SkepticLance

abciximab said AFAIK (please correct me if I'm wrong), viruses are not a major part of any ecosystem as nutrition, commensals, or symbiotes. While viruses are not nutrients, commensals or symbionts, their impact as parasites and pathogens is dramatic. In the ocean, there are 100,000,000 virus particles per ml of seawater. If this has no significant ecological effect, then I would be most surprised. In terrestrial ecosystems, viruses are equally abundant. They are the cause of a very big proportion of animal and plant diseases, causing death and debilitation wholesale. They have a massive ecological impact. A leading theory as to their evolution is that they began as bacterial parasites, and 'devolved' into a much simpler form. This can be seen in some of the small bacteria today that live an entirely parasitic life style. For example : Mycoplasma genitalium is a very simplified bacterium, which has lost most of its genes relating to metabolic regulation, as compared to free living, non parasitic bacteria. It is well on the way to becoming virus-like.

Your question is diabolocal in that it implies evil, but evil does not exist. If you are black, you will save the black child. If you are white, you will save the white child. There is nothing to be gained by trying to put some value judgement on this. It boils down to this. If you are a black parent, you treat black children like your own. If you are are white parent, then white children are like your own. Racism does not enter this. Just instinct. The entire question is unfair and implies lies as conclusions.

Brian said : We do not definitively know that we came from a small number of individuals, simply because there are no records. Sorry Brian. That is not correct. We have the genetic record of mitochondria. Since mitochondria come only from our mothers, we can judge how many women there were in the past by the number of different kinds of mitochondria there are. This is done by evaluating the gene sequences on mitochondrial DNA. A similar result can be achieved for the male line by evaluating DNA sequences in the Y chromosome, which males get from their fathers. Results of these tests show that at one time, the total number of Homo sapiens individuals was very small. Our species is at least 200,000 years old, as shown by fossils of that age. They are clearly different (though the difference is minor) from fossil Homo sapiens of 100,000 years ago. This shows that humans do evolve, over that 100,000 year time period. To my knowledge, no Homo sapiens fossils older than 200,000 years have been discovered, though, of course, fossils of other Homo species have been found older than that.

If you want to use schizophrenia as an example, please learn to spell it.

Ecoli said : So we shouldn't develop medicines targeted to African Americans because it's not PC to point out genetic differences? Actually, that is a perfect example of the point I was making. Dump PC if it is contrary to science. If a medicine works better with a particular racial group, then it should be used that way, since it is good science to do so. Forget the PC if it gets in the way of scientific reality.

Some aspects of political correctness are good. Some are neutral. Some are bad. Not being racist is a form of PC that is good. Calling a woman Ms instead of Mrs is PC and harmless - just not terribly useful either. Pushing a view that is PC but just plain wrong is bad. As science oriented people, we should be mostly concerned about PC when it is not scientifically correct. For example : in certain circles, it is PC to believe that all behavioural differences between individuals is the result of conditioning, not genetics. That is not scientifically correct, and we should oppose that form of PC, and support the kind of research that will nail down the real causes. There are people who believe that all criminal behaviour is the result of defects in Society. That is also something we should oppose. It is not scientifically correct (a lot of criminal behaviour is common across a wide range of societies), and is liable to lead people into 'remedial' action that will simply make matters worse.

Putting all the religious and pseudoreligious bulldust to the side, there are two very good reasons why human cloning is not a good idea. 1. There is a very high failure rate in all cloning. To get a single human clone, you would need perhaps 200 volunteer women to provide surrogate wombs. Of these, something like 199 would suffer miscarriages, and we all know how emotionally traumatic that is. In other words, attempts at cloning will carry a big cost in human suffering. 2. There is a very high deformity rate in clones. The one in 200 that actually gave rise to a viable human clone would likely have produced a human with serious health problems. This is another way to create human suffering. Of course, advances in technology may solve both problems. If and when that happens, cloning will simply be another strategy to enable human reproduction.

ParanoiA said : I would fight for him to have the right to hate me. Fair enough. But I would put the Asshole in prison for trying to get other people to hate me. Your feelings are your feelings, and that is a human right. But to incite hatred is a crime.

I suspect that the biggest problem with human impact on global ecosystems is our variability. That is, we do not settle down to doing the same thing over and over for thousands of years. Our way of life is constantly changing. This means that other organisms are unable to adapt. There are other organisms that have a massive impact on ecosystems. The African elephant, for example, is responsible for the vast tracts of grassland in Africa, and the destruction of large areas of rainforest. Any tree that dares to grow up high gets pushed over so the elephants can browse on its top leaves. Since this has been going on for so long (millions? of years), the ecology has adapted and there is a diverse set of grassland species. Humans, though, keep changing.

I do not believe homogenisation is the long term fate of Homo sapiens. A Scientific American article a few years back by a couple of NASA guys (Yes, Dolores, this IS rocket science!) showed that there was no theoretical reason why we should not colonise the galaxy. They suggested that the first humans to reach another star system would do so within 1000 years. Assuming this is correct, there will be an enormous time delay between anyone leaving Planet X and getting to Planet Y, (many decades). This would mean that population growth on any colony would be by natural reproduction, not immigration. The barriers to gene transfer should result in independent evolution (or varied genetic engineering changes) on each system. Imagine the diversity in a few 100,000 years!

It's all kind of silly. All humans, regardless of race are within 99.8% of every other human in terms of genetic make up. So what's the fuss?

Chupacabra said : Anyhow, measures to exterminate rats and other introduced species who threaten endemic bird populations in places like New Zealand, actually reduce local "biodiversity" Actually, speaking as a New Zealander who is extremely interested in nature conservation, I have to mostly disagree with this. It is true that, with enough effort, anything can be stuffed up. However, mostly, efforts to eliminate rats and other pests have resulted in substantial increases in biodiversity. For example : I am a member of the "Friends of Tiritiri Matangi" . This is a bunch of people replanting and repopulating with native birds the island of Tiritiri Matangi. A few years back we had a massive rat killing effort. The poisons killed a few native birds, but the care we took minimised that. And the results were spectacular. We saw a population explosion of the rare and endangered birds on the island. This was so effective that we are now mist netting these same birds to export them to other islands, since Tiritiri Matangi now has an excess! I can name a whole lot of other places within New Zealand where results have been similar. Places where species on the edge of extinction are now growing in numbers very rapidly. Getting rid of pests, if done professionally and effectively, is an amazing tool for increasing biodiversity.

Of course you are right in what you say, it's very beautiful, but not very realistic from my point of view. Actually it is very realistic and quite doable. It already happened with the Green Revolution. There are hundreds of millions of peasant farmers in India, Pakistan and elsewhere who repeatedly plant wheat and rice crops that are genetically superior to old stock, and produce more food per acre than would have been earlier possible. They bypass politics to do this, since they already have the superior crops. Africa, sadly, missed out on this revolution. However, with GM, we have a second chance. Give the poor African farmers the superior gene stock, and they will plant and harvest it for many generations without any political interferance.

zyncod. Banana trees grow a 'leaflet' bunch at the base of the tree. To propogate, this is cut off and planted. Each generation requires times to grow a small tree.

zyncod You are correct in theory. However, quantitatively, you are pushing a rather heavy barrow. Bacteria develop new traits through mutations, and the most advantageous survive. Many hundreds of generations are required. To use this process with flowering plants such as bananas, but without sexual reproduction and the genetic variation associated with sexual reproduction, would take forever.

On GMO's / hunger and politics. One of the most reliable means of solving the hunger problem is to bypass the politics. You do this by empowering people to produce their own food, without requiring input from their own government or from aid agencies. This is the approach used in the Green Revolution, which is supposed to have saved a billion people from malnutrition. GM crops can help do the same. Once the poor farmers have GM seeds that produce a more productive food crop, they can save the seeds and replant them from year to year. So, for example, the insect resistant maize will give greater yields, and hence less hunger every year once peasant farmers have this resource. To say that hunger is due to politics is true, but unhelpful. To give people the resources to bypass politics and feed themselves - that is a wonderful gift.

Thanks for the interesting reference, Aardvark. Implication given is that the change to seedlessness (and probably greater size?) was due to polyploidy. As I understand it, this is a mutation rather than breeding.

Aardvark Interesting post, and I am sure you are correct. Doesn't alter the fact that you cannot breed a seedless banana from wild seeded varieties. The fact that you get occasional mutations in cuttings does not alter this either.

ecoli said : And I'm not sure if I buy the argument that GMO crops will help stop hunger in Africa. There is truth in what you say, at least at the present time, but probably not for the reason you believe. The real problem is political. That is, we have a whole lot of anti-GM activists telling African governments not to accept GM crops. Thus, the introduction of necessary technology is an uphill battle. Case in point. 200 million sub saharan African depends mainly on corn as their staple food - often as a kind of maize porridge. This group is heavily represented in the 840 million people known to be malnourished. Yet 40% of the maize crop each year is lost to insect attack - adding a hell of a lot to the problem. There is already in existence an insect resistant GM maize suitable for cultivation across large parts of Africa. It has not been permitted to be introduced. Cassava is another vitally important crop for Africa. There are two virus diseases that devastate the crop. A GM virus resistant cassava was made, totally resistant to one of these viruses. The researchers were set to add resistance to the second, but their funding dried up. Why? It appears to be the result of anti-GM activism. Yes, GM has the potential to drastically reduce hunger in Africa. And no, it will not happen until current political activists stop their very damaging activities.

Bascule. The reason I did not previously enter this thread is that I think the issue is just too trivial to warrant a new thread. However, since you insist ... I discovered from the Agbioview email newsletter in a discussion of GM work on bananas that the original seedless variety is a mutation, not bred. However, I did not keep the quote and I will not go back over perhaps 200 issues to find it, when the argument is so damn trivial. However, I have been thinking about this. I cannot imagine how normal selective breeding could result in a seedless variety without some major genetic change (ie. a mutation). Normal selective breeding requires genetic variation, or else how can you select an advantageous variation. Genetic variation comes from sexual reproduction. Cuttings yield the equivalent of identical twins. If you permit a flowering plant to reproduce sexually, you get seed formation. If no seeds, there was no sexual reproduction. No sexual reproduction means no genetic variation, and no progress in breeding. So to get selective breeding, sexual reproduction (hence seeds) are needed. No seeds means no sex which means no breeding. Hey. Even to breed a strain that has only a smaller number of seeds is going to be difficult. To breed a strain (without a mutation) with no seeds appears to me to be impossible. If you disagree with me, that is fine. However, let's end this silly discussion one way or the other.

Bascule, I do not quite understand why you feel the need to reply in such vehement terms. Surely, the origin of the humble banana is not something that requires this. My original source is a posting by Professor Anthony Trewavas on the Agbioview email magazine. You can find this email journal on google. http://www.agbioworld.org I have not changed my tune. Here is my original comment copied. The original seedless banana was not bred. It was a particular mutation discovered in the wild. Bascule, you said : A seedless plant is, by definition, sterile. Any seedless mutants are doomed to instant death. Yes, it is sterile. But it can be propogated using cuttings. And that is how it has spread world wide. Bascule, Come on. Then origin of the humble banana is not of Earth shattering import. Why have you reacted so strongly?

Just by analogy, Orca (also called 'Killer Whales') hunt small fish such as sardines. They will pick up a number of small fish in one mouth-full. This is a predator that kills seals, dolphins, whales (and here in New Zealand, the local pod specialises in sting rays and sharks). Yet they are adept enough to carry out a kind of 'filter feeding' by engulfing a number of small fish at one time, and ejecting the water without losing the fish. If we assume that flamingos began that way, then any mutations or other genetic changes that improved their ability to ingest organic matter while ejecting water is a selective advantage. Once the process begins, it can carry on to the current level of adaptation.

This seems a rather trivial subject to get emotional over. However, I am not wrong. Seeded bananas are the 'natural' type, but now form a very small minority of banana plants, though the majority in the wild. Both Gros Michel and Cavendish varieties are mutants. Did you think, Bascule, that particular mutations occurred only once? A major reason that a big GM research project on bananas is under way is the simple fact that there is so little genetic variation amonst seedless types. Obviously, only one genome for every line coming from one mutation. The Cavendish variety is under threat by Sigatoka disease, so called because it was first reported in the Sigatoka region of Fiji. (pronounced Sing-ah- Toh- kah). Since the mutant cannot be cross bred, the only effective method of producing a disease resistant variety is GM.

Bascule said : The real reason the banana plant can't adapt is because it has been bread to be seedless and must reproduce with cuttings, eliminating its ability to adapt to the ravages of Panama disease This is not quite true. The original seedless banana was not bred. It was a particular mutation discovered in the wild. Since seeded bananas are almost impossible to eat, the mutation was immediately put to use. Bananas can be grown from cuttings taken near the base of the tree, and thus this mutant was spread around the world. The original seeded banana continues to grow in the wild, but has not been cultivated for the obvious reason. The use of seedless mutants has not reduced banana genetic diversity, which remains as it always was. However, those that are propogated from cuttings of the same origin are all the same genome, and are thus vulnerable to a new disease. There have been other mutants without seeds discovered, and this is the origin of the several genetic strains of edible banana.

We do not actually have to envisage any mutation at all to get things started. It is quite possible for a totally unmodified organism to 'filter-feed' albeit inefficiently. Imagine our primeval flamingo to be is a bird with a large beak. It strikes the water chasing fish. Ejects the water that comes in with the fish, and swallows. Except this time there is no fish. Even so, a significant amount of organic material may be in the water, and this it swallows. If a bird develops the habit of swallowing organic rich water, when fish are less available, it is the start. Mutations after that are advantageous if they assist this 'filter-feeding'.