Fossils show middle stage of the evolution of flatfish eyes to one side of their head
FISH FAMILY TREEThis image illustrates the simplified family tree showing the gradual evolution of flatfish eye asymmetry. The drawings show the most ancient fossil (left) with symmetrical eye sockets. Amphistium and Heteronectes, the reexamined fossil fish, show asymmetrical skulls, but maintain eyes on opposite sides of the head. The other two fish drawings show the asymmetrical eye locations and skull of the most current flatfish species.Matt Friedman, University of Chicago
A new look at the fossils of primitive flatfish offer
evidence that these fish — well-known for having both eyes on one side of their
head — started out symmetrical and gradually evolved their one-sided trait.
Evolutionary biologists have floundered to explain how bottom-dwelling,
carnivorous flatfish, such as flounder and plaice, evolved to have both eyes on
one side of their head. Previous analyses of fossil evidence concluded that the
change was abrupt. But reexamination of ancient fossils now supports the hypothesis
that the flatfish eye position actually evolved over thousands to millions of
years. The findings appear in the July 9 Nature.
Fossil evidence had already shown that flatfish ancestors
had one eye on each side of the head. But no evidence had existed for a
transition between a symmetrical skull and one-sided skull. Matt Friedman, a
graduate student at the University
of Chicago, looked more
closely at 45-million-year-old fossils of primitive flatfish and found the
transition species: One eye had moved, but it had not crossed the midline of the
fish’s body, as seen in today’s flatfish, Friedman reports.
The fossils, Friedman says, deliver a clear picture of how
this flatfish group changed from a standard fish with eyes on both sides to one
with eyes on only one side of the head.
The flatfish eyes and skeletal structure underwent small,
incremental changes, says Alex Schreiber, a developmental biologist who studies
flatfish at St. Lawrence University in Canton, N.Y., and was not involved in the study. The fishes’
evolution was, in essence, gradual, he says.
CHANGESEyes on one side: This series of skeletal images shows how a flatfish skull changes as one eye migrates to join the other. This process happens as fish go from fry to adult. A close look at fossils suggests evolution of this trait took many thousands to millions of years. Click on the image for more.Alex Schreiber, St. Lawrence University, the Carnegie Institution
Darwin and his contemporaries began the debate as to how flatfish
eyes evolved, arguing either for gradual evolution, as Darwin did, or for evolution by punctuated leaps.
By presenting “unambiguous evidence” for the gradual change,
Friedman now takes that debate into the 21st century, says paleontologist
Philippe Janvier of the Muséum National d'Histoire Naturelle in Paris, France,
who was not involved in the research.
Watch flatfish development:
This video shows the development of a flatfish from its
juvenile to adult stage. Near the end, the fish's eyes appear together on
one side of its head. The stages of development
of one flatfish essentially mirror the evolutionary history of adult flatfish morphology.
This video shows the skeletal changes that a flatfish goes
through as it develops into an adult fish. The eye socket in the fish's skull
actually grows toward the other eye socket and, in the end, the fish has both
eyes on one side of its head. Both videos are courtesy of Alex Schreiber, the Carnegie Institute of Washington and St.
Lawrence University in Canton, N.Y.
look especially at: #7. Culture is the universal driver of genetic evolution
WHAT IS CULTURE
Culture, A Ubiquitous Biological Entity
A Recapitulation
1. General comprehension of evolutionary biology is an essential pre-requisite to the study and comprehension of cultural anthropology.
2. Culture is a basic biological entity. It is the ubiquitous elaboration- extension of the sensing of and reactions to, by the genome, to the goings-on beyond the outermost membrane of its housing, the cell, and of multicelled organisms, to the totality of their outer and inner environments.
Culture has been selected for survival of the genome as means of extending its exploitation capabilities of the out-of-cell circumstances, consequent to the earlier evolution and selection of the genome's organ, its outermost cell membrane (OCM), for control of the in-cell state of the environment.
3. Every cultural element is an organism's artifact that involves biological intra-/inter-cell expression and/or process. Biological and cultural domains are not ontologically distinct. Culture inheres in biology.
The core (wordnet.princeton) definition of "intelligence" is "the ability to comprehend, to understand and profit from experience". These surviving abilities are different for the different phenotypes within a genotype, therefore each phenotype has its own meaning of "intelligence".
Intelligence is to culture approximately as essential amino acids are to proteins. Culture evolves in response to circumstances only by use of intelligence and to the extent and scope feasible by the extent and scope of intelligence.
5. In human cultures ethnocentrisms are phenotypic cases of anthropocentrism; biologically both are normal Darwinian biological survival phenomena. Ethnocultures are human phenotypic survival tools.
6. Life is a phenomenon of temporary energy constraint. It pops in out of its matrix, the energy constrained in Earth's biosphere by Earth's organisms, which are the many varieties of genomes, the communal interdependent life forms of the primal, once-independent, genes, the formers and conservers of life's energy on Earth.
7. Culture is the universal driver of genetic evolution
The major course of natural selection is not via random mutations followed by survival, but via interdependent, interactive and interenhencing selection of biased genes replication routes at their alternative-splicing-steps junctions, effected by the cultural feedback of the second stratum multicells organism or monocells community to their prime stratum genes-genome organisms.
8. Science is a human cultural artifact, a tool of human survival
During the recent several centuries in the course of human history Science has been evolving at an accelerating rate as a provider of convincing, ever closer approaching, approximate models of the real world. We understand that Science is one of the components of our Culture, the totality of our capabilities to observe the environment, react to it and exploit it for our satisfaction and survival. There is a distinct, even if still small, growing spreading tendency to accept the findings of evolving Science with ever increasing respect and appreciation, especially in the realms of all forms and types of its progenies - technology and life disciplines.
9. The crucial 21st century question facing humanity is how much further and into which additional disciplines may or should Science be welcome and adopted by society at large, with what hopes and with what expectations.
Which doctrine(s) may or should be welcome and adopted, with what plans or hopes and with what expectations?
Life is a temporary affair. It is temporary on all scales at all levels.
Life's purpose is ours to decide and ours to fulfil. The arguments about life's doctrines should ensue from our choices of life's purpose.
Text Size
#7. Culture is the universal driver of genetic evolution
WHAT IS CULTURE
Culture, A Ubiquitous Biological Entity
A Recapitulation
1. General comprehension of evolutionary biology is an essential pre-requisite to the study and comprehension of cultural anthropology.
2. Culture is a basic biological entity. It is the ubiquitous elaboration- extension of the sensing of and reactions to, by the genome, to the goings-on beyond the outermost membrane of its housing, the cell, and of multicelled organisms, to the totality of their outer and inner environments.
Culture has been selected for survival of the genome as means of extending its exploitation capabilities of the out-of-cell circumstances, consequent to the earlier evolution and selection of the genome's organ, its outermost cell membrane (OCM), for control of the in-cell state of the environment.
3. Every cultural element is an organism's artifact that involves biological intra-/inter-cell expression and/or process. Biological and cultural domains are not ontologically distinct. Culture inheres in biology.
4. Culture And Intelligence
http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q--?cq=1&p=247
The core (wordnet.princeton) definition of "intelligence" is "the ability to comprehend, to understand and profit from experience". These surviving abilities are different for the different phenotypes within a genotype, therefore each phenotype has its own meaning of "intelligence".
Intelligence is to culture approximately as essential amino acids are to proteins. Culture evolves in response to circumstances only by use of intelligence and to the extent and scope feasible by the extent and scope of intelligence.
5. In human cultures ethnocentrisms are phenotypic cases of anthropocentrism; biologically both are normal Darwinian biological survival phenomena. Ethnocultures are human phenotypic survival tools.
6. Life is a phenomenon of temporary energy constraint. It pops in out of its matrix, the energy constrained in Earth's biosphere by Earth's organisms, which are the many varieties of genomes, the communal interdependent life forms of the primal, once-independent, genes, the formers and conservers of life's energy on Earth.
7. Culture is the universal driver of genetic evolution
The major course of natural selection is not via random mutations followed by survival, but via interdependent, interactive and interenhencing selection of biased genes replication routes at their alternative-splicing-steps junctions, effected by the cultural feedback of the second stratum multicells organism or monocells community to their prime stratum genes-genome organisms.
8. Science is a human cultural artifact, a tool of human survival
During the recent several centuries in the course of human history Science has been evolving at an accelerating rate as a provider of convincing, ever closer approaching, approximate models of the real world. We understand that Science is one of the components of our Culture, the totality of our capabilities to observe the environment, react to it and exploit it for our satisfaction and survival. There is a distinct, even if still small, growing spreading tendency to accept the findings of evolving Science with ever increasing respect and appreciation, especially in the realms of all forms and types of its progenies - technology and life disciplines.
9. The crucial 21st century question facing humanity is how much further and into which additional disciplines may or should Science be welcome and adopted by society at large, with what hopes and with what expectations.
Which doctrine(s) may or should be welcome and adopted, with what plans or hopes and with what expectations?
Life is a temporary affair. It is temporary on all scales at all levels.
Life's purpose is ours to decide and ours to fulfil. The arguments about life's doctrines should ensue from our choices of life's purpose.
Dov Henis
http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q--?cq=1
Please login or register to participate.