Skull sheds light on human-Neanderthal relationship

Retrieved from a cave in northern Israel, the partial skull provides the first evidence that Homo sapiens inhabited that region at the same time as Neanderthals. (Reuters: Nikola Solic)

A partial skull, found in a cave in Israel, is shedding light on the pivotal moment in early human history when our species left Africa and encountered our close cousins the Neanderthals.

Anthropologist Israel Hershkovitz, from Tel Aviv University, called the skull "an important piece of the puzzle of the big story of human evolution."

The findings of the research, led by Hershkovitz, are published today in the journal Nature.

The upper part of the skull - the domed portion without the face or jaws - was unearthed in Manot Cave in Israel's Western Galilee.

Scientific dating techniques determined the skull was about 55,000 years old, a time period when members of our species were thought to have been marching out of Africa,

The researchers say characteristics of the skull suggest the individual was closely related to the first Homo sapiens populations that later colonized Europe.

They also say the skull provides the first evidence that Homo sapiens inhabited that region at the same time as Neanderthals, our closest extinct human relative.

Previous genetic evidence suggests our species and Neanderthals interbred around the time the skull is dated to, with all people of Eurasian ancestry still retaining a small amount of Neanderthal DNA as a result.

"It is the first direct fossil evidence that modern humans and Neanderthals inhabited the same area at the same time," says palaeontologist Bruce Latimer of Case Western Reserve University in Cleveland, another of the researchers.

"The co-existence of these two populations in a confined geographic region at the same time that genetic models predict interbreeding promotes the notion that interbreeding may have occurred in the Levant region," Hershkovitz says.

The robust, large-browed Neanderthals prospered across Europe and Asia from about 350,000 to 40,000 years ago, going extinct sometime after Homo sapiens arrived.

Scientists say our species first appeared about 200,000 years ago in Africa and later migrated outwards. The cave is located along the sole land route for ancient humans to take from Africa into the Middle East, Asia and Europe.

Latimer says he suspects the skull belonged to a woman, although the researchers could not say definitively.

The cave, sealed off for 30,000 years, was discovered in 2008 during sewage line construction work. Hunting tools, perforated seashells perhaps used ornamentally and animal bones have been excavated from the cave, along with further human remains.

Source: ABC

Scientists find 240-million-year-old parasite that infected mammals' ancestor

Scott Gardner. Credit: Craig Chandler, University Communications.

An egg much smaller than a common grain of sand and found in a tiny piece of fossilized dung has helped scientists identify a pinworm that lived 240 million years ago.

It is believed to be the most ancient pinworm yet found in the fossil record.

The discovery confirms that herbivorous cynodonts -- the ancestors of mammals -- were infected with the parasitic nematodes. It also makes it even more likely that herbivorous dinosaurs carried pinworms.

Scott Gardner, a parasitologist and director of the Harold W. Manter Laboratory of Parasitology at the University of Nebraska-Lincoln, was among an international group of scientists who published the study in the journal Parasites & Vectors.

"This discovery represents a first for our team and I think it opens the door to finding additional parasites in other species of fossil organisms," he said.

The team found the pinworm egg in a coprolite -- fossilized feces -- collected in 2007 at an excavation site in Rio Grande do Sul state in southern Brazil.

The coprolite was collected at a site with abundant fossilized remains of cynodonts. Previously, an Ascarid-like egg -- resembling a species of nematode commonly found in modern-day mammals -- was found in the coprolite.

The pinworm egg, representing an undescribed or "new species," was named Paleoxyuriscockburni, in honor of Aidan Cockburn, founder of the Paleopathology Association.

The structure of the pinworm egg placed it in a biological group of parasites that occur in animals that ingest large amounts of plant material. Its presence helped scientists deduce which cynodont species, of several found at the collection site, most likely deposited the coprolite.

Since the field of paleoparasitology, or the study of ancient parasites, emerged in the early 20th century, scientists have identified parasites of both plants and animals that date back as far as 500 million years ago.

The study of parasites in ancient animals can help determine the age of fossilized organisms and help establish dates of origin and diversification for association between host species and parasites. Coprolites are a key part of the study, enabling a better understanding of the ecological relationships between hosts and parasites.

Other members of the team were Jean-Pierre Hugot of the National Museum of Natural History in Paris; Victor Borba, Juliana Dutra, Luiz Fernando Ferreira and Adauto Araujo of Oswaldo Cruz Foundation in Rio de Janeiro; Prisiclla Araujo and Daniela Leles of Fluminense Federal University in Rio de Janeiro; and Atila August Stock Da-Rosa of the Federal University of Santa Maria in Rio Grande do Sul.

Source: University of Nebraska-Lincoln

Out of India: Finding the origins of horses, rhinos

An artist’s depiction of Cambaytherium thewissi. Credit: Elaine Kasmer

Working at the edge of a coal mine in India, a team of Johns Hopkins researchers and colleagues have filled in a major gap in science's understanding of the evolution of a group of animals that includes horses and rhinos. That group likely originated on the subcontinent when it was still an island headed swiftly for collision with Asia, the researchers report Nov. 20 in the online journal Nature Communications.

Modern horses, rhinos and tapirs belong to a biological group, or order, called Perissodactyla. Also known as "odd-toed ungulates," animals in the order have, as their name implies, an uneven number of toes on their hind feet and a distinctive digestive system. Though paleontologists had found remains of Perissodactyla from as far back as the beginnings of the Eocene epoch, about 56 million years ago, their earlier evolution remained a mystery, says Ken Rose, Ph.D., a professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine.

Rose and his research team have for years been excavating mammal fossils in the Bighorn Basin of Wyoming, but in 2001 he and Indian colleagues began exploring Eocene sediments in Western India because it had been proposed that perissodactyls and some other mammal groups might have originated there. In an open-pit coal mine northeast of Mumbai, they uncovered a rich vein of ancient bones. Rose says he and his collaborators obtained funding from the National Geographic Society to send a research team to the mine site at Gujarat in the far Western part of India for two weeks at a time once every year or two over the last decade.

The mine yielded what Rose says was a treasure trove of teeth and bones for the researchers to comb through back in their home laboratories. Of these, more than 200 fossils turned out to belong to an animal dubbed Cambaytherium thewissi, about which little had been known. The researchers dated the fossils to about 54.5 million years old, making them slightly younger than the oldest known Perissodactyla remains, but, Rose says, it provides a window into what a common ancestor of all Perissodactyla would have looked like. "Many of Cambaytherium's features, like the teeth, the number of sacral vertebrae, and the bones of the hands and feet, are intermediate between Perissodactyla and more primitive animals," Rose says. "This is the closest thing we've found to a common ancestor of the Perissodactyla order."

Cambaytherium and other finds from the Gujarat coal mine also provide tantalizing clues about India's separation from Madagascar, lonely migration, and eventual collision with the continent of Asia as Earth's plates shifted, Rose says. In 1990, two researchers, David Krause and Mary Maas of Stony Brook University, published a paper suggesting that several groups of mammals that appear at the beginning of the Eocene, including primates and odd- and even-toed ungulates, might have evolved in India while it was isolated. Cambaytherium is the first concrete evidence to support that idea, Rose says. But, he adds, "It's not a simple story."

"Around Cambaytherium's time, we think India was an island, but it also had primates and a rodent similar to those living in Europe at the time," he says. "One possible explanation is that India passed close by the Arabian Peninsula or the Horn of Africa, and there was a land bridge that allowed the animals to migrate. But Cambaytherium is unique and suggests that India was indeed isolated for a while."

Rose said his team was "very fortunate that we discovered the site and that the mining company allowed us to work there," although he added, "it was frustrating to knowing that countless fossils were being chewed up by heavy mining equipment." When coal extraction was finished, the miners covered the site, he says. His team has now found other mines in the area to continue digging.

Source:  Johns Hopkins Medicine