A Yale-led scientific team has produced the most comprehensive family tree for birds to date, connecting all living bird species — nearly 10,000 in total — and revealing surprising new details about their evolutionary history and its geographic context.
Analysis of the family tree shows when and where birds diversified — and that birds’ diversification rate has increased over the last 50 million years, challenging the conventional wisdom of biodiversity experts.
“It’s the first time that we have — for such a large group of species and with such a high degree of confidence — the full global picture of diversification in time and space,” said biologist Walter Jetz of Yale, lead author of the team’s research paper, published Oct. 31 online in the journal Nature. (more…)
Dissolution or creation of huge gypsum deposits changed sulfate content of the oceans
Scientists have discovered a potential cause of Earth’s “icehouse climate” cooling trend of the past 45 million years. It has everything to do with the chemistry of the world’s oceans.
“Seawater chemistry is characterized by long phases of stability, which are interrupted by short intervals of rapid change,” says geoscientist Ulrich Wortmann of the University of Toronto, lead author of a paper reporting the results and published this week in the journal Science.
“We’ve established a new framework that helps us better interpret evolutionary trends and climate change over long periods of time. The study focuses on the past 130 million years, but similar interactions have likely occurred through the past 500 million years.” (more…)
While the disappearance of Neanderthals remains a mystery, paleoanthropologists have an increasing understanding of what allowed their younger cousins, Homo sapiens, to conquer the planet. According to Ariane Burke, Professor in the Department of Anthropology at the Université de Montréal, the rapid dispersal of anatomically modern humans was not so much due to superior intelligence or improved hunting or gathering techniques, but rather to the creation of symbolic objects that allowed them to extend their social relations across vast territories.
Symbolism and social exchanges
Homo sapiens arrived in Europe some 45,000 years ago, from Africa. In less than 15,000 years, they managed to occupy the whole of Europe and Eurasia—an extremely rapid expansion. Neanderthals, on the other hand, were born of Europe, appearing on the continent more than 250,000 years ago, after their ancestors, Homo ergaster, had established there 600,000 years earlier. Though physiologically well adapted to the cold climate of the glacial and postglacial periods, why were Neanderthals not as successful as their newly landed rivals in colonizing the continent? (more…)
ANN ARBOR, Mich.— Fifty million years ago, India slammed into Eurasia, a collision that gave rise to the tallest landforms on the planet, the Himalaya Mountains and the Tibetan Plateau.
India and Eurasia continue to converge today, though at an ever-slowing pace. University of Michigan geomorphologist and geophysicist Marin Clark wanted to know when this motion will end and why. She conducted a study that led to surprising findings that could add a new wrinkle to the well-established theory of plate tectonics – the dominant, unifying theory of geology. (more…)
Geologists at Yale University have proposed a new theory to describe the formation of supercontinents, the epic process by which Earth’s major continental blocks combine into a single vast landmass. The new model radically challenges the dominant theories of how supercontinents might take shape.
In a paper published Feb. 9 in the journal Nature, Yale researchers introduce a process called orthoversion, in which each succeeding supercontinent forms 90 degrees from the geographic center of its ancient predecessor. Under the theory, the present-day Arctic Ocean and Caribbean Sea will vanish as North and South America fuse during a mutual northward migration that leads to a collision with Europe and Asia. (more…)
*Anatomically modern humans interbred with more archaic hominin forms even before they migrated out of Africa, a UA-led team of researchers has found.*
It is now widely accepted that anatomically modern humans of the species Homo sapiens originated in Africa and eventually spread throughout the world. Ancient DNA recovered from fossil Neanderthal bones suggests they interbred with more archaic hominin forms once they had left their evolutionary cradle for the cooler climates of Eurasia, but whether they exchanged genetic material with other, now extinct archaic hominin varieties in Africa remained unclear.
It’s not often that plants are described as diabolical, but spotted knapweed has that rare distinction. A 2004 issue of Smithsonian magazine, for instance, dubbed it the “wicked weed of the West,” a “national menace” and a “weed of mass destruction.”
Such reports were overstated and incorrect, but the press wasn’t making this stuff up. It was summarizing research results published in leading academic journals.(more…)
