A question about genetics

[Mark]

Here's a question that's been bugging me, I don't know why but it has and I would appreciate it if some one could shed some light on it.

Let's say there are two children and let's scientifically call them A and B. Going back 50 generations:

A's parents, and their parents, and their parents parents etc all had their child at the age of 20

B's parents, and their parents, and their parents parents etc all had their child at the age of 30

Is child B more evolved because their genes are from older and more experienced parents? (I realise there will be 500 years difference between them)

I think what I'm asking is, at what point in life do the evolutionary traits and life experience get passed on to a gene that would pass to a child? At what point do they stop?

Any ideas?

[Mark]

May I add that between the ages of 20 - 30 the generations of family B studied and worked.

[martell1]

they don't - it would be more nurture than nature. http://en.wikipedia.org/wiki/Nature_versus_nurture

[Huguenot]

Well, since they all survived to procreate, there was no evolutionary selection at all. Evolution assumes that reproduction is curtailed in species less well adapted to their environment.

Evolution sometimes gets confused with advancement, but it's not, it's adaptation. Hence you can evolve to be more stupid if the world around you became less challenging.

I'd just add that it's always been accepted that cultural/educational traits are not inherited genetically (which would negate the whole debate), however recent research has suggested that cultural items can be transmitted...

[mockney piers]

Your evolutionary cards are dealt at conception as your DNA maps out the mutations that may, or may not contribute to enhanced chances of survival.

Indeed all survived Huguenot, but some may have had a genetic propensity to survive the black death, and procreated with someone else who did thus helping ensure that unbroken line, so we can't be sure that no evolutionary processes happened.

In fact aren't we* all the result of an unbroken chain of successful procreation of at least 50 generations?

*apart from those of us made from mud or ribs of course.

[mockney piers]

Mind you, with things like radiation and powerful chemicals that can alter your DNA sequences, I guess it can be post conception now.

In fact do these hiccups occur in the womb post conception? Ask a scientist Mark.

I watched X-Men last night, so I know everything...

[karter]

mockney piers Wrote:

-------------------------------------------------------

> Mind you, with things like radiation and powerful

> chemicals that can alter your DNA sequences, I

> guess it can be post conception now.

>

> In fact do these hiccups occur in the womb post

> conception? Ask a scientist Mark.

>

> I watched X-Men last night, so I know everything...

You only watched it last night? Emma Frost doesn't have a bun in the oven now does she?

Edit due to multitasking.:-/

[Brendan]

At any stage has any of A or Bs forefathers worked in a secret government laboratory and suffered a freak accident exposing them to radiation and/or toxic waste?

[annaj]

Huguenot, have you got a reference for that research? Sounds interesting.

Mark, the ten additional years of learning and working that each generation of B parents had would not change their genetics. Experience and learning changes behaviour, but not genes.

Genetic mutation usually happens during cell division. There are two types of cell division one which produces an exact copy of the cell with all its genetic material and one which produces a cell with exactly half the genetic material of the original. It is the second type of division, meiosis, that produces eggs and sperm.

Put simply, I'm not really much of a scientist, each human cell contains 23 pairs of chromosomes that hold all of our DNA.

During meiosis the chromosomes line up in pairs and the cell splits in two with one of each pair going into each cell. So, each egg or sperm contains half the parent's DNA and, because the order in which the chromosomes line up is not fixed, each egg or sperm is different. Mutation is most likely to happen during the process of cell division when, again a massive over simplification, chromosomes can split unevenly or become damaged.

Genetic disorders either occur as a result of this kind of mutation, Down's syndrome for example is the extra duplication of one particular chromosome, or through so called Mendalian inheritance, were one or both parents passes down a defective gene.

Mockney, radiation, infections and drugs can all affect and even stop normal development in the womb leading to birth defects, but these are congenital (present at birth) rather than genetic. A person with the typical limb shortening deformity caused by their mother taking thalidomide during pregnancy can have a child with entirely normal limbs, because it was their development affected by the drug not their DNA.

Back to your question Mark, child A and child B would be very different, because as you said they would have been born 500 years apart and had entirely different experiences and influences, but the things that we experience and learn do not change our DNA.

[Huguenot]

I didn't realise that this example was real enough to cite Black Death, I thought it was just a question of whether something that has an equal number of iterations would evolve differently based on cultural issues?

Recent research suggested that children of 50 year old men averaged 3 points lower on IQ tests than those of 20 year old men, owing to genetic mutation. Over 50 generations that could have a significant impact.

If you have children at 30 rather than 20, then you're likely to be more secure financially and less stressed, which reduces the chances of negative mutation. However, if this was 500 years ago, you'd be dead by 35 so the kid would have to look after itself and may not make it at all?

[Brendan]

Unlike Darwin?s original ideas on evolution it is not just random mutations that may or may not work out for the best. The current thought is that evolution is actually an adaptive trait, different organisms of the same species can evolve the same traits to cope with their environment without being directly related to each other. It can also happen at different rates depending on conditions. (I do have references for this and will dig them out when I get home this evening)

Still 50 generations and 500 years aren?t long enough for anything significantly noticeable to have evolved genetically. (well as far as I know but I'm no expert)

Now what would be interesting is if you had 2 sets of genetically identical individuals. Identical twins perhaps. 1 set male and the other female. You paired them off into 2 couples and dropped them in 2 completely different environments isolated from any other genetic interference. An artic tundra and a tropical archipelago perhaps.

Then you observed their offspring and how over the generations they evolved differently to adapt to their environments. You could then measure how many generations it will take until they became 2 genetically distinct species.

You would have to be immortal though and perhaps have 2 planets at your disposal for the experiment to work properly.

[Huguenot]

Annaj, I can't find that research. I have whole bundles of science mags lying around the house, and it would've been in one of those :(

It was interesting because it suggested that cultural issues actually impact the genetic make-up of individuals during their own lifetime.

[Brendan]

That makes sense though Huguenot because evolution is an adaption to enviroment and culture can influence your environment.

[mockney piers]

Brendan, I've a feeling your experiment would be forcing siblings to procreate and things would be a little doomed in no short time, just look at those german emigr? utopian experiments in Argentina.

And it all sounds like pushing the morality envelope of science (especially the conquering another life supporting planet)

Of course, there were special dispensations for the scions of Adam and Eve, both genetically and morally speaking. In fact has anyone mapped the mud genome?

[Brendan]

Do not bother me with your petty concerns mortal.

[Moos]

I know what you mean, Brendan, Mockers is no fun at all with all that moralistic whining. What happened to the spirit of the new frontier, eh?

[mockney piers]

My GCSE science project involved scaring my pet gerbil to see if it could learn conditioned behaviour. Mwah ha hah.

My dad hated it and I was forced to give it up to a friend. It escaped his cage and got sucked into a hoover by his mum.

RIP Gerby.

[Brendan]

How many generations of gerbils will it take before they develop the ability to survive inside a vacuum cleaner?

[Moos]

.....or film stars' bottoms?

P.S. poor Gerbil, I feel quite sad now.

[Brendan]

So if you had 2 genetically identical pairs of gerbils. You put 1 pair inside a vacuum cleaner and the other inside a film star?s bottom. How many generations will it take before they evolve into 2 distinct species?

[Ted Max]

You're going to get to two species of mole quite quickly, aren't you? One set will have adapted to living on five pence pieces, raisins and fragments of human skin. And the other will have specialised to living inside a hoover.

[Xena Worried prince]

Annaj

I heard a similar theorem a few years ago that talks about the risks of older parents having children.

It has been the belief that a woman of over 35 has a higher risk of producing a baby with genetic defaults, however the new belief is that it is not the woman but the man that causes the defaults (read Defects in the baby) as a woman is born with all her eggs intact (therefore never produces any new ones and as a result cell division to create new eggs doesn't occur) where as a man produces spermatozoa by cell division, with each new Sperm being grown and created. Therefore the theory went on to state that the older a man is the more chance he has of producing defective sperm and the higher a chance he has of producing damaged offspring.

Therefore the scientists who brought this theory up state that an older woman has a higher chance of producing offspring with defects if their partner is also older, however if their partner is younger then the chances decrease and if they are a young woman with an older partner then the chances also increase dramatically. (ergo it is always the males fault not the womans)

Not sure if this theory has been verified but it makes sense when you consider the way that humans produce eggs and spermatozoa. (it also makes the younger man fancying granny in Little Britain a bit more palatable)

I guess going back to the original question by Mark, then quite possibly yes there will be differences between the children but to see if it is a result of parents age, parents genetics or parents lifestyle then you would need to conduct the experiment with identical twins all they way down the evolutionary path (hmmm, now give me ?100 million and I will start the experiment off)

[HAL9000]

Mark Wrote:

> I think what I'm asking is, at what point in life

> do the evolutionary traits and life experience get

> passed on to a gene that would pass to a child? At

> what point do they stop?

I think this wiki article will answer your question:

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

[Mikecg]

Life experience doesnt get passed on through genetics, life experience makes us who we are.

[Kells]

Even 50 generations seems like a very short time in evolutionary terms. Although I'm not an expert in population genetics by any means.