Evolution: How We Know it Happened & Why it Matters

Posted on January 12, 2011 by RichardPrins

A Skeptic video on YouTube with Dr. Donald Prothero:

The hottest cultural controversy of 2005 was the Intelligent Design challenge to the theory of evolution, being played out in classrooms and courtrooms across America. The crux of the argument made by proponents of Intelligent Design is that the theory of evolution is in serious trouble. They claim that the evidence for evolution is weak, the gaps in the theory are huge, and that these flaws should be taught to students. In this brilliant synthesis of scientific data and theory, Occidental College geologist, paleontologist, and evolutionary theorist Dr. Donald Prothero will present the best evidence we have that evolution happened, why Darwins theory still matters, and what the real controversies are in evolutionary biology.

Dr. Donald Prothero teaches Physical and Historical Geology, Sedimentary Geology, and Paleontology. His specialties are mammalian paleontology and magnetic stratigraphy of the Cenozoic. His current research focuses on the dating of the climatic changes that occurred between 30 and 40 million years ago, using the technique of magnetic stratigraphy. He is the author of “Evolution of the Earth,” “Bringing Fossils to Life,” “After the Dinosaurs,” “Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals,” and the textbook “Sedimentary Geology.”

Complex, Multicellular Life from Over Two Billion Years Ago Discovered

Posted on July 4, 2010 by RichardPrins

Via ScienceDaily:

The discovery in Gabon of more than 250 fossils in an excellent state of conservation has provided proof, for the first time, of the existence of multicellular organisms 2.1 billion years ago. This finding represents a major breakthrough: until now, the first complex life forms (made up of several cells) dated from around 600 million years ago.

Virtual reconstruction (by microtomography) of the external morphology (on the left) and internal morphology (on the right) of a fossil specimen from the Gabonese site. (Credit: Copyright CNRS Photo Library / A. El Albani & A. Mazurier)

These new fossils, of various shapes and sizes, imply that the origin of organized life is a lot older than is generally admitted, thus challenging current knowledge on the beginning of life. These specimens were discovered and studied by an international multidisciplinary team of researchers led by Abderrazak El Albani of the Laboratoire “Hydrogéologie, Argiles, Sols et Altérations” (CNRS/Université de Poitiers). Their work, due to be published in Nature on 1st July, will feature on the cover of the journal.

The first traces of life appeared in the form of prokaryotic organisms, in other words organisms without a nucleus, around three and a half billion years ago. Another major event in the history of life, the “Cambrian explosion” some 600 million years ago, marked a proliferation in the number of living species. It was accompanied by a sudden rise in oxygen concentration in the atmosphere. What happened between 3.5 billion and 600 million years ago though? Scientists have very little information about this era, known as the Proterozoic. Yet, it is during this crucial period that life diversified: to the prokaryotes were added the eukaryotes, single or multicelled organisms endowed with a more complex organization and metabolism. These large-sized living beings differ from prokaryotes by the presence of cells possessing a nucleus containing DNA.

Video (French)

While studying the paleo-environment of a fossil-bearing site situated near Franceville in Gabon in 2008, El Albani and his team unexpectedly discovered perfectly preserved fossil remains in the 2.1 billion-year-old sediments. They have collected more than 250 fossils to date, of which one hundred or so have been studied in detail. Their morphology cannot be explained by purely chemical or physical mechanisms. These specimens, which have various shapes and can reach 10 to 12 centimeters, are too big and too complex to be single-celled prokaryotes or eukaryotes. This establishes that different life forms co-existed at the start of the Proterozoic, as the specimens are well and truly fossilized living material. (…)

Large colonial organisms with coordinated growth in oxygenated environments 2.1 Gyr ago. Nature, 2010; 466 (7302): 100 DOI: 10.1038/nature09166

Other reports: Nature, ScienceNews, Highly Allochthonous, Pleiotropy, Wired Science, TheScientist.

Update 20100716: Pharyngula: An unpaleontological lament for lost molecules and shattered cells and the cruelty of time

Science Shorts 20100616

Posted on June 16, 2010 by RichardPrins

Outliving the Ice Age: Tale of a Rhinoceros (ScienceDaily) >
Species extinction is a fundamental part of evolution: the best adapted species survives, while others die out. A new study shows why, after 800,000 years of successful survival, a species of rhinoceros suddenly disappeared.

Sharper than Hubble: Large Binocular Telescope achieves major breakthrough (PhysOrg)
The next generation of adaptive optics has arrived at the Large Binocular Telescope (LBT) in Arizona, providing astronomers with a new level of image sharpness never before seen. Developed in a collaboration between Italy`s Arcetri Observatory of the Istituto Nazionale di Astrofisica (INAF) and the University of Arizona`s Steward Observatory, this technology represents a remarkable step forward for astronomy.

Insomniacs have different brains, researcher says (ScienceDaily)
The brains of older adults with chronic sleep problems look different from those of adults who have enjoyed enough sleep. Yet the older adults function well despite their lack of sleep. They switch to a continuous form of mild stress, as a result of which they sometimes even perform better than contemporaries who enjoy a good night’s sleep, according to a Dutch researcher.

Experience shapes the brain’s circuitry throughout adulthood (EurekAlert!)
The adult brain, long considered to be fixed in its wiring, is in fact remarkably dynamic. Neuroscientists once thought that the brain’s wiring was fixed early in life, during a critical period beyond which changes were impossible. Recent discoveries have challenged that view, and now, research by scientists at Rockefeller University suggests that circuits in the adult brain are continually modified by experience.

Massive black holes ‘switched on’ by galaxy collision (PhysOrg)
The centre of most galaxies harbours a massive black hole. Our Milky Way galaxy is one of these – the exotic object there however is reasonably calm, unlike some super-massive gravity monsters in other galaxies. Scientists at the Max Planck Institute for Extraterrestrial Physics and other institutions around the world have now analysed 199 of these galaxies and discovered what makes the black holes at the galaxy centres become active: The black holes were “switched on” some 700 million years ago after major galaxy merger events.

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Science Shorts 20100611

Posted on June 11, 2010 by RichardPrins

Harbor seals’ whiskers as good at detecting fish as echolocating dolphins (EurekAlert!)
Seals use their whiskers to track hydrodynamic trails left by passing fish, but how sensitive are the whiskers? Testing the responses of a seal to trails left by an artificial fin, Wolf Hanke and colleagues from the University of Rostock found that seals can detect trails up 35s after a fin has passed. Fish can cover 100s of meters in that time, so the whiskers compare well with the performance of echolocating whales and dolphins.

The Chance for Life on Io (PhysOrg) >
Jupiter`s moon Io is the most volcanically active body in the solar system. Could it also be a habitat for life?

Were some gigantic Jurassic sea creatures warm-blooded? (Scientific American)
In ancient Mesozoic seas, the biggest predators might not have been entirely cold-blooded killers. Rather, a new study suggests some of these rapacious reptiles might have been able to regulate their own body temperature , thereby expanding their hunting ranges.

Model explains rapid transition toward division of labor in biological evolution (ScienceDaily)
The transition from colonies of individual cells to multicellular organisms can be achieved relatively rapidly, within one million generations, according to a new mathematical model that simplifies our understanding of this process.

Planck Mission: Space Probe Peers Into Dark Cosmos (PhysOrg)
Imagine watching the birth of the universe — the Big Bang — from the outside. What would you have seen?

Many famous comets originally formed in other solar systems (ScienceDaily)
Many of the most well known comets, including Halley, Hale-Bopp and, most recently, McNaught, may have been born in orbit around other stars, according to a new theory by an international team of astronomers.

Science Shorts 20100601

Posted on June 1, 2010 by RichardPrins

Concealed patterns beneath life’s variety (PhysOrg)
Although the tropics appear to the casual observer to be busily buzzing and blooming with life’s rich variety when compared with temperate and polar regions -a fact that scientists have thoroughly documented -the distribution of species in space and time actually varies around the globe in surprising and subtle ways. So explains Janne Soininen of the University of Helsinki in an article published in the June 2010 issue of BioScience.

Natural selection for moderate testosterone surprises scientists (ScienceDaily)
A field study of the relationship between testosterone and natural selection in an American songbird, the dark-eyed junco, has defied some expectations and confirmed others. Scientists report that extreme testosterone production — high or low — puts male dark-eyed junco at a disadvantage in both survival and reproduction outside their semi-monogamous breeding pairs.

New species of plant-eating dinosaur named for ‘grinding mouth and wrinkle eye’ (ScienceDaily) >
A team of paleontologists has described a new species of herbivore dinosaur based upon an incomplete skeleton found in western New Mexico. The new species, Jeyawati rugoculus, thrived near the shore of a vast inland sea 91 million years ago.

Mars was Wet, but was it Warm? (PhysOrg)
Mars is frozen today, but when it was young there may have been liquid water on its surface. What does the latest evidence indicate about the ancient martian climate? Understanding the past environment of Mars can help future missions “follow the water” in the search for alien life.

Did fornicating Farm Girls boost the rise of atheism in Britain? (Epiphenom)
These days, Britain is one of the most atheistic countries around. It wasn’t always like that, of course, but one of the problems with trying to work out how the present state of affairs came about is that there are very few statistics on religion the stretch back far enough.

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Science Magazine Special Feature: The Neandertal (draft) genome

Posted on May 6, 2010 by RichardPrins

In the 7 May 2010 issue of Science, Green et al. report a draft sequence of the Neandertal genome composed of over 3 billion nucleotides from three individuals, and compare it with the genomes of five modern humans. A companion paper by Burbano et al. describes a method for sequencing target regions of Neandertal DNA. A News Focus, podcast segment, and special online presentation featuring video commentary, text, and a timeline of Neandertal-related discoveries provide additional context for their findings.

[Note: The papers by Green et al. and Burbano et al., as well as the special presentation and podcast, are free to all site visitors.]

References: Richard E. Green et al.: A Draft Sequence of the Neandertal Genome, Science 328 (5979), 710. [DOI: 10.1126/science.1188021]

Hernán A. Burbano et al.: Targeted Investigation of the Neandertal Genome by Array-Based Sequence Capture, Science 328 (5979), 723. [DOI: 10.1126/science.1188046]

Neandertal museum reconstruction. AFP/Getty Images