Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Evolutionary Research Disproves Living Missing Link Theories

16.02.2011
Genetic research proves worm has evolved to be less sophisticated than its ancestors

Evolution is not a steady march towards ever more sophisticated beings and therefore the search for the living "missing links" is pointless, according to findings published by a team of researchers led by Dr. Hervé Philippe of the Université de Montréal's Department of Biochemistry.

"Aristotle was the first to classify organisms – from the least to the most sophisticated. Darwin's theory of evolution continued this idea, with the concept of a hierarchy of evolution. This way of thinking has led researchers and skeptics alike to look for less sophisticated ancestors in order to prove or disprove evolution," Philippe explained. "What we now know is that evolution does not happen in a single direction – when people talk about a missing link, they're generally excluding the possibility of more sophisticated ancestors."

The researchers compared the genomes of two kinds of marine worms with simple morphology – Xenoturbellida and Acoelomorpha – with those of other animals. They demonstrated that their previous position at the base of the bilateral symmetry animal group – that includes insects, mollusks and vertebrates – was inaccurate. "Instead, we determined that Xenoturbellida and Acoelomorpha are closely related to the complex deuterostomes, which is a major lineage containing sea urchins, humans and sharks," Philippe said. "I've put them in that order intentionally because it seems strange, which demonstrates our tendency to always put organisms in order of complexity." The findings mean that the worms had evolved from a more sophisticated ancestor through major simplifications.

"We did already know that most parasitic organisms had evolved to be less sophisticated than their ancestors – they lost certain abilities that they no longer needed. The independently living Xenoturbellida and Acoelomorpha do not fall in this category," Philippe said. The research is a striking example for the important role of secondary simplification in evolution and is part of 20 year project that is nearing completion. The findings were published in Nature on February 10, 2011.

Une récente étude sur l'évolution réfute les théories sur le chaînon manquant vivant

La recherche génétique prouve que certains vers marins ont évolué vers une complexité réduite, comparativement à celle de leurs ancêtres

MONTRÉAL, le 10 février 2011 – Selon des découvertes publiées par une équipe de chercheurs dirigée par le professeur Hervé Philippe, du Département de biochimie de l'Université de Montréal, l'évolution n'est pas une marche constante vers des êtres de plus en plus sophistiqués et, par conséquent, la quête de chaînons manquants parmi les espèces vivant aujoud'hui n'est pas pertinente. « Aristote a été le premier à classifier les organismes, du plus simple au plus complexe. La théorie de l'évolution de Darwin a étendu cette notion, ajoutant l'idée d'une classification hiérarchique des organismes. Cette façon de penser a conduit des scientifiques – et des sceptiques – à chercher des ancêtres moins complexes, de manière à prouver ou réfuter l'évolution », a expliqué monsieur Philippe. « Ce que nous savons maintenant, c'est que l'évolution ne se produit pas dans une seule direction. Quand les gens parlent d'un chaînon manquant, ils mettent généralement de côté la possibilité d'ancêtres plus complexes que les espèces actuelles. »

L'équipe internationale de chercheurs a comparé les génomes de deux espèces de vers marins présentant une morphologie simple, les Xenoturbellida et les Acoelomorpha, avec ceux d'autres animaux. Ils ont démontré que leur ancienne position à la base du groupe des animaux à symétrie bilatérale – comprenant insectes, mollusques et vertébrés – n'était pas appropriée. « À la place, nous avons déterminé que les Xenoturbellida et les Acoelomorpha font partie des deutérostomiens, une sous-division importante réunissant les oursins, les humains et les requins », a ajouté le professeur Philippe. « L'ordre de ces trois groupes est intentionnel, cela semble étrange, mais démontre notre tendance à toujours ranger les organismes par ordre de complexité. » Cette découverte signifie que l'évolution de ces vers marins, à partir d'un ancêtre plus complexe, s'est déroulée à travers d'importantes simplifications.

« Nous savions déjà que la plupart des organismes parasitaires ont évolué pour devenir moins complexes que leurs ancêtres; ils ont perdu certaines aptitudes dont ils n'ont plus besoin. Les Xenoturbellida et les Acoelomorpha, qui vivent de façon indépendante, ne font pas partie de cette catégorie », a déclaré Hervé Philippe. Réalisée dans le cadre d'un projet s'échelonnant sur près de 20 ans et touchant à sa fin, l'étude est un exemple frappant du rôle important de la simplification secondaire dans l'évolution. Les résultats ont été publiés le 10 février 2011, dans Nature.

William Raillant-Clark | Newswise Science News
Further information:
http://www.umontreal.ca

More articles from Life Sciences:

nachricht Ageless ears? Elderly barn owls do not become hard of hearing
26.09.2017 | Carl von Ossietzky-Universität Oldenburg

nachricht eTRANSAFE – collaborative research project aimed at improving safety in drug development process
26.09.2017 | Fraunhofer-Gesellschaft

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

The material that obscures supermassive black holes

26.09.2017 | Physics and Astronomy

Ageless ears? Elderly barn owls do not become hard of hearing

26.09.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>