I would like to venture an explanation.

But first, I am curious as what is meant by "identical stages" of their
development. does it mean:

1. There is a time in their development when they look identical?
2. The embryos happen to be of the exactly the same age (this would
presume the 3 embryos in the photographs were conceived on the same
day).
3. Both 1 & 2.

I am presuming you are using meaning (1).

Well, I think it is inaccurate to say the would look identical. Yes,
mammalian embryos of differing species do reach a stage where they
would look VERY similar i.e. they share many common features, but I
think not identical. Certainly, they would differ to some extent in
size and shape even of those common features.

Thereby, I notice that the use of the term "identical features" might
be better rephrased as "very similar common features". It can be
argued that even at birth, they still share many common features,
though now the similarities in looks would be less.

An explanation I would venture is that between conception as a
fertilised egg and the time of birth, the shape of each of these
embryos go from a simple undifferentiated body structure to a more
complex differentiated body structure, each one developing differently
according to their DNA codings.

In the simple undifferentiated body structures, it is not unlikely that
the shapes and looks of their external features would differ that much
from another. But as development progresses, and each embryo according
to its DNA gains more unique features such as colouring, size, shape,
fur, feathers etc...they will differ more and more. Common features
being retained, but those features differing in many aspects.

Being the discussion group that this is, I recognise that SJAB1958, by
bringing up this topic, was making a stab at the creation-evolution
controversy. Hence, I will address this topic from that angle.

My explanation above, which I believe is correct, is compatible with
both creationism and evolutionism. At least as far as explaining why
those embryos look similar. What is interesting is when we ask the
question of "why is this so?" The evolutionist attempts to use the
fact of embryological similiarities as proof of evolution in terms of
common descent. The creationist need go no further than my explanation
other than that the creator deity decided to start all those embryos
from a simple similarly-shaped egg which then divides and
differentiates.

Both sides I believe are at an impasse, if it wasn't for the
interesting fact that it has been observed that in various species,
some of the features common to all during the embryo stages later on
disappear in various species. Just a couple of examples, gill slits
appear in all mammals only to disappear later on. Teeth appear in the
aquatic mamals only to be reabsorbed by the body. How to explain this
phenomenon?

The evolutionist explains it as a result of traces of parts of DNA
encoding left over from previous and common ancestral species that
later evolved into different and diverse species.

So far I have not seen a creationist explanation as to why such
features appear only to disappear later on. The only explanation I can
imagine is that their creator deity had some hidden undiscernable
purpose for doing so and that the features actually appear to serve
some function (that for some reason has as yet eluded discovery, even
by observation using powerful instruments such as microsopes), and
disappear, when the features are no longer necessary.

I would like to venture an explanation.

But first, I am curious as what is meant by "identical stages" of their
development. does it mean:

1. There is a time in their development when they look identical?
2. The embryos happen to be of the exactly the same age (this would
presume the 3 embryos in the photographs were conceived on the same
day).
3. Both 1 & 2.

I am presuming you are using meaning (1).

Well, I think it is inaccurate to say the would look identical. Yes,
mammalian embryos of differing species do reach a stage where they
would look VERY similar i.e. they share many common features, but I
think not identical. Certainly, they would differ to some extent in
size and shape even of those common features.

Thereby, I notice that the use of the term "identical features" might
be better rephrased as "very similar common features". It can be
argued that even at birth, they still share many common features,
though now the similarities in looks would be less.

An explanation I would venture is that between conception as a
fertilised egg and the time of birth, the shape of each of these
embryos go from a simple undifferentiated body structure to a more
complex differentiated body structure, each one developing differently
according to their DNA codings.

In the simple undifferentiated body structures, it is not unlikely that
the shapes and looks of their external features would differ that much
from another. But as development progresses, and each embryo according
to its DNA gains more unique features such as colouring, size, shape,
fur, feathers etc...they will differ more and more. Common features
being retained, but those features differing in many aspects.

Being the discussion group that this is, I recognise that SJAB1958, by
bringing up this topic, was making a stab at the creation-evolution
controversy. Hence, I will address this topic from that angle.

My explanation above, which I believe is correct, is compatible with
both creationism and evolutionism. At least as far as explaining why
those embryos look similar. What is interesting is when we ask the
question of "why is this so?" The evolutionist attempts to use the
fact of embryological similiarities as proof of evolution in terms of
common descent. The creationist need go no further than my explanation
other than that the creator deity decided to start all those embryos
from a simple similarly-shaped egg which then divides and
differentiates.

Both sides I believe are at an impasse, if it wasn't for the
interesting fact that it has been observed that in various species,
some of the features common to all during the embryo stages later on
disappear in various species. Just a couple of examples, gill slits
appear in all mammals only to disappear later on. Teeth appear in the
aquatic mamals only to be reabsorbed by the body. How to explain this
phenomenon?

The evolutionist explains it as a result of traces of parts of DNA
encoding left over from previous and common ancestral species that
later evolved into different and diverse species.

So far I have not seen a creationist explanation as to why such
features appear only to disappear later on. The only explanation I can
imagine is that their creator deity had some hidden undiscernable
purpose for doing so and that the features actually appear to serve
some function (that for some reason has as yet eluded discovery, even
by observation using powerful instruments such as microsopes), and
disappear, when the features are no longer necessary.

I would like to venture an explanation.

But first, I am curious as what is meant by "identical stages" of their
development. does it mean:

1. There is a time in their development when they look identical?
2. The embryos happen to be of the exactly the same age (this would
presume the 3 embryos in the photographs were conceived on the same
day).
3. Both 1 & 2.

I am presuming you are using meaning (1).

Well, I think it is inaccurate to say the would look identical. Yes,
mammalian embryos of differing species do reach a stage where they
would look VERY similar i.e. they share many common features, but I
think not identical. Certainly, they would differ to some extent in
size and shape even of those common features.

Thereby, I notice that the use of the term "identical features" might
be better rephrased as "very similar common features". It can be
argued that even at birth, they still share many common features,
though now the similarities in looks would be less.

An explanation I would venture is that between conception as a
fertilised egg and the time of birth, the shape of each of these
embryos go from a simple undifferentiated body structure to a more
complex differentiated body structure, each one developing differently
according to their DNA codings.

In the simple undifferentiated body structures, it is not unlikely that
the shapes and looks of their external features would differ that much
from another. But as development progresses, and each embryo according
to its DNA gains more unique features such as colouring, size, shape,
fur, feathers etc...they will differ more and more. Common features
being retained, but those features differing in many aspects.

Being the discussion group that this is, I recognise that SJAB1958, by
bringing up this topic, was making a stab at the creation-evolution
controversy. Hence, I will address this topic from that angle.

My explanation above, which I believe is correct, is compatible with
both creationism and evolutionism. At least as far as explaining why
those embryos look similar. What is interesting is when we ask the
question of "why is this so?" The evolutionist attempts to use the
fact of embryological similiarities as proof of evolution in terms of
common descent. The creationist need go no further than my explanation
other than that the creator deity decided to start all those embryos
from a simple similarly-shaped egg which then divides and
differentiates.

Both sides I believe are at an impasse, if it wasn't for the
interesting fact that it has been observed that in various species,
some of the features common to all during the embryo stages later on
disappear in various species. Just a couple of examples, gill slits
appear in all mammals only to disappear later on. Teeth appear in the
aquatic mamals only to be reabsorbed by the body. How to explain this
phenomenon?

The evolutionist explains it as a result of traces of parts of DNA
encoding left over from previous and common ancestral species that
later evolved into different and diverse species.

So far I have not seen a creationist explanation as to why such
features appear only to disappear later on. The only explanation I can
imagine is that their creator deity had some hidden undiscernable
purpose for doing so

and that the features actually appear to serve
some function (that for some reason has as yet eluded discovery, even
by observation using powerful instruments such as microsopes), and
disappear, when the features are no longer necessary.

In article <1129794111.136043.327520@g47g2000cwa.googlegroups.com>,
"SJAB1958" <balfres@hotmail.com> wrote:

I have three photographs of three mammals (one of which is aquatic) at
identical stages of their development.

All Three show front and hind limb buds, a tail and what appear to be
gill slits between the body and the head.

I will be happy to show them to anyone who is interested and thinks
they can identify each one's species.

And then explain why they all share identical features as embryos but
are completely different at birth.

Wild guesses, using cues other than the morphology:

1 is human, just because I'm guessing from your clues that one is
going to be a tailless ape.

2 is dolphin; the photo is unfamiliar to me, and your clues tell me
one is going to be a cetacean.

I swear I've seen embryo 3 somewhere before. I'm guessing a cat,
from comparison of the shape of the head with one of MK Richardson's
photos, and because it's probably some familiar animal.

This test is really unfair, because the right answer is actually
that unless we're very, very familiar with the development of the
specific organism at that particular stage, we can't tell.

Couldn't you at least have tossed in a 24h Danio embryo in there?
That one I would have gotten.

--
pz http://pharyngula.org/