Researchers have found evidence which suggests that evolution drives animals to become increasingly more complex.
Looking back through the last 550 million years of the fossil catalogue to the present day, the team investigated the different evolutionary branches of the crustacean family tree.
They were seeking examples along the tree where animals evolved that were simpler than their ancestors.
Instead they found organisms with increasingly more complex structures and features, suggesting that there is some mechanism driving change in this direction.
“If you start with the simplest possible animal body, then there’s only one direction to evolve in – you have to become more complex,” said Dr Matthew Wills from the Department of Biology & Biochemistry at the University of Bath who worked with colleagues Sarah Adamowicz from from the University of Waterloo (Canada) and Andy Purvis from Imperial College London.
“Sooner or later, however, you reach a level of complexity where it’s possible to go backwards and become simpler again.
“What’s astonishing is that hardly any crustaceans have taken this backwards route. Instead, almost all branches have evolved in the same direction, becoming more complex in parallel.
“This is the nearest thing to a pervasive evolutionary rule that’s been found.
“Of course, there are exceptions within the crustacean family tree, but most of these are parasites, or animals living in remote habitats such as isolated marine caves.
“For those free-living animals in the ‘rat-race’ of evolution, it seems that competition may be the driving force behind the trend.
“What’s new about our results is that they show us how this increase in complexity has occurred. Strikingly, it looks far more like a disciplined march than a milling crowd.”
Dr Adamowicz said: “Previous researchers noticed increasing morphological complexity in the fossil record, but this pattern can occur due to the chance origination of a few new types of animals.
“Our study uses information about the inter-relatedness of different animal groups – the ‘Tree of Life’ – to demonstrate that complexity has evolved numerous times independently.”
Like all arthropods, crustaceans’ bodies are built up of repeating segments. In the simplest crustaceans, the segments are quite similar - one after the other. In the most complex, such as shrimps and lobsters, almost every segment is different, bearing antennae, jaws, claws, walking legs, paddles and gills.
The American biologist Leigh Van Valen coined the phrase ‘Red Queen’ for the evolutionary arms race phenomenon. In Through the Looking-Glass Lewis Carroll’s Red Queen advises Alice that: “It takes all the running you can do, to keep in the same place.”
“Those crustacean groups going extinct tended to be less complex than the others around at the time,” said Dr Wills.
“There’s even a link between average complexity within a group and the number of species alive today.
“All organisms have a common ancestor, so that every living species is part of a giant family tree of life.”
Dr Adamowicz added: “With a few exceptions, once branches of the tree have separated they continue to evolve independently.
“Looking at many independent branches is similar to viewing multiple repeated runs of the tape of evolution.
“Our results apply to a group of animals with bodies made of repeated units. We must not forget that bacteria – very simple organisms – are among the most successful living things. Therefore, the trend towards complexity is compelling but does not describe the history of all life.”
This research was recently published in the Proceedings of the National Academy of Sciences.
Adapted from materials provided by University of Bath.
Article reposted from Science Daily
2 responses so far ↓
Dov Henis // Mar 27, 2008 at 3:18 pm
Darwinism Corrected To Tomorrow’s Comprehension.
Darwinians, It Is Culture That Drives Evolution!
March 16 2008
http://www.physforum.com/index.php?showtopic=14988&st=165&#entry323376
“By plain common sense it is therefore culture, the ubiqitous biological entity, that drives earth life evolution.”
March 1 2008
“Culture Is Biology, It Imprints Genetics”
http://forum.physorg.com/index.php?showtopic=14988&st=165&#entry316631
I. Quotes from “Chimp and human communication trace to same brain region”
http://www.eurekalert.org/pub_releases/2008-02/cp-cah022108.php
” An area of the brain involved in the planning and production of spoken and signed language in humans plays a similar role in chimpanzee communication.
This might be interpreted in one of two ways:
One interpretation of our results is that chimpanzees have, in essence, a ‘language-ready brain’. By this, we are suggesting that apes are born with and use the brain areas identified here when producing signals that are part of their communicative repertoire.
Alternatively, one might argue that, because our apes were captive-born and producing communicative signals not seen often in the wild, the specific learning and use of these signals ‘induced’ the pattern of brain activation we saw. This would suggest that there is tremendous plasticity in the chimpanzee brain, as there is in the human brain, and that the development of certain kinds of communicative signals might directly influence the structure and function of the brain.”
II. Quotes from earlier postings in this thread:
Culture Is Biology, It Affects Genetics
The Common Mistake: Genetic Changes Have NOT Made Us Human; Human Culture Has Been Changing Our Genetics.
A. http://www.eurekalert.org/pub_releases/2007-12/uou-ahe120607.php
Are humans evolving faster?
Findings suggest we are becoming more different, not alike.
B. http://www.eurekalert.org/pub_releases/2007-12/uow-gsp120507.php
Genome study places modern humans in the evolutionary fast lane.
C. http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q–?cq=1&p=207
From my postings way back in 2005, which cites genetic evidence/demonstration of the workings of human cultural evolution:
- From Science, 2 Sept 2005: “Page’s team compared human and chimp Ys to see whether either lineage has lost functional genes since they split.
The researchers found that the chimp had indeed suffered the slings and arrows of evolutionary fortune. Of the 16 functional genes in this part of the human Y, chimps had lost the function of five due to mutations. In contrast, humans had all 11 functional genes also seen on the chimp Y. “The human Y chromosome hasn’t lost a gene in 6 million years,” says Page. “It seems like the demise of the hypothesis of the demise of the Y,” says geneticist Andrew Clark of Cornell University in Ithaca, New York.
Chimp’s genome has been continuing survival by physiologically adapting to changing environments.
- But look at this: From Science, Vol 309, 16 Sept 2005, Evolving Sequence and Expression:”An analysis of the evolution of both gene sequences and expression patterns in humans and chimpanzees…shows that…surprisingly, genes expressed in the brain have changed more on the human lineage than on the chimpanzee lineage, not only in terms of gene expression but also in terms of amino acid sequences”.
Surprisingly…???
Human’s genome continued survival mainly by modifying-controling its environment.
- And I suggest that detailed study of other creatures that, like humans, underwent radical change of living circumstances, for example ocean-dwelling mammals, might bring to light unique effects of culture-evolution processes and features of evolutionary implications parallel to those of humans.
D. Chapter II, Life, Tomorrow’s Comprehension:
http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q–?cq=1&p=372
Natural Selection Is A Two Level Interdependent Affair
1) Evolution ensues from genome/genes modifications (”mutations”), inherently ever more of them as new functional options arise for the organism.
2) Modifications of genome’s functional capabilities can be explained by the second-stratum organism’s culture-life-experience feedbacks to its genome, its prime/base organism. The route-modification selection of a replicating gene, when it is at its alternative-splicing-steps junctions, is biased by the feedback gained by the genome, the parent organism, from the culture-life-experience of its progeny big organism. THIS IS HOW EVOLUTION COMES ABOUT.
3) The challenge now is to figure out the detailed seperate steps involved in introducing and impressing the big organism’s experiences (culture) feedbacks on its founding parents’ genome’s genes, followed by the detailed seperate steps involved in biasing-directing the genes to prefer-select the biased-favored splicing.
4) I find it astonishing that only very few persons, non-professional as well as professional biologists-evolutionists, have the clear conception that selection for survival occurs on two interdependent levels - (a) during the life of the second-stratum progeny organism in its environment, and (b) during the life of its genome, which is also an organism. Most, if not all, persons think - incorrectly - that evolution is about randomly occurring genes-genome modifications (”mutations”) followed with selection by survival of the progeny organism in its environment. Whereas actually evolution is the interdependent , interactive and interenhencing selection at both the two above levels.
E. Eventually
Eventually it will be comprehended that things don’t just “happen”, “mutate”, randomly in the base-prime organism, genome, constitution; the capability of the base-prime organisms to “happen” and “mutate” is indeed innate, but things “happen” and “mutate” not randomly but in biased directions, affected by the culture-experience feedback of the second level multi-cell organisms (or the mono-cell communities).
Dov Henis
http://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q–?cq=1
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