Evolution
In last week’s column I described how Bill Irvine uses radio astronomy techniques to detect and identify organic compounds in interstellar space. Why is it so important for the origin of life on Earth that organic compounds are scattered throughout our galaxy? The reason is that they represent a possible source for the organic compounds required for life to begin, delivered by a rain of comets and dust particles after the moon-forming event. The alternative source is synthesis by chemical reactions on the Earth’s surface. We don’t yet know which source was primary, but we do know one thing…
I recently came across a radio lecture given by Dr Lee Alan Dugatkin on 7.6.2007, titled "Is Goodness Natural?" It deserves comment. (An article on the same subject but with some differences in text was published at Huffington Post.)
The talk began well with some historical background describing the attempts by Charles Darwin, Thomas Huxley, Peter Kropotkin and W. D. Hamilton to explain the origin of goodness, (in the sense of being nice to one another,) in light of evolutionary theory. He concluded that the first three had failed to adequately explain goodness, (Kropotkin’s great work “…
Researchers writing in Nature magazine say the fossil skeleton of a newly discovered carnivorous animal, Puijila darwini, is a "missing link" in the evolution of the group that today includes seals, sea lions, and the walrus.
Modern seals, sea lions, and walruses all have flippers—limb adaptations for swimming in water. These adaptations evolved over time, as some terrestrial animals moved to a semi-aquatic lifestyle. Until now, the morphological evidence for this transition from land to water was weak.
Skeletal illustration of Puijila darwini. Credit: Mark A. Klingler/…
The fossil record usually shows what adult animals looked like. But the appearance and lifestyle of juvenile animals often differ dramatically from those of the adults. A classic example is provided by frogs and salamanders. New discoveries from Uppsala, Cambridge and Duke Universities, published in Science, show that some of the earliest backboned land animals also underwent such changes of lifestyle as they grew up.
Professor Per Ahlberg at the Department of Physiology and Developmental Biology, Uppsala University, together with Jennifer Clack, Cambridge University, and Viviane Callier,…
New evidence gleaned from CT scans of fossils locked inside rocks may flip the order in which two kinds of four-limbed animals with backbones were known to have moved from fish to landlubber.
Both extinct species, known as Ichthyostega and Acanthostega, lived an estimated 360-370 million years ago in what is now Greenland. Acanthostega was thought to have been the most primitive tetrapod, that is, the first vertebrate animal to possess limbs with digits rather than fish fins.
But the latest evidence from a Duke graduate student's research indicates that Ichthyostega may have been closer…
Human alcoholic tendencies go way back, as described in one of the most interesting paragraphs I've ever read in a scientific paper:
In the warm tropical climate of sub-Saharan Africa, where the human species emerged, sweet fruit slurries can achieve an alcoholic content of 5% or more. If early hominids were primarily fruit eaters, at least up until about 1–2 Mya, when they began focusing more on tubers and animal fat and protein, they can be expected to have adapted biologically. One result, among many, is that about 10% of the enzymes in the human liver, including alcohol dehydrogenase,…
Last week I described how Fred Hoyle, in 1946, came up with the idea that carbon is synthesized in hot stars toward the end of their lifetime, and we now know that carbon and the other elements of life are strewn into interstellar space when the star explodes. In his later career, Hoyle was never able to match his earlier triumph of carbon nucleosynthesis, but he certainly tried. Together with his colleague Chandra Wickramasinghe, now at Cardiff University in Wales, he co-authored a series papers and books that proposed an alternative hypothesis for one of the…
Neanderthals, a distinct Middle Pleistocene population, inhabited a vast geographical area extending from Europe to western Asia and the Middle East from 30,000 to 100,000 years ago. Were they a homogenous group or separate sub-groups in which differences could be observed?
Paleoanthropological studies since the 1950s, based on morphological skeletal evidence, have offered some support for the existence of three different sub-groups: one in Western Europe, one in southern Europe and another in the Levant.
Researchers Virginie Fabre, Silvana Condemi and Anna Degioanni from the…
A fierce debate is in progress. Human slaughter or natural demise....
Giant beavers, oversized ground sloths, and huge armadillo-like creatures all disappeared within a couple of thousand years — a mere heartbeat in geological terms. Was it just hard living on cold ice or were humans to blame for this massive loss? Scholars hotly dispute whether or not we were solely responsible for these extinctions. We certainly played a role.
Significantly however, the disagreement is based on arguments about what effects the changing environment had on these animals, about the timing of human arrival in…
In works on evolution written by a certain class of biologist we can often see “for the good of the species” references derided in no uncertain terms. Comments such as “fuzzy thinking”, “they got it wrong” and so on have become so habitual that they almost go unnoticed. But is the “for the good of the species” idea really all that bad? It might well be that some comments and discussions are indeed fuzzy, in that they might be poorly thought out or presented. But here’s a discussion from Robert Ardrey’s The Social Contract to consider. Ardrey described the communication between starlings as an…