Modern life had a single origin
http://whyevolutionistrue.wordpress.com/2010/05/15/modern-life-had-a-single-origin/#comments
If you’ve been reading the evolution websites, you’ll know about the very nice paper in this week’s Nature by Douglas Theobald. (You may remember Theobald as the author of one of the greatest creationism-refuting websites of all: 29+ Evidences for Macroevolution: The Scientific Case for Common Descent. If you haven’t seen it, you should). In the new paper, Theobald makes a few conservative assumptions to show that the probability that all living species descend from a universal common ancestor is infinitely higher than any other hypothesis, including those of multiple origins of the kingdoms (Bacteria, Eukarya, and Archaea) or of rampant horizontal gene transfer betweeen species that would, by mixing genomes, make life look as though it had a single origin when it didn’t.
(Why Evolution Is True, May 15, 2010)
The Proof Is in the Proteins: Test Supports Universal Common Ancestor for All Life
http://www.scientificamerican.com/article.cfm?id=universal-common-ancestor&sc=WR_20100514
One researcher put the basic biological assumption of a single common ancestor to the test–and found that advanced genetic analysis and sophisticated statistics back up Darwin’s age-old proposition
Earth’s first life-form, floating in the proverbial froth of the primordial seas that eventually gave rise to trees, bees and humans, is not just a popular Darwinian conceit but also an essential biological premise that many researchers rely on as part of the foundation of their work.
In the 19th century, Charles Darwin went beyond others, who had proposed that there might be a common ancestor for all mammals or animals, and suggested that there was likely a common ancestor for all life on the planet—plant, animal and bacterial.
(Scientific American, May 13, 2010)
Cambrian survivors – weird critters which (temporarily) cheated extinction
When the Cambrian period comes up in conversation, it is usually in reference to the evolutionary “explosion” which occurred around 530 million years ago. Animal fossils from before that time are typically small or are only traces, but in the latter half of the period (spanning ~488 to 542 million years ago) there is a dramatic increase in the diversity and disparity of organisms. The “small shelly fauna” of earlier times is replaced by a riot of organisms interacting with each other in complex ecosystems – it is one of the most dramatic changes seen in the entire fossil record.
What is often forgotten, however, is that many of these weird critters disappeared by the end of the Cambrian in an extinction which appears to have swept away much of what had so recently (from a geological perspective) evolved.
That seemed like the best explanation, anyway, but there was one problem. We know of the existence of many strange Cambrian creatures because they have been recovered from sites of exceptional preservation which fossilized them with soft parts intact. Such sites are virtually unknown from the time right after the Cambrian, during the early days of the Ordovician period (~488-432 million years ago), making it difficult to know precisely when some of the extinct lineages disappeared. Now, as luck would have it, such an Ordovician site has been found in Morocco, and among the exceptionally-preserved fossils within it are creatures thought to have vanished millions of years before.
(Laelaps, May 13, 2010)
The Burgess Shale fauna was around a lot longer than we thought
We all know the Burgess Shale fauna from Steve Gould’s book Wonderful Life, which described it as a group of fantastic animals lacking any affinity with modern-day animals. Gould suggested that they went extinct without issue in the Cambrian, about 505 million years ago, but could easily have given rise to modern animals if the “tape of life” had been rewound.
Later work by Simon Conway Morris and others, of course, showed that the Burgess Shale fauna, although weird, did have affinities with modern groups like arthropods, lobopods (Onychophora) and annelids. Indeed, some of the fauna could have been ancestors of modern groups, although there still seem to be bizarre forms—called the “problematica”—without affinities to modern animals.
(Why Evolution Is True, May 13, 2010)
The first metazoa living in permanently anoxic conditions.
http://f1000biology.com/article/qnhnys9vmmkcjt7/id/2844956
Anoxic environments are very harsh for the metazoa, and animals can survive in them for limited periods. The deep bottoms of some seas (e.g. the Black Sea) are anoxic and are deprived of metazoan life. Also some parts of the Mediterranean Sea bottom are anoxic, but there are some metazoa that can live there. They are Loricifera with special adaptations to such particularly severe environments. The exploration of biodiversity still provides stunning surprises, and this is surely one!
(Faculty of 1000:Biology, April 14, 2010)
Anaerobic Animals Discovered on Sea Floor
This is pretty neat: scientists have apparently discovered the first example of truly anaerobic animal life (i.e. an animal that can survive in the absence of oxygen). This isn’t some sort of fuzzy critter, though; instead, these are tiny (less than 1 mm in length) animals that were found on the floor of the Mediterranean Sea. The animals belong to the phylum Loricifera (see illustration below). Significantly, these animals lack mitochondria, the sub-cellular organelles where oxygen is employed to produce ATP in aerobic (oxygen-dependent) life.
(The Scientific Activist, April 7, 2010)
A new fossil species found in Spain
http://www.eurekalert.org/pub_releases/2010-03/f-sf-anf032510.php
In the ’80s, Spanish researchers found the first fossils of Cloudina in Spain, a small fossil of tubular appearance and one of the first animals that developed an external skeleton between 550 and 543 million years ago. Now palaeontologists from the University of Extremadura have discovered a new species, Cloudina carinata, the fossil of which has preserved its tridimensional shape.
“Cloudina carinata is characterised by its elaborate ornamentation and complexity of the shells and tube that are formed when inserted”, Iván Cortijo, main author and researcher in the Area of Palaeontology at the University of Extremadura, describes to SINC.
(EurekAlert.org, March 25, 2010)
Palaeontology: Do the locomotion
http://www.economist.com/science-technology/displaystory.cfm?story_id=15603919
The earliest animal tracks yet found have been unearthed in Canada
ONE of the greatest mysteries of the history of life is the Cambrian explosion. Prior to 560m years ago, animal fossils are rare. Then, in a geological eyeblink, they become common. Shelly creatures such as trilobites and brachiopods, of whose ancestors there is little sign in the rocks, are suddenly everywhere. Biologists would dearly love to know what happened.
(The Economist, March 4, 2010)
A paleobiologist’s response to Darwin’s Dilemma
http://whyevolutionistrue.wordpress.com/2010/02/13/a-paleobiologists-response-to-darwins-dilemma/
I’ve posted twice (here and here) about the intelligent-design movieDarwin’s Dilemma, a DVD of which was sent to me by participant and young-earth creationist Paul Nelson. When I was in the UK two weeks ago, I gave the DVD to a friend studying paleontology at Oxford University, who in turn showed it to a group of students and faculty.
(Why Evolution is True, February 13, 2010)
‘Primal Soup’ Theory Nixed: Earth’s Chemical Energy Jump-started Life
(The Daily Galaxy, February 2, 2010)
Rotting Fish Spoil Ideas about Early Life-Forms’ Simplicity
http://www.scientificamerican.com/article.cfm?id=early-vertebrate-evolution
Five hundred million years ago, spineless chordates slunk through Earth’s Cambrian oceans. These unassuming creatures would eventually give rise to more complex vertebrates such as fish, dinosaurs and even us, so they are crucial evidence for scientists trying to trace animal evolution’s early steps. But because these organisms lacked bones or shells, the soft-tissue features that managed to survive the fossilization process have made the specimens look very primitive, possibly excessively so.
(Scientific American, January 31, 2010)
The Origin of Life on Earth
http://www.scientificamerican.com/article.cfm?id=origin-of-life-on-earth
- Researchers have found a way that the genetic molecule RNA could have formed from chemicals present on the early earth.
- Other studies have supported the hypothesis that primitive cells containing molecules
similar to RNA could assemble spontaneously, reproduce and evolve, giving rise to all life. - Scientists are now aiming at creating fully self-replicating artificial organisms in the laboratory—essentially giving life a second start to understand how it could have started the first time.
(Scientific American, September 2009)
The Origin of Life: A case is made for the descent of electrons
http://www.americanscientist.org/issues/feature/2009/3/the-origin-of-life/1
In this article we present a view gaining attention in the origin-of-life community that takes the question out of the hatchery and places it squarely in the realm of accessible, plausible chemistry. As we see it, the early steps on the way to life are an inevitable, incremental result of the operation of the laws of chemistry and physics operating under the conditions that existed on the early Earth, a result that can be understood in terms of known (or at least knowable) laws of nature. As such, the early stages in the emergence of life are no more surprising, no more accidental, than water flowing downhill.
(American Scientist, May-June, 2009)
What Came First in the Origin of Life? New Study Contradicts the ‘Metabolism First’ Hypothesis
http://www.sciencedaily.com/releases/2010/01/100108101433.htm
A new study 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. . . .
(Science Daily, January 9, 2010)
Nova: Origins
http://www.pbs.org/wgbh/nova/origins/
Site features many PBS Nova programs about the origins of life.
Exploring Life’s Origins
http://exploringorigins.org/
The goal of this project is to use molecular illustration and animation to help describe origins of life research and theories to broad audiences. Illustrations and animations may be downloaded in the Resources for Educators section.
The Origin of Life
http://www.talkorigins.org/faqs/abioprob/originoflife.html
Science shows us that the universe evolved by self-organization of matter towards more and more complex structures. Atoms, stars and galaxies self-assembled out of the fundamental particles produced by the Big Bang. In first-generation stars, heavier elements like carbon, nitrogen and oxygen were formed. Aging first-generation stars then expelled them out into space – we, who consist of these elements, are thus literally born from stardust. The heaviest elements were born in the explosions of supernovae. The forces of gravity subsequently allowed for the formation of newer stars and of planets. Finally, in the process of biological evolution from bacteria-like tiny cells (the last universal common ancestor) to all life on earth, including us humans, complex life forms arose from simpler ones. . . .
Lost City of Hydrothermal Vents
http://www.scientificamerican.com/article.cfm?id=lost-city-of-hydrothermal
Scientists on a research cruise aboard the Atlantis have stumbled upon a spectacular discovery in the Atlantic Ocean: a system of hydrothermal vents so vast they have named it the Lost City. Indeed, this vent field is the largest yet known. Moreover, the vents appear to have formed under unique circumstances that should shed light on ancient hydrothermal systems, as well as on the evolution of the surrounding area.
(Scientific American, December 2009)
Life’s Origin May Have Been a Shallow Affair
In finding answers to the mystery of the origin of life, scientists may not have to dig too deep. New research is shedding light on shallower waters as a possible location for where life on Earth began.
Hydrothermal vents have been a focus of origin of life studies ever since the first one was discovered in 1977. These were mainly deep vents that averaged 2,100 meters [1.3 miles] down on the ocean floor. The hot gasses emanating from the center of the Earth through these vents could reach temperatures greater than 300 degrees Celsius.
(LiveScience, December 9 2009)
2.5 Billion-Year-Old Event Triggered Greatest Environmental Change Earth Has Ever Seen
http://tr.im/EJEc Humans might not be walking the face of the Earth were it not for the ancient fusing of two prokaryotes — tiny life forms that do not have a cellular nucleus. Endosymbiosis refers to a cell living within another cell. If the cells live together long enough, they will exchange genes; they merge but often keep their own cell membranes and sometimes their own genomes.
“We have been overlooking how important cooperation is,” UCLA molecular biologist James A. Lake said. “If two prokaryotes get together, they can change the world. They restructured the atmosphere of the Earth. It’s a message that evolution is giving us: Cooperation is a way to get ahead.”