Evolution: What Real Scientists Have to Say

Very good and very interesting Set, I have only one comment. In western culture, up until the 17th century, and in North America (particularly New England) until the end of the 18th century, religion was the vocabulary in which almost all major issues, economic, political or social was discussed. Thus the religious terminology tends to obscure other issue which are at the root of what ever conflict one looks at. Much of what looks like a conflict over competing ideologies is at root a conflict between central and local authority and where the locus of decision making is to lie. The simplistic explanation is that decenters or local control advocates mostly fall broadly into what we would now call the Protestant camp and conservatives or advocates of central control into the Orthodox or Catholic camp. The problem with local control is there is no overt means of maintaining a coherent uniform consensus on any issue over the long term so these movements may start out as radical but move towards cultural conservatism. Combined this with a state of rapid cultural change and you have an explosive situation. Which brings us to the current problem with fundamentalism world wide, and the issue of evolution.

I've been curious lately regarding viruses in this regard. I'd be very curious to see some stuff on the diversity of viruses in this regard. The more I learn about prokaryotic genetics, the more it seems that viruses shouldn't really be classified so much as separate entities rather than trussed-up transposable elements. There's very little difference between the genetic elements that infect bacteria and those that the bacteria supposedly "use" to their own benefit. Selfish genes and all that, I s'pose. Still fascinated by retroviruses, as well...



Another bit of trivia (sorry folks who are carrying on the very interesting sociological discussion)... There is a species of caterpillar-parasitizing wasp that when it lays its eggs in the caterpillars butt also infects it with a virus that shuts down its immune response, so that the larvae can develop unmolested. The weird thing is that it turns out this virus doesn't live on its own: it comes from the wasps genome. So either here is a pseudovirus that evolved in the wasp's genome or a caterpillar virus or retrovirus that accidentally found its way (through insertion or reverse transcription) into the wasp's genome (or some combination of the two). Weird stuff...

Cool!

Among the listed causes of mutation are these:

Types of mutations:

1. Retroviruses
Certain viruses have the ability to insert a copy of themselves into the genome of a host. The chemical that make this possible (reverse transcriptase) is widely used in genetic engineering.

Effects of retroviruses: Usually this is a way for the virus to get the host to do the work of reproducing the virus. Sometimes, however, the inserted gene mutates and becomes a permanent part of the host organism's genome. Depending on the position of the viral DNA in the host genome, genes may be disrupted or their expression altered. When insertions occur in the germline of multicellular organisms, they can be passed on vertically.

2. Higher level transfer
Some parasites can pick up genetic material from one organism and carry it to the next. This has been observed in fruit flies in the wild.

Effects of higher level transfer: When this happens novel alleles can spread much more rapidly through a species than they would for ordinary gene flow.

3. Symbiotic transfer
When two organisms exist in a close symbiotic relationship one may "steal" genes from the other. The most notable example of this are mitochondria. In most organisms with mitochondria most of the original mitochondrial genes have moved from the mitochondria to the nuclear genome.

Effects of symbiotic transfer: A major effect is that the symbiotic relationship changes from being optional to be obligatory.

Source: http://www.talkorigins.org/faqs/mutations.html#types

BBB
Do I understand correctly that viruses cannot survive nor reproduce without a host while bacteria can? If so, then are bacteria the most successful life form on Earth?

BBB

Bacteria are certainly the most ubiquitous.

Re: BBB


If success is measured by biomass and variety and generations and antiquity, then bacteria would probably be considered very successful.

Viruses are barely considered to be living things. They are so simple that their entire life process can be described by chemistry (genetic chemistry).

Multicellular animals on the other hand can attain consciousness, which could be considered a great success, even though we are a collection of cells, few of which could survive on its own, and none of which can achieve consciousness on its own.

Or we could generalize and say that DNA is the only form of life on this planet, and that it is the *only* successful organism on this planet.

Most biologists do not consider viruses living at all, as they do not produce machinery to reproduce themselves (no ribosomes).

Bacteria are immensely successful. In fact, in a healthy adult animal, bacterial cells outnumber "own" cells by as much as 10 to 1 -- and they are of immense importance to you. Bacteria and Archaeons might also be considered far more successful than plants and animals in terms of the variety of habitats they can live in (temperatures ranging from below freezing to above boiling) and in the chemicals they can use for food and energy. Eukaryotic cells (plants, animals, and "protozoa") are fantastically limited in these regards.