Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


What came first in the origin of life? A study contradicts the 'metabolism first' hypothesis

The study was carried out by 3 European researchers, 1 from Universitat Autònoma de Barcelona

A research published in Proceedings of National Academy of Sciences rejects the theory that the origin of life stems from a system of self-catalytic molecules capable of experiencing Darwinian evolution without the need of RNA or DNA and their replication.

The research, which was carried out with the participation of Mauro Santos, researcher of the Department of Genetics and Microbiology at Universitat Autònoma de Barcelona (UAB), has demonstrated that, through the analysis of what some researchers name "compound genomes", these chemical networks cannot be considered evolutionary units because they lose properties which are essential for evolution when they reach a critical size and greater level of complexity.

The North American Space Agency (NASA) defines life as a "self-sustaining chemical system capable of Darwinian evolution". The scientific theories on the origin of life revolve around two main ideas: one focuses on genetics - with RNA or DNA replication as an essential condition for Darwinian evolution to take place - and the other focuses on metabolism. It is clear that both situations must have begun with simple organic molecules formed by prebiotic processes, as was demonstrated by the Miller-Urey experiment (in which organic molecules were created from inorganic substances). The point in which these two theories differ is that the replication of RNA or DNA molecules is a far too complex process which requires a correct combination of monomers within the polymers to produce a molecular chain resulting from the replication.

Until now no plausible chemical explanation exists for how these processes occured. In addition, defenders of the second theory argue that the processes needed for evolution to take place depend on primordial metabolism. This metabolism is believed to be a type of chemical network entailing a high degree of mutual catalysis between its components which, in turn, eventually allows for adaptation and evolution without any molecular replication.

In the first half of the 20th century, Alexander Oparin established the "Metabolism First" hypothesis to explain the origin of life, thus strengthening the primary role of cells as small drops of coacervates (evolutionary precursors of the first prokaryote cells). Dr Oparin did not refer to RNA or DNA molecules since at that time it was not clear just how important the role of these molecules was in living organisms. However he did form a solid base for the idea of self-replication as a collective property of molecular compounds.

Science more recently demonstrated that sets of chemical components store information about their composition which can be duplicated and transmitted to their descendents. This has led to their being named "compound genomes" or composomes. In other words, heredity does not require information in order to be stored in RNA or DNA molecules. These "compound genomes" apparently fulfil the conditions required to be considered evolutionary units, which suggests a pathway from pre-Darwinian dynamics to a minimum protocell.

Researchers in this study nevertheless reveal that these systems are incapable of undergoing a Darwinian evolution. For the first time a rigorous analysis was carried out to study the supposed evolution of these molecular networks using a combination of numerical and analytical simulations and network analysis approximations. Their research demonstrated that the dynamics of molecular compound populations which divide after having reached a critical size do not evolve, since during this process the compounds lose properties which are essential for Darwinian evolution.

Researchers concluded that this fundamental limitation of "compound genomes" should lead to caution towards theories that set metabolism first as the origin as life, even though former metabolic systems could have offered a stable habitat in which primitive polymers such as RNA could have evolved.

Researchers state that different prebiotic Earth scenarios can be considered. However, the basic property of life as a system capable of undergoing Darwinian evolution began when genetic information was finally stored and transmitted such as occurs in nucleotide polymers (RNA and DNA).

Maria Jesus Delgado | EurekAlert!
Further information:

Further reports about: DNA DNA molecule Darwinian Oparin RNA living organism organic molecule

More articles from Studies and Analyses:

nachricht Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University

nachricht New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>