recessive traits will be expressed.\n\nFinally, a small popluation is usually isolated from the larger one, so it might be exposed to specific environmental conditions that force adaptation or create some selective pressure. One famous example of this is Darwin's finches, on the Galapagos islands: because each island has specific types of plants, each island's population of birds was under pressure to adopt to eat those plants, and they each ended up with a beak taylored to their own island's seeds.
376212
Because the social structure of lions strongly decreases the potential for  inbreeding , lots of harmful recessive mutations have been 'allowed' to build up.  Genetic diseases thus crop up a lot where inbreeding occurs.\nCheetahs who went through a bottleneck are much less affected by inbreeding, in a sense they were forced to inbreed to an extent,  harmfull recessive mutations died out with the disesed animals.
418411
If all humans started in Africa a very long time ago, they did not all stay there.  They wandered.  And as they wandered, tribal groups formed which were isolated one from another.  The characteristics of a given tribe were selected out in response to different environments.  Thus, for example, northern Europeans store fat on their bodies efficiently (way too efficiently for modern times!) to protect them from the cold winters.  The closer to the equator a tribe is, the darker skin is more valuable, and selection brings it to the forefront.  \n\nSo that's how we separated.  Now, with world wide transportation, we are coming together once more.  And as people from different gene pools breed, they produce the healthy children who have fewer matching of recessive traits.  Recessive traits are more likely to be the ones that cause problems.  So yes, it is better for us to mix, for the evolution of the species as a whole, and for the beauty and good health of the individual children thus created.
309255
NO it is not, it is a cellular mutation that can be reversed. To find our more check out the link.
377417
Don't know about "proof", but most peoples inter-marry/breed to increase the size of their gene pool. It is hard to believe that any of these cultures remained completely isolated.
1155079
Our history as a species also has left genetic signals in regional populations. For example, in addition to having higher levels of genetic diversity, populations in Africa tend to have lower amounts of linkage disequilibrium than do populations outside Africa, partly because of the larger size of human populations in Africa over the course of human history and partly because the number of modern humans who left Africa to colonize the rest of the world appears to have been relatively low (Gabriel et al. 2002). In contrast, populations that have undergone dramatic size reductions or rapid expansions in the past and populations formed by the mixture of previously separate ancestral groups can have unusually high levels of linkage disequilibrium (Nordborg and Tavare 2002).\n\nIn the field of population genetics, it is believed that the distribution of neutral polymorphisms among contemporary humans reflects human demographic history. It is believed that humans passed through a population bottleneck before a rapid expansion coinciding with migrations out of Africa leading to an African-Eurasian divergence around 100,000 years ago (ca. 5,000 generations), followed by a European-Asian divergence about 40,000 years ago (ca. 2,000 generations).\n\nThe rapid expansion of a previously small population has two important effects on the distribution of genetic variation. First, the so-called founder effect occurs when founder populations bring only a subset of the genetic variation from their ancestral population. Second, as founders become more geographically separated, the probability that two individuals from different founder populations will mate becomes smaller. The effect of this assortative mating is to reduce gene flow between geographical groups, and to increase the genetic distance between groups. The expansion of humans from Africa affected the distribution of genetic variation in two other ways. First, smaller (founder) populations experience greater genetic drift because of increased fluctuations in neutral polymorphisms. Second, new polymorphisms that arose in one group were less likely to be transmitted to other groups as gene flow was restricted.\n\nMany other geographic, climatic, and historical factors have contributed to the patterns of human genetic variation seen in the world today. For example, population processes associated with colonization, periods of geographic isolation, socially reinforced endogamy, and natural selection all have affected allele frequencies in certain populations (Jorde et al. 2000b; Bamshad and Wooding 2003). In general, however, the recency of our common ancestry and continual gene flow among human groups have limited genetic differentiation in our species
421424
People who live in large cities are less likely to be inbred.
394899
the specific mutation of the hemoglobin chain creates a less friendly environment for the malarial protazoans.  scientist aren't quite sure yet what it is that makes it less friendly.  but because of this people in mediteranean and african areas are who have one copy of the faulty gene are more immune to malarial infections which will give them a greater chance to survive long enough to reproduce, thus increasing the prevalance of the mutated gene in the population.  natural selection, my friend.
715110
1.  It's the "selfish gene" factor.  The purpose behind reproduction is to increase the allele frequency of your particular alleles, in the population.  Your siblings would share a good portion of your particular alleles, and thus it's more "evolutionarily sound" for you to avoid killing them.\n\n2.  Cannibalism will happen as a result of environmental signaling factors, of which lack of other foods and crowding are the most common.
759462
Homozygous recessive?
586577
I don't think so. homogeneous populations are more vulnerable to diseases. This is because large numbers of the population share the same genes. The more diversified the gene pool the better the chances of survival. That's one of the reasons people reproduce sexually as opposed to asexually. So spread those genes around. :)
560142
One of each pair is derived from either parents. Also due to the diploid nature of chromosomes genotypes as homozygous dominant, homozygous recessive and heterozygous can be found. Thus a recessive character can be avoided to the maximum.
433113
Several animal species exhibit homosexuality. It can actually be beneficial in an evolutionary sense if care is taken of siblings or other relatives. On the other hand, evolution does not respond to *future* threats, so any genes for homosexulaity would not have had time to spread in response to overpopulation.
234596
Everyone who reproduces passes his/her genes on to future generations.  If you assume a population's birth and death rates are independent of light/dark skin genes then this means that whatever ratio is currently in place will stay that way.  (Also assume the population is isolated: no large fluxes of different ratios of phenotypes are coming in or leaving.)\n\nIf you ignore death rates, then populations grow exponentially.  This is characterized by a doubling time.  Say the doubling time is like 20 years (made up number) and your population of 100 individuals is 75 dark and 25 light.  If you wait 20 years then there will be 200 individuals: 150 dark skinned people and 50 light skinned people.  The ratios are still 75% and 25%.  The ratios will be constant whether or not different phenotypes reproduce with each other, too.  However, gene expression (dominant, recessive) could make the ratios look different on the outside (favoring the appearance of the dominant phenotype), but the actual gene ratios would still be constant.
212418
There are some break through research that homophobes would like to keep under wraps.  It,s looking like homosexuality is more in genetics and brain chemistry.  People can't really turn gay, or at least not for the right reasons.  You can't choose who you are attracted to.
341693
The mother and child will have *nearly* identical DNA.  There will be a few mutations because mutations are ubiquitous, but 99.99+% of their DNA will be the same.