No the cause of down sydrome is the reliance of the human on a gene tat we got from the neanderthall dna we got during interbreeding with them.
Haw many black people have you seen with down syndrome?
Buh-bye!
[Moderator Note]
I have for the moment suspended mla1 for multiple warnings as well as failure to follow moderator instructions. Further action will depend on discussion among the moderation staff.
Colibri
General Questions Moderator
Quite a few, actually - but then, I live in a city about 85% of African descent so it’s not too surprising to find a few examples in the neighborhood.
Really, this whole “Neanderthal genes are inherently inferior/defective/cause disease” bit is starting to take on racist overtones…
Quoth md2000:
And if that were to happen, it would also be evolution. Evolution tends towards greater fitness for the environment, and when the environment changes, what evolution tends towards also changes.
It should also be noted that evolution in many cases means running the Red Queen’s race, working as fast as possible just to stay in the same place. Consider cockroaches, for example: So far as we can tell, modern cockroaches are nearly identical to their ancestors that lived a hundred million years ago. Does this mean they haven’t evolved since then? Quite the contrary. Rather, the cockroach is apparently extremely well suited to the niche it occupies in the environment. Every so often, as is the case with all organisms, a cockroach will hatch that’s a little different from other cockroaches in some way. If the difference made that cockroach better suited for its environment, then it would tend to have more offspring than other cockroaches, and those genes would eventually spread through the population. But since the cockroach is already so close to perfect, any change away from the cockroach norm is overwhelmingly likely to be for the worse, not better. So any deviation away from cockroachiness is selected against, and those genes dwindle and disappear, leaving the population unchanged. If the cockroach were not already so ideal, then we’d see much greater variation over millions of years, if only due to random drift.
I know people like to repeat that about cockroaches, but I wonder how unusual it really is. “Cockroach”, after all, is an entire order of insects consisting of thousands of species adapted to countless environmental niches. I don’t think it’s all that unusual, especially for insects, for an order to contain a few species that appear morphologically similar to the earliest ancestral forms known, and others looking rather different.
For the record, after discussion with other members of the staff the ban has now been made permanent.
Last I checked, cockroaches and mantids were both considered to be in the same order. But otherwise, I agree.
Order or Super Order, depending on who is doing the classifying. But yes, closely related at that level.
The cockroach evidence thing is interesting. What evidence is there that cockroaches haven’t changed in millions of years besides physical appearance? The coelocanth is purported to be unchanged in millions of years, except for being 100 times larger than any fossils found (unless there’s something new I haven’t heard about). We have other threads discussing the failures of genetic identificiation based on superficial characteristics.
The species, and even genera (and I suspect even families), of cockroaches that exist today are not the same ones that existed a hundred million years ago. And they are of course genetically different than their ancestors.
And of course we don’t perceive physical differences among cockroach species with the same detail we do among species that are more closely related to us. Cockroach species that differed from each other physically as much as we do from chimps or gorillas would be perceived by us as being very similar.
I suspected as much. Another fail for superficial charactistics. Mythbusters also debunked the ‘cockroach immunity to radiation’ claim.
Yes, we’re probably talking about 2 separate issues here:
Where is human evolution going? In the last few hundred thousand years or so, we evolved (wild ass guess) some sort of sympathy-empathy-bonding that means we will continue to support people who are incapable of taking care of themselves - the less capable, the less productive. With the advent of agriculture and settlements, when you don’t have haul an invalid around everywhere, this process has accelerated. Agriculture also allows for a surplus of food (sometimes) to support these types; settlements mean protection so awareness, mobility and strength to defend yourself from hazards are less necessary.
The industrial revolution has accelerated this tend; a much larger surplus means we can support a lot more “unproductive” members of society. The scientific revolution has done more - we enable the survival of those with genes that would most likely cause a person to either not survive or not reproduce in a less forgiving environment. Hemophilia, diabetes, very bad eyesight, low intelligence (if it is hereditary), even infertility can all be treated.
Is this bad? Not exactly, in our current context. More people needing medical support, more people incapable of being productive members of society - we can easily afford to take care of these people with our modern society.
In the long term, we come to the second problem: Man is evolving to be more “dependent” and individually incapable. (“Homo depends”?) Not a problem in our current society, but if there is a significant disruption of the support systems (aka. change in enviroment) then there will be a very strong “selection” for the new environment. This is evolution in action.
Do you have evidence for this? What are the “dependent” genes? Hemoplilia was around and propogated before there was treatment for it, because its hard to get rid of recessive genes even if they are detrimental. People have been cooperating to survive going back to our pre-Sapiens ancestors. Where is this lack of human ‘capability’?
I think Chronos has it right. Distribution of genetic factors is certainly changing over time, but not necessarily resutlting in significant changes to humans. Big changes require mutation and/or long isolation. Humans are not very isolatable. That combined with the huge diverse population makes it difficult for mutations to propogate widely (although if beneficial, they wouldn’t disappear easily either).
Chronos had it right - we are running the Red Queen’s Race. I recall reading that the hemophilia that many of Queen Victoria’s descendants had was likely a spontaneous mutation in her or her mother. Many such detrimental genes are. As fast as they pop up, until recently they were weeded out, people having that gene tend to have medical problems and more likely to die before they have a chance to reproduce. Similarly, it is suggested that Type I Diabetes is herditary, but also often appears spontaneously. Nowadays, that gene will survive thanks to Banting and Best.
Genes mutate all the time. If these “transcription errors”(?) are serious enough to impact the proper development of the offspring, miscarriage or sickness and death are often the result. Otherwise, if the errors are in the unused parts of the DNA, they simply provide evidence about how separate 2 populations are genetically.
Current evolution studies suggest even a minor differential reproduction rate can, over many generations, result in a gene becoming very common or very rare, depending on its effects. If everyone with blue eyes died without reproducing, there would still be brown-eyed people with 1 recessive blue-eye gene. Over time, however, that gene would in fact beocme less of the population, as the brown(blue) types would end up with 25% less reproducing offspring than brown-brown types.
What if genetic treatments can soon remedy that dependency away in advance, both for the individual and for later offspring?
People will never back off the dominant-brown, recessive-blue misconception because they learned it in high school biology and that makes it sacrosanct. High school biology teachers will happily sit there and preach the doctrine that the world is made up of 2 kinds of people, brown-eyed people and blue-eyed people and that all depends on which gene you got.
They’ll sit there and preach that doctrine while looking into a classroom of kids who prove it false and the kids will duly note it even though they can easily prove it false just by looking into the eyes of the people who sit around them.
It’s really the downside of being a good student. You’re destined to live a life never really understanding that what is commonly taken as fact is always meant to be questioned and doctrinaire science - the kind that tells you that something has always been a certain way and will always be that way - is always ever-changing.
And on top of all the other misconceptions perpetrated in this thread, a 25 percent chance of a certain phenotype manifesting is nowhere near meager.
Eugenics is kind of a loaded word. They wouldn’t keep their hands off your deaf gene any more than they’d keep their hands off my “family history of heart attack” gene. Both genetic conditions are undesirable, as just about anyone would agree.