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Evolution debate enters ‘round two' (Proposal in Kansas: Change the definition of 'Science')
Kansas City Star ^ | Jan 30, 2005 | DIANE CARROLL

Posted on 01/30/2005 2:25:47 PM PST by gobucks

*snip* The conservatives who attacked evolution because it conflicted with the Genesis account of how the world was created have faded into the background.

In their place are professionals such as Harris who support intelligent design, a theory that states some aspects of the universe and living things are best explained by intelligent causes, not chance. Darwin's theory of evolution doesn't always add up, they say, and students should hear more about its shortcomings.

“There are only two options,” said Harris, who is leading this year's fight. “Life was either designed or it wasn't.”

That's not the point, evolution defenders reply. Science is about searching for natural explanations of the world, they say, and has no room for a theory based on faith.

The public will join the debate beginning Tuesday, when the first of four public hearings on new science standards will be held in Kansas City, Kan.

*snip*

So far, no state board of education has required the teaching of intelligent design. And the Kansas supporters of intelligent design are not asking that it be mandated, said Harris, who is on a committee that is rewriting the science standards.

Harris and seven other members of the 26-member committee instead propose students be “more adequately informed” on evolution.

The eight submitted a proposal to the state Board of Education. One recommendation was to change the definition of science. The current definition, they say, limits inquiry because it allows only “natural” explanations. They want it to be more objective and to allow students “to follow the evidence wherever it leads.”

Evolution supporters said such a change would shake science at its foundation.

(Excerpt) Read more at kansascity.com ...


TOPICS: Culture/Society; Front Page News; Politics/Elections; US: Kansas
KEYWORDS: acanthostega; atheists; christians; creationuts; crevolist; crevotion; darwin; evolution; ichthyostega; ignorance; scienceeducation
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To: Mockingbird For Short
How do you feel the theory of evolution should be taught in our schools? As a theory? as fact?

Like this

Why shouldn't Creationism (everything created "after its kind") be taught as well?

Because that hypothesis has been repeatedly falsified by the evidence.

Are living things, reproducing "after their kind", not to be considered as science?

Actually, it's part of evolutionary biology, and *is* taught in science class. However, it is also taught that over time the "kinds" themselves can change, can bifurcate (and re-bifurcate ad infinitum), can go extinct, and so on, because that's what the evidence overwhelmingly indicates.

41 posted on 01/31/2005 12:51:20 AM PST by Ichneumon
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To: Rudder
The difference is that Darwin and the scientists who have followed use data collected via the scientific method. What data does the ID side use?

So then, data collected via revelation is not as strong as data collected via the scientific method? Who better to receive the data from than the Designer? You see, I still think it comes down to an issue of choice or acceptance. (P.S. Rudder, I appreciate the politeness and respect with which you reply!)

42 posted on 01/31/2005 12:56:21 AM PST by Mockingbird For Short ("An irreligious fanatic is just as dangerous as a religious fanatic.")
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To: Rudder
The difference is that Darwin and the scientists who have followed use data collected via the scientific method. What data does the ID side use?

So then, data collected via revelation is not as strong as data collected via the scientific method? Who better to receive the data from than the Designer? You see, I still think it comes down to an issue of choice or acceptance. (P.S. Rudder, I appreciate the politeness and respect with which you reply!)

43 posted on 01/31/2005 1:02:32 AM PST by Mockingbird For Short ("An irreligious fanatic is just as dangerous as a religious fanatic.")
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To: gobucks
A: ID er's in Kansas: Follow the evidence where it leads.

Horse manure. Following the evidence where it leads for the past 140 years has led to Darwinian evolution being the only valid scientific theory which can account for the evidence. Unfortunately, the ID'ers don't *like* where the evidence has led, and thus they want to kick over the apple-cart and add "fairness" and "equal time" and stuff like that to try to trump the results of the evidence.

B: Scientist's response: Follow the evidence only if it is natural. Otherwise, the foundations of science will be shaken (and that is a bad thing how?).

Horse manure again. This is not the "scientist's response" to the ID twaddle, nor does science explicitly rule out "non-natural evidence" (although beats me what in the hell *that* might be). Science follows the evidence which is available, and looks for ways to acquire more evidence (via experiments, etc.) If you've got more evidence which you think they haven't already taken into consideration, feel free to present it.

Hmmmm. Do I get a star if I pick 'A'?

No, you get a "F" for using the "straw man" and "false dichotomy" fallacies.

44 posted on 01/31/2005 1:04:23 AM PST by Ichneumon
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To: rhtwngwarrior
I agree ... what these so called scientists are missing is that the Bible is objective Truth

Muslims say the same thing about the Koran. Which of the two clashing "objective Truths" shall we go with, and why?

and they want to cast doubt on that we're made in God's image.

No they don't. These conspiracy theories are just goofy.

If there was such a thing as evolution God would of mentioned it in His Book -- He doesn't say "in the beginning I created some ooze that you eventually came out of due to chance."

What, you don't think that "let the waters and the earth bring forth" various forms of life sounds a lot like life evolving out the earthy/watery "ooze"?

Maybe you're just not reading it right.

45 posted on 01/31/2005 1:08:40 AM PST by Ichneumon
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To: Charlotte Corday
A proper scientific approach would be, if the evidence led to intelligent design, to then try and determine the origins of the designers and methods used in the design process.

...and if that's what the evidence was indicating, science would be very excited at the prospect of learning about that intelligence and its methods.

The problem for the ID'ers is that so far, the evidence fails to lead to conclusions of intelligent design.

46 posted on 01/31/2005 1:10:30 AM PST by Ichneumon
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To: gobucks
["Science can only test the 'natural', or more specifically, the material."]

Who sez so? And wouldn't that mean science actually helps create materialists if that is the 'only' thing kids are allowed to test in school?

He's speaking of scentific investigations, not the kind of "learn about science" labwork kids do in school.

But in any case, how exactly would you suggest that science go about "testing the supernatural"?

Isn't it a bad idea that science should paint itself into a 'anti-God' corner like that - can science afford this approach over the long term?

Oh, puh-leaze... Investigating the natural world is in no way synonymous with being "anti-God"... Sheesh.

I mean, really now .... there's an awful lot of future grant money riding on questions like these, especially given how many Christians pay the taxes from which all that grant cash flow originates.

Well heck, go right ahead and start up that "science of the unnatural" research program then, you could clean up.

47 posted on 01/31/2005 1:14:31 AM PST by Ichneumon
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To: Ichneumon
Because that hypothesis has been repeatedly falsified by the evidence.

Are living things, reproducing "after their kind", not to be considered as science?

Actually, it's part of evolutionary biology, and *is* taught in science class. However, it is also taught that over time the "kinds" themselves can change, can bifurcate (and re-bifurcate ad infinitum), can go extinct, and so on, because that's what the evidence overwhelmingly indicates.

Why did you say in your first answer that the "after its kind" method of reproduction has proven to be untrue, but in your second answer you say that it IS taught in school.

By "bifurcate" do you mean evolve into an entirely new species?

48 posted on 01/31/2005 1:14:38 AM PST by Mockingbird For Short ("An irreligious fanatic is just as dangerous as a religious fanatic.")
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To: Woodworker; PatrickHenry; gobucks; bencarter; LiteKeeper; WomanBiologist; 185JHP; ...
Could you please give me some links to the experiments run to verify the theory of macro-evolution (cow into walrus, frog into kitten. etc.)

Here you go... I'm sorry this is such a vanishingly small fraction of the whole, but I'm short on time at the moment. These are mostly in the realm of the molecular evidence for macroevolution (DNA and biochemical studies, etc.) When you're done with these (or if you'd like to look at a taste of the biogeographical, cladistic, paleontological, morphological, statistical, and so on lines of evidence), let me know and I'll post more:

29+ Evidences for Macroevolution: The Scientific Case for Common Descent

The Evolution of Improved Fitness by random mutation plus selection

Ancient Jumping DNA May Have Evolved Into Key Component Of Human Immune System

Transposition mediated by RAG1 and RAG2 and its implications for the evolution of the immune system

Evolution of immune reactions

New insights into V(D)J recombination and its role in the evolution of the immune system

Evolution and developmental regulation of the major histocompatibility complex

Evolution of the IL-6/class IB cytokine receptor family in the immune and nervous systems

Layered evolution in the immune system. A model for the ontogeny and development of multiple lymphocyte lineages

Development of an immune system

The ancestor of the adaptive immune system was the CAM system for organogenesis

The evolutionary origins of immunoglobulins and T-cell receptors: possibilities and probabilities

Evolutionary perspectives on amyloid and inflammatory features of Alzheimer disease

Organization of the human RH50A gene (RHAG) and evolution of base composition of the RH gene family.

Molecular evolution of the vertebrate immune system.

Morphostasis: an evolving perspective.

Rapid evolution of immunoglobulin superfamily C2 domains expressed in immune system cells.

Reconstructing the evolution of vertebrate blood coagulation from a consideration of the amino acid sequences of clotting proteins

Evolutionary assembly of blood coagulation proteins

Exon and domain evolution in the proenzymes of blood coagulation and fibrinolysis

Evolution of proteolytic enzymes

Evolution of vertebrate fibrin formation and the process of its dissolution.

Common Parasite Overturns Traditional Beliefs About The Evolution And Role Of Hemoglobin

Scientists Discover How Bacteria Protect Themselves Against Immune System

The Evolution of Hemoglobin

Globins in nonvertebrate species: dispersal by horizontal gene transfer and evolution of the structure-function relationships

Reduction of two functional gamma-globin genes to one: an evolutionary trend in New World monkeys

Evolutionary history of introns in a multidomain globin gene

Hemoglobin A2: origin, evolution, and aftermath

Early evolution of microtubules and undulipodia

Flagellar beat patterns and their possible evolution

A temporary flagellate (mastigote) stage in the vahlkampfiid amoeba Willaertia magna and its possible evolutionary significance

The evolutionary origin and phylogeny of eukaryote flagella

Molecular analysis of archael flagellins: similarity to the type IV pilin-transport superfamily widespread in bacteria

Molecular evolution of the C-terminal cytoplasmic domain of a superfamily of bacterial receptors involved in taxis

Dynein family of motor proteins: present status and future questions

Origins of the nucleate organisms

The evolutionary origin and phylogeny of microtubules, mitotic spindles and eukaryote flagella

The evolution of cellular movement in eukaryotes: the role of microfilaments and microtubules

Kinesin Motor Phylogenetic Tree

Evolution of a dynamic cytoskeleton

Isolation, characterization and evolution of nine pufferfish (Fugu rubripes) actin genes

Evolution of chordate actin genes: evidence from genomic organization and amino acid sequences

Structural comparisons of muscle and nonmuscle actins give insights into the evolution of their functional differences

Molecular evolution of glutamate receptors: a primitive signaling mechanism that existed before plants and animals diverged.

Co-evolution of ligand-receptor pairs in the vasopressin/oxytocin superfamily of bioactive peptides

The evolution of the synapses in the vertebrate central nervous system

Evolutionary origins of multidrug and drug-specific efflux pumps in bacteria.

A comprehensive evolutionary analysis based on nucleotide and amino acid sequences of the alpha- and beta-subunits of glycoprotein hormone gene family.

The puzzle of the Krebs citric acid cycle: assembling the pieces of chemically feasible reactions, and opportunism in the design of metabolic pathways during evolution

The evolution of metabolic cycles

Evolution of the first metabolic cycles

Chemical evolution of the citric acid cycle: sunlight photolysis of the amino acids glutamate and aspartate

Speculations on the origin and evolution of metabolism

The Molecular Anatomy of an Ancient Adaptive Event

New prospects for deducing the evolutionary history of metabolic pathways in prokaryotes: aromatic biosynthesis as a case-in-point

Biochemical pathways in prokaryotes can be traced backward through evolutionary time

Enzyme specialization during the evolution of amino acid biosynthetic pathways

Enzyme recruitment in evolution of new function

Evolution of glycolysis

Bioenergetics: the evolution of molecular mechanisms and the development of bioenergetic concepts

Theoretical approaches to the evolutionary optimization of glycolysis--chemical analysis

The evolution of kinetoplastid glycosomes

Stepwise molecular evolution of bacterial photosynthetic energy conversion

Evolution of photosynthetic reaction centers and light harvesting chlorophyll proteins

Evolution of photosynthetic reaction centers

Early evolution of photosynthesis: clues from nitrogenase and chlorophyll iron proteins

Evolution of the control of pigment and plastid development in photosynthetic organisms

Chemical evolution of photosynthesis

Molecular evolution of ruminant lysozymes

Adaptive evolution of lysozyme: changes in amino acid sequence, regulation
of expression and gene number

Evolution of stomach lysozyme: the pig lysozyme gene

The evolution of trichromatic color vision by opsin gene duplication in New World and Old World primates

The Evolution of Color Vision

Molecular basis for tetrachromatic color vision

Molecular evolution of the Rh3 gene in Drosophila

Interphotoreceptor retinoid-binding protein. Gene characterization, protein repeat structure, and its evolution

Spectral tuning and molecular evolution of rod visual pigments in the species flock of cottoid fish in Lake Baikal

The evolution of rhodopsins and neurotransmitter receptors

Optimization, constraint, and history in the evolution of eyes

A pessimistic estimate of the time required for an eye to evolve

Sequence analysis of teleost retina-specific lactate dehydrogenase C: evolutionary implications for the vertebrate lactate dehydrogenase gene family

The eye of the blind mole rat (Spalax ehrenbergi): regressive evolution at the molecular level

The evolution of eyes.

Programming the Drosophila embryo

Evolution of chordate hox gene clusters

Hox genes in brachiopods and priapulids and protostome evolution.

Radical evolutionary change possible in a few generations

Evolution Re-Sculpted Animal Limbs By Genetic Switches Once Thought Too Drastic For Survival

Flatworms Are Oldest Living Ancestors To Those Of Us With Right And Left Sides Researchers Report In Science

The origin and evolution of animal appendages

Hox genes in evolution: protein surfaces and paralog groups

Evolution of the insect body plan as revealed by the Sex combs reduced expression pattern

Sea urchin Hox genes: insights into the ancestral Hox cluster

Theoretical approaches to the analysis of homeobox gene evolution

Teleost HoxD and HoxA genes: comparison with tetrapods and functional evolution of the HOXD complex

Evolutionary origin of insect wings from ancestral gills

Tracing backbone evolution through a tunicate's lost tail

Classification and phylogeny of the MADS-box multigene family suggest defined roles of MADS-box gene subfamilies in the morphological evolution of eukaryotes

Modification of expression and cis-regulation of Hoxc8 in the evolution of diverged axial morphology.

The ParaHox gene cluster is an evolutionary sister of the Hox gene cluster.

Gene duplications in evolution of archaeal family B DNA polymerases

Adaptive amino acid replacements accompanied by domain fusion in reverse transcriptase

Molecular evolution of genes encoding ribonucleases in ruminant species

Studies on the sites expressing evolutionary changes in the structure of eukaryotic 5S ribosomal RNA

Evolution of a Transfer RNA Gene Through a Point Mutation in the Anticodon

Archaeal translation initiation revisited: the initiation factor 2 and eukaryotic initiation factor 2B alpha-beta-delta subunit families

Universally conserved translation initiation factors

Genetic code in evolution: switching species-specific aminoacylation with a peptide transplant

Evolution of transcriptional regulatory elements within the promoter of a mammalian gene.

Codon reassignment and amino acid composition in hemichordate mitochondria.

Reconstructing the evolution of vertebrate blood coagulation from a consideration of the amino acid sequences of clotting proteins

Determining divergence times of the major kingdoms of living organisms with a protein clock

The multiplicity of domains in proteins

Characterization, primary structure, and evolution of lamprey plasma albumin

The origins and evolution of eukaryotic proteins

Evolution of vertebrate fibrin formation and the process of its dissolution.

Vastly Different Virus Families May Be Related

Selective sweep of a newly evolved sperm-specific gene in Drosophila

Activated acetic acid by carbon fixation on (Fe,Ni)S under primordial conditions

Molecular evolution of the histidine biosynthetic pathway

Accelerated evolution in inhibitor domains of porcine elafin family members

Tandem arrangement of the human serum albumin multigene family in the sub-centromeric region of 4q: evolution and chromosomal direction of transcription

The B12-dependent ribonucleotide reductase from the archaebacterium Thermoplasma acidophila: an evolutionary solution to the ribonucleotide reductase conundrum

Ancient divergence of long and short isoforms of adenylate kinase: molecular evolution of the nucleoside monophosphate kinase family

Convergent evolution of antifreeze glycoproteins in Antarctic notothenioid fish and Arctic cod

Evolution of antifreeze glycoprotein gene from a trypsinogen gene in Antarctic notothenioid fish

Evolution of an antifreeze glycoprotein

A model for the evolution of the plastid sec apparatus inferred from secY gene phylogeny

The evolutionary history of the amylase multigene family in Drosophila pseudoobscura

Accelerated evolution of Trimeresurus okinavensis venom gland phospholipase A2 isozyme-encoding genes

The evolution of an allosteric site in phosphorylase

Molecular evolution of fish neurohypophysial hormones: neutral and selective evolutionary mechanisms

Pseudogenes in ribonuclease evolution: a source of new biomacromolecular function?

Evolution of hemopoietic ligands and their receptors. Influence of positive selection on correlated replacements throughout ligand and receptor proteins

Evolutionary relationships of the carbamoylphosphate synthetase genes

The molecular evolution of the small heat-shock proteins in plants

Phylogenetic analysis of carbamoylphosphate synthetase genes: complex evolutionary history includes an internal duplication within a gene which can root the tree of life

Duplication and functional divergence in the chalcone synthase gene family of Asteraceae: evolution with substrate change and catalytic simplification

Evolutionary history of the 11p15 human mucin gene family.

Molecular evolution of the aldo-keto reductase gene superfamily.

Molecular evolution allows bypass of the requirement for activation loop phosphorylation of the Cdc28 cyclin-dependent kinase.

A Classification of Possible Routes of Darwinian Evolution

Generation of evolutionary novelty by functional shift

Mobile DNA Sequences Could Be The Cause Of Chromosomal Mutations During The Evolution Of Species

A domain model for eukaryotic DNA organization: a molecular basis for cell differentiation and chromosome evolution.

The domain model for eukaryotic DNA organization. 2: A molecular basis for constraints on development and evolution.

Minor Shuffle Makes Protein Fold

Genetic Stowaways May Contribute To Evolutionary Change

Evolutionary Molecular Mechanism In Mammals Found

Complete Genomes

Genetic redundancy caused by gene duplications and its evolution in networks of transcriptional regulators

Strong evolutionary conservation of broadly expressed protein isoforms in the troponin I gene family and other vertebrate gene families

Cases of ancient mobile element DNA insertions that now affect gene regulation

Punctuated evolution caused by selection of rare beneficial mutations

The origin of programmed cell death

The origin and early development of biological catalysts

DNA secondary structures and the evolution of hypervariable tandem arrays

Episodic adaptive evolution of primate lysozymes

Genome plasticity as a paradigm of eubacteria evolution

Evolutionary motif and its biological and structural significance

Neutral and nonneutral mutations: the creative mix--evolution of complexity in gene interaction systems

Exon shuffling and other ways of module exchange

Introns and gene evolution

New Drosophila introns originate by duplication.

Evolution and the structural domains of proteins

The role of constrained self-organization in genome structural evolution

A possible origin of newly-born bacterial genes: significance of GC-rich nonstop frame on antisense strand

The coevolution of gene family trees

The evolution of metabolic cycles

The emergence of major cellular processes in evolution

A hardware interpretation of the evolution of the genetic code

Speculations on the origin and evolution of metabolism

Probabilistic reconstruction of ancestral protein sequences

The contribution of slippage-like processes to genome evolution

Molecular evolution in bacteria

The structural basis of molecular adaptation.

Mitochondrial DNA: molecular fossils in the nucleus

Cases of ancient mobile element DNA insertions that now affect gene regulation

Tiggers and DNA transposon fossils in the human genome

The eye of the blind mole rat (Spalax ehrenbergi): regressive evolution at the molecular level

Tiggers and DNA transposon fossils in the human genome

Gene competition and the possible evolutionary role of tumours

New Scientist Planet Science: Replaying life

Molecular evolution of an arsenate detoxification pathway by DNA shuffling

UB Researcher Developing Method That Employs Evolution To Develop New Drug Leads

Directed evolution of a type I antifreeze protein expressed in Escherichia coli with sodium chloride as selective pressure and its effect on antifreeze tolerance

Directed evolution of biosynthetic pathways. Recruitment of cysteine thioethers for constructing the cell wall of Escherichia coli

Exploring the functional robustness of an enzyme by in vitro evolution

Evolutionary algorithms in computer-aided molecular design

Mutations to the Rescue

Evolution of Enzymes for the Metabolism of New Chemical Inputs into the Environment

Evolution of Amino Acid Metabolism Inferred through Cladistic Analysis

Integrating the Universal Metabolism into a Phylogenetic Analysis

Invertebrate Data Predict an Early Emergence of Vertebrate Fibrillar Collagen Clades and an Anti-incest Model

Tachykinin and Tachykinin Receptor of an Ascidian, Ciona intestinalis: EVOLUTIONARY ORIGIN OF THE VERTEBRATE TACHYKININ FAMILY

DNA Replication Fidelity

Serial segmental duplications during primate evolution result in complex human genome architecture

Phylogeny determined by protein domain content

Evolutionary Genomics of Nuclear Receptors: From Twenty-Five Ancestral Genes to Derived Endocrine Systems

Gene Loss, Protein Sequence Divergence, Gene Dispensability, Expression Level, and Interactivity Are Correlated in Eukaryotic Evolution

The Evolution of Controlled Multitasked Gene Networks: The Role of Introns and Other Noncoding RNAs in the Development of Complex Organisms

Phylogenetic Dating and Characterization of Gene Duplications in Vertebrates: The Cartilaginous Fish Reference

Dating the Tree of Life

An Insect Molecular Clock Dates the Origin of the Insects and Accords with Palaeontological and Biogeographic Landmarks

Diversity, taxonomy and evolution of medium-chain dehydrogenase/reductase superfamily

Molecular archaeology of the Escherichia coli genome

Comparative Genomics of the Eukaryotes

Millions of Years of Evolution Preserved: A Comprehensive Catalog of the Processed Pseudogenes in the Human Genome

Asymmetric Sequence Divergence of Duplicate Genes

The Genetic Core of the Universal Ancestor

Evolutionary History of Chromosome 20

The Complete Mitochondrial DNA Sequence of Scenedesmus obliquus Reflects an Intermediate Stage in the Evolution of the Green Algal Mitochondrial Genome

Reconstructing large regions of an ancestral mammalian genome in silico

Occurrence and Consequences of Coding Sequence Insertions and Deletions in Mammalian Genomes

The Origin of Human Chromosome 1 and Its Homologs in Placental Mammals

Sister grouping of chimpanzees and humans as revealed by genome-wide phylogenetic analysis of brain gene expression profiles

Genome Evolution at the Genus Level: Comparison of Three Complete Genomes of Hyperthermophilic Archaea

The Evolution of Trichromatic Color Vision by Opsin Gene Duplication in New World and Old World Primates

Obcells as Proto-Organisms: Membrane Heredity, Lithophosphorylation, and the Origins of the Genetic Code, the First Cells, and Photosynthesis (Journal of Molecular Evolution, Volume 53 - Number 4/5, 2001)

N-Carbamoyl Amino Acid Solid-Gas Nitrosation by NO/NOx: A New Route to Oligopeptides via alpha-Amino Acid N-Carboxyanhydride. Prebiotic Implications (Journal of Molecular Evolution, Volume 48 - Number 6, 1999

Chemical interactions between amino acid and RNA: multiplicity of the levels of specificity explains origin of the genetic code (Naturwissenschaften, Volume 89 Number 12 December 2002)

The Nicotinamide Biosynthetic Pathway Is a By-Product of the RNA World (Journal of Molecular Evolution, Volume 52 - Number 1, 2001)

On the RNA World: Evidence in Favor of an Early Ribonucleopeptide World

Inhibition of Ribozymes by Deoxyribonucleotides and the Origin of DNA

Genetic Code Origin: Are the Pathways of Type Glu-tRNAGln to Gln-tRNAGln Molecular Fossils or Not?

Researchers Engineer A Way To Improve T-Cell Receptors

Digital Organisms Give Life To Questions Of Evolution

Lies, Damned lies, Statistics, and Probability of Abiogenesis Calculations

Purdue Study Breathes New Life Into Question Of How Life Began

Ammonia From The Earth's Deep Oceans A Key Step In The Search For Life's Origins

Whitehead Study Supports Existence Of Ancient RNA World Helps Provide Insight Into Early Evolution Of Life

Yale Scientists Recreate Molecular Fossils Now Extinct That May Have Existed At The Beginning Of Life

A whole old world

The path from the RNA world.

Relics from the RNA world.

A supersymmetric model for the evolution of the genetic code.

The hydrogen hypothesis for the first eukaryote.

Kick-start for life on earth

The Beginnings of Life on Earth

Are the Odds Against the Origin of Life Too Great to Accept? : Addenda to Review of David Foster's The Philosophical Scientists

You asked for "(cow into walrus, frog into kitten. etc.)", how about a fossil sequence showing transitionals from fish to elephant? All of the named specimens are actual fossil finds:
Fish to Amphibian transition:

1. Cheirolepis, (early Devonian, 400 million years ago) -- Primitive bony ray-finned fishes that gave rise to the vast majority of living fish. Heavy acanthodian-type scales, acanthodian-like skull, and big notocord.

2. Osteolepis (mid-Devonian, 390 million years ago) -- One of the earliest crossopterygian lobe-finned fishes, still sharing some characters with the lungfish (the other lobe-finned fishes). Had paired fins with a leg-like arrangement of major limb bones, capable of flexing at the "elbow", and had an early-amphibian-like skull and teeth.

3. Eusthenopteron, Sterropterygion (mid-late Devonian, 380 million years ago) -- Early rhipidistian lobe-finned fish roughly intermediate between early crossopterygian fish and the earliest amphibians. Skull very amphibian-like. Strong amphibian- like backbone. Fins very like early amphibian feet in the overall layout of the major bones, muscle attachments, and bone processes, with tetrapod-like tetrahedral humerus, and tetrapod-like elbow and knee joints. But there are no perceptible "toes", just a set of identical fin rays. Body & skull proportions rather fishlike.

4. Panderichthys, Elpistostege (mid-late Devonian, about 370 Mya) -- These "panderichthyids" are very tetrapod-like lobe-finned fish. Unlike Eusthenopteron, these fish actually look like tetrapods in overall proportions (flattened bodies, dorsally placed orbits, frontal bones! in the skull, straight tails, etc.) and have remarkably foot-like fins.

5. Obruchevichthys(middle Late Devonian, about 370 Mya -- Discovered in 1991 in Scotland, these are the earliest known tetrapod remains. The humerus is mostly tetrapod-like but retains some fish features. The discoverer, Ahlberg (1991), said: "It [the humerus] is more tetrapod-like than any fish humerus, but lacks the characteristic early tetrapod 'L-shape'...this seems to be a primitive, fish-like character....although the tibia clearly belongs to a leg, the humerus differs enough from the early tetrapod pattern to make it uncertain whether the appendage carried digits or a fin. At first sight the combination of two such extremities in the same animal seems highly unlikely on functional grounds. If, however, tetrapod limbs evolved for aquatic rather than terrestrial locomotion, as recently suggested, such a morphology might be perfectly workable."

6. Hynerpeton, Acanthostega, Ichthyostega (late Devonian, 360 Mya) -- A little later, the fin-to-foot transition was almost complete, and we have a set of early tetrapod fossils that clearly did have feet. The most complete are Ichthyostega, Acanthostega gunnari, and the newly described Hynerpeton bassetti (Daeschler et al., 1994). (There are also other genera known from more fragmentary fossils.) Hynerpeton is the earliest of these three genera (365 Ma), but is more advanced in some ways; the other two genera retained more fish- like characters longer than the Hynerpeton lineage did. Acanthostega still had internal gills, adding further support to the suggestion that unique tetrapod characters such as limbs with digits evolved first for use in water rather than for walking on land. Acanthostega also had a remarkably fish-like shoulder and forelimb. Ichthyostega was also very fishlike, retaining a fish-like finned tail, permanent lateral line system, and notochord. It turns out that Acanthostega's front foot had eight toes, and Ichthyostega's hind foot had seven toes, giving both feet the look of a short, stout flipper with many "toe rays" similar to fin rays. All you have to do to a lobe- fin to make it into a many-toed foot like this is curl it, wrapping the fin rays forward around the end of the limb. In fact, this is exactly how feet develop in larval amphibians, from a curled limb bud. Hynerpeton, in contrast, probably did not have internal gills and already had a well-developed shoulder girdle; it could elevate and retract its forelimb strongly, and it had strong muscles that attached the shoulder to the rest of the body (Daeschler et al., 1994).

7. Labyrinthodonts (eg Pholidogaster, Pteroplax) (late Dev./early Miss., 355 Mya) -- These larger amphibians still have some icthyostegid fish features, such as skull bone patterns, labyrinthine tooth dentine, presence & pattern of large palatal tusks, the fish skull hinge, pieces of gill structure between cheek & shoulder, and the vertebral structure. But they have lost several other fish features: the fin rays in the tail are gone, the vertebrae are stronger and interlocking, the nasal passage for air intake is well defined, etc.

Amphibian to Reptile transition:

8. Pholidogaster (Mississippian, about 330 Ma) -- A group of large labrinthodont amphibians, transitional between the early amphibians (the ichthyostegids, described above) and later amphibians such as rhachitomes and anthracosaurs.

9. Proterogyrinus (late Mississippian, 325 Mya) -- Classic labyrinthodont-amphibian skull and teeth, but with reptilian vertebrae, pelvis, humerus, and digits. Still has fish skull hinge. Amphibian ankle. 5-toed hand and a 2-3-4-5-3 (almost reptilian) phalangeal count.

10. Limnoscelis, Tseajaia (late Carboniferous, 300 Mya) -- Amphibians apparently derived from the early anthracosaurs, but with additional reptilian features: structure of braincase, reptilian jaw muscle, expanded neural arches.

11. Solenodonsaurus (mid-Pennsylvanian) -- An incomplete fossil, apparently between the anthracosaurs and the cotylosaurs. Loss of palatal fangs, loss of lateral line on head, etc. Still just a single sacral vertebra, though.

12. Hylonomus, Paleothyris (early Pennsylvanian) -- These are protorothyrids, very early cotylosaurs (primitive reptiles). They were quite little, lizard-sized animals with amphibian-like skulls (amphibian pineal opening, dermal bone, etc.), shoulder, pelvis, & limbs, and intermediate teeth and vertebrae. Rest of skeleton reptilian, with reptilian jaw muscle, no palatal fangs, and spool-shaped vertebral centra. Probably no eardrum yet.

13. Paleothyris (early Pennsylvanian) -- An early captorhinomorph reptile, with no temporal fenestrae at all.

14. Protoclepsydrops haplous (early Pennsylvanian) -- The earliest known synapsid reptile. Little temporal fenestra, with all surrounding bones intact. Had amphibian-type vertebrae with tiny neural processes. (reptiles had only just separated from the amphibians)

15. Clepsydrops (early Pennsylvanian) -- The second earliest known synapsid.

Reptile to Mammal transition:

16. Archaeothyris (early-mid Pennsylvanian) -- A slightly later ophiacodont. Small temporal fenestra, now with some reduced bones (supratemporal). Braincase still just loosely attached to skull. Slight hint of different tooth types. Still has some extremely primitive, amphibian/captorhinid features in the jaw, foot, and skull. Limbs, posture, etc. typically reptilian, though the ilium (major hip bone) was slightly enlarged.

17. Varanops (early Permian) -- Temporal fenestra further enlarged. Braincase floor shows first mammalian tendencies & first signs of stronger attachment to rest of skull (occiput more strongly attached). Lower jaw shows first changes in jaw musculature (slight coronoid eminence). Body narrower, deeper: vertebral column more strongly constructed. Ilium further enlarged, lower-limb musculature starts to change (prominent fourth trochanter on femur). This animal was more mobile and active. Too late to be a true ancestor, and must be a "cousin".

18. Haptodus (late Pennsylvanian) -- One of the first known sphenacodonts, showing the initiation of sphenacodont features while retaining many primitive features of the ophiacodonts. Occiput still more strongly attached to the braincase. Teeth become size-differentiated, with biggest teeth in canine region and fewer teeth overall. Stronger jaw muscles. Vertebrae parts & joints more mammalian. Neural spines on vertebrae longer. Hip strengthened by fusing to three sacral vertebrae instead of just two. Limbs very well developed.

19. Dimetrodon, Sphenacodon or a similar sphenacodont (late Pennsylvanian to early Permian, 270 Ma) -- More advanced pelycosaurs, clearly closely related to the first therapsids (next). Dimetrodon is almost definitely a "cousin" and not a direct ancestor, but as it is known from very complete fossils, it's a good model for sphenacodont anatomy. Medium-sized fenestra. Teeth further differentiated, with small incisors, two huge deep- rooted upper canines on each side, followed by smaller cheek teeth, all replaced continuously. Fully reptilian jaw hinge. Lower jaw bone made of multiple bones & with first signs of a bony prong later involved in the eardrum, but there was no eardrum yet, so these reptiles could only hear ground-borne vibrations (they did have a reptilian middle ear). Vertebrae had still longer neural spines (spectacularly so in Dimetrodon, which had a sail), and longer transverse spines for stronger locomotion muscles.

20. Biarmosuchia (late Permian) -- A therocephalian -- one of the earliest, most primitive therapsids. Several primitive, sphenacodontid features retained: jaw muscles inside the skull, platelike occiput, palatal teeth. New features: Temporal fenestra further enlarged, occupying virtually all of the cheek, with the supratemporal bone completely gone. Occipital plate slanted slightly backwards rather than forwards as in pelycosaurs, and attached still more strongly to the braincase. Upper jaw bone (maxillary) expanded to separate lacrymal from nasal bones, intermediate between early reptiles and later mammals. Still no secondary palate, but the vomer bones of the palate developed a backward extension below the palatine bones. This is the first step toward a secondary palate, and with exactly the same pattern seen in cynodonts. Canine teeth larger, dominating the dentition. Variable tooth replacement: some therocephalians (e.g Scylacosaurus) had just one canine, like mammals, and stopped replacing the canine after reaching adult size. Jaw hinge more mammalian in position and shape, jaw musculature stronger (especially the mammalian jaw muscle). The amphibian-like hinged upper jaw finally became immovable. Vertebrae still sphenacodontid-like. Radical alteration in the method of locomotion, with a much more mobile forelimb, more upright hindlimb, & more mammalian femur & pelvis. Primitive sphenacodontid humerus. The toes were approaching equal length, as in mammals, with #toe bones varying from reptilian to mammalian. The neck & tail vertebrae became distinctly different from trunk vertebrae. Probably had an eardrum in the lower jaw, by the jaw hinge.

21. Procynosuchus (latest Permian) -- The first known cynodont -- a famous group of very mammal-like therapsid reptiles, sometimes considered to be the first mammals. Probably arose from the therocephalians, judging from the distinctive secondary palate and numerous other skull characters. Enormous temporal fossae for very strong jaw muscles, formed by just one of the reptilian jaw muscles, which has now become the mammalian masseter. The large fossae is now bounded only by the thin zygomatic arch (cheekbone to you & me). Secondary palate now composed mainly of palatine bones (mammalian), rather than vomers and maxilla as in older forms; it's still only a partial bony palate (completed in life with soft tissue). Lower incisor teeth was reduced to four (per side), instead of the previous six (early mammals had three). Dentary now is 3/4 of lower jaw; the other bones are now a small complex near the jaw hinge. Jaw hinge still reptilian. Vertebral column starts to look mammalian: first two vertebrae modified for head movements, and lumbar vertebrae start to lose ribs, the first sign of functional division into thoracic and lumbar regions. Scapula beginning to change shape. Further enlargement of the ilium and reduction of the pubis in the hip. A diaphragm may have been present.

22. Dvinia [also "Permocynodon"] (latest Permian) -- Another early cynodont. First signs of teeth that are more than simple stabbing points -- cheek teeth develop a tiny cusp. The temporal fenestra increased still further. Various changes in the floor of the braincase; enlarged brain. The dentary bone was now the major bone of the lower jaw. The other jaw bones that had been present in early reptiles were reduced to a complex of smaller bones near the jaw hinge. Single occipital condyle splitting into two surfaces. The postcranial skeleton of Dvinia is virtually unknown and it is not therefore certain whether the typical features found at the next level had already evolved by this one. Metabolic rate was probably increased, at least approaching homeothermy.

23. Thrinaxodon (early Triassic) -- A more advanced "galesaurid" cynodont. Further development of several of the cynodont features seen already. Temporal fenestra still larger, larger jaw muscle attachments. Bony secondary palate almost complete. Functional division of teeth: incisors (four uppers and three lowers), canines, and then 7-9 cheek teeth with cusps for chewing. The cheek teeth were all alike, though (no premolars & molars), did not occlude together, were all single- rooted, and were replaced throughout life in alternate waves. Dentary still larger, with the little quadrate and articular bones were loosely attached. The stapes now touched the inner side of the quadrate. First sign of the mammalian jaw hinge, a ligamentous connection between the lower jaw and the squamosal bone of the skull. The occipital condyle is now two slightly separated surfaces, though not separated as far as the mammalian double condyles. Vertebral connections more mammalian, and lumbar ribs reduced. Scapula shows development of a new mammalian shoulder muscle. Ilium increased again, and all four legs fully upright, not sprawling. Tail short, as is necessary for agile quadrupedal locomotion. The whole locomotion was more agile. Number of toe bones is 2.3.4.4.3, intermediate between reptile number (2.3.4.5.4) and mammalian (2.3.3.3.3), and the "extra" toe bones were tiny. Nearly complete skeletons of these animals have been found curled up - a possible reaction to conserve heat, indicating possible endothermy? Adults and juveniles have been found together, possibly a sign of parental care. The specialization of the lumbar area (e.g. reduction of ribs) is indicative of the presence of a diaphragm, needed for higher O2 intake and homeothermy. NOTE on hearing: The eardrum had developed in the only place available for it -- the lower jaw, right near the jaw hinge, supported by a wide prong (reflected lamina) of the angular bone. These animals could now hear airborne sound, transmitted through the eardrum to two small lower jaw bones, the articular and the quadrate, which contacted the stapes in the skull, which contacted the cochlea. Rather a roundabout system and sensitive to low-frequency sound only, but better than no eardrum at all! Cynodonts developed quite loose quadrates and articulars that could vibrate freely for sound transmittal while still functioning as a jaw joint, strengthened by the mammalian jaw joint right next to it. All early mammals from the Lower Jurassic have this low-frequency ear and a double jaw joint. By the middle Jurassic, mammals lost the reptilian joint (though it still occurs briefly in embryos) and the two bones moved into the nearby middle ear, became smaller, and became much more sensitive to high-frequency sounds.

24. Cynognathus (early Triassic, 240 Ma; suspected to have existed even earlier) -- We're now at advanced cynodont level. Temporal fenestra larger. Teeth differentiating further; cheek teeth with cusps met in true occlusion for slicing up food, rate of replacement reduced, with mammalian-style tooth roots (though single roots). Dentary still larger, forming 90% of the muscle-bearing part of the lower jaw. TWO JAW JOINTS in place, mammalian and reptilian: A new bony jaw joint existed between the squamosal (skull) and the surangular bone (lower jaw), while the other jaw joint bones were reduced to a compound rod lying in a trough in the dentary, close to the middle ear. Ribs more mammalian. Scapula halfway to the mammalian condition. Limbs were held under body. There is possible evidence for fur in fossil pawprints.

25. Diademodon (early Triassic, 240 Ma; same strata as Cynognathus) -- Temporal fenestra larger still, for still stronger jaw muscles. True bony secondary palate formed exactly as in mammals, but didn't extend quite as far back. Turbinate bones possibly present in the nose (warm-blooded?). Dental changes continue: rate of tooth replacement had decreased, cheek teeth have better cusps & consistent wear facets (better occlusion). Lower jaw almost entirely dentary, with tiny articular at the hinge. Still a double jaw joint. Ribs shorten suddenly in lumbar region, probably improving diaphragm function & locomotion. Mammalian toe bones (2.3.3.3.3), with closely related species still showing variable numbers.

26. Probelesodon (mid-Triassic; South America) -- Fenestra very large, still separate from eyesocket (with postorbital bar). Secondary palate longer, but still not complete. Teeth double-rooted, as in mammals. Nares separated. Second jaw joint stronger. Lumbar ribs totally lost; thoracic ribs more mammalian, vertebral connections very mammalian. Hip & femur more mammalian.

27. Probainognathus (mid-Triassic, 239-235 Ma, Argentina) -- Larger brain with various skull changes: pineal foramen ("third eye") closes, fusion of some skull plates. Cheekbone slender, low down on the side of the eye socket. Postorbital bar still there. Additional cusps on cheek teeth. Still two jaw joints. Still had cervical ribs & lumbar ribs, but they were very short. Reptilian "costal plates" on thoracic ribs mostly lost. Mammalian #toe bones.

28. Pachygenelus, Diarthrognathus (earliest Jurassic, 209 Ma) -- These are trithelodontids. Inflation of nasal cavity, establishment of Eustachian tubes between ear and pharynx, loss of postorbital bar. Alternate replacement of mostly single- rooted teeth. This group also began to develop double tooth roots -- in Pachygenelus the single root of the cheek teeth begins to split in two at the base. Pachygenelus also has mammalian tooth enamel, and mammalian tooth occlusion. Double jaw joint, with the second joint now a dentary-squamosal (instead of surangular), fully mammalian. Incipient dentary condyle. Reptilian jaw joint still present but functioning almost entirely in hearing; postdentary bones further reduced to tiny rod of bones in jaw near middle ear; probably could hear high frequencies now. More mammalian neck vertebrae for a flexible neck. Hip more mammalian, with a very mammalian iliac blade & femur. Highly mobile, mammalian-style shoulder. Probably had coupled locomotion & breathing.

29. Sinoconodon (early Jurassic, 208 Ma) -- The next known very ancient proto-mammal. Eyesocket fully mammalian now (closed medial wall). Hindbrain expanded. Permanent cheekteeth, like mammals, but the other teeth were still replaced several times. Mammalian jaw joint stronger, with large dentary condyle fitting into a distinct fossa on the squamosal. This final refinement of the joint automatically makes this animal a true "mammal". Reptilian jaw joint still present, though tiny.

Proto-mammal to Placental Mammal transition:

30. Kuehneotherium (early Jurassic, about 205 Ma) -- A slightly later proto-mammal, sometimes considered the first known pantothere (primitive placental-type mammal). Teeth and skull like a placental mammal. The three major cusps on the upper & lower molars were rotated to form interlocking shearing triangles as in the more advanced placental mammals & marsupials. Still has a double jaw joint, though.

31. Eozostrodon, Morganucodon, Haldanodon (early Jurassic, ~205 Ma) -- A group of early proto-mammals called "morganucodonts". The restructuring of the secondary palate and the floor of the braincase had continued, and was now very mammalian. Truly mammalian teeth: the cheek teeth were finally differentiated into simple premolars and more complex molars, and teeth were replaced only once. Triangular- cusped molars. Reversal of the previous trend toward reduced incisors, with lower incisors increasing to four. Tiny remnant of the reptilian jaw joint. Once thought to be ancestral to monotremes only, but now thought to be ancestral to all three groups of modern mammals -- monotremes, marsupials, and placentals.

32. Peramus (late Jurassic, about 155 Ma) -- A "eupantothere" (more advanced placental-type mammal). The closest known relative of the placentals & marsupials. Triconodont molar has with more defined cusps. This fossil is known only from teeth, but judging from closely related eupantotheres (e.g. Amphitherium) it had finally lost the reptilian jaw joint, attaing a fully mammalian three-boned middle ear with excellent high-frequency hearing. Has only 8 cheek teeth, less than other eupantotheres and close to the 7 of the first placental mammals. Also has a large talonid on its "tribosphenic" molars, almost as large as that of the first placentals -- the first development of grinding capability.

33. Endotherium (very latest Jurassic, 147 Ma) -- An advanced eupantothere. Fully tribosphenic molars with a well- developed talonid. Known only from one specimen. From Asia; recent fossil finds in Asia suggest that the tribosphenic molar evolved there.

34. Vincelestes neuquenianus (early Cretaceous, 135 Ma) -- A probably-placental mammal with some marsupial traits, known from some nice skulls. Placental-type braincase and coiled cochlea. Its intracranial arteries & veins ran in a composite monotreme/placental pattern derived from homologous extracranial vessels in the cynodonts. (Rougier et al., 1992)

35. Kennalestes and Asioryctes (late Cretaceous, Mongolia) -- Small, slender animals; eyesocket open behind; simple ring to support eardrum; primitive placental-type brain with large olfactory bulbs; basic primitive tribosphenic tooth pattern. Canine now double rooted. Still just a trace of a non-dentary bone, the coronoid, on the otherwise all-dentary jaw. "Could have given rise to nearly all subsequent placentals." says Carroll (1988).

Placental mammal to elephant transition:

36. Protungulatum (latest Cretaceous) -- Transitional between earliest placental mammals and the condylarths (primitive, small hoofed animals). These early, simple insectivore- like small mammals had one new development: their cheek teeth had grinding surfaces instead of simple, pointed cusps. They were the first mammal herbivores. All their other features are generalized and primitive -- simple plantigrade five-toed clawed feet, all teeth present (3:1:4:3) with no gaps, all limb bones present and unfused, pointy-faced, narrow small brain, eyesocket not closed.

37. Minchenella or a similar condylarth (late Paleocene) -- Known only from lower jaws. Has a distinctive broadened shelf on the third molar.

38. Phenacolophus (late Paleocene or early Eocene) -- An early embrithopod (very early, slightly elephant-like condylarths), thought to be the stem-group of all elephants.

39. Pilgrimella (early Eocene) -- An anthracobunid (early proto-elephant condylarth), with massive molar cusps aligned in two transverse ridges.

40. Unnamed species of proto-elephant (early Eocene) -- Discovered recently in Algeria. Had slightly enlarged upper incisors (the beginnings of tusks), and various tooth reductions. Still had "normal" molars instead of the strange multi-layered molars of modern elephants. Had the high forehead and pneumatized skull bones of later elephants, and was clearly a heavy-boned, slow animal. Only one meter tall.

41. Moeritherium, Numidotherium, Barytherium (early-mid Eocene) -- A group of three similar very early elephants. It is unclear which of the three came first. Pig-sized with stout legs, broad spreading feet and flat hooves. Elephantish face with the eye set far forward & a very deep jaw. Second incisors enlarged into short tusks, in upper and lower jaws; little first incisors still present; loss of some teeth. No trunk.

42. Paleomastodon, Phiomia (early Oligocene) -- The first "mastodonts", a medium-sized animals with a trunk, long lower jaws, and short upper and lower tusks. Lost first incisors and canines. Molars still have heavy rounded cusps, with enamel bands becoming irregular. Phiomia was up to eight feet tall.

43. Gomphotherium (early Miocene) -- Basically a large edition of Phiomia, with tooth enamel bands becoming very irregular. Two long rows cusps on teeth became cross- crests when worn down. Gave rise to several families of elephant- relatives that spread all over the world. From here on the elephant lineages are known to the species level.

44a. The mastodon lineage split off here, becoming more adapted to a forest browser niche, and going through Miomastodon (Miocene) and Pliomastodon (Pliocene), to Mastodon (or "Mammut", Pleistocene).

44b. Meanwhile, the elephant lineage became still larger, adapting to a savannah/steppe grazer niche:

45. Stegotetrabelodon (late Miocene) -- One of the first of the "true" elephants, but still had two long rows of cross-crests, functional premolars, and lower tusks. Other early Miocene genera show compression of the molar cusps into plates (a modern feature ), with exactly as many plates as there were cusps. Molars start erupting from front to back, actually moving forward in the jaw throughout life.

46. Primelephas (latest Miocene) -- Short lower jaw makes it look like an elephant now. Reduction & loss of premolars. Very numerous plates on the molars, now; we're now at the modern elephants' bizarre system of one enormous multi-layered molar being functional at a time, moving forward in the jaw.

47. Primelephas gomphotheroides (mid-Pliocene) -- A later species that split into three lineages, Loxodonta, Elephas, and Mammuthus:

  1. Loxodonta adaurora (5 Ma). Gave rise to the modern African elephant Loxodonta africana about 3.5 Ma.
  2. Elephas ekorensis (5 Ma), an early Asian elephant with rather primitive molars, clearly derived directly from P. gomphotheroides. Led directly to:
    • Elephas recki, which sent off one side branch, E. hydrusicus, at 3.8 Ma, and then continued changing on its own until it became E. iolensis.
    • Elephas maximus, the modern Asian elephant, clearly derived from
    • E. hysudricus. Strikingly similar to young E. hysudricus animals. Possibly a case of neoteny (in which "new" traits are simply juvenile features retained into adulthood).
  3. Mammuthus meridionalis, clearly derived from P. gomphotheroides. Spread around the northern hemisphere. In Europe, led to M. armeniacus/trogontherii, and then to M. primigenius. In North America, led to M. imperator and then M. columbi.
The Pleistocene record for elephants is very good. In general, after the earliest forms of the three modern genera appeared, they show very smooth, continuous evolution with almost half of the speciation events preserved in fossils. For instance, Carroll (1988) says: "Within the genus Elephas, species demonstrate continuous change over a period of 4.5 million years. ...the elephants provide excellent evidence of significant morphological change within species, through species within genera, and through genera within a family...."

Species-species transitions among the elephants:

  • Maglio (1973) studied Pleistocene elephants closely. Overall, Maglio showed that at least 7 of the 17 Quaternary elephant species arose through smooth anagenesis transitions from their ancestors. For example, he said that Elephas recki "can be traced through a progressive series of stages...These stages pass almost imperceptibly into each other....In the late Pleistocene a more progressive elephant appears which I retain as a distinct species, E. iolensis, only as a matter of convenience. Although as a group, material referred to E. iolensis is distinct from that of E. recki, some intermediate specimens are known, and E. iolensis seems to represent a very progressive, terminal stage in the E. recki specific lineage."
  • Maglio also documented very smooth transitions between three Eurasian mammoth species: Mammuthus meridionalis --> M. armeniacus (or M. trogontherii) --> M. primigenius.
  • Lister (1993) reanalyzed mammoth teeth and confirmed Maglio's scheme of gradual evolution in European mammoths, and found evidence for gradual transitions in the North American mammoths too.
(Most of the above text is from the link provided at the start of this post, and is the result of hard work by Kathleen Hunt, who deserves the credit. I've just extracted the relevant individual portions and assembled them into one direct fish-to-elephant sequence.) If you like that, here are a few hundred more.

Similar fossil sequences can be listed for the majority of other major-group transitions.

Oh, heck, I suppose I have time for one more. How about the dinosaur-to-bird transition?

The cladogram for the evolution of flight looks like this:

(Note -- each name along the top is a known transitional fossil; and those aren't all that have been discovered.) Here's a more detailed look at the middle section:

Fossils discovered in the past ten years in China have answered most of the "which came first" questions about the evolution of birds from dinosaurs.

We now know that downy feathers came first, as seen in this fossil of Sinosauropteryx:

That's a close-up of downy plumage along the backbone. Here's a shot of an entire fossil

Sinosauropteryx was reptilian in every way, not counting the feathers. It had short forelimbs, and the feathers were all the same size. Presumably, the downy feathers evolved from scales driven by a need for bodily insulation.

Next came Protarchaeopteryx:

It had long arms, broad "hands", and long claws:

Apparently this species was driven by selection to develop more efficient limbs for grasping prey. One of the interesting things about this species is that the structure of the forelimb has been refined to be quite efficient at sweeping out quickly to grab prey, snap the hands together, then draw them back towards the body (mouth?). The specific structures in question are the semilunate carpal (a wrist bone), that moves with the hand in a broad, flat, 190 degree arc, heavy chest muscles, bones of the arm which link together with the wrist so as to force the grasping hands to spread out toward the prey during the forestroke and fold in on the prey during the upstroke. Not only is this a marvelously efficient prey-grabbing mechanism, but the same mechanism is at the root of the wing flight-stroke of modern birds. Evolution often ends up developing a structure to serve one need, then finds it suitable for adaptation to another. Here, a prey-grasping motion similar in concept to the strike of a praying mantis in a reptile becomes suitable for modifying into a flapping flight motion.

Additionally, the feathers on the hands and tail have elongated, becoming better suited for helping to sweep prey into the hands.

Next is Caudipteryx:

This species had hand and tail feathers even more developed than the previous species, and longer feathers, more like that of modern birds:

However, it is clear that this was still not a free-flying animal yet, because the forelimbs were too short and the feathers not long enough to support its weight, and the feathers were symmetrical (equal sized "fins" on each side of the central quill). It also had very reduced teeth compared to earlier specimens and a stubby beak:

But the elongation of the feathers indicates some aerodynamic purpose, presumably gliding after leaping (or falling) from trees which it had climbed with its clawed limbs, in the manner of a flying squirrel. Feathers which were developed "for" heat retention and then pressed into service to help scoop prey were now "found" to be useful for breaking falls or gliding to cover distance (or swooping down on prey?).

Next is Sinornithosaurus:

Similar to the preceding species, except that the pubis bone has now shifted to point to the back instead of the front, a key feature in modern birds (when compared to the forward-facing publis bone in reptiles). Here are some of the forearm feathers in detail:

Long feathers in detail:

Artists' reconstruction:

Next is Archaeopteryx:

The transition to flight is now well underway. Archaeopteryx has the reversed hallux (thumb) characteristic of modern birds, and fully developed feathers of the type used for flight (long, aligned with each other, and assymetrical indicating that the feathers have been refined to function aerodynamically). The feathers and limbs are easily long enough to support the weight of this species in flight. However, it lacks some structures which would make endurance flying more practical (such as a keeled sternum for efficient anchoring of the pectoral muscles which power the downstroke) and fused chest vertebrae. Archaeopteryx also retains a number of clearly reptilian features still, including a clawed "hand" emerging from the wings, small reptilian teeth, and a long bony tail. After the previous species' gliding abilities gave it an advantage, evolution would have strongly selected for more improvements in "flying" ability, pushing the species towards something more resembling sustained powered flight.

Next is Confuciusornis:

This species had a nearly modern flight apparatus. It also displays transitional traits between a reptilian grasping "hand" and a fully formed wing as in modern birds -- the outer two digits (the earlier species had three-fingered "hands") in Confuciusornis are still free, but the center digit has now formed flat, broad bones as seen in the wings of modern birds.

Additionally, the foot is now well on its way towards being a perching foot as in modern birds:

It also has a keeled sternum better suited for long flight, and a reduced number of vertebrae in the tail, on its way towards becoming the truncated tail of modern birds (which while prominent, is a small flap of muscle made to look large only because of the long feathers attached).

From this species it's only a small number of minor changes to finish the transition into the modern bird family.

(Hey, who said there are no transitional fossils? Oh, right, a lot of dishonest creationists. And there are a lot more than this, I've just posted some of the more significant milestones.)

There's been a very recent fossil find along this same lineage, too new for me to have found any online images to include in this article. And analysis is still underway to determine exactly where it fits into the above lineage. But it has well-formed feathers, which extend out from both the "arms" and the legs. Although it wasn't advanced enough to fully fly, the balanced feathering on the front and back would have made it ideally suited for gliding like a flying squirrel, and it may be another link between the stage where feathers had not yet been pressed into service as aerodynamic aids, and the time when they began to be used more and more to catch the air and developing towards a "forelimbs as wings" specialization.

So in short, to answer the question about how flight could have developed in birds, the progression is most likely some minor refinement on the following:

1. Scales modified into downy feathers for heat retention.
2. Downy feathers modified into "straight" feathers for better heat retention (modern birds still use their body "contour feathers" in this fashion).
3. Straight feathers modified into a "grasping basket" on the hands (with an accompanying increase in reach for the same purpose).
4. Long limbs with long feathers refined to better survive falls to the ground.
5. "Parachute" feathers refined for better control, leading to gliding.
6. Gliding refined into better controlled, longer gliding.
7. Long gliding refined into short powered "hops".
8. Short powered flight refined into longer powered flight.
9. Longer powered flight refined into long-distance flying.

Note that in each stage, the current configuration has already set the stage for natural selection to "prefer" individuals which better meet the requirements of the next stage. Evolution most often works like this; by taking some pre-existing ability or structure, and finding a better use for it or a better way to make it perform its current use.

(Did I hear someone in the back row say something about there being "no evidence" for evolution? This is just a minor sampling. I'll be happy to post more.)
49 posted on 01/31/2005 1:43:16 AM PST by Ichneumon
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To: gobucks
ID is not a scientific theory because it cannot be proven or disproven in a laboratory or by other scientific methods. It's an idea that you either take on faith, or you don't. As such it has no place being taught in a science classroom.

Why is this so hard?

50 posted on 01/31/2005 1:46:37 AM PST by Zeroisanumber
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To: Mockingbird For Short
Why did you say in your first answer that the "after its kind" method of reproduction has proven to be untrue, but in your second answer you say that it IS taught in school.

The first was in reference to "created after its kind" (not reproduction), and the second was in reference to "reproducing after its kind".

I took the first to mean "each kind separately created" -- if you meant something else, just let me know.

By "bifurcate" do you mean evolve into an entirely new species?

Pretty much, yeah. "Bifurcate" means "fork", basically, as in to split into two and to head down two separate paths.

Usually an entire species won't evolve into a new species -- instead the more common event is that a "splinter" group will separate and evolve off in another direction while the "parent" group remains relatively the same or evolves off in a different direction.

Of course, then each of the two resulting species can split again, etc. This is how we've ended up with the millions of different species living today, far fewer species near the beginning, and how the thousands of different mammal species all descended from a common "first" ancestral mammal species, and so on.

51 posted on 01/31/2005 1:52:58 AM PST by Ichneumon
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To: Ichneumon
I'm sure you will see this as a rather silly question, but I'll ask anyway! :)

Note that in each stage, the current configuration has already set the stage for natural selection to "prefer" individuals which better meet the requirements of the next stage.

Why can't each "stage" of the bird shown, simply be similar birds with slight differences, such as the differences between a grackle and a crow?

52 posted on 01/31/2005 1:54:06 AM PST by Mockingbird For Short ("An irreligious fanatic is just as dangerous as a religious fanatic.")
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To: Zeroisanumber; gobucks
ID is not a scientific theory because it cannot be proven or disproven in a laboratory or by other scientific methods. It's an idea that you either take on faith, or you don't. As such it has no place being taught in a science classroom. Why is this so hard?

From what I gather, some folks think that if they can "disprove" evolution, then ID somehow "wins" by default and is thus "proven".

They're wrong, of course (by which I mean that disproving one theory is never itself positive evidence for any other hypothesis, even if it seems the "only" alternative), but that seems to be the notion they've got.

53 posted on 01/31/2005 1:55:34 AM PST by Ichneumon
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To: VinceJS
Randomness or chance have no rigorous mathematical or scientific definition.

Exsqueeze me? I take it you've never taken a decent Statistics course...

Nor is it possible to design a foolproof test for "randomness"

No, but the point is that one can detect *non-randomness* pretty easily. If there were actually an "invisible hand" loading the dice, its intervention would stick out like a sore thumb (no pun intended) in statistical analysis.

Thus, claiming life arose out of "random" events is not science.

That claim (that something is "not science" if it's based on the properties of randomness) is going to come as a *big* surprise to the quantum physicists... Not to mention the classical physicists, since things like the Gas Laws and Thermodynamics and Fluid Flow and Aerodynamics and Buoyancy, among just a few examples, are all results of the reliable statistical properties of large numbers of interacting objects (molecules, in the case of most of classical physics).

54 posted on 01/31/2005 2:03:26 AM PST by Ichneumon
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To: VinceJS; gobucks
Moreover, from information theory information doesn't just pop out of nowhere.

Yes, actually, it does. Or can, anyway. And nothing in "information theory" says otherwise.

Somehow, some way the information necessary to construct a system as complex as the human brain must have been encoded into the universe.

Nope. There's no "law of conservation of information". Information *can* be created without limit.

As for how "order can arise from chaos" informationally, it's pretty simple (in concept, anyway) -- Stochastic processes make "random information" (or pseudo-random, if you prefer, makes no difference to the result), commonly known in data-processing as "noise", and then selection concentrates the pearls of more "useful" information while discarding the "useless". Rinse, repeat. In short, by evolutionary processes, which provably *do* generate what the creationists like to (inaccurately) call "specified complexity".

Or, if you like, an earlier version of this argument is the attempt to disprove evolution from thermodynamics and the law of entropy. The evolutionists' correct response is that this only applies in a closed system,

Correct -- that, and the anti-evolutionists confuse "available energy" with "information"...

but what that means is that the information (or order, if you prefer) must have been elsewhere in the universe.

No, actually, no it doesn't mean that.

So, eventually the debate is going to have to reduce to debating the origins of the universe

Nope. Although that is an interesting question in its own right.

55 posted on 01/31/2005 2:16:28 AM PST by Ichneumon
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To: VadeRetro; Junior; longshadow; RadioAstronomer; Doctor Stochastic; js1138; Shryke; RightWhale; ...
EvolutionPing
A pro-evolution science list with over 230 names. See list's description at my homepage. FReepmail to be added/dropped.

56 posted on 01/31/2005 3:29:47 AM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)
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To: Ichneumon
Incredible cornucopia of information!

Your link on "the evolution of eyes" needs updating. The info is at the old link. It's now: The evolution of eyes.

57 posted on 01/31/2005 3:38:15 AM PST by PatrickHenry (<-- Click on my name. The List-O-Links for evolution threads is at my freeper homepage.)
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To: Mockingbird For Short
There are some brilliant scholars out there who don't "accept" evolution as an explanation for different species. "Accepting" a particular theory IS a matter of faith.

And how many of those "brilliant scholars" who don't accept evolution are biologists who have studied the data; and how many of those aren't also religious fundamentalists. About 100x as many biologists who have studied the data do accept evolution, and they comprise multiple religions as well as agnostics and atheists. BTW, define "brilliant" in this context; would it mean producing opinions that mesh with your religious pre-conceptions? There is precious little brilliance in Dembski's or Behe's output, most of which is poorly argued fluff aimed at persuading the general public rather than scientists.

58 posted on 01/31/2005 3:56:56 AM PST by Thatcherite (Conservative and Biblical Literalist are not synonymous)
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To: Hajman
"Science can't test anything beyond what we can observe, but it can theorize about that which can't be observed (it just can't prove the unobserved)."

Yes, science 'can' theorize about that which can't be observed .... but, pray tell, when it comes to intelligent design, why is it they REFUSE to theorize? They refuse to discuss reasons why ID is illogical. It is just 'wrong' a priori. How is that rational? Why are kids taught, by scientists, that to theorize about the unobserved is 'crazy'?

(IMHO it is because scientists are quite aware that all moral rulebooks, especially the sexaul one, are suddenly subject to change if ID is involved at all.) I really liked listening to what you had to say. I wish the scientists would listen to it too...

59 posted on 01/31/2005 3:58:18 AM PST by gobucks (http://oncampus.richmond.edu/academics/classics/students/Ribeiro/laocoon.htm)
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To: gobucks
A devout clergyman sought every opportunity to impress upon the mind of his son the fact, that God takes care of all his creatures.

Happening, one day, to see a crane wading in quest of food, the good man pointed out to his son the perfect adaptation of the crane to get his living in that manner.

"See," said he, "how his legs are formed for wading! What a long slender bill he has! Observe how nicely he folds his feet when putting them in or drawing them out of the water! He does not cause the slightest ripple. He is thus enabled to approach the fish without giving them any notice of his arrival."

"My son," said he, "it is impossible to look at that bird without recognizing the design, as well as the goodness of God, in thus providing the means of subsistence."

"Yes," replied the boy, "I think I see the goodness of God, at least so far as the crane is concerned; but after all, father, don't you think the arrangement a little tough on the fish?"

-R.G. Ingersoll

60 posted on 01/31/2005 4:11:50 AM PST by Uncle Fud
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