Re: I've found an array of missing links in the fossil records.

From: Martyn Harrison (nospam_at_spammers.of.the.world.unite)
Date: 07/29/04 

Date: Thu, 29 Jul 2004 10:58:30 GMT

Apparently on date 29 Jul 2004 00:33:29 -0700, jameselger@hotmail.com (The
Flavored Coffee Guy) said:

>The lecture starts here.
>
>http://news.bbc.co.uk/1/hi/sci/tech/323657.stm

This is a quite interesting story.

There are some problems with this idea, and it stems from why we regard
Neanderthal sapiens, and sapiens sapiens, to be separate species.

Hns gestation process is to give birth to the baby while it has a soft, small
skull and the child then continues to develop outside of the womb. As a result
of this strategy, Hns females have hips that are more or less the same width as
Hns males, and also means Hns babies are evolved to complete their gestation
post natal.

Hss gestation is to give birth to a developed baby. This means the mother must
have hips that are sufficiently wide to allow the child's head to pass through.
A consequence of this strategy is that human babies are evolved to complete
gestation pre natal, and also that Hss females have broader hips than Hss
males.

Unthinkable numbers of Hss babies and mothers died in childbirth, before
medicine developed, because they happened to have hips that were too narrow to
give birth. Hss is unusual among primates in the sense that Caesarian Section
is often employed to enable childbirth.

Both of these evolutionary strategies come about as a result of the enlarged
and expanded cranium associated with sapiens, i.e. the big brain relative to
the body frame causes a need for evolution of wider hips, post natal
development, or whatever.

Now, the point about this, these strategies are not actually compatible. When
you have developed an evolutionary strategy, you can't mix that with a
different strategy and expect it to work. When you have wings, you can fly,
when you have a powerful tail, you can swim. Gain both to some reduced extent,
and you can neither fly nor swim properly. Mess with the actual strategies that
enable successful birth, and you are heading towards a long string of
unsuccessful attempts at birth which will probably also kill the mother at some
point.

Ok, so finding a four year old child with a mixture of genes from Hns and Hss
shows that it can be achieved, that's pretty interesting.

I wonder to what extent, natural selection would favour the more prolific
species, i.e. as modern Hss is "wide hipped female" in nature, as narrow hipped
females would not reproduce, to what extent have any Hns genes been passed on?
It also seems to indicate that any hybridisation was between a large group of
Hss and a smaller group of Hns, as otherwise modern man would have the post
natal gestation favoured and predominantly Hns genes, I would imagine.

>My conclusion, is that in the process of evolution the sudden
>appearance of species is possible. But, it is a result of a virus,
>leaving a chunk of DNA behind. The first link proves that the nature,
>and naturally found viruses do leave behind some select amount of DNA,
>and it does enter into the reproductive system in just such a fashion
>that it is passed in breeding. The second link acknowledges the same
>is true but assumes that such genetic information cannot be passed on
>to the next generation. The first article proves otherwise, and that
>the mitochondrial DNA can pass modified genes through the ovary. This
>is true because, in humans only the females pass the mitochondrial
>DNA.

Ok, there are two main places where DNA is found (and it's not a human thing,
it's true of most animals, possibly all.) There is the Mitochondrial DNA, and
there is a the Nuclear DNA. Genes are found in the Nucleus and during the
function of sexual reproduction, the Nucleal DNA mixes between the female and
the male.

This mixing of DNA is evolution and involves the changing of genes from being a
straight copy of the parent, to being a mixture of father and mother (or with
suitable terms for hermaphrodites, etc.)

The Mitochondrial DNA (easier to refer to this as mtDNA) doesn't mix, and
mostly is supplied by the mother, and replicates in the cell to make (usually)
identical copies of the source mtDNA. I'd have said it was all from the mother
but I think that might be slightly overstressing the state.

If I read your description right, you are proposing a transfer of genes by a
virus? This would be extremely difficult to achieve as you need the insult to
the DNA to take place after the genetic mixing during the reproductive act, and
before the first cell division, as otherwise the DNA will be inconsistent and
the offspring will be non-viable. I don't believe it is possible to have a
duplicate infection / insult event that affects two or four cells in exactly
the same way.

I would also regard it as highly unlikely that a random insertion of DNA
material into one or more chromosomes, could result in a viable animal more
often than in a freak situation, and that this probability becomes
exponentially more remote for higher life forms like human beings, where many
aspects are a knife-edge compromise between one choice and another.

Of course, the fact that your example hybrid was young and dead, may support
this a bit as a poor set of genes might well lead to early death. Still, I
think it is far more likely to be a simple matter of inter-species sexual
reproduction, where the child gained both sapiens^2 genes and Neanderthal genes
through mixed parentage.

Relevant Pages

  • PBS & Neanderthal DNA...
    ... They say no HNS DNA remains in modern man, HSS. ... But then they show that the *only* DNA which they have is mitochondrial. ...
    (sci.archaeology)
  • News: Where Is Human Evolution Heading?
    ... Where Is Human Evolution Heading? ... The race's DNA is changing faster than ever; ... our genes are playing catch-up against modern scourges?like ... it doesn't take a Nobel Prize in genetics to imagine that babies could ...
    (talk.origins)
  • DNA and Alleles
    ... One article on population genetics states, ... natural selection, genetic drift, mutation, migration and nonrandom ... What is the relationship between genes and a ... subset of a cell's DNA. ...
    (sci.bio.evolution)
  • Article: Genetic Network Guards Against Lethal DNA Damage
    ... 'Genetic Network' Guards Against Lethal DNA Damage ... The discovery in yeast cells of a genetic network that guards against lethal ... combinations of mutated human genes, according to researchers at The Johns ... The yeast cell is an excellent model for this kind of study because 25 ...
    (sci.bio.evolution)
  • Re: Developing a focused set of questions for IDists - Comments encouraged
    ... It could be given evidence by finding hidden messages or images inside ... of DNA. ... Nobody has claimed it not possible. ... duck could get cow genes. ...
    (talk.origins)