Evolution

Recent re-examination of a 100,000 year old early human skull using micro-CT scans has revealed the interior configuration of a temporal bone thought to occur only in Neanderthals.

The fossilized human skull was found during 1970s excavations at the Xujiayao site in China's Nihewan Basin.  Since Western Europe and Eastern Asia are a long way apart, "The discovery places into question a whole suite of scenarios of later Pleistocene human population dispersals and interconnections based on tracing isolated anatomical or genetic features in fragmentary fossils," said study co-author Erik Trinkaus, PhD, anthropology professor at Washington University in St. Louis. 


Evolutionary adaptations have allowed Tibetans to have no trouble living at 13,000 feet, but how they became able to conquer the harsh environment of hypoxia has long been a mystery.


A small tree or shrub found in mountainous Central and South American rainforests has a most unusual relationship with the birds that pollinate its flowers, according to a new study - the plant known as Axinaea offers up its male reproductive organs as a tempting and nutritious food source for the birds.

As the birds seize those bulbous stamens with their beaks, they are blasted with pollen by the flowers' complex "bellows" organs. The birds then deliver that pollen to receptive female floral organs as they forage on.

Food bodies situated on male reproductive organs are otherwise only known from beetle-pollinated flowers. There is no other known example among plants of such a precise and anatomically distinct bellows organ.


Many traits unique to humans are thought to have originated in the genus Homo between 2.4 and 1.8 million years ago in Africa.

What are the evolutionary factors that drove them?

A large brain, long legs, the ability to craft tools and prolonged maturation periods were all thought to have evolved together at the start of the Homo lineage as African grasslands expanded and Earth's climate became cooler and drier. However, new climate and fossil evidence analyzed by a team of researchers suggests that these traits did not arise as a single package. Rather, several key ingredients once thought to define Homo evolved in earlier Australopithecus ancestors between 3 and 4 million years ago, while others emerged significantly later.


The dominant hypothesis for the reason that northern Europeans developed light skin is that they needed to absorb more ultraviolet (UV) light to make more vitamin D, which is vital for healthy bones and immune function.

Not so, says a U.C. San Francisco dermatologist.  Peter Elias, MD, and colleagues write in Evolutionary Biology that changes in the skin's function as a barrier to the elements made a greater contribution than alterations in skin pigment in the ability of northern Europeans to make vitamin D. They write that genetic mutations compromising the skin's ability to serve as a barrier allowed fair-skinned Northern Europeans to populate latitudes where too little ultraviolet B (UVB) light for vitamin D production penetrates the atmosphere.


Old World monkeys have undergone a remarkable evolution in facial appearance as a way of avoiding interbreeding with closely related and geographically proximate species, according to a new paper which provides best evidence to-date for the role of visual cues as a barrier to breeding across species.

The researchers studied guenons—a group of more than two dozen species of monkeys indigenous to the forests of Central and West Africa. Many different species of guenons are often sympatric—they live in close proximity to each other, with multiple species often traveling, feeding, and sleeping side-by-side. Therefore interbreeding, which could result in afflicted infertile offspring, remains an unwelcome possibility. 


An electric discharge experiment simulates early Earth conditions using relatively simple starting materials. The reaction is ignited by a spark, simulating lightning, which was likely very common on the early Earth.

The 1958 reaction samples were analyzed by Parker and his current mentor, Facundo M. Fernández, a professor in the School of Chemistry and Biochemistry at Georgia Tech. They conducted liquid chromatography- and mass spectrometry-based analyses and found that the reaction samples from 1958 contained peptides. Scientists from NASA's Johnson Space Center and Goddard Space Flight Center were also involved in the analysis.


Writing about the weird soft-bodied fossils found in the Burgess Shale in the Canadian Rockies, paleontologist Stephen Jay Gould noted that of 25 initial body plans exhibited by the fossils, all but four were quickly eliminated.

If we rewound the tape, he asked, and cast the dice once more, would the same four body plans be selected? He thought it unlikely.

Obviously, we can't repeat the Burgess Shale, but Ken Olsen, an associate professor of biology at Washington University in St. Louis, says there are other ways to ask whether evolution is repeatable. One is to look at related species that have independently evolved the same traits and ask if the same genes are responsible and, if so, whether the same mutations led to the trait.


A research group uncovered that the development of wings in fruit flies does not progress synchronously with the organism's development. Instead, it is coordinated with the whole body only at distinct 'milestones'. This study helps explain how an organism facing environmental and physiological perturbations retains the ability to build correct functional organs and tissues in a proportional adult body.


During evolutionary diversification of vertebrate limbs, the number of toes in even-toed ungulates such as cattle and pigs was reduced and transformed into paired hooves. Scientists at the University of Basel have identified a gene regulatory switch that was key to evolutionary adaption of limbs in ungulates.