Sorry to butt-in, but ....
quote:
Originally posted by John Paul:
1. Do you believe that mutations are heritable?
2. Do you believe that the patterns of such heritable mutations can be used to infer relatedness?
1) Is tricky. Yes mutations are heritable. Neutral, harmful and beneficial, mutations can be passed on. However in sexual reproduction they don’t always get passed on. I’m not as tall as my grandfather was, but I am taller than my parents (were). My father was color-blind, I am not, nor are my sisters and brothers, but I have a nephew that can’t see green (not the Special Agent). However his brother’s vision is OK.
It's not tricky. Mutations are heritable, you agreed.
Girls are rarely colour blind, since the gene that causes it is on
the X chromosome, and is recessive. The same location doesn't exist
in Y, so boys only need one colour-blind X to be colour blind.
(Probably a simplification I think that was how it was taught to
me in 'O' level biology)
Your sisters have a fifty-fifty chance of carrying colour blindness
so they have inhereted the trait/mutation.
Whether something IS passed on has no bearing on whether it is
heritable. They are two separate issues.
quote:
Originally posted by John Paul:
In humans this is evident- not every organism that is born gets a chance to mate and not every mating couple can conceive. No mating or conception no chance of passing on of the DNA....
Like I say, not relevent to whether something is heritable,
only to whether it is actually inherited ... so irrelevent to
the question asked.
quote:
Originally posted by John Paul:
That said, if adaptive mutations were the norm (Dr. Lee Spetner), they would become more readably fixed because they would occur population wide due to the organisms’ DNA reacting directly to environmental pressure(s). However adaptive mutations, unless applied to cleverly written evolutionary algorithm acting with an incrementally sequenced genetic algorithm, couldn’t account for the grand sweep of the theory of evolution.
What we would have to determine is what was it about the alleged shared mutations that allowed them to be fixed in the populations? IOW why were they selected for (kept in the population) over this alleged span of time (5+ millions years)?
Agreed ... the question is not how the mutations come about, but
how they are fixed in a population. Natural selection seems to
spring to mind here.
You have hit upon an interesting idea... evolution is mutation (by some mechanism) + selection (by some mechanism).
quote:
Originally posted by John Paul:
2) I don’t think that every person with sickle-cell anemia is related to the first person that got the mutation that caused that disease and was able to pass it on. (Sickle-cell anemia is caused by a point mutation in a specific locus- a substitution of a T for an A in the codon for the sixth amino acid of the beta chain in the human hemoglobin protein. That mutation changes a glutamic acid to a valine.) Is everyone with Downs syndrome related? The same goes for all genetic diseases. Do you think that every person with the same genetic disease is related to each other? That DNA gets passed on to the offspring doesn’t mean chimps and humans share a common ancestor.
As I previously stated As for apparent similar mutations, again given that we have a restricted selection of possibilities for change to occur, it could be more of a coincidence than it is coinciding. I would like to change that to most likely be more of a coincidence
Down's syndrome (as I understand it) is a kind of first-generation
mutation. That is, the mutation occurs at the particular gammete
rather than being passed on. Wonder if downs syndrome individuals
produce Down's offspring? Don't know.
Isn't sickle cell anaemia restricted to certain ethnicities?
Doesn't that suggest common ancestry in recent times for the
trait?
I think the suggestion is that if the conditions exist which tend
to promote mutation, that large numbers of the population will
have affected gametes ... in that case any modern trait may be
traced back to a group/population rather than an individual (I guess).
quote:
Originally posted by John Paul:
Mutations occurring and getting passed on is just part of the problem. And a mutation getting fixed in a population is another.
Which is why 1) isn't tricky at all.
quote:
Originally posted by John Paul:
What the theory of evolution requires is for mutations to accumulate in such a way as to eventually give rise to new structures and organs (assuming of course the alleged starting population(s) didn’t have arms, legs, a spine or a brain). Is there even a way to test if that premise is feasible?
I think techniques and results coming out of genetic engineering
work may provide a means of testing such hypotheses. Look at that
crustacean leg inhibition for a start.
OK I know that's 'loss of a trait' if you look at it one way, but
isn't it the gain of a trait if it happened the other?