Here are some questions that trouble me about evolution:

1)  Why do we just assume that an ancient homonid fossil is an
"ancestor" of man?  On what grounds do we assume this and NOT that it
is simply some ape-like/man-like animal that is now extinct?

2)  Radioactive decay.  How do we know that carbon-dating is not
flawed by a "tipping-point"?  That is, how do we know that, at some
point, after a measured decay, the radioactivity does not
precipitiously fall off?  Wouldn't that skewer or dating ability?

3)  While there is obvious diversity WITHIN a species, at what point
do we make the decision that a species has evolved into another
species?  That is, at what point does a snake that has evolved from
birds become "not a bird" instead of just a really unique sort of
bird?

4)  Lastly, isn't is circular to say that a fossil is such-and-such an
age just because it is found in a particular layer of rock...and then
to say that that layer of rock is such-and-such years old because
certain fossils are found in it?  Is this how it is done?

Thank you!

1) As far as I know, there is no way of proving definitively that any
fossil is an ancestor of any species.  Science is based on using the
theory which best fits the facts at hand.  If these fossils were not
ancestors of man, fish, mammals or whatever then this simply gives
rise to different questions.

2) You have to extrapolate at some point. I'm sure there are lots of
resources on the internet about this but try these:

http://www.tim-thompson.com/radiometric.html

http://www.straightdope.com/mailbag/mcarbon14.html

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/cardat.html

Remember, they can carbon date really old living things with dead
things inside them - i.e. trees - hence cross correlating with
an(other) empirically proved method. Also, by using other methods such
as ice layers in the arctic.

How do you know your car won't run out of gas when you set off to
travel 20 miles on a full tank? You don't, but you extrapolate from
previously gathered data.  How do we know that silicone chips won't
spontaneously explode after 50 years?  We don't - but I'm quite
confident to have them around the house.

3) Goodness knows - but here's the Wikipedia article on it:

http://en.wikipedia.org/wiki/Species

Note that Wikipedia can be changed by anyone at any time, so treat
information there with caution.

4) They can date rock (see question 2 links) and get a very rough idea
of a fossil's age from that.  Fossils less than around 60,000 years
old can be tested using Carbon dating themselves.

I have deliberately not given a comprehensive answer as a researcher
should be able to.

Good questions, by the way.

You aren't doing well in your science classes, are you?

After you've studied biology, chemistry, geology, and a few other
things required for a science degree, you'll come to pretty much the
same conclusions most scientists come to. While evolution doesn't
answer every question related to our origin, neither does the tax code
answer every question about taxes, nor does the criminal code deal
with every crime. That's why regular research and continuous updating
is needed.

The best way to try to disprove evolution is to excel in the fields
that it relies on for proof. Most of the "gotcha" moments lay-persons
have is from being mis- or ill-informed.

Responding to your questions, in order:

1) There is, of course, the postulate that speciation does occur, and
therefore there were in very remote times early ancestors to our
species, Homo Sapiens sapiens. But it also so happens that there exist
today living animals which formally & genetically have a very high
percent similarity to ourselves: the great apes in general, and
chimpanzees most particularly. If they're so very close to being like
us, then we expect that they are, evolutionarily, just branches of a
tree of speciation that split some time in the past. We humans would
likely be another branch. It's then expected that humans & apes have
"common" ancestors, and the remains of organisms which are clearly
ape-like at early times are expected to occupy some point on the
ape/human historical trajectory.

   But are they really genetic ancestors to humans? All one can say is
that there is clearly a statistical progression of hominid anatomy in
the fossil record as a function of date. The fossils are there. Apes &
humans are here. Why would only apes have fossil evidence of ancestry
but not humans?

   Plus, in recent years genetic surveys have accrued a very robust
body of evidence that all living humans are genetically rooted to a
small population of ancestors living on the African continent at some
time in the distant past. Given that all people today are related to
ancient Africans, and all the most ancient hominid fossils are found
in Africa, there is some sense to seeing this all as not accidentally
related.

2) As for radioactive decay itself, the known physics of this decay
has no room in it for the half-life of a decaying mass to abruptly
change. It's not unthinkable that this could happen, but there's no
obsevation of this happening, and good rason not to expect it to
happen: radioactive decay is a thoroughly quantum mechanical process,
and is thus, at the scale of the decaying atomic nucleus, determined
randomly, and will continue unabated in this mode 'til the decaying
mass is fully decayed.

   It is true of course that the levels of the radioisotope used for
dating dead organisms, carbon-14, has not necessarily been in constant
abundance in Earth's ecosystem throughout history. It has changed as
geological sources of C-14 have fluctuated. Specialists in C-14 dating
must resort to adjusting date estimates using tables of inependently
gathered data on the isotope's changes. Also keep in mind that carbon
dating is only considered to be reliable up to a certain point. Carbon
dating is not used exclusively for dating all objects for all possible
times. Dating is estimated by other techniques as well.

3) Keep in mind that by clearly stating that there is diversity within
a species, it is implied that the definition of a species is clearly
made. As for what this definition is, biologists typically say that
two organisms are in two different species when they are incapable of
interbreeding. They are too genetically different for their
reproductive systems to be able to respond to one anothers' genetic
contributions, sperm & egg. It's basically a mixing of oil & water.

   At any rate, the defintion of a "species" isn't very relevant to
the question of evolutionary change. All that the word "species" means
is that we, as organised thinkers, have decided what it is that we
mean by two "kinds" of organism. What really, ultimately matters in
evolution is that one organism can be incrementally genetically
different from its parent(s), and that it can live long enough to make
its own offspring. A very long sequence of such offspring, having
opportunity for genetic differentiation with each generation, can
produce over time an organism which is strikingly different from its
early ancestors.

   As a handy illustration consider the history of the automobile.
Cars have incrementally changed over the decades. My Honda hybrid
shares basic similarities with the earliest horseless carriages, but
no one would confuse the two. They are at two opposing ends of a long
lineage of generational differences.

4) Yes, it would be curcular to age a fossil by its geological
context, and then to turn about & date the geology by citing the age
of its embedded fossils. But fortunately that's not the way it's done.
If geologists relied solely upon the fossils of organsims to date
geological features, then they'd be bat-blind upon studying strata
which contain no such fossils. They do, in fact, employ other
independent methods.

You forgot a question. Why hasn't the Coelacanth changed/evolved ? 

How can a "theory" be taught as fact? 

 As for science or at least some "scientists", they have been wrong
soooo many times. Evolution is just one example. no? The word is flat,
eggs are bad for you, a high fat diet is terrible for you, the earth
is the center of the universe everything revolves aroud it. Don't get
me wrong there are a LOT of facts that are facts.

"You forgot a question. Why hasn't the Coelacanth changed/evolved ?" 

   Good question. Well, what makes you think that it is required (by
evolutionary theory) to undergo evolution? What makes you think the
coelecanth hasn't undergone evolution?

   The lineage to which modern coelecanths belong may have bifurcated
geneticaly any number of times over the course of history. Maybe
you've eaten from some of those branches. The branch which carries the
variant which we call "coelecanth" is interesting to scientists mainly
because it was, provisionally, thought to be extinct. There are other
organisms which have displayed similar lack of anatomical changes even
over tens of millions of years. For example, crocodiles & turtles are
very nearly the same, anatomically, as their distant relatives in the
fossil record.

   There's nothing in evolutionary theory which mandates that a
lineage undergo either obvious structural or more subtle genetic
differentiation. It's simply that such changes are explicitly
possible, and as a matter of record do occur. It is, of course, quite
likely that genetic changes will occur, and almost certainly the
genomes of modern coelecanths, crocodiles, turtles, etc. aren't
identical to those of their ancestors. My genome isn't 100% identical
to that of either of my parents, and that's only one generation ago.

   But suppose that a mutation occurs at some point in the lineage of
a coelecanth. Suppose also that this mutation is not harmful to the
host organism; it doesn't get the organism killed before it makes its
own offspring, which will then carry the new, slightly different
genome. Does this mean that the earlier coelecanth genome suddenly
becomes extinct? No, not at all. The previous genetic lineage can
continue to make offspring. At the point of the cited mutation, the
lineage splits, and they're on their way to potentially two separate
species. But the earlier genome can potentially make it unscathed
indefinitely through history. It just depends on how well adapted it
is to whatever predominant environmental pressures it will encounter
over time.

   In the case of the coelecanth, the variety which holds the interest
of biologists has survived to this day because it hasn't (yet) been
rendered extinct. Maybe a thousand branches in its lineage's past have
become extinct. Maybe a thousand others are thriving today. Same goes
for crocs & turtles.

   And keep in mind what I said about subtle genetic changes. Genetic
change doesn't always translate to obvious anatomical changes. Many
such changes may involve the emergence of small, specialised organs,
or brain chemistry. Such changes may not be detectible in fossils.

"How can a "theory" be taught as fact?" 

   Well first, the "theory" of evolution is a fact, meaning that it is
a matter of fossil record that changes have occurred. It's just like
looking at a motion picture frame by frame. The image on any frame
*is* different from the ones adjacent to it. If you look at frames
which are very well separated, they are strikingly different. This
what's found in dated fossil records.

   The question then is exactly what propels speciation, and the
answer is that offspring can & often do have genomes which are
different by some percentage from their parent organisms. This is
known to be a fact of the world, that genetic changes occur. What
else, then, would be sufficiently factual -empirical- to teach in a
science-based biology class? Evolution is a theory which must work
hard for a living, or it will be fired by its employer. Thus far
evolutionary theory works VERY hard. It works as hard for biologists
as does plate tectonics for geologists, or quantum mechanics for
chemists & physicists.

"As for science or at least some "scientists", they have been wrong
soooo many times. Evolution is just one example. no? The word is flat,
eggs are bad for you, a high fat diet is terrible for you, the earth
is the center of the universe everything revolves aroud it. Don't get
me wrong there are a LOT of facts that are facts."

   Keep in mind at least a couple of things. First, that not only
scientists but everyone is mistaken a great deal of the time about a
great many things. Second, that scientists in particular aren't in
principle in the business of pretending to be immutably correct.

   The whole idea of "scientific" inquiry precisely is that people can
be mistaken, and that it takes time, effort and even good fortune to
make discoveries about the objects of inquiries. No answer to a well
formed question can be considered so sacred as to be held above
criticism or scrutiny. Thus, even though once the world was,
provisionally, thought to be flat, it is now understood to be
something much closer to a sphere, due to the march of progress in
both the body of evidence & theory in response to the evidence. Earth
once was, with some reason, thought to be the center of the cosmos. In
time progress was made, and now evidence points to some other picture
of the world. Newtonian gravity was once King, then it was dethroned
by Einsteinian gravity, because it matches the evidence orders of
magnitude better than Newton's theory. And even as we speak evidence
is accumulating which suggests that an even more comprehensive theory
of gravity may be in order.

   Saying that scientists have been wrong in the past is in no way an
adequate criticism by which to dismiss the fruits of scientific
research. Scientists, when they are being scientific, allow the march
of progress. It's possible to cite that not all people calling
themselves "scientists" really treat knowledge in this fashion. True
enough, but that's just individuals falling victim to the same
weaknesses as any human. Individuals may succumb to sentimentalities,
but this is not itself science. Some people are weak, and others are
strong. There are strong individuals who do practice good science. But
when they don't, they are called on it by their peers. Albert Einstein
is a famous example of one person who alternately changed the
complexion of one corner of our worldview and then rejected, purely
for reasons of his own personal tastes, another equally robust corner.
He was both revered for his contributions and criticised for his
foolishness.

   Everyone seeks "comfort & reassurance". What is it that comforts an individual? 

   Many people require themselves to believe in a worldview, an idea
on how the world itself works, in order to be comfortable with
themselves. Thus, they gravitate toward dogma-based religions, which
offer whole worldviews for very little effort of the mind.

   A scientist, on the other hand, is comforted not by carelessly
buying into boutique religious worldviews, which by their very natures
discourage their adherents from finding cracks in their own
foundations. A scientist seeks personal comfort, but what comforts a
scientist is not the easy possession of answers, but the asking of the
questions, and treating answers skepically. Something offered up as an
answer to a hard question must pass the test of experiment before even
being considered for hire. A parcticing scientist does *want* a
worldview, a way of understanding the very machinery of the world. But
said individual would rather live knot knowing than carelessly hire a
weak, poor working theory.

   To boil it down, religious dogmatists hunger for answers, whereas
scientists hunger for questions. Scientists believe not in their own
theories (i.e., "answers"), but in science itself.

joe916-ga, how do you know that you exist at all?  Could we not all be
simply constructs in your own mind?

How about a "Matrix" like reality, where everything is a figment of
someoene else's imagination, fed to you be super wires directly into
your brain?

I'll let you figure out the relevancy of the above claptrap to your question.

murunbuchstansinger-ga 
In response  I think therefore I am. (I also have a Google user name)
The Matrix has a lot on christian insinuations.(may be the wrong word
but I am vocabularity challenged.

qed100-ga 


   How convenient that those that don't show evolution haven't evolved. 
   May have bifurcated",Wheres the proof?. " provisionally, thought to
be extinct", until it was found.
 "There's nothing in evolutionary theory", later you say it is fact.
  Suppose, suppose. Suppose that a bifurcation never occurred. 
  "My genome isn't 100% identical
to that of either of my parents, and that's only one generation ago.",
you are still human and your ancestor will still be human.
  The evidence is accumulating but unprovable by the scientists own
admission so I suppose that it will also "evolve" into  fact just like
the hypothesis of evolution..
"organisms which have displayed similar lack of anatomical changes even
over tens of millions of years. For example, crocodiles & turtles are
very nearly the same, anatomically, as their distant relatives in the
fossil record",  you forgot to include man, wheres the proof.


Many people, to be comfortable with themselves, gravitate toward
misconceptions which cannot be proven. They refuse to believe in the
truth that man is a created being by THE higher power. They do not
approach the "science" of evolution in the manner with a open mind but
instead approach it with preconceived ideas which they already 
believe to be right,  just like the previously  stated earth flat, sun
revolving around the earth, the coelacanth being extinct..  They try
to find "facts" which can support their ideas and when these ideas
cannot be proven they generate some other reason which cannot be
proven to support their delusional fact. Certainly there have been
changes to species but there is no satisfactory proof of evolving into
another.
So evolution is currently being "provisionally" taken as fact. 


What I'm trying to say in a nut shell is 
Evolution is incorrect. Creationism is true. Both are a matter of faith.

"Many people, to be comfortable with themselves, gravitate toward
misconceptions which cannot be proven."

   Yes. That's right. You do.

joe916-ga, evolution has far more evidence than "creationism". By "far
more", I mean a lot.  By a lot I mean lots and lots.  In fact, you
could interpret "lots and lots" to mean more than lots.

You benefit in your every day life from people following theories that
have been far less sound than evolution - in the form of technological
progress.  This progress takes the form of everything from "the wheel"
to the modern PC.

If you choose to ignore this particular part of scientific knowledge,
but benefit from others, then that is your perogative.  Your problem,
however, is that evolutionary theory does impact on other parts of
your life in the form of research in other areas.

Your ignorance is supported by the knowledge of others.  You are lucky
to benefit from this.  As we are not a society run by absolutists -
such as, let us say, religious fundamentalists, you are free to air
your opinions.

Please, read some books without being tempted to burn them.

"joe916-ga, evolution has far more evidence than "creationism". By "far
more", I mean a lot.  By a lot I mean lots and lots.  In fact, you
could interpret "lots and lots" to mean more than lots."

   Exactly. Saying that evolutionary theory and Bible-belt creationism
are equally based upon faith alone is like saying that one has between
zero & very, very little understanding of the content of evolutionary
theory. They aren't even in the same country, let alone a common
ballpark.

   Occasionally I'll encounter an individual who utters the "gotcha"
argument, "If man evolved from apes, then *why* are there still
apes!?" Being just plain weary of this tired, old example of not
knowing of what one speaks, I often reply, "When you've learned what
evolutionary theory actually says, feel free to come back and argue."

Please correct me, with facts, if I am wrong, but this is what is known: -
Organisms change from generation to generation due to 3 things: -
1) Reshuffling and loss of current genes
2) Addition or change of new gene material due to mutations.
3) Natural selection removing organisms with detrimental traits caused by
(1) & (2).

By (1) reshuffling and loss of current genes alone, no new gene
material  can be added to the gene pool. The new generation will at
best keep all the parents genes (in the case of asexual reproduction).
More likely, however, (in the case of sexual reproduction) the new
generation will receive a combination of genes from both parents and
this will likely be only a subset of all the genes in the parents.
Therefore, a reduction of genes corresponding with specialisation of
traits will appear in the new generation. That's why no amount of
selective breeding of poodles alone will return  the dogs back to
their original wild (wolf?) kind. They have already lost the genes
responsible for all those wolf traits. The only way to have a poodle's
young get back those other lost traits is for the poodle to breed with
their original kind.

By (2) Addition or change of new gene material due to mutations, we
may  have new gene material but every documented case of mutation has
never added any complexity to the new generation despite tests done
across thousands of generations in labs. The mutation has always been
either detrimental to the new generation, and/or or a reduction of the
genes. Eye-less fish in caves, or wingless beetles on windy islands
have changed from fish with eyes and beetles with wings. The once
useless eyes of the fish in dark caves are no longer a liability for
infection, and the beetles are less likely to be blown off the island
into the sea than if they were fiying. Therefore, these variations,
although a beneficial mutation, are clearly a loss of gene material.

By (3) natural selection removing organisms with detrimental traits
caused by (1) & (2), we see that natural selection is only the quality
control 'officer' responsible for rejecting what has already been
made. It can't add new gene material either.

From (1), (2) and (3) above we see that organisms may change, lose
trait potential, and devolve till they  become unable to procreate
before dying. Organisms cannot evolve into more complex creatures.
Moreover, inheritable mutations (which are, on average, by far
detrimental but may not manifest their trait in the young till both
parents have the mutant genes) will possibly cause undesirable genes
to accumulate in future generations at an exponential rate. Possibly,
we are just starting to see the slow beginning of this trend in
humans. All of this is the opposite of Darwinian Evolution.

It is interesting to note that this situation is exactly what we see
is  advocated by the Bible whereby each organism will only reproduce
after its own kind. If it is already inter-breedable, it is of the
same kind. It might change quickly from generation from generation as
the combination of genes it receives changes, but it won't evolve
"upwards" like from fish to philosopher. Like I said, please correct
me, with facts, if I am wrong, but this is what is known.