For the last few years, astronomers have faced a puzzle: The vast majority of asteroids that come near the Earth are of a type that matches only a tiny fraction of the meteorites that most frequently hit our planet.
Since meteorites are mostly pieces of asteroids, this discrepancy was hard to explain, but a team from MIT and other institutions has now found what it believes is the answer to the puzzle. The smaller rocks that most often fall to Earth, it seems, come straight in from the main asteroid belt out between Mars and Jupiter, rather than from the near-Earth asteroid (NEA) population.
Science & Technology
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| ©Photo: Dennis Kunkel - Color: Ekaterina Latypova |
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Microorganisms from a mud sample collected in Lake Washington. The purple and orange organisms are relatives of Methylotenera mobilis, whose complete DNA sequence is now published. |
When entrepreneurial geneticist Craig Venter sailed around the world on his yacht sequencing samples of seawater, it was an ambitious project to use genetics to understand invisible ecological communities. But his scientific legacy was disappointing - a jumble of mystery DNA fragments belonging to thousands of unknown organisms.
Sagalassos, Turkey - Tuesday morning, archaeologists of the Katholieke Universiteit Leuven team (Belgium) directed by Marc Waelkens uncovered the colossal portrait head of the Roman empress Faustina, wife of the emperor Antoninus Pius, who ruled from A.D. 138 to 161. According to Waelkens, the excavation team was ecstatic at the discovery.
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| ©Sagalassos Archaeological Research Project |
| Excavators prop up the newly found head of the empress Faustina the Elder |
A robot controlled by a blob of rat brain cells could provide insights into diseases such as Alzheimer's, University of Reading scientists say.
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| ©BBC |
| The robot and rat brain cells work together |
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Some confusion has arisen over our account of Neanderthals, which said at one point that they are thought to have died out 30,000 years ago, but at another that this happened 40,000 years ago. Our correspondent's best judgment now is that they disappeared somewhere between these two dates. As to their height, which has also been disputed, that seems usually to have been between 5ft 4in and 5ft 7in.
Strands of DNA recovered from the fossilized leg bone of a Neanderthal have shed light on the fragility of the ancient population and pinpointed when they first split from what were to become modern humans.
The global climate is a complex system - something that isn't simply controlled by the concentration of a single greenhouse gas or one type of cloud in the sky. Researchers have completed a study on the effects of aerosol layers and their influence on cloud formation, a key parameter in understanding and controlling local climate. If you're a mad scientist bent on global weather domination, start taking notes now.
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| ©Daniel Sol |
| Parrots have a big brain and are also one of the most evolutionarily diversified bird clades. |
Ever since Darwin, evolutionary biologists have wondered why some lineages have diversified more than others. A classical explanation is that a higher rate of diversification reflects increased ecological opportunities that led to a rapid adaptive radiation of a clade. A textbook example is Darwin finches from Galapagos, whose ancestor colonized a competitors-free archipelago and rapidly radiated in 13 species, each one adapted to use the food resources in a different way.
This and other examples have led some to think that the progenitors of the major evolutionary radiations are those that happened to be in the right place and at the right time to take advantage of ecological opportunities. However, is it possible that biological diversification not only depends on the properties of the environment an ancestral species finds itself in, but also on the features of the species itself? Now a study supports this possibility, suggesting that possessing a large brain might have facilitated the evolutionary diversification of some avian lineages.
The classic image of Galileo Galilei has the 16th century Italian scientist dropping two balls of differing weights from the Leaning Tower of Pisa and observing them hitting the ground at the same time. Though that scenario was probably no more than one of Galileo's thought experiments - his known tests involved rolling balls down inclines - it does illustrate his towering reputation as a scientific revolutionary. Galileo helped paved the way for classic mechanics and made huge technological and observational leaps in astronomy. Most famously, he championed the Copernican model of the universe, which put the sun at its center and the earth in orbit. The Catholic Church deemed Galileo's 1632 book Dialogue Concerning the Two Chief World Systems heresy, banned it, forced Galileo to recant his heliocentric views and condemned him to house arrest. He died in his Florence home in 1642.
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Corvallis, Oregon -- From foraging techniques to pollen gathering patterens, bee behavior is the focus of many research projects at Oregon State University.
But the latest major discovery happened here by accident.
One of the driest deserts in the world, the Saharan Tenere Desert, hosted at least two flourishing lakeside populations during the Stone Age, a discovery of the largest graveyard from the era reveals.
The archaeological site in Niger, called Gobero, was discovered by Paul Sereno at the University of Chicago, during a dinosaur-hunting expedition. It had been used as a burial site by two very different populations during the millennia when the Sahara was lush.
Careful examination of 67 graves - a third of the 200 plots on the site - has uncovered unprecedented details about the lifestyles of the people who inhabited the green Stone Age "desert", says Sereno.
"The first people who used the Gobero cemetery were Kiffian, hunter-gatherers who grew up to two metres tall," says Elena Garcea of the University of Cassino in Italy and one of the scientists on the team. The large stature of the Kiffian suggests that food was plentiful during their time in Gobero, 10,000 to 8,000 years ago.
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| ©Mike Hettwer, courtesy Project Exploration |
| Dark skull, left: The skull of this mature Kiffian male was found at the cemetery at Gobero. Light Skull, right: This Tenerian male died in the prime of his life at about 18 years of age. |
The archaeological site in Niger, called Gobero, was discovered by Paul Sereno at the University of Chicago, during a dinosaur-hunting expedition. It had been used as a burial site by two very different populations during the millennia when the Sahara was lush.
Careful examination of 67 graves - a third of the 200 plots on the site - has uncovered unprecedented details about the lifestyles of the people who inhabited the green Stone Age "desert", says Sereno.
"The first people who used the Gobero cemetery were Kiffian, hunter-gatherers who grew up to two metres tall," says Elena Garcea of the University of Cassino in Italy and one of the scientists on the team. The large stature of the Kiffian suggests that food was plentiful during their time in Gobero, 10,000 to 8,000 years ago.
