EVIDENCE FOR EVOLUTION?
Historical Development of the
Theory of Evolution
According to the Encyclopedia of Biological Sciences,
evolution has been a philosophical speculation since Empedocles (495-435 B.C.)
and even before[1]. However, in
the absence (at that time) of a reasonable hypothesis of a mechanism for
evolution, he had not been able to convince many of his contemporaries. Since then eight schools of thought
have in turn attempted to explain how evolution actually occurred, (though some
have run concurrently and some that died have experienced resurrections at
later dates) So in an attempt to understand the evidence there is some
advantage in looking first at each of these schools of evolutionary thought.
Pangenesis
Hippocrates
(c 460 BC – c 470 BC), known as the father of medicine, suggested an
explanation called pangenesis.
According to this idea, particles called pangenes, from each part of an
organismÕs body collect in the eggs or sperm and are then passed to the next
generation. If pangenesis were
true, changes that occur in various parts of the body during an organismÕs life
could be passed on to the next generation. The Greek philosopher Aristotle rejected this idea as
simplistic saying that what is inherited is the potential to produce body
features, rather than particles of the features themselves.[2]
Pangenesis proves incorrect on several counts. The reproductive cells are not composed of particles from somatic (body) cells, and changes in somatic cells do not usually influence eggs and sperm. This means that if you build a large body by weight lifting, your body does not transmit that information to your reproductive cells. ÒThis may seem like common sense today; but the pangenesis hypothesis and the idea that traits acquired during an individuals lifetime are passed on to offspring prevailed well into the nineteenth centuryÓ[3]
Lamarckism
The first major effort to deal with the origin of species on an evolutionary basis was that of Lamarck (1744-1829). He proposed the gradual development of species from similar predecessors on the basis of four principles: That all organisms tend to increase in size; that new organs arise because of new needs, and because of the activities resulting from such needs; That use of an organ results in its further development, while disuse results in its degeneration; and finally; that changes produced by the action of these principles during the lifetime of an individual are inherited by its progeny (inheritance of aquired characters), so that the results are cummulative over long periods of time, thus resulting in the origin of species.[4]
Many
High school & University texts use his example of a giraffe to illustrate
his beliefs. He said if a giraffe
stretched its neck for leaves, a Ònervous fluidÓ would flow into its neck and
make it longer. Its offspring
would inherit the longer neck. He
also believed that organs which organisms ceased using, would shrink or atrophy.
Lamarck was unsuccessful, in gaining wide aceptance, partly because of the opposition of Cuvier, the most influential zoologist of the time, but more because attempts to verify his basic theses, especially the inheritance of acquired characters, gave discordant or equivocal results.
Orthogenesis
Van NostrandÕs Scientific Encyclopedia says:
Òorthogenesis is a theory of organic evolution which assumes the occurrence of progressive change in
living things along definite lines of development.
In Fossil series it is always possible to see orderly progression or retrogression from form to form. According to some evolutionists this type of evolution has taken place under the impulse of unknown
controlling factors as a directive tendency. Others point out that one result of evolution is certain to be
an ancestral series which, if isolated, appears to be orthogenetic.
Since every heritage must have certain potentialities, the evolution of any group must proceed along the
lines made possible by these potentialities. To this extent orthogenesis is an established principle. No
comprehensive theory of evolution, however, fails to admit the existence of other factors, at least in a
directive capacity, and so orthogenesis is not to be regarded as an explanation of organic evolution.Ó
Creative Evolution
Wikipedia explains:[5]
Creative Evolution (French: LÕƒvolution crŽatrice) is a 1907 book by French philosopher Henri Bergson. Its English translation appeared in 1911. The book provides an alternative explanation for DarwinÕs mechanism of evolution, suggesting that evolution is motivated by an Žlan vital, a Òvital impetusÓ that can also be understood as humanityÕs natural creative impulse. The book was very popular in the early decades of the twentieth century, before the neo-Darwinian synthesis was developed.
Bergson also concluded that Darwinism had failed to explain why life:
ÒEvolved in the direction of greater and greater complexity. The earliest living things were simple in
character and well adapted to their environments. Why did the evolutionary process not stop at this
stage? Why did life continue to complicate itself Òmore and more dangerouslyÓ[6]
A major
problem that Bergson unsuccessfully tried to deal with was explaining the
origin of this vital force and demonstrating exactly how it functions to
produce new life forms. Among the many other problems with the theory was the
fact that it did not explain well why evolution took the route that it did
instead of a chaotic path.[7]
BergsonÕs
theory was honoured with a Nobel prize because it appeared to a large number of
scholars to be a plausible explanation for the source of genetic variety which
natural selection could fine tune.
When it was discarded, those who put their faith in BergsonÕs theory
were forced to postulate another mechanism.[8]
Hopeful Monsters
The hopeful monsters hypothesis is a biological theory which suggests that major evolutionary transformations have occurred in large leaps between species due to macromutations.[9] Wikipedia continues:
The German geneticist Richard Goldschmidt (1878-1958) was the first scientist to use the term Òhopeful
monsterÓ. Goldschmidt thought that small gradual changes could not bridge the hypothetical divide
between microevolution and macroevolution. In his book The Material Basis of Evolution (1940) he
wrote Òthe change from species to species is not a change involving more and more additional atomistic
changes, but a complete change of the primary pattern or reaction system into a new one, which
afterwards may again produce intraspecific variation by microevolution. Goldschmidt believed the large
changes in evolution were caused by macromutations (large mutations). His ideas about
macromutations became known as the hopeful monster hypothesis.
According to Goldschmidt Òbiologists seem inclined to think that because they have not themselves
seen a ÔlargeÕ mutation, such a thing cannot be possible. But such a mutation need only be an event of
the most extraordinary rarity to provide the world with the important material for evolutionÓ.
Stephen Jay Gould (1941-2002) had attempted to update the ideas of Goldschmidt by redefining the
concept of Òhopeful monsterÓ in a way that can be kept in the neo-Darwinian framework via an
extension. In an article titled The Return of Hopeful Monsters (1977) Gould argued that the recent
discovery of regulatory genes offered new evidence which supported some of GoldschidtÕs postulates
and that small changes in the embryological Òconstraint systemsÓ can produce large morphological
transformation in the adult, and possibly macro-evolutionary pathways.
Many scientists rejected the hopeful monster hypothesis as genetics research seemed to show that large
mutations
would be lethal.[10]
Panspermia
A very attractive webpage gives the following introduction to Panspermia.[11]
Panspermia is a greek word that translates literally as Òseeds everywhereÓ. The panspermia hypothesis
states that the ÒseedsÓ of life exist all over the Universe and can be propagated through space from one
location to another. Some believe that life on Earth may have originated through these ÒseedsÓ.
Mechanisms for panspermia include the deflection of interstellar dust by solar radiation pressure and
extremophile micro-organisms travelling through space within an asteroid, meteorite or comet.
Panspermia does not provide an explanation for evolution or attempt [to] pinpoint the origin of life in
the universe, but it does attempt to solve the mysteries of the origin of life on Earth and the transfer of
life throughout the Universe.
Another web page concludes:[12]
What can be seen from the theory of Panspermia is that the evidence for both sides is strong.
Experiments to study microorganisms in
space are few, for example The Living Interplanetary Flight
Experiment which aims to test whether microorganisms can survive in the harsh conditions of space.
Since evidence for panspermia can only be effectively collected from Earth based experiments, only the
hope that enough evidence can be collected to either prove or disprove the Theory of Panspermia will
keep the debate going.
Jeffery Bada, director of the NASA Specialised Centre of Research and Training in Exobiology at Scripps Institute for Oceanography, states that most meteorites would simply get too hot and would destroy most amino acids and organic material during entry to the earthÕs atmosphere. In this paper, the only way to get significant organic material to earth was through interplanetary dust particles (IDPs)[13]. Bada heated IDPs and found that during entry they can easily heat up to 1200 C, easily hot enough to destroy most organisc material. Apparently the only amino acid that ever remained during BadaÕs realistic simulations was glycine. Bada called this Òbad newsÓ if you were interested in originating life based on material from outer-space.[14]
Quantum Evolution
According to Wikipedia Quantum evolution is a component of George Gaylord Simpson's multi-tempoed theory of
evolutionary change, proposed to explain the rapid emergence of higher taxonomic groups, as interpreted from the fossil
record.
According to Simpson, evolutionary rates differ from group to group and even
among closely related lineages. These different rates of evolutionary change
were designated by Simpson as horotelic (medium tempo), bradytelic (slow tempo), and tachytelic (rapid tempo).
Quantum evolution differed from these styles of change in that it involved a
drastic shift in the adaptive zones of certain classes of animals. The word
"quantum" therefore refers to an "all-or-none reaction",
where transitional forms are particularly unstable, and perished rapidly and
completely. Although quantum evolution may happen at any taxonomic level [15],
it plays a much larger role in "the origin of taxonomic units of
relatively high rank, such as families, orders, and classes."[16]
According to Simpson16,
quantum evolution relied heavily upon Sewall WrightÕs theory of random genetic
drift. Simpson believed that major
evolutionary transitions would arise when small populations—isolated and
limited from gene flow—would fixate upon unusual gene combinations. This
"inadaptive phase" (by genetic drift) would then (by natural
selection) drive a deme population from one stable adaptive peak to another on
the adaptive fitness landscape.
However, Simpson[17]
wrote that it was still controversial:
"whether prospective adaptation as prelude to quantum evolution
arises adaptively or inadaptively. It was concluded above that it usually
arises adaptively . . . . The precise role of, say, genetic drift in this
process thus is largely speculative at present. It may have an essential part
or none. It surely is not involved in all cases of quantum evolution, but there
is a strong possibility that it is often involved. If or when it is involved,
it is an initiating mechanism. Drift can only rarely, and only for lower
categories, have completed the transition to a new adaptive zone."
This preference for adaptive over inadaptive forces led Stephen Jay
Gould[18]
to call attention to the "hardening of the Modern Synthesis", a trend
in the 1950s where adaptationism took precedence over the pluralism of
mechanisms common in the 1930s and 40s.
Simpson[19] considered
quantum evolution his crowning achievement, being "perhaps the most
important outcome of [my] investigation, but also the most controversial and
hypothetical."
It is revealing that Wikipedia also states[20]
that this theory would only be useful if indeed there were evidence that some
sort of adaptive mutation occurs - in other words, if there were experimental
data showing that the classical model of random mutation is lacking, and that
certain mutations are "preferred" (occur more frequently) because they confer a greater
benefit to the organism. This is a controversial subject in and of itself; a
plethora of papers have been published on the enigmatic phenomenon of adaptive
mutation and the issue of their origin and mechanism remains unresolved. To
date there is no such generally accepted mechanistic explanation of adaptive
mutation.
Punctuated Equilibrium
According
to Berkely UniversityÕs Evolution website[21], Punctuated equilibrium is an
important but often-misinterpreted model of how evolutionary change happens.
Punctuated equilibrium does not:
1. Suggest
that Darwin's theory of evolution by natural selection is wrong.
2. Mean
that the central conclusion of evolutionary theory, that life is old and
organisms
share a common ancestor, no longer holds.
3. Negate
previous work on how evolution by natural selection works.
4. Imply
that evolution only happens in rapid bursts.
Punctuated
equilibrium predicts that a lot of evolutionary change takes place in short
periods of time tied to speciation events. Here's an example of how the model
works:
1. Stasis: A population of molluscs is
experiencing stasis, living, dying, and getting fossilized every few hundred
thousand years. Little observable evolution seems to be occurring judging from
these fossils.
2. Isolation: A drop in sea level forms a lake
and isolates a small number of molluscs from the rest of the population.
3. Strong selection and rapid
change: The small,
isolated population experiences strong selection and rapid change because of
the novel environment and small population size: The environment in the newly
formed lake exerts new selection pressures on the isolated molluscs. Also,
their small population size means that genetic drift influences their evolution.
The isolated population undergoes rapid evolutionary change. This is based on
the model of peripatric speciation.
4. No preservation: No fossils representing
transitional forms are preserved because of their relatively small population
size, the rapid pace of change, and their isolated location.
5. Reintroduction: Sea levels rise, reuniting the
isolated molluscs with their sister lineage.
6. Expansion and stasis: The isolated population expands
into its past range. Larger population size and a stable environment make
evolutionary change less likely. The formerly isolated branch of the mollusc
lineage may out-compete their ancestral population, causing it to go extinct.
7. Preservation: Larger population size and a larger
range move us back to step 1: stasis with occasional fossil preservation.
This
process would produce the following pattern in the fossil record:
Evolution
appears to happen in sharp jumps associated with speciation events.
We
observe similar patterns in the fossil records of many organisms. For example,
the fossil records of certain foraminiferans (single-celled protists with
shells) are consistent with a punctuated pattern.
|
|
|
|
However, it
is also important to note that we observe examples of gradual, non-punctuated,
evolution in the fossil record too. The question that needs answering is: what
are the relative frequencies of punctuated and gradual change?
¥ Foraminiferan micrograph courtesy of the National
Collection of Foraminifera © Smithsonian
Institution
¥ Foraminiferan graph after Malmgren, Berggren, and Lohmann (1983)
So Gould and Eldredge in this model have shown theoretical processes that could explain some of the data in the fossil record but they give no mechanism for the biological change itself, and they admit Óstability within species must be considered as a major evolutionary problemÓ[22] They also admit that ÔDarwinian extrapolation cannot fully explain large-scale change in the history of lifeÕ [23]. Gould had already stated that ÔThe absence of fossil evidence for intermediary stages between major transitions in organic design, indeed our inability, even in our imagination, to construct functional intermediates in many cases, has been a persistent and nagging problem for gradualistic accounts of evolution.Õ[24] So objectively neither theory can provide any evidence for the evolution of more complex life forms from less complex forms.
Symbiogenesis
Symbiogenesis[25]
a theory stating that many eukaryotic cell structures, including mitochondria,
chloroplasts, and kinetic, or mitotic, centers (containing centrioles,
blepharoplasts, and flagella), originate as a result of the prolonged symbiosis
between eukaryotes and prokaryotes, for example, bacteria and blue-green algae.
According to this theory, a mitochondrion is an endosymbiont that originates
from a free-living aerobic bacterium that has penetrated an older anaerobic
bacterium; as a result, the latter bacterium becomes aerobic.
The
mitochondria present in the cells of all eukaryotes, especially those that are
bacilliform, resemble certain bacteria in that they continually bend and twist.
They are more similar to a whole prokaryotic organism than the other components
of a eukaryotic cell, with the exception of chloroplasts. The latter, according
to the theory of symbiogenesis, originate from blue-green algae, which, having
become the endosymbionts of eukaryotic cells, lose their independence and adapt
themselves to performing photosynthesis.
The
founders of the theory of symbiogenesis included the Russian and Soviet
scientists K. S. Merezhkovskii (1905, 1909), A. S. Famintsyn (1907), and B. M.
Kozo-Polianskii (1924, 1937). The theory has recently been developed in
research conducted by A. L. Takhtadzhian (1972), the American biologist L.
Margules (Sagan) (1967, 1970), and the British biologist J. Bernal (1969)[26].
So if we
have two organisms merging their information, or information being transferred
from one species to another by viruses, we do not derive any new information,
we only see a reshuffling of existing information. Without new information we cannot have the development of
new creatures, capable of new skill sets, or any kind of new ability.
Darwinism
Darwinism according to the Free Dictionary[27] was a concept of evolution developed in the mid-19th century by
Charles Robert Darwin. Darwin's meticulously documented observations led him to
question the then current belief in special creation of each species. After
years of studying and correlating the voluminous notes he had made as
naturalist on H.M.S. Beagle, he was prompted by the submission (1858) of an almost identical theory
by A. R.Wallace to
present his evidence for the descent of all life from a common ancestral
origin; his monumental Origin of Species was published in 1859. Darwin observed (as had
Malthus) that although all organisms tend to reproduce in a geometrically
increasing ratio, the numbers of a given species remain more or less constant.
From this he deduced that there is a continuing struggle for existence, for
survival. He pointed out the existence of variations—differences among members of the
same species—and
suggested that the variations that prove helpful to a plant or an animal in its
struggle for existence better enable it to survive and reproduce. These
favorable variations are thus transmitted to the offspring of the survivors and
spread to the entire species over successive generations. This process he
called the principle of natural selection (the expression "survival
of the fittest" was later coined by Herbert Spencer). In the same way,
sexual selection (factors influencing the choice of mates among animals) also
plays a part. In developing his theory that the origin and diversification of
species results from gradual accumulation of individual modifications, Darwin
was greatly influenced by Sir Charles Lyell's treatment of the doctrine of
uniformitarianism. Darwin's evidence for evolution rested on the data of
comparative anatomy, especially the study of homologous structures in different
species and of rudimentary (vestigial) organs; of the recapitulation of past
racial history in individual embryonic development; of geographical
distribution, extensively documented by Wallace; of the immense variety in
forms of plants and animals (to the degree that often one species is not
distinct from another); and, to a lesser degree, of paleontology. As originally
formulated, Darwinism did not distinguish between acquired characteristics,
which are not transmissible by heredity, and genetic variations, which are
inheritable. Modern knowledge of heredity—especially the concept of mutation,
which provides an explanation of how variations may arise—has supplemented and modified the
theory, but in its basic outline Darwinism is now
universally accepted by scientists.
This last sentence is just not true. Macbeth, a Harvard trained lawyer who
has made a study of Darwinian theory for many years has cited some prominent
scientists who no longer accept Classical Darwinism or anything like it. He summarises Prof. Hardin as saying Òcountless minds have perceived that Darwinism has failedÓ[28]. A number of scientists I know see the
weaknesses in Darwinian theory but stay with it hoping to find supporting
evidence for it in the future. Dr
Eiseley is also of that view.[29] Dr David Penny (lecturer in evolution)
went a little further, saying he knew that one day they would find the evidence[30]. This means they
admit to not having that evidence now.
Returning to Macbeth, he says[31]:
The
most important testimony comes from Professor Simpson, since he is generally
regarded as the
dean
of modern evolutionists. He takes
great pride in the synthetic theory, which is the work of many
hands,
including those of Fisher, Ford, Wright, Sir Julian Huxley, Waddington,
Dobzhansky, Mayr,
Stebbins,
and Simpson himself. Clearly it is
the ruling line of thought today.
Equally clearly, it is not
the
same thing as classical Darwinism.
Simpson is explicit: ÒThe full-blown theory is quite different
from
DarwinÕs and has drawn its materials from a variety of sources largely
non-Darwinian.Ó
Macbeth adds on the next page:
ÒLet
the reader bear in mind, however, that the large and easy aspect of evolution
– the fact that change has taken place and that species have appeared and
disappeared – remains untouched even if classical Darwinism is put on the
shelf. We say Not Proven to
DarwinÕs suggestion as to how and why, but we do not return to fundamentalism.Ó Note no reasons are given for not
returning to a belief that an intelligent God created lifeÕs major forms and
that there has been some variation since that time.
Neo-Darwinism
More recently the term neo-Darwinism and other terms have
been used to describe evolutionary theory, so as to avoid the increasing embarassment
that new findings in palaeontology and molecular biology bring to the Darwinian
model of Evolution. One Dr of
molecular biology (who does not accept creation as an explanation either)
Michael Denton[32], concludes
his book by saying:
ÒThe
influence of evolutionary theory on fields far removed from biology is one of
the most spectacular
examples
in history of how a highly speculative idea for which there is no really hard
scientific evidence
can
come to fashion the thinking of a whole society and dominate the outlook of an
age. Considering its
historical
significance and the social and moral transformation it caused in western
thought, one might
have
hoped that Darwinian theory was capable of a complete, comprehensive and
entirely plausible
explanation
for all biological phenomena from the origin of life on through all its diverse
manifestations
up to, and including, the intellect of man.
That it is neither fully plausible, nor comprehensive, is
deeply troubling. One might
have expected that
a
theory of such cardinal importance, a theory that literally changed the world,
would have been
something
more than metaphysics, something more than myth.
He
concludes by saying: Ultimately the Darwinian theory of
evolution is no more nor less than the great
cosmogenic
myth of the twentieth centuryÓ.
Most people consider evolution to be an indisputable fact. So how do we account for statements by reputable scientists that call it a Òfairy taleÓ. For example Dr Lewis Bounoure, Director of the Zoological Museum and Director of Research at the National Centre for Scientific Research in France who declares ÒEvolution is a fairy tale for grownups.Ó[33]
ÒIf evolution were an undeniable fact, how do we account for the thousands of scientists worldwide, creationists and non-creationists alike, who say the theory of evolution is false scientifically; indeed, that it has more conclusive evidence against it than any evidence ever offered for it? Many of these scientists have their PhDs in the ÒhardÓ sciences (biology, paleontology, genetics, biochemistry, and molecular biology.) from leading universities.Ó[34]
If you would like to contemplate or review some of the evidence these scientists use to refute biological evolution then click the link here.