Synthesizing the super fly:
Here is a bit that resembles science fiction.  See whether you like it.

Fruit flies have fewer chromosomes than people.  I have never heard that contradicted so let’s accept it.

Fruit fly chromosomes do not undergo recombination.  I have read that somewhere.  It was a surprise to me.   I thought recombination was the way they figured out where genes lay on chromosomes.  You know what it is.  Supposed you have a chromosome segment that goes (not using the letters for anything but to mark the sequence of segments of whatever size in a chromosome: abcdefghijk and another that goes ABCDEFGHIJK.  The chromosomes are homologous, which means the place on the first chromosome where “a” resides is the place on the other chromosome where “A” resides.  “A” and “a” might be identical or might not for present purposes.  Well during a process called meiosis, which occurs during the production of gametes, the two chromosomes can break and rejoin so that now these segments run: abcdeFGHIJK and ABCDEfghijk.  I shan’t go into how this looks under the microscope as it happens, but you can look that up.  Starting with a segment beginning with “a” ending with “k,” you will get one beginning with “a” ending with “K” at a certain rate, once however many generations.  That frequency or rate will be faster than the change of “a” … “c” becoming “a” … “C.”  By keeping track of enough events you can figure out where the genes you can identify lie in sequence.

I thought that was basic and had been done, but according to the reference I have long since lost it has not.  Let’s go with it, because then it gets kind of fun.

I have tinkered a bit with models of gene pools.  I cannot say it is categorically true, but in my experience GENES THAT INTERACT IN HARMFUL WAYS DO MORE HARM WHEN THE RECOMBINATION RATE IS HIGHER.  It’s not really a surprise.  They way you get rid of a harmful gene, or a harmful whatever else might be on that chromosome, is by eliminating a carrier.  With high rates of recombination you just about have to eliminate one carrier per harmful element.  But with little or no recombination you may be able to dump a number of them on the same chromosome when you eliminate the individual.  (I don’t mean you would.  I mean selective pressure would.) 

Anyway, that’s how it works in my hands.

So imagine the day when we are total masters of DNA.  We know just what it does.  If we want to eliminate a bad gene in the population, we can identify the carrier eggs and ova, fix them right, and then let nature carry on.  If we want to add a good gene, we can do the same things.  Yes, I know.  This leads into an ethical quagmire.  But some day we are going to have to wade through that quagmire since we shall, in fact, have the technical expertise some day.  Maybe not.  But maybe.

We can expect in those days that there will continue to be interactions between genes.  And there will continue to be mutations of genes.  We can fix anything, but screening every gene ovum and sperm in the population might be prohibitive. 

Recombination has its function in nature, but in that day we shall be assuming we are smarter than nature (in fact we so assume now, despite ample evidence that we are often badly wrong in doing so), so we shall have no need for recombination.  In fact, on the same principle, we would be happy to have fewer chromosomes since in effect recombination simply gives us more, smaller and variable chromosomes. 


So we shall look enviously at the fruit fly.  With its modest number of chromosomes and putatively absent recombination, it will be able to handle harmful mutations in interacting genes better than we.  Reengineering our own chromosomes might be tricky.  But there is another way.  We can simply stick all the genes we want to have as people onto fruit fly chromosomes.  Do a little editing and you wind up with a creature that has fruit fly chromosomes with human genes and whatever else we want to bring along, you know, the information about when to use those genes.  It will look like a human.  It will have the same antigenic structure as a human.  You will only know it’s really a fly if you do a microscope study of its reproducing cells.

Of course a bigger insect might have the same advantages and be easier to work with, you know, bigger and tougher.  Cockroaches come to mind.  It would make an interesting addition to the traditional family pictures on the desk at the office.  (I know.  No more offices.  It’s all cubicles.  And no more printed pictures, it’s all on your telephone, but forgive the anachronism.)  “Yes, that’s my grandma.  I keep her at home in formaldehyde.”

Didn’t they say that ultimately roaches would take over the world?

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