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Australopithecus sediba had a hand built for making stone tools (picture by Peter Schmid; courtesy of Lee Berger and the University of Witwatersrand)

Australopithecines lived in Africa some 4 million to 2 million years ago. Scientists speculate that the australopithecines gave rise to our own genus, Homo, sometime around 2 million years ago, but there’s not much fossil evidence to show exactly when or how this happened. But last year, scientists led by Lee Berger of the University of Witwatersrand announced they had found a possible candidate ancestor of Homo: Australopithecus sediba. The species lived 1.977 million years ago and resembled Homo in many ways.

This week, the researchers published five papers in the journal Science that provide a more in-depth look at the species. Experts are excited about the fossils, but do not agree on where A. sediba belongs in the human family tree—and in some sense, its discovery muddies the picture of human evolution at this critical transition 2 million years ago.

The new studies analyze two partial skeletons found in Malapa Cave in South Africa: a 12- to 13-year-old male and an adult female. Here’s a rundown of the key findings:

Brain: The researchers studied the size and shape of the young male’s brain by taking X-ray scans of his skull and creating a virtual 3-D endocast. A. sediba had a small brain—420 cubic centimeters—only slightly bigger than a chimpanzee brain or half the size of a Homo erectus brain. But the shape and organization of part of the frontal lobe appear similar to Homo. The team says this may mean brain reorganization came before a big jump in brain size in humans.

Pelvis: The pelvis had a mix of australopithecine- and Homo-like traits. This is interesting because some of A. sediba’s more advanced traits, like the shape and orientation of the ilium, were thought to have evolved in the genus Homo to accommodate bigger-brained babies as they came through the birth canal. But since A. sediba had these features and a small brain, another factor probably drove the evolution of these traits; they could be the result of spending even more time walking on the ground and less time in the trees, the researchers suggest.

Hands and Feet: The team found a nearly complete wrist and hand for the species as well as a partial foot and ankle. The foot had a unique mix of traits not seen in any other hominid, suggesting A. sediba had its own form of upright walking and probably still climbed trees. The hand also indicates A. sediba was a climber, but it shows that the hominid had the musculature and anatomy necessary for a “precision grip,” when the thumb meets the fingertips. This movement is what allows you to thread a needle or hold a pencil—and it probably enabled A. sediba to make and use stone tools, the researchers say, although they have not yet found any tools with the species.

Here’s why A. sediba complicates things. For the species to be the ancestor of Homo, it had to have lived before the first species of that genus. That’s just common sense. And it’s true for what the researchers call the “earliest uncontested evidence” of Homo: Homo erectus, at 1.9 million years ago.

But then there’s the contested evidence. At roughly 2.4 million years ago—before A. sediba— a species called H. habilis (“handy man”) lived in Africa, although the researchers say there is disagreement over what fossils should be included in this species. If this handy man is really the earliest member of Homo, it’s hard to call A. sediba an ancestor (unless, perhaps, additional fossil finds push back A. sediba’s age).

In some ways, H. habilis is more human-like than earlier hominids; it had a much larger brain, for example. But in other ways, such as the anatomy of the hand, A. sediba is more human-like than H. habilis, Berger and his colleagues say. What does this all mean? It’s unclear. But at the very least, several different types of Homo-like hominids probably all lived at about the same time—making it a “most challenging endeavor,” the researchers say, to figure out how these forms relate to each other and which if any best represents the ancestor of our genus.

As paleoanthropologists like to say, more fossils may help clarify things—or muddle them even more.

If these bones have been gnawed on, scientists can tell if it was an herbivore or a carnivore doing the chewing (courtesy of flickr user striatic)

When you see news stories with headlines like “Crocodile Ate Our Human Ancestors,” do you ever wonder how the archaeologists knew that the bones had been chewed by a certain creature? This is harder than it seems because carnivores aren’t the only creatures munching on bones, and herbivores are not the strict vegans we think they are. Herbivores eat bones. They’re not delving in to get the yummy marrow, though. Herbivores chew only on dry bones and only when they’re mineral-deprived; the bones provide essential nutrients, phosphorus and a bit of sodium.

This interesting little factoid led a group of archaeologists to conduct a study in a protected bit of Spanish forest so they could learn how to tell apart bones chewed by herbivores and carnivores. (Their results appear in the Journal of Archaeological Science.) They collected 249 bits of bone that had evidence of gnawing, examined them in detail and documented the different types of damage.

Carnivores, the researchers found, chewed on fresh bones that had lots of marrow and lots of meat attached to them. They would sometimes move the bones to a new location and/or pile a bunch together. Their toothmarks consisted of depressions, puncture marks and grooves. And they frequently scooped out the bones.

The damage from herbivores, though, was different. These animals chewed old, dry bones, and their toothmarks, mostly grooves, often appeared on top of signs of weathering. Herbivores preferred flat bones—such as tibias, mandibles and ribs—that they could more easily hold in their mouths. They like to chew on the ends of bones, holding them like a cigar, which can produce an easily recognized forked end.

The researchers carried out their study so that other archaeologists will have a guide for when they encounter gnawed bones. But more important, probably for you, now you know: If you spot a deer in the forest that looks like he’s chewing on the end of a whitish cigar, don’t worry. It hasn’t turned into some rabid were-deer; it just needs a mineral supplement.

Llamas can still be found at Machu Picchu today (image courtesy of flickr user Santiago S.V.)

The Incas dominated much of South America for centuries, building a vast empire that stretched high into the Andes where the terraced city of Machu Picchu still inspires wonder. Now scientists in France and Peru, reporting in the journal Antiquity, reveal what made it all possible: llama dung.

The researchers analyzed mud cores from the bottom of a lake near the Incan town of Ollantaytambo in Peru. These sediment samples contain a record of past environmental conditions in the area. (In some places, scientists have found cores that give records stretching back tens of thousands of years). In the Peruvian sample, the researchers found a sudden increase in maize (corn) pollen starting around 2,700 years ago. Unlike the wild-grown quinoa that the Incas had previously relied upon to survive, cultivated maize provided more energy and could be stored or transported long distances, perfect for fueling a growing empire. But how were they able to grow maize high up in the mountains?

The mud samples also provide that answer. About the same time that there was an increase in maize pollen, there was an increase in oribatid mites, tiny insects that live in soil and feed on feces. The researchers conclude that dung from llamas—which the Incas had domesticated hundreds of years previously—provided food for all those mites. Llamas “defecate communally so [their dung] is easily gathered,” Alex Chepstow-Lusty of the French Institute of Andean Studies explained to the Guardian. The Incans could then use the poop as fertilizer for their maize fields, which reached elevations up to 11,000 feet above sea level. “This widespread shift to agriculture and societal development was only possible with an extra ingredient—organic fertilizers on a vast scale,” Chepstow-Lusty says.

A mummified princess from Thebes (known as Luxor during her time) is the earliest person known to have had coronary heart disease (courtesy of flickr user Rita Willaert)

You might be under the impression that hardening of the arteries, a.k.a. atherosclerosis, is a modern problem. That our diets, rich in animal fats and processed foods, are the problem, and if we only ate like humans used to not so long ago, we’d have no need for bypass surgeries and no one would ever die of a heart attack. But atherosclerosis is common in Egyptian mummies, say scientists who imaged dozens in Egypt, going as far back as 1550 B.C. (Their study, recently published in the journal Cardiovascular Imaging, was presented at the International Conference of Non-Invasive Cardiovascular Imaging earlier this week.)

The researchers created CT scans of 52 ancient Egyptian mummies at the National Museum of Antiquities in Cairo (the mummies couldn’t leave, so the scans were done at the museum). They could see arteries in 44 of the mummies. Of those, 20 had calcification, a marker for atherosclerosis, in their arteries, and in three of the mummies that calcification could be seen in coronary arteries.

Calcification in the right (RCA) and left (LCA) coronary arteries appears white in this CT scan (courtesy of the European Society of Cardiology)

The mummies with signs of atherosclerosis tended to be those that had lived the longest; they averaged 45 years old. One of the three with coronary heart disease was the princess Ahmose-Meryet-Amon, who lived in Thebes around 1580 to 1530 B.C. and died in her 40s; two of her three main coronary arteries were blocked. If she had lived today, “she would have needed bypass surgery,” said one of the study’s co-authors, Gregory Thomas of the University of California, Irvine. She is now known as the earliest person in history to have suffered from coronary heart disease.

At the time when the princess lived, the Egyptian diet consisted of fruit and vegetables, bread, beer and a little domesticated, lean meat, which may sound like a doctor’s recommendation for how to avoid the very problem the princess had. So how did her arteries end up with so much calcification? The researchers have a couple of theories. Parasitic infections were common in ancient Egypt, and the resulting inflammatory response may have predisposed her body to atherosclerosis, much as HIV appears to do so today. Foods during that time were often preserved in salt, which could have had an adverse effect. Or the princess may have eaten a different diet than the average Egyptian; as a royal, she could have feasted on luxury foods like meat, cheese and butter, the very items that heart doctors tell us to avoid.

George Pollard Jr. was not a very lucky sea captain. In 1819, he became captain of the whaling ship Essex, out of Nantucket, Massachusetts, and headed for the Pacific Ocean. Just four days out, though, a storm struck and damaged the ship. Still, Pollard pressed on, rounding Cape Horn in January 1820 and then sailing north. Worse luck struck in November, when the ship was rammed twice by a large sperm whale. The Essex sank, and the crew piled into the small whaleboats with as much supplies as they could carry. It wasn’t enough, however—many men died and some had to resort to cannibalism to survive. The first mate wrote an account of the ordeal, and it inspired Herman Melville to write Moby Dick about Captain Ahab and his quest for the white whale.

When Pollard returned to Nantucket, he was given command of another whaling ship, the Two Brothers. And his back luck held. On the night of February 11, 1823, the ship struck a shallow reef off French Frigate Shoals, about 600 miles northwest of Hawaii. The crew members fared better that time, at least, and were rescued the next day by another Nantucket whaling ship. But Pollard’s career as a whaling captain was over. He made one trip on a merchant vessel and then spent the rest of his life as a night watchman, safe on dry ground in Nantucket.

A diver examines an anchor from the Two Brothers (credit: NOAA)

The Two Brothers remained hidden on the bottom of the sea until 2008 when marine scientists went on an expedition to the Northwestern Hawaiian Islands to study the marine life there. This area is part of the Papahānaumokuākea Marine National Monument, 140,000 square miles of protected ocean and one of the world’s largest protected areas.

Divers on the expedition first spotted a large anchor, the first clue that there might be some bigger find on the seafloor. Then they found other items, such as cast-iron pots, called trypots, of the type used to melt whale blubber, indicating that it wasn’t just any old wreck; marine archaeologists concluded that they had found a whaling ship.

Expeditions in 2009 and 2010 turned up items such as ceramics and glass that helped the scientists date the wreck, and first-hand accounts from sailors who had been on the Two Brothers approximately matched the location of the find. Now the scientists are ready to publicly conclude that the wreck was Captain Pollard’s ill-fated ship.

This is the first wrecked Nantucket whaling ship to ever be found, which is rather amazing considering how many hundreds of those ships were in existence during Nantucket’s whaling heyday in the 1700s and early 1800s, and how many must have sunk; whaling was never a safe occupation. “Shipwreck sites like this are important in helping tell the stories of the early days of sailing, including whaling and maritime activities both in the Pacific and around the world,” said Papahānaumokuākea Marine National Monument maritime archaeologist Kelly Gleason, who led the expedition.