3-D analysis of dog fossils sheds light on domestication debate

In an effort to settle the debate about the origin of dog domestication, a technique that uses 3-D scans of fossils is helping researchers determine the difference between dogs and wolves.

3D plot of PC1–3 mandible shape variation. Black: dogs, dark grey: Alaskan wolves, light grey: European wolves, 
dark red: Ivolgin fossils, green: Ust’-Polui fossils, purple: Pleistocene Alaskan wolves, cyan: 1600CE fossil dogs, 
orange: unknown Alaskan fossil canids, pink: 1600CE fossil wolf [Credit: Scientific Reports (2017)]

In the ongoing debate, one camp believes dogs were domesticated in the Paleolithic age (more than 17,000 years ago), when humans were hunter-gatherers. The other camp believes domestication occurred in the Neolithic age (17,000 to 7,000 years ago), when humans first established agriculture and civilizations.

Abby Grace Drake, a senior lecturer in the Department of Ecology and Evolutionary Biology, and her colleagues have been analyzing 3-D scans of ancient fossil canid mandibles to determine whether they belong to dogs or wolves. The answer, they find, is not so simple.

The researchers found that in the early stages of domestication, the skull changed shape but evolution of the mandible lagged behind and did not co-evolve with the skull. Their study is reported in the journal Scientific Reports.

"A lot of the fossil evidence for the date of dog domestication is based on morphological [structural] analysis of mandibles," said Drake, the paper's first author. Robert Losey, an anthropologist at the University of Alberta, Canada, is a senior co-author of the paper. "Our study shows that when you measure modern dog mandibles and wolf mandibles using 3-D measurements you can distinguish them, and yet when we looked at these fossil mandibles, they don't look like dogs or wolves."

Wolves have fairly straight mandibles while dog mandibles are curved, structural features that become evident in a 3-D scan. In a proof of principle, when analyzing the 3-D structures of mandibles of modern dogs, Drake and colleagues correctly classified 99.5 percent of the samples as being dog or wolf.

This video shows how a canid mandible changes shape and curves during its transition from wolf to dog 

[Credit: Abby Grace Drake/Cornell University]

However, 3-D analysis of fossil records from four ancient sites, two from Russia and two from Alaska, found that most of those fossil mandibles could not be classified as either dog or wolf, even though features in canid skulls from the same sites as well as other data proved that the samples were dog remains.

Other evidence also showed that these canids were domesticated: The remains were found within human dwellings, remains at both the Russian sites revealed butchery marks, indicating that they were eaten, and isotope analysis of canid and human remains from one of the sites - Ust'-Polui, in the Russian Arctic - showed canids and humans were both eating fish, and humans were feeding their canids.

Since mandibles do not appear to evolve as rapidly as the skull, the results show they are not reliable for identifying early dog fossils, Drake said.

Four of 26 fossil mandibles from Ust'-Polui, which was occupied from 250 B.C. to 150 B.C., were identified as dogs, while three of the mandibles from the site were identified as wolves.

At another site, Ivolgin, in southern Russia, occupied between 300 B.C. and 200 B.C., none of the 20 mandibles were identified as dogs, though 8 were identified as wolves. All of the skulls found at these sites, 12 from Ivolgin and five from Ust'-Polui, were clearly identified as dogs.

Canid fossils of wolves and dogs from the Alaskan sites from 1600 CE were used as controls and to compare genetic testing against the structural 3-D data.

A 2015 paper by Drake and Michael Coquerelle, an anthropologist at the University Rey Juan Carlos in Alcorcon, Spain, and a co-author on the current paper, used the 3-D technique to refute a claim that dogs existed 30,000 years ago. That claim was based on linear caliper measurements of skulls. Linear measurements are inaccurate because dog and wolf skull sizes overlap, Drake said. On the other hand, 3-D analysis of skulls uses landmarks across the skull to identify differences between dogs and wolves in the angle of the muzzle, or snout, and in the angling of the eye orbits.

"The earliest dogs I've seen in my analysis are from 7,000 to 9,000 years ago," Drake said.

Author: Lindsey Hadlock | Source: Cornell University [September 21, 2017]

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60 ancient shipwrecks found by climate scientists at bottom of Black Sea

Dozens of perfectly preserved ancient shipwrecks have been found at the bottom of the Black Sea. A total of 60 wrecks were discovered dating back as far as 2,500 years, including galleys from the Roman, Byzantine and Ottoman empires.

Dozens of perfectly preserved ancient shipwrecks have been found at the bottom of the Black Sea. This image shows a 3D 
model of a Roman ship lying in over 2000m (650 ft) of water. Its mast still stands, both quarter rudders with their tillers
 are still attached. Rope is still draped over the frames due to the preservation of materials 
in the Black Sea’s anoxic conditions [Credit: BlackSeaMap]

Scientists stumbled upon the graveyard while using underwater robots to survey the effects of climate change along the Bulgarian coast. Because the Black Sea contains almost no light or oxygen, little life can survive, meaning the wrecks are in excellent condition.

Researchers say their discovery is 'truly unrivalled'. Many of the ships have features that are only known from drawings or written description but never seen until now. Carvings in the wood of some ships have remained intact for centuries, while well-preserved rope was found aboard one 2,000-year-old Roman vessel.

The wrecks, such as this one from the Medieval period, are astonishingly well preserved due to the anoxic conditions 
(absence of oxygen) of the Black Sea below 150 metres (490 ft). This trading vessel was found with 
the towers on the bow and stern still mostly in place [Credit: Rodrigo Pacheco-Ruiz]

The project, known Black Sea Maritime Archaeology Project (Black Sea MAP), involves an international team led by the University of Southampton's Centre for Maritime Archaeology.

Ed Parker, CEO of Black Sea MAP, said: 'Some of the ships we discovered had only been seen on murals and mosaics until this moment. There's one medieval trading vessel where the towers on the bow and stern are pretty much still there. It's as if you are looking at a ship in a movie, with ropes still on the deck and carvings in the wood. When I saw that ship, the excitement really started to mount – what we have found is truly unrivalled.'

Shown here is a shipwreck from the Ottoman period discovered 300 metres beneath the Black Sea. Many of the 
wrecks' details and locations are being kept secret by the team to ensure they remain undisturbed 
[Credit: Rodrigo Pacheco-Ruiz]

Most of the vessels found are around 1,300 years old, but the oldest dates back to the 4th Century BC. Many of the wrecks' details and locations are being kept secret by the team to ensure they remain undisturbed.

Black Sea water below 150 metres (490 ft) is anoxic, meaning the environment cannot support the organisms that typically feast on organic materials, such as wood and flesh. As a result, there is an extraordinary opportunity for preservation, including shipwrecks and the cargoes they carried.

The researchers used two Remotely Operated Vehicles (pictured) to survey the sea bed. These have discovered a number 
of wrecks over a series of expeditions spanning three years, including the one pictured from the Byzantine period, 
found in October last year [Credit: Rodrigo Pacheco-Ruiz]

Ships lie hundreds or thousands of metres deep with their masts still standing, rudders in place, cargoes of amphorae and ship's fittings lying on deck. Many of the ships show structural features, fittings and equipment that are only known from drawings or written description but never seen until now.

Project leader Professor Jon Adams, of the University of Southampton, said: 'This assemblage must comprise one of the finest underwater museums of ships and seafaring in the world.'

While the primary focus of the project is to carry out geophysical surveys, shipwrecks, including this one from the 
Ottoman period, have given new insights into how communities live on the shores of the Black Sea 
[Credit: Rodrigo Pacheco-Ruiz]

The expedition has been scouring the waters 1,800 metres (5,900ft) below the surface of the Black Sea since 2015 using an off-shore vessel equipped with some of the most advanced underwater equipment in the world. The vessel is on an expedition mapping submerged ancient landscapes which were inundated with water following the last Ice Age.

The researchers had discovered over 40 wrecks across two previous expeditions, but during their latest trip, which spanned several weeks and returned this month, they uncovered more than 20 new sites.

Scientists have accidentally discovered a graveyard of ancient shipwrecks while using underwater Remotely Operated 
Vehicles to survey the effects of climate change along the Bulgarian coast. Pictured are researchers exploring 
a recently discovered 2,000-year-old Roman galley buried in the seabed [Credit: BlackSeaMap]

Returning to the Port of Burgas in Bulgaria, Professor Jon Adams said: 'Black Sea MAP now draws towards the end of its third season, acquiring more than 1300km [800 miles] of survey so far, recovering another 100m (330 ft) of sediment core samples and discovering over 20 new wreck sites, some dating to the Byzantine, Roman and Hellenistic periods.' 

The researchers are using two Remotely Operated Vehicles (ROVs) to survey the sea bed. One is optimised for high resolution 3D photography, while the other, called Surveyor Interceptor, 'flies' at four times the speed of conventional ROVs.

The researchers had discovered over 40 wrecks across two previous expeditions, but during their latest trip, which 
returned this month, they uncovered more than 20 new sites, including a 2,000-year-old Roman galley 
shown here [Credit: BlackSeaMap]

The Interceptor carries an entire suite of geophysical instrumentation, as well as lights, high definition cameras and a laser scanner. Since the project started, Surveyor Interceptor has set new records for depth at 5,900ft (1,800 metres) and sustained speed  of over six knots (7mph), and has covered 1,250 kilometres (776 miles).

Among the wrecks are ships from the Roman, Ottoman and Byzantine Empires, which provide new information on the communities on the Black Sea coast. Many of the colonial and commercial activities of ancient Greece and Rome, and of the Byzantine Empire, centred on the Black Sea.