I was reading this:
http://edition.cnn.com/2016/05/04/health...index.html


And it got me to thinking. . . there must be a genetic pattern for a "toe," and then a counter of some type.  So you could arbitrarily (I assume) program a DNA sequence to have any number of toes or fingers, and yet, magically, they "turn out."  The baby's toes all look good, he's just got the wrong number of them.

In other words, the human body actually isn't completely represented in the DNA, but as a sequence of instructions ABOUT a human body-- for example, how many toes it should have.

Stuff to think about.

Quote:In other words, the human body actually isn't completely represented in the DNA, but as a sequence of instructions ABOUT a human body

Erm...isn't DNA a sequence of instructions about a human body?

Boru

(May 7, 2016 at 9:32 am)bennyboy Wrote: I was reading this:
http://edition.cnn.com/2016/05/04/health...index.html


And it got me to thinking. . . there must be a genetic pattern for a "toe," and then a counter of some type.  So you could arbitrarily (I assume) program a DNA sequence to have any number of toes or fingers, and yet, magically, they "turn out."  The baby's toes all look good, he's just got the wrong number of them.

In other words, the human body actually isn't completely represented in the DNA, but as a sequence of instructions ABOUT a human body-- for example, how many toes it should have.

Stuff to think about.

What makes you conclude that the body isn't represented in the DNA from the example you quote? Maybe you could also clarify what you mean by the Body being represented vs. having instructions about the body.

(May 7, 2016 at 9:32 am)bennyboy Wrote: I was reading this:
http://edition.cnn.com/2016/05/04/health...index.html


And it got me to thinking. . . there must be a genetic pattern for a "toe," and then a counter of some type.  So you could arbitrarily (I assume) program a DNA sequence to have any number of toes or fingers, and yet, magically, they "turn out."  The baby's toes all look good, he's just got the wrong number of them.

In other words, the human body actually isn't completely represented in the DNA, but as a sequence of instructions ABOUT a human body-- for example, how many toes it should have.

Stuff to think about.

Number of toes is determined by the timing of the deployment of certain chemical signals. Watch Your Inner Fish episode one if you want to learn about it. DNA is frequently analogized more as a recipe than a set of coded traits. Each step represents an occurrence in the development of the organism, but there isn't a one to one correspondence between genes and traits.

(May 7, 2016 at 9:36 am)BrianSoddingBoru4 Wrote:

Quote:In other words, the human body actually isn't completely represented in the DNA, but as a sequence of instructions ABOUT a human body

Erm...isn't DNA a sequence of instructions about a human body?

Boru

That's right.  My point is that the DNA doesn't carry separate instructions about, for example, each finger.  Rather, it carries a description of what a "finger" is, and then an arbitrary amount of information describing what to do with that idea.

To me this is important, because an idealistic model is medium-independent in a sense: it would be more proper to say that the human body is an expression of ideas which happen to be represented in DNA, than to say that the DNA expresses itself as a human body.

(May 7, 2016 at 10:32 am)Alex K Wrote: What makes you conclude that the body isn't represented in the DNA from the example you quote? Maybe you could also clarify what you mean by the Body being represented vs. having instructions about the body.

I should say that the DNA doesn't represent a blueprint for a body: "The door is 2.5m tall and 1.5m wide", but rather as a collection of relative principles: "The door should be 2x taller than the kitchen window" etc.

I think people in this thread might be thinking "Well, duh. This is all known and obvious." However, to me there might be important philosophical implications. For example, an idealistic model is medium-independent: if you could decode the entire DNA strand as a collection of relative ideas into say a database, you could recreate the human species without using DNA at all.

Another implication is that evolution could be much faster than we normally think of it. If there were a real benefit to having a different number of fingers, we wouldn't see people with stumpy little 6th fingers, then slightly more defined 6th fingers over millions of years. We'd see x% of the population having 6 fingers, with that % spiking pretty rapidly depending on the genetic fitness advantage it would give.

(May 7, 2016 at 5:55 pm)bennyboy Wrote: Another implication is that evolution could be much faster than we normally think of it.  If there were a real benefit to having a different number of fingers, we wouldn't see people with stumpy little 6th fingers, then slightly more defined 6th fingers over millions of years.  We'd see x%  of the population having 6 fingers, with that % spiking pretty rapidly depending on the genetic fitness advantage it would give.

How is that different from the manner in which evolution is typically understood to have occurred? A sixth finger might not have any other particular advantage except perhaps those with six fingers tend to attract more sexual partners. And then the five digit creatures, to compensate for the attractiveness that the sixth little finger bears to the other gender, have to work harder, and thus the population would result in many stronger, faster, five digit creatures, in competition with those that are moderately weaker and slower but more attractive given their sixth little finger. Then wouldn't the spread of the gene pool for six digits remain more or less unchanged, or result in only a very gradual, moderate increase over long periods of time, given whichever consistently retained a slight edge?

Following Jor's comment (good one) it ain't all DNA.

https://en.wikipedia.org/wiki/Hedgehog_s...ertebrates

https://en.wikipedia.org/wiki/Morphogen

(May 7, 2016 at 6:16 pm)Mudhammam Wrote:

(May 7, 2016 at 5:55 pm)bennyboy Wrote: Another implication is that evolution could be much faster than we normally think of it.  If there were a real benefit to having a different number of fingers, we wouldn't see people with stumpy little 6th fingers, then slightly more defined 6th fingers over millions of years.  We'd see x%  of the population having 6 fingers, with that % spiking pretty rapidly depending on the genetic fitness advantage it would give.

How is that different from the manner in which evolution is typically understood to have occurred? A sixth finger might not have any other particular advantage except perhaps those with six fingers tend to attract more sexual partners. And then the five digit creatures, to compensate for the attractiveness that the sixth little finger bears to the other gender, have to work harder, and thus the population would result in many stronger, faster, five digit creatures, in competition with those that are moderately weaker and slower but more attractive given their sixth little finger. Then wouldn't the spread of the gene pool for six digits remain more or less unchanged, or result in only a very gradual, moderate increase over long periods of time, given whichever consistently retained a slight edge?

It's not really at odds with evolution at all.  My point is that like our mental understanding of things, the DNA represents a collection of ideas which are reworked or recycled, rather than a "set piece" for a species.

The body is all there is and it is represented by DNA.

-Hammy