Questions about Evolution (yoinked from different thread...)

iguana

sensibleken wrote: »

If evolution is driven by mutation, how come we aren't all out boinking x-men? Is it because wolverine can't put on a condom without ripping it?

Because our mutations are far less dramatic (unfortunately:(). If you, as an adult, can drink milk without getting an upset stomach then you are a recent mutant and slightly different from the majority of the species. But The Uncanny MilkMen wouldn't have sold as many comics.

sensibleken

iguana wrote: »

Because our mutations are far less dramatic (unfortunately:(). If you, as an adult, can drink milk without getting an upset stomach then you are a recent mutant and slightly different from the majority of the species. But The Uncanny MilkMen wouldn't have sold as many comics.

True. And the prohibitive price of fixing the roof when storm was last over doesnt help either.

Also, I now have a song by the dead milkmen in my head

amacachi

iguana wrote: »

Because our mutations are far less dramatic (unfortunately:(). If you, as an adult, can drink milk without getting an upset stomach then you are a recent mutant and slightly different from the majority of the species. But The Uncanny MilkMen wouldn't have sold as many comics.

Coupla litres a day, woo!

Galvasean

sensibleken wrote: »

Also, I now have a song by the dead milkmen in my head

Try this instead:

CerebralCortex

http://www.youtube.com/watch?v=-vQ2RVqJCNM

Lol.

Craven99

Sam Vimes wrote: »

E.g. giraffes didn't grow longer necks because their genomes somehow recognised that there were good leaves on higher branches, random mutations gave some of them longer necks and these allowed them to get these higher leaves that their shorter necked brethren couldn't reach. Longer necked ones lived where shorter necked ones died, hence longer necked giraffes.

You know I am pretty certain that Giraffes evolved longer necks as a mechanism for fighting in displays of mating and not, as was thought previoulsy, to enable them to reach higher up leaves etc.
Only read about this relatively recently!

Galvasean

I read that too. Although I would have thoughtthe figting elements would have been more of an evolutionary 'after thought' so to speak.

Capt'n Midnight

darjeeling wrote: »

It looks to me that the genome has evolved to evolve.

...
I also think that higher (complex, multicellular) organisms are sophisticated ways of coordinating genes that evolved in much simpler ancestral organisms. Potential for evolution in simple, unicellular bacteria, yeasts etc. is enormous, given the massive numbers and short life cycles of these lifeforms. In contrast, potential for evolving new genes in, say, humans is much lower. Instead, complex organisms have relatively few mutations that change the proteins themselves (compare, say, chimps & humans), and rather more regulatory changes that lead to a bit more of one protein being made and a bit less of another etc, etc.

actually it's more the reverse

evolution is conservative , if we evolved at a great rate we'd have a lot more cancer so there may be built in mechanisms to prevent this

some reckon that having two sexes is part of an evolutionary arms race against parasites. It gives us larger organisms the ability to micro-evolve every generation where the differences between us are in the grand scheme of things quite small and so it's usually more of a blend of characteristics.

The one huge trick microorganisms have over us is that genes can be transferred across species so it's possible for one species to inherit antibiotic resistance from another via phage or whatever. [insert rant here about how future generations will look back at the wasted opportunity of the golen age of antibiotics and propose we research phage instead ]

a lot of theories about evolution have been simulated on computers and some of the results have been non-obvious. Models that looked at genes that conveyed no competitive advantage showed that such genes could be eliminated or become universal in a finite population in relatively short time.

robindch

Capt'n Midnight wrote: »

The one huge trick microorganisms have over us is that genes can be transferred across species so it's possible for one species to inherit antibiotic resistance from another via phage or whatever.

Microorganisms? Some of these clever little buggers have DNA that can be read backwards as well as forwards. How amazingly cool is that?

Capt'n Midnight wrote: »

research phage instead

I gather a lot of phage research has taken place in Tblisi, Georgia:

http://en.wikipedia.org/wiki/George_Eliava_Institute

Not sure whether they're still out in front, but I believe they did a lot of good research in their time.

darjeeling

Capt'n Midnight wrote: »

actually it's more the reverse

evolution is conservative , if we evolved at a great rate we'd have a lot more cancer so there may be built in mechanisms to prevent this

My point is that complex organisms have an enormous number of genes in common due to common ancestry, and that these genes all originally arose in much simpler, more numerous and more rapidly replicating ancestors.

In complex organisms, we get a bit of gene loss where genes turn out not to be all that necessary, and elsewhere a bit of duplication and subsequent evolution to give slightly novel genes. We don't really expect to see a load of radically new protein-coding genes that have appeared in recent evolutionary times in, say, primates, because the numbers don't allow for it. (NB genes jumping in from viruses or bacteria are the exception)

Capt'n Midnight wrote: »

some reckon that having two sexes is part of an evolutionary arms race against parasites. It gives us larger organisms the ability to micro-evolve every generation where the differences between us are in the grand scheme of things quite small and so it's usually more of a blend of characteristics.

That certainly seems a likely part of the explanation, though the question of why sex and sexes evolved (and why males are allowed to get away with being males) is an intriguing one yet to be fully answered.

Capt'n Midnight wrote: »

The one huge trick microorganisms have over us is that genes can be transferred across species so it's possible for one species to inherit antibiotic resistance from another via phage or whatever. [insert rant here about how future generations will look back at the wasted opportunity of the golen age of antibiotics and propose we research phage instead ]

This is another way in which bacteria can evolve rapidly: they are shockingly promiscuous, and swap genes all over the place, such that it's difficult to come up with a family tree. That's why we now think in terms of the 'pan-genome' when it comes to bacteria, as two bacteria that we lump together as the same species may actually contain a very different set of 'optional add-on' genes.

ColmDawson

robindch wrote: »

Some of these clever little buggers have DNA that can be read backwards as well as forwards.

Clearly an intelligent design feature to ensure that Muslims too can read God's wonderful tapestry of life!

nozzferrahhtoo

Craven99 wrote: »

You know I am pretty certain that Giraffes evolved longer necks as a mechanism for fighting in displays of mating and not, as was thought previoulsy, to enable them to reach higher up leaves etc.
Only read about this relatively recently!

Actually the most recent thing I heard was that they have long necks so they can reach the water to drink it....

... sounds mad, but what I mean by this is that it was their long legs that were the evolutionary advantage, not their long necks. That evolution selected the long necks was as a reaction to the legs to compensate for the disadvantages of the legs.

A strange inversion of reasoning indeed. Many people think only of the advantage of their necks because it is the most distinctive feature about them. They rarely think that the elongation of the neck was a reaction to the more advantageous elongation of their legs.

DapperGent

iguana wrote: »

Can we combine it? Bearded Emperor Tamarin monkeys have an interesting reproductive system. They ovulate twice per cycle and almost always give birth to fraternal twins. To get the optimal benefit from this female BET monkeys mate with 2 males during their fertile period. Then when the twins are born neither father knows which, if either, baby is his but must do all he can to help the mother and babies survive just in case one or both is his. The males form a love/hate relationship and must co-operate to help the mother look after her twins, each "father" taking one baby when the mother goes foraging. She indicates she wants them to come take the babies by sticking her tongue out at them.

I'm totally going to pitch this as a sitcom.

Capt'n Midnight

The nerve that goes between the brain and the voice box loops under the heart.

In a Giraffe it's about 5m long

In some dinosaurs this would imply a nerve 30m longer than is needed.

Capt'n Midnight

darjeeling wrote: »

We don't really expect to see a load of radically new protein-coding genes that have appeared in recent evolutionary times in, say, primates, because the numbers don't allow for it.

Then again Gelada baboons (not actually true baboons) can eat grass

darjeeling

Capt'n Midnight wrote: »

Then again Gelada baboons (not actually true baboons) can eat grass

As this is A&A, the key scriptural reference is Isaiah 40:6 - 'All flesh is grass'. This, while an overstatement, has a kernel of truth: grass eaters are found in quite diverse orders of mammals - artiodactyls, perissodactyls, lagomorphs, rodents and primates to name the ones I can think of. Many diverse species of mammals eat other leaves too (many primates included), so I don't see that there's anything terribly special about geladas.

And, while I know of no gelada sequencing project, I don't expect we'd find them to have evolved a radically new set of genes to digest grass. It's possible they've co-opted cellulose-digesting bacteria to do the job, though - if so - they've not done it as efficiently as those champion grass eaters the cows.

darjeeling

Here's a remarkable paper that came out in Nature last month, and that bears on what I was speculating about above (link & press release).

The paper investigates when the genes we find today in living creatures first evolved. Over a quarter of modern gene families were born in a period of rapid evolution between 3.3 and 2.8 billion years ago (the 'Archean expansion'), and almost all the gene families studied had appeared by around a billion years ago (NB this research excluded genes that are not shared by multiple species and some families of non-bacterial origin).

The authors go on to relate gene birth to the chemistry of the planet, showing that the first appearance of genes involved in metabolism of oxygen and other elements generally tracks increasing availability of these elements. In the supplement, they estimate the number of genes in the last common ancestor of all life to be just 183 - horizontal transfer means that genes 'born' afterwards have nevertheless crossed over into most living things today. Very clever stuff!

.

MonkeyBalls

Really impressed by how much some of you guys know. Evolution is a very reviled and misunderstood theory. Misconceptions about it persist, even among the non-religious.

CiaranMT

darjeeling, would that paper be available on college databases?

darjeeling

CiaranMT wrote: »

darjeeling, would that paper be available on college databases?

Yes, if your college has an electronic subscription to Nature, then you should be able to get hold of it. Otherwise, it'll be in most college libraries.

CiaranMT

darjeeling wrote: »

Yes, if your college has an electronic subscription to Nature, then you should be able to get hold of it. Otherwise, it'll be in most college libraries.

If I regain any motivation to better myself in the next week or so I'll look into it, cheers