Getting a DNA match is all well and good. But since – as they always say – each piece of DNA contains the blueprint for the entire organism, could we ever get to the point where we could feed a DNA evidence sample into a machine and get out a reconstructed photo of the perp at, say, every ten-year interval from 10 to 70?
I know, I know, I know, I know, *I know * that such reconstructions would have to be based partly on unknowns and appearance-altering influences from after the perp’s birth – things like weight gain, scars, tattoos, nose jobs, skin blemishes, muscular development, etc. (Oh, by the way, did I mention that I know that already?)
But determining certain fixed (or very likely) characteristics, like eye and hair color, approximate height, approximate facial appearance, etc. could put a face on the perpetrator of many an otherwise unsolvable crime.
Even ignoring physiological developmental differences caused by environmental factors, It would require modelling of the entire process of development, on a molecular level; I’m going to say no; we don’t have anything even remotely like the ability to do it. We’d have enormous difficulty doing it for a mushroom, let alone a human.
Even ignoring physiological developmental differences caused by environmental factors, It would require modelling of the entire process of development, on a molecular level; I’m going to say no; we don’t have anything even remotely like the ability to do it. We’d have enormous difficulty doing it for a mushroom, let alone a human.
Huh? You surprise me here. Didn’t we (the scientists) finish mapping the Human Genome? And for things like eye and hair colour, wouldn’t we know at what place in the genome to look (we know they code some type of melanim, and they work in recessive/dominant pairs), so eventually, there will be a map of the human genome, where Chromosome 6, the 5th dark band from the top codes this protein, which leads to this characteristic… and feeding this into a computer, I could see (though no photo but) a description like “blue eyes, brown hair, height between 1,70m and 1,80 m (barring developmental problems and illnesses), tendency to be fat/have lots of muscles, x% chance of high blood pressure (and the tpyical symptoms that result from that) etc.”
Not as good as a photo, but more than the blood group, I’d expect.
It’s theoretically possible for some traits, but there’s no such thing as a gene for height, weight, or muscularity. More likely we’d be able to tell the person’s blood type, hair color, eye color, gender, maybe get a pretty good guess at their racial/ethnic background.
But remember that although each cell contains the complete genome of the individual, a DNA sample might not contain whole live cells any more…just DNA fragments.
And although the Human Genome Project is complete that doesn’t mean we understand what every DNA sequence codes for, or what exact DNA sequences map to what alleles. So for instance, we know that there’s a gene for eye color, with an allele for brown eyes and an allele for blue eyes. We might even know where that gene is located on which chromosome. But that doesn’t neccesarily mean that a geneticist could compare read a DNA sequence and tell whether that particular sequence would result in blue eyes or brown eyes.
And DNA tests aren’t done by sequencing anyway. See here:
Well, it is theoretically possible that someday we would be able to take a DNA sample and figure out which alleles the individual had for the various genes that code for eye color.
But we’re certainly nowhere near that ability today. The DNA testing done today is generally done on what’s called “junk” DNA, because it is much more variable that gene DNA. Given a DNA sample from a crime scene and a DNA sample from a suspect you can match or exclude the suspect with only a small number of site matches. But knowing the suspect’s eye color isn’t exactly a huge break in the case. And even with a hypothetical complete sequencing the description you get back will be pretty vague…“Suspect has brown eyes (when not wearing contacts), wavy black hair (when hair is not permed, straighted, curled, shaved, colored, under a wig or hat), cafe au lait skin (assuming average levels of tanning), male, mixed african, european, and native american heritage, likely has a larger nose than average (assuming no rhinoplasty), slender build (assuming suspect doesn’t sit in a chair and eat hostess cupcakes and watch soap operas all day every day).” You certainly aren’t going to be able to generate a picture of the suspect like police sketch artists can do from a witness description.
But that isn’t going to help much to find the suspect. It superficially rules out lots of people…but won’t be any more helpful than today’s “suspect is a black male in his 20s” descriptions.
Of course there will be lots of other traits you would know…blood type, rh type, dozens of other blood and tissue factors. And if you had a complete database of trait of every individual in the world, you could match the person exactly. But you don’t need a complete genome of every person in the world, just a DNA profile. If we assume in the future that techniques have improved so much that generating a description from a DNA sample can be done, then a complete DNA database of everyone in the country isn’t so far out of line. But then there’s no need to generate the description. You have the DNA sample, search the database, and in a few minutes you find the one (or two in the case of identical twins) person in the world who has that DNA. Why not go all the way?