Squishy Bear Face

“No man is an island entire of itself;

every man is a piece of the continent, a part of the main;

if a clod be washed away by the sea,

Europe is the less, as well as if a promontory were,

as well as any manner of thy friends or of thine own were;

any man’s death diminishes me,

because I am involved in mankind.

And therefore never send to know for whom

the bell tolls; it tolls for thee.”

(John Donne, 1624)

For almost 400 years, the first sentence to this poem has served as metaphor for our lives: no man (or woman) is an island. No one can prosper living alone. Every person is a part of society, and each other. We can’t be alone. We need each other.

Sorry to say it Donne, but we are actually islands. Living, thriving islands. Each one of us carries around millions of bacteria that live, reproduce and die within us. Ed Yong recently explores the splendour of the unseen ecosystems within us, in his new book I Contain Multitudes. From the outside an animal looks like a lonely, empty island. But, like all islands, they are flourishing and rich with species.

There are plenty of wonderful examples of real islands which have incredible ecosystems. Being isolated for millions of years allows some fantastical creatures to evolve. Think of the oversized, flightless pigeon, the Dodo, on the island of Mauritius, or the giant Moa species on New Zealand, and the giant lemurs on Madagascar. The list goes on. Left alone natural, and sexual, selection will create some incredibly beautiful creatures.

One island has perhaps the most unique flora and fauna around today: Australia.

Drifting alone for around 30 million years across the vastness of the oceans, it is on Australia where marsupials reign. Before the continent of Australia found itself, it was joined with many landmasses into one pretty big one called Pangaea: this was a supercontinent. With one connected area of land animals could move with relative ease from one part to another.  Marsupials first turn up in the fossil record in Northern Pangaea (North America) around 65 million years ago, they spread southwards, across South America, over Antarctica and to Australia. Through the great movements of the Earth’s tectonic plates, around 30 million years ago Australia divorced itself from the other landmasses. Carrying with it unique animals. Animals that rear their young in a pouch: the marsupials.

The supercontinent

The supercontinent Pangaea, where all the land masses were joined together as one. Australia is at the bottom right, squished with Antarctica. (Image Public Domain)

Marsupials can be found today in North and South America, but there they have been overshadowed by placental mammals (the mammals like you and I where babies are nourished in the tummy by the placenta). Australia however, until very recently, only had placental mammals which were no real competition to the marsupials: bats. This allowed the marsupials to adapt to the changing environment, and evolve into some incredible creatures. An enormous variety of kangaroos, bigger than a human, sprung across the grasslands: one kangaroo may have even walked instead of hopped. A marsupial lion ambushed its prey from trees. Giant lizards, three times the size of today’s Komodo Dragons, stalked the bush. This really was an island of lost beasts. And they were big beasts.

The Order Diprotodontia, which includes kangaroos, koalas and wombats, also includes the biggest marsupials to have ever lived. Within the sub-family Diprotodontinae was the well-known, largest marsupial, Diprotodon. There was another sub-family, Zygomaturinae, which also had another giant species, the not so well-known Zygomaturus trilobus.

You might be thinking ‘Great, another massive wombat. What’s so different to Diprotodon to have another blog post?” And rightly so. Because Zygomaturus is just another giant wombat. It isn’t even the biggest wombat. But, like the Mona Lisa, this wonderful creature is more mysterious than meets the eye.

In honour of 27 years since Quantum Leap first airing, and for ease for you, we will call our beast Ziggy. (Whoa Boy! 27 years?! Where did that go!) Although a good number of fossils of Ziggy have been found across Australia and Tasmania, this still remains a rather enigmatic creature. Perhaps the oddest part of this animal is the skull: so odd that reconstructions are somewhat comical. A good friend who suggested writing about this strange marsupial, called it ‘squishy bear face’ because of reconstructions they had seen! And it does rather look like a bear that ran into a wall.

A bear that has run in to a wall?

A bear that has run in to a wall? Nope, this is Zygomaturus trilobus. (Image Nobu Tamura. Public Domain)

Ziggy’s head is weird. Very weird. And very different to Diprotodon in many ways. The skull was huge. So big, that it was filled with sinus cavities to make it a little lighter. The teeth were complex compared to its big cousin. Complex teeth patterns makes the teeth stronger. The enamel is not just on the outside of the tooth (like our teeth) but weaved into the tooth, making it able to wear down slower. And this indicates that Ziggy could eat coarser tougher foods.

A quick sketch of Ziggy's skull. Note the strange pointy bit of bone sticking out on the nose. (Art by Jan Freedman)

A quick sketch of Ziggy’s skull. Note the strange pointy bit of bone sticking out on the nose. (Art by Jan Freedman)

One part of Ziggy’s skull in particular has caused a lot of speculation about how this creature may have lived: the peculiar bony attachment on its nose. It is a big bone attachment, and no one really knows what it was for. Some researchers have suggested Ziggy actually had a trunk. Although others point out that a trunk needs a broad surface to have the muscles attach too, like in an elephant (which Ziggy doesn’t). Other researchers suggest that there was a high nasal cavity because it had a similar lifestyle to a hippopotamus. Yet another idea is that the bony attachment held a horn, and with horns being extremely rare to fossilise, none have ever been discovered. The consensus appears to be that this big nasal bone held some pretty big upper lips: a large muscular flap of skin hung from the face – not as long or muscular for a trunk, but strong enough to manipulate objects.

The bones in the skeleton are equally strange. This was a stocky beast. The front leg bones were long, but muscle scars show they had very big muscles. Like elephants with their relatively thin leg bones, they were good walkers, but poor runners (because the thinner bones cannot take the weight and enormous stresses produced by running). These front legs also had some pretty serious claws. And again, no one really knows why. Giant claws could have been used for digging for food, or perhaps defence. As we saw with some species of giant ground sloths, big claws could have been used for digging burrows. (I should say, the possibility of Ziggy digging burrows is my own speculation. There is, as of yet, no evidence of any palaeo-burrows in Australia. And compared to giant ground sloth skeletons, the arm bones do look less robust for digging.)

Ziggy was a pretty big wombat. (Image by Jan Freedman)

Ziggy was a pretty big beast. (Image by Jan Freedman)

Fossils of Ziggy have been found all over Australia, and Tasmania. The distribution of the finds indicates that this giant wombat did prefer slight wetter environments to live in. Diprotodon was more widely distributed. The continent may have been large enough to be home to two species of large herbivores because of their different diets: Ziggy happily chomping through tough vegetation, while Diprotodon was at home enjoying luscious, softer green leaves.

The fossil finds of Ziggy and other Pleistocene giants. Notice Ziggy's distribution is close to the coast. (Image from Quaternary Extinctions. page 264).

The fossil finds of Ziggy and other Pleistocene giants. Notice Ziggy’s distribution is close to the coast. (Image from Quaternary Extinctions. page 264).

Ziggy and her kind were around for over 15 million years, which is a pretty long time for any Sub-Family. Her success was due to her isolation. Island living animals have the time to adapt to the changing environments on that island, and the other inhabitants. So when a new animal appears, it can cause havoc. This happened when North and South America joined together and animals from both land masses moved up and down, entering new environments, and wiping out species. And something happened in Australia too. Around 35,000 years ago Ziggy vanished. She clung on in small populations on Tasmania. But by around 24,000 years ago, Ziggy vanished forever.

Her disappearance coincides with the arrival of humans around 50,000 years ago. However, with these early Australian living out in the open, there are few sites showing clear evidence of hunting. (This is compared to the abundant fossils found in caves in Europe and America where the remains are more protected from the outside world.) As a little aside, thanks to Lee Constable, I recently discovered that wombats will pee if their bottoms are tickled. Obviously, the first thing I thought when I saw this, was did the first Australians try something like this with Ziggy? Tickling a giant wombat’s bottom would have been an interesting thing to witness.

At around the time Ziggy and her kind started to disappear, the world was changing. Sea levels were lower as water was trapped in the great ice sheets in the northern hemisphere. Worldwide, the climate was drier. Australia was moving slowly northwards, getting warmer, and beginning to lose its luscious tropical rain forests. As with many of the great Pleistocene extinctions, there was likely to be more than one factor contributing to the end of this species. Ecological stresses would have put intense pressure on small groups. Coupled with a new carnivore on the scene, our squishy faced bear vanished forever.


“We are all islands”? “He disagrees with Donne?!” Now, dear reader, you may be wondering where my romantic side has gone. For those who have followed this blog for the last two and half years, you will know I am a romantic at heart. And there is nothing wrong with romanticising science so long as the reader comes away swoon by the gorgeous key facts. I do believe 400 years ago, Donne had it right. No one should be alone. The ocean we live in each day is full of other islands. We may go along drifting, bumping into other islands every now and again. Perhaps we let them float by. Maybe we hold onto them. Even with millions of people around us, our little lives can sometimes seem as big, and empty, as an ocean. Life is short. Don’t let something special drift by.

Written by Jan Freedman (@JanFreedman)

A special thanks to Gilbert Price, vertebrate paleoecologis at The University of Queensland, for his help with gathering information for this post.

Further reading:

Black, K. H., et al. (2010). ‘First comprehensive analysis of cranial ontolgeny in a fossil marsupial – from a 15 million year old cave deposit in Northern Australia.’ Journal of Vertebrate Paleontology. 30(4). pp.993-1011. [Abstract only]

Johnson, C. (). Australia’s Mammal Extinctions, a 50,000 year history. Cambridge University Press. [Book]

Martin, P. & Klein, R. G. (Eds) (1989). Quaternary extinctions. University of Arizona Press. [Book]

McNamara, K. & Murray, P. (2013). Prehistoric Mammals of Western Australia. Western Australian Museum. [Book]

Megirian, D., et al. (2010). ‘An Australian land mammal age biochronolgical scheme.’ Paleobiology. 36(4). pp.658-671. [Full article]

Meredith, R. W., Westerman, M., & Springer, M. S. (2009). ‘A phylogeny of Diprotodonta (Marsupialia) based on sequences of five nuclear genes.’ Molecular Phylogenetics and Evolution. 51. pp.554-571. [Abstract only]

Pate, F. D., et al. (2002). ‘Last recorded evidence for megafauna at Wet Cave, Naracoorte, South Australia. 45,000 years ago.’ Australian Archaeology. 54. pp.53-55. [Abstract only]

Price, G. (2008), ‘Taxonomy and palaeobiology of the largest‐ever marsupial, Diprotodon Owen, 1838 (Diprotodontidae, Marsupialia).’ Zoological Journal of the Linnean Society 153.2. 369-397. [Abstract only]

Prideauz, G. J., et al. (2010). ‘Timing and dynamics of Late Pleistocene extinctions in southwestern Australia.’ Proceedings of the National Academy of Sciences of the United States of America. 107(51). pp.22157-22162. [Abstract only]

Price, G. (2012), ‘Plio-Pleistocene climate and faunal change in central eastern Australia.’ Episodes-Newsmagazine of the International Union of Geological Sciences 35. 1  160.

Turny, C. S.M., et al. (2008). ‘Late-surviving megafauna in Tasmania, Australia, implicate human involvement in their extinction.’ Proceedings of the National Academy of Sciences of the United States of America. 104(43). pp.12150-12153. [Abstract only]

Posted in Zygomaturus | 5 Comments

Turtle Power

In the canonical tale, Big Chuck D’s visit to the Galapagos was a “Eureka!” moment, where he instantly worked out his theory of evolution by natural selection after observing the different species of finches on the archipelago’s varying islands. Almost nothing about this tale is true. Darwin’s collecting in the Galapagos was haphazard and unlabelled; he had to retrospectively fill in the blanks on his specimens when he got back to England with the help of shipmates. The idea of natural selection did not appear fully formed in Charlie’s brain but percolated there over many years at Down House, coupled with his continual tinkering and experimenting. The idea of different forms inhabiting different islands was something discussed on the Galapagos during his visit. But it was the giant tortoises that were the subject.

“My attention was first called to this fact by the Vice-Governor, Mr. Lawson, declaring that the tortoises differed from the different islands, and that he could, with certainty tell from which island any one was brought.”

The  species of Chelonoidis nigra found in the Galapagos and Aldabrachelys gigantea of the Seychelles and Aldabra are the only surviving giant tortoises (and we very nearly lost them too). Go back a few hundred years and there were various, now extinct, species of giant tortoise on Madagascar and the Mascarenes. Back in the Pleistocene we had something even more wonderful (quelle surprise!) in the mellifluous meiolaniids. These giants were the convergent herptile version of the glyptodonts and ankylosaurs that had independently hit upon a similar niche.


The distribution of giant tortoises. Green=extant, Red=meiolaniids. Map from http://www.d-maps.com


Wild Santa Cruz tortoise Chelonoidis nigra porteri. Image author’s own.


Observing megafauna at Charles Darwin Research Centre, Santa Cruz, Galapagos. Image author’s own.

When I visited the Galapagos I had the intense pleasure of hanging out at the Charles Darwin research centre and chilling with some of the rescued giant tortoises that reside there. It really was special just being able to sit and watch a giant wild creature, naïve to the special threat that humans usually pose, and happy to go about its feeding without fear. Even if it had wanted to attack me, the worst it could probably inflict was a serious gash from its keratinous beak. The meiolaniids, on the other hand, basically scream out from every apomorphy “back off, man”. Shell? Spikes. Skull? Oh my god, so many spikes. Tail? You bet there were spikes.


Skull of Niolamia argentina from Patagonia. Public Domain image vie Wikimedia Commons


Reconstructed skeleton of Meiolania platyceps from Lord Howe Island at the AMNH. Image by Claire Houck via Wikimedia Commons


Close up on the armoured tail of Meiolania platyceps from Lord Howe Island Maritime Museum. Image by Fanny Schertzer via Wikimedia Commons


Wonderful public domain image of a meiolaniid. Via Wikimedia Commons

The Meiolanidae are known from the southern continents that made up Gondwanaland, particularly South America and Australia. Two of the best known species from Oz are Meiolania oweni (now Ninjemys oweni, more on this later) found in Queensland, and Meiolania platyceps, known from Lord Howe Island. Lord Howe Island is a pretty tiny chunk of volcano way out in the middle of the south pacific, hinting that this was a very widespread family of hero-turtles. In fact, meiolaniid fossils have been found on New Caledonia, Vanuatu, and other Polynesian islands.


Lord Howe Island: Tiny and in the middle of nowhere between Australia and New Zealand. Via Wikimedia Commons

The history of their discovery involves some very famous Victorian naturalists. Richard Owen first erroneously identified a mixed assemblage of bones from Australia that included Meiolania, as Megalania prisca the giant monitor lizard. “Darwin’s Bulldog” T. H. Huxley then set him right in an appropriately sassy publication with the putdown “What Megalania prisca may be I do not pretend to say” <sips tea>. In South America, Florentino Ameghino, Francisco Moreno and Santiago Roth (who were involved with excavation of Mylodon cave in Patagonia) described Patagonian Meiolania material (now known as Niolamia argentina). Moreno even published descriptions of Meiolania/Niolamia in a paper with a description of the famous Mylodon darwinii skin from Ultima Esperanza. Niolamia as a taxonomic entity seems to result from the perils of a 19th century science that relied on postal communication and deciphering cursive.


A cartoon of Richard Owen(L) and Thomas Huxley(R) satirising their well-known antipathy towards each other in matters of science. This is referred to in Charles Kingsley’s “The Water Babies” from where this image by Linley Sambourne is taken. Via Wikimedia Commons

In terms of when this living wartortle actually roamed, the fossils give us the answer. The specimens from mainland Australia are Pleistocene in age and coeval with Diprotodon, Thylacoleo, Megalania, and the other marsupial megafauna. The Lord Howe island material is certainly Pleistocene and possibly even Holocene in age. Material from New Caledonia has been found in layers dated to just 1,720±70 years, but could have been redeposited. However, the most interesting dating comes from Vanuatu. Here dozens of bones of ?Meiolania damelipi found in the lowest midden layers of a Lapita cemetery were only 2890-2760 years old. This corresponds exactly with the first evidence for people on these islands. Like the ground sloths, woolly mammoths and other vanished taxa, it seems incontrovertible that humans first wiped out the continental populations before finding their isolated island outposts and slaughtering them there too.

If only Michelangelo, Donatello, Raphael, and Leonardo could have taught the meiolaniids some self-defense! But wait. I referred earlier to the taxonomic reshuffling that turned Meiolania oweni into Ninjemys oweni and didn’t explain why. Prolific meiolaniid author Eugene Gaffney has devoted a lifetime to studying these awesome creatures and in his expert opinion the Pleistocene Australian material is generically distinct from the later Lord Howe material. He needed to erect a new genus name and I leave his most bodacious explanation for the etymology of Ninjemys below.

“Etymology: Ninja in allusion to that totally rad, fearsome foursome, epitomizing shelled success; emys, turtle.”


Written by Ross Barnett (@DeepFriedDNA)

Further Reading:

Darwin, C. R. The Voyage of the Beagle. New York: Penguin, 1839.[Full Text]

Gaffney, E. S. “The Cervical and Caudal Vertebrae of the Cryptodiran Turtle, Meiolania platyceps, from the Pleisocene of Lord Howe Island, Australia.” American Museum Novitates, no. 2805 (1985): 1-29.[Full Text]

———. “The Cranial Morphology of the Extinct Horned Turtle Meiolania platyceps, from the Pleistocene of Lord Howe Island, Australia.” Bulletin of the American Museum of Natural History 175, no. 4361-480 (1983).[Full Text]

———. “Ninjemys, a New Name for “Meiolaniaoweni (Woodward), a Horned Turtle from the Pleistocene of Queensland.” American Museum Novitates, no. 3049 (1992): 1-10.[Full Text]

———. “The Postcranial Morphology of Meiolania platyceps and a Review of the Meiolaniidae.” Bulletin of the American Museum of Natural History, no. 229 (1996): 165.[Full Text]

Gaffney, E. S., J. C. Balouet, and F. De Broin. “New Occurrences of Extinct Meiolaniid Turtles in New Caledonia.” American Museum Novitates, no. 2800 (1984): 1-6.[Full Text]

Huxley, T. H. “Preliminary Note on the Fossil Remains of a Chelonian Reptile, Ceratochelys sthenurus, from Lord Howe’s Island, Australia.” Proceedings of the Royal Society of London Series B-Biological Sciences 42 (1887): 232-38.[Full Text]

Moreno, F. P. “Note on the Discovery of Miolania and of Glossotherium (Neomylodon) in Patagonia.” Geological Magazine Decade IV. Volume VI, no. IX (1899): 25-29.[Full Text]

Owen, R. “Description of Some Remains of the Gigantic Land-Lizard (Megalania prisca, Owen) from Australia. Part Ii.” Philos Trans R Soc Lond B Biol Sci 171 (1880): 1037-50.[Full Text]

———. “On Parts of the Skeleton of Meiolania platyceps (Owen).” Philosophical Transactions of the Royal Society B-Biological Sciences 179 (1888): 181-91.[Full Text]

Sterli, J., and M. S. de la Fuente. “Re-Description and Evolutionary Remarks on the Patagonia Horned Turtle Niolamia argentina Ameghino, 1899 (Testudinata, Meiolaniidae).” Journal of Vertebrate Paleontology 31, no. 6 (2011): 1210-29.[Abstract]

White, A. W., T. H. Worthy, S. Hawkins, S. Bedford, and M. Spriggs. “Megafaunal Meiolaniid Horned Turtles Survived until Early Human Settlement in Vanuatu, Southwest Pacific.” Proceedings of the National Academy of Sciences of the United States of America 107, no. 35 (2010): 15512-16.[Full Text]

Posted in Meiolania | Tagged , , , , , , , , , , , , , , , , , , , | Leave a comment

Staying put: the what, when, and how of the first farmers

We’ve all thought about making lifestyle changes at some point. Joining a running group. Going on a diet. Stopping smoking. So did our hunter-gatherer ancestors. They made what would be perhaps one of the greatest lifestyle changes in the history of our species: they started what would become farming. And it caught on, having vast implications for the world we know today.

For most of our time on earth humans have practised what is known as a hunter-gathering lifestyle; a nomadic lifestyle where food, largely meat, is obtained and shared through foraging. Although there are still some groups practising this mode of subsistence, in multiple parts of the world individuals and populations underwent a massive paradigm shift to a new way of life. From the end of the Pleistocene humans began to settle; we began to cultivate the land, to herd animals and drink milk continuously into adulthood. No longer was supply in shortage but instead in surplus.

A comparative timeline of the origins of agriculture and associated technologies. Drawn by Dr. Chris Stevens as part of the ComPAg project.

A comparative timeline of the origins of agriculture and associated technologies. Drawn by Dr. Chris Stevens as part of the ComPAg project.

This way of acquiring food, and by “owning” the land they lived on, spawned social hierarchy, currency and many other socio-political and cultural changes. It was the event that perhaps changed the very nature of our species. This process occurred at least three times around the world: the Middle East, Latin America and China. Farming not only profoundly changed the face of humanity but also changed the terms of humanities relationship with the world. But what drove this change? Researchers are working hard to try and understand why this happened, why it was so successful and how it spread.

Some of the earliest evidence of farming anywhere in the world has been found in the Fertile Crescent (south eastern Turkey, north eastern Iraq, and western Iran); a crescent shaped piece of moist, cultivable land situated between the arid Arabian Desert to the South and the Armenian highlands to the North. Archaeological sites in the region tell stories of rich civilisations with evidence of early crop cultivation and crop storage. For example, the Neolithic site of Chogha Golan (Ilam Province, present-day Iran) is known for a striking record of the cultivation of wild plants and some of the earliest appearances of domesticated crop species such as wheat and barley. Stone tools from the site include mortars, pounders, pestles and grinding slabs for processing grains and other foods. There is also strong evidence for the presence of domesticated livestock in the region including goats, sheep, pigs and cows. Rather importantly, it is also thought to be one of the first places we brewed beer. Based on the archaeological record it appears that from this fertile region farming spread through Turkey, Greece and Cyprus by 6500BCE, and then spread through the Balkans, Central Europe and the Mediterranean eventually reaching Britain around 4000BCE. As a historical process this change is called the Neolithic revolution (the term Neolithic relates to the adoption of agriculture and it’s distinct culture).

Trench at the Neolithic site of Chogha Golan at the foot of the Zagros Mountains, Iran.

Trench at the Neolithic site of Chogha Golan at the foot of the Zagros Mountains, Iran.

By the rate of spread you might think that farming was a sensible idea with immediate rewards. But what remains a puzzle is that at least to begin with, farming doesn’t appear to be that beneficial. Imagine, as a hunter-gatherer, that you decided to try a new strategy and stop moving; to settle in one place and to take up a lifestyle that would become what we now know as farming. As life goes on you begin to face new challenges; living in large groups of people, close to animals, accumulating stinky bio-waste and rubbish. Disease begins spreading between you, between your animals and between your crops. The good wheat you’ve worked hard to grow and store has become ridden with pests. You’re working harder for longer hours with less reward. You think to yourself, tired and shivering with fever, was this really worth it?

So if it wasn’t immediately a good strategy, why did those first hunter-gatherers who started farming keep doing it and why did it catch on? One line of research is exploring the different factors that caused our hunter-gatherer ancestors to make the switch. Using mathematical models it is possible to theoretically simulate various situations and conditions and extrapolate what implications they may have. Using a model-based approach is particularly important in this scenario because we are investigating events that happened a long time ago: you can’t go back in time and investigate using the standard tools an anthropologist might today. Models are also useful where lots of independent factors are interacting in a way that is difficult to understand using intuition, as is the case here.

Recent research exploring the historical dynamics of farming suggests that the development and persistence of farming is most probable in a model where the first hunter-gatherers to start farming were in small groups of a handful or so individuals. They also conclude that ownership of land (property rights) is an important factor and that in some instances it is possible for a farming way of life to persist even if it results in less food than you might get from hunter-gathering – not intuitive at all! So it appears farming may initially have grown from small groups of individuals trying out new methods but where the idea of land ownership was important.

As we’ve said this shift created a corresponding need for new technologies and with it a culture change. Some key definers of Neolithic life include developments in architecture, tools, figurines and jewellery. Pottery was also important, with large jars created to store excess grain becoming more decorated as the Neolithic persisted, allowing many archaeological sites to be defined chronologically based on the kinds of pottery vessels discovered. Burial practice and mythology also changed shown through the appearance of ceremonial monuments including the famous Stonehenge. And of course monuments of this kind only make sense if you live a sedentary life-style. Why bother creating such a spectacle if you have to move on in search of the next meal soon after?

The world famous monument of Stonehenge was erected in the Late Neolithic around 2500BCE.

The world famous monument of Stonehenge was erected in the Late Neolithic around 2500BCE.

Farming didn’t just change us culturally but also genetically and so analysis of DNA is another important tool in exploring this transition. The debate that continued for many years was how farming spread in to Europe from the Near East. Did plucky groups of inventors develop this new way of life and it was swiftly copied throughout Europe by way of word of mouth (the “cultural diffusion” model)? Or did those first farmers migrate to new areas with their novel technology displacing and replacing the existing hunter-gatherer groups they met along the way (“demic diffusion” model)? Although these models should not be regarded as mutually exclusive they do offer a testable hypothesis for geneticists.

One way geneticists have been trying to answer these questions is using DNA extracted from remains of some of the very first European farmers (ancient DNA). By comparing the DNA of early farmer individuals to the DNA of people alive today these competing ideas can be explored. It might seem simple but it turns out that working with very old DNA is fraught with difficulties. When an organism is alive, DNA repair enzymes work hard to maintain the integrity of DNA. After death however these enzymes stop working and the DNA immediately begins to degrade breaking up strands into smaller and smaller pieces and changing the genetic code. This process continues over time and is sped up in warm and wet climates. What’s more, particularly when working with human ancient DNA, there is a high risk of contamination. When the degraded DNA you are trying to work with closely resembles that of you, the researcher in the lab, the excitement of your new discovery is quickly quashed by the realisation you have cross-contaminated your sample! That being said, with improved technology such as next generation sequencing, the field of ancient DNA research is expanding rapidly. One key development was the discovery that the petrous bone of the inner ear contains a startling amount of DNA, hidden, relatively untouched by contaminating bacteria and somewhat immune to the effect of warm temperatures, lying deep within the skull.

Human skeleton from an archaeological excavation in Northern Greece (Paliambela Excavation Project Archive - credit K. Kotsakis and P.Halstead).

Human skeleton from an archaeological excavation in Northern Greece (Paliambela Excavation Project Archive – credit K. Kotsakis and P.Halstead).

DNA extracted from the petrous bone of human remains found in Anatolia and Greece (some of the earliest farming sites) has been used to directly test the hypotheses of demic versus cultural diffusion models. By comparing the DNA of Europeans alive today with DNA from these very early Anatolian and Greek farmers it has been shown that all Neolithic farmers look genetically similar to present day Southern Europeans and that the patterns of shared ancestry extend all the way back to North-West Anatolia. This suggests a wide-spread migration and replacement by farmer individuals moving into Europe and that the change to farming in Europe was mediated by moving people rather than primarily by the spread of ideas.

The story gets more complicated if we consider the genetic status of the first farmer individuals beyond Anatolia. Despite the challenge of the warm climate of the Near East ancient DNA has recently been obtained from human remains from the heart of the Fertile Crescent – those individuals that lived right at the very dawn of farming. Recent work involving three research groups compared DNA from very old human farmer remains found in Fertile Crescent to DNA from other early farmers, late hunter-gatherers and modern individuals. Very strikingly, considering the genetic status of individuals from this region, it was found that there were in fact genetically distinct groups of early farmers occupying this region.

Genetic analyses showed that these early Iranian farmers were not the ancestors of farmers in Europe and instead closely resemble modern day groups from Armenia, Pakistan and India. What is more, ancient DNA samples from early farmers in the Southern Levant (Israel and Jordan) were different again, likely spreading their farming culture southwards in to East Africa. It seems this revolution was brought about by groups of people who were extremely genetically different. These new finds will direct researchers to look for more archaeological sites in order to better characterise how these distinct groups have contributed to present day genetic diversity and what this means for how farming spread to other parts of the globe.

Ancient DNA from human remains in Iran (blue) and Anatolia (red) show very different genetic affinities to modern day populations suggesting multiple origins for farming and evidence of an eastwards expansion (adapted from Broushaki et al. 2016).

Ancient DNA from human remains in Iran (blue) and Anatolia (red) show very different genetic affinities to modern day populations suggesting multiple origins for farming and evidence of an eastwards expansion (adapted from Broushaki et al. 2016).

But we don’t just have to look at humans. Farming involved the domestication of crops and animals and this leaves its own genetic signature. One active line of enquiry is analysing archaeological remains and performing genetic analyses comparing the DNA from present day domestic species to Neolithic plant and animal remains. Barley, for example is largely regarded as a founder crop of Neolithic agriculture. Recent work, which extracted the genome sequences of five 6,000 year-old barley grains (the oldest plant genome reconstructed to date) discovered at Yoram Cave in Israel, found that these first domesticated barley grains are surprisingly genetically similar to modern day domestic barley but strikingly different genetically to the wild forms grown in the Levant today. This suggests that barley was indeed domesticated within the upper Jordan Valley of the Fertile Crescent, which agrees well with known archaeological sites.

The same can also be said of animals. The Zagros region of Iran has largely been regarded as the site of domestication of the goat from the wild Bezoar goat to a domesticate form more like we know today. Ancient DNA analysis, this time of mitochondrial DNA (DNA passed down exclusively through the female line) from goat remains, reveals that this region is the likely progenitor of the domestic goat and that the mitochondrial DNA lineage of goats from this region is the same as that responsible for population expansions into West Iran, the South Caucasus and beyond.

Dry preservation of plant remains from excavations (left) and a well preserved, desiccated barley grain found at Yoram cave (right)

Dry preservation of plant remains from excavations (left) and a well preserved, desiccated barley grain found at Yoram cave (right)

Neolithic goat jaw bone from Göytepe (Image courtesy of Nagoya University).

Neolithic goat jaw bone from Göytepe (Image courtesy of Nagoya University).

So farming was adopted multiple times in the Fertile Crescent by small groups of hunter-gatherers that were remarkably genetically distinct from one another. The spread of farming involved the movement of people who took with them new domesticated forms of plants and animals as well as new technologies, social organisations, culture and ideas. And it was this that profoundly changed the world in which we live today.

Written by Lucy van Dorp (@LucyvanDorp)

Edited by Jan Freedman (@JanFreedman)

Further Reading:

Broushaki, M.G Thomas, V. Link et al. (2016). ‘Early Neolithic Genomes from the Eastern Fertile Crescent’. Science. 353, 6298. pp.499-503. [Abstract only]

Dounias, & A. Froment. (2011). ‘From foraging to farming among present-day forest hunter-gatherers: consequences on diet and health.’ International Forestry Review. 13, 3. pp.294-304. [Abstract only]

Gallego Llorente, S. Connell, E.R. Jones et al. (2016). ‘The genetics of an early Neolithic pastoralist from the Zagros, Iran.’ Scientific Reports. 6. p.31326. [Full article]

Hofmanova, S. Kreutzer, G. Hellenthal et al.,(2016). ‘Early farmers from across Europe directly descended from Neolithic Aegeans.’ PNAS. 113(25). pp.6886-91. [Full article]

Gallagher, S. Shennen, & M.G. Thomas, (2015). ‘Transition to farming more likely for small, conservative groups with property rights, but increased productivity is not essential.’ PNAS. 112(46). pp.14218-23. [Abstract only]

Kadowaki, K. Ohnishi, S. Arai, et al.,(2016). ‘Mitochondrial DNA Analysis of Ancient Domestic Goats in the Southern Caucasus: A Preliminary Result from Neolithic Settlements at Göytepe and Hacı Elamxanlı Tepe.’ International Journal of Osteoarchaeology. pp.1099-1212. [Abstract only]

Lazaridis, D. Nadel, G. Rollefson et al., (2016). ‘Genomic insights into the origin of farming in the ancient Near East.’ Nature. 536. Pp.419-424. [Abstract only]

F.H. Mazdarani, M.T. Akbari, R.M.N. Fard et al., (2014). ‘Molecular dentification of Capra hircus in East Chia Sabz, an Iranian pre-pottery Neolithic site, central Zagros, based on mtDNA.’ The Journal of Animal & Plant Sciences. 24(3). pp.945-950. [Full article]

Mascher, V.J. Schuenemann, U. Davidovich et al., (2016). ‘Genomic analysis of 6,000-year-old cultivated grain illuminates the domestication history of barley.’ Nature Genetics. 48. pp.1089-1093. [Abstract only]

Mathieson, I. Lazaridis, N. Rohland et al., (2015). ‘Genome-wide patterns of selection in 230 ancient Eurasians.’ Nature. 528. pp.499-503. [Abstract only]

Omrak, T. Gunther, C. Valdiosera et al. (2016). ‘Genomic Evidence Establishes Anatolias the Source of the European Neolithic Gene Pool.’ Current Biology. 26(2). pp.270 [Abstract only]

Riehl, M. Zeidi, & N. J. Conard, (2013). ‘Emergence of Agriculture in the Foothills of the Zagros Mountains of Iran.’ Science. 341. pp.65–67. [Abstract only]

Willcox. (2013). ‘The Roots of Cultivation in Southwestern Asia.’ Science. 341. pp.39-40.[Abstract only]

Posted in Homo sapiens | Leave a comment

Disappearing into the heavens

Some years ago I witnessed a dinosaur attack. There was a flash of brown, then a thud. It was over in a second. Sharp powerful claws gripped its prey, pinning it against the ground. Then it began to feast. I never saw it coming. The wood pigeon never saw it coming.

The beautiful light grey bird was bobbing along quite happily in my garden, picking up seeds fallen from my bird feeder. I was watching it move: that classic bob of the head in sync with those scaly legs and claws. Then, out of nowhere, a blur. A sparrow hawk had shot out of the sky, landing on the pigeon, flattening it to the ground. Perhaps stunned, perhaps not, the pigeon had no chance. The sharp curved, super sharp beak of the sparrow hawk began to pluck away feathers so it could gorge on the flesh beneath.

The reign of the dinosaurs has never left us. Humans have witnessed similar dinosaur killings for millennia. But none on such as scale as this beast you are about to read about.

The beautiful Eurasian Sparrow Hawk (Accipiter nisus). (Image by Christian Knoch)

The beautiful Eurasian Sparrow Hawk (Accipiter nisus). (Image by Christian Knoch. Public Domain.)

Birds, the only surviving group of dinosaurs, total nearly 10,000 different species. Aside from fish they are the most successful group of vertebrates, living on every single continent. And they are incredibly diverse. Some have lost use of their wings, to return to land living. Others have enormous webbed feet and become expert swimmers. Sharp beaks tear flesh. Thick beaks crush nuts. Thin beaks pluck worms. Elaborate feathers seduce. This is an amazing group of animals.

Over the last 66 million years, since the extinction of their relatives, there have been some spectacular species. None more so than the giant flightless birds. There was the long reign of the giant terror birds, who stomped on the planet for over 60 million years. There was the frightful European Gastornis, from around 55 million years ago to around 35 million years ago. Big birds even roamed Australia. These were all very big. And all would have been bloody terrifying to see in the flesh. But none would have killed as that sparrow hawk did.

A giant bird (Image by Jan Freedman)

The American Terror Birds were enormous. (Image by Jan Freedman)

There were giant fliers who may fit the bill (excuse the pun). A giant relative to the buzzard, mis-named the Woodward ‘Eagle’, was massive compared to today’s buzzards (or eagles) alive today. The enormous, aptly named Monster Birds would have dwarfed condors alive today. These were both gliders; hovering on warm thermals, searching for that carcass. One extinct giant hunted like our sparrow hawk. Only this beast’s prey was much, much larger than wood pigeons.

New Zealand was home to just a small number of mammals, all of which were bats. This left this dramatic landscape open for other groups to exploit and exploit it the birds certainly did. There was the wonderfully named Mysterious Starling, the Laughing Owl, the Long-billed Wren, the Stout-legged Wren, and even a species of penguin. Isolated for millions of years, the islands of New Zealand were evolutions’ aviaries. With no mammals on the islands (except for three species of bat), birds had free reign of many new niches. There were also many species of Moa: huge flightless, grazing birds that only became extinct in the 1600s.

A reconstruction of the upland Moa. (Megalapteryx sp.) from Baron Rothschild’s book “Extinct Birds”. (Public Domain)

A reconstruction of the upland Moa. (Megalapteryx sp.) from Baron Rothschild’s book “Extinct Birds”. (Public Domain)

Carnivores evolved alongside the herbivores: large harriers (Eyles Harrier), and several types of hawks. Yet, none of these came close to the ultimate New Zealand carnivore: Te Hōkioi.

“This bird, Hōkioi was seen by our ancestors. We…have not seen it – that bird has disappeared nowadays. The statement of our ancestor was that it was a powerful bird, a very powerful bird. It was a very large hawk. Its resting place was on the top of mountains; it did not rest on the plains…Its colour was red and black and white. It was a bird of (black) feathers, tinged with yellow and green; it had a bunch of red feathers on top of its head.” (Maori Legend)

Around 700 years ago, the first humans settled on New Zealand. They saw this bird while it was alive. And, today it lives on in their stories.

Hōkioi was an Eagle. An enormous eagle. The heaviest eagle so far discovered. Outrageously enormous claws first excavated in 1871, gave this beast the name Harpagornis moorei: ‘harpa’ meaning grappling hook, and ‘gornis’ meaning bird. (The species, moorei was given after the landowner were the fossils were first found, George Moore.) Harpagornis, also called Haast’s Eagle after its discoverer, was huge. Females weighed up to around 15kg and males up to 11.5kg: compare this to just a meagre 4kg for a male and 6.6kg for female golden eagles. With wingspans of just 3m, just a fraction longer than a golden eagle, you may think that Harpagornis was oddly disproportionate. It was, however, perfectly endowed for its lifestyle. It was a hunter. An active, surprisingly agile hunter.

Just like a sparrow hawk, Harpagornis flew through forests and scrublands, with relative ease. With a shorter wingspan, it would be able to manoeuvre with relative ease when it went for the attack. Incredible fossil remains tell us what the Haast’s Eagle was preying on. Several Moa pelvis remains have very large holes in them: holes made by the powerful talons of Harpagornis. From high up vantage points, Harpagornis would launch itself, gliding effortlessly through forests. It would land with such a force that its claws pierced through the Moas’ bones. This makes my sparrow hawk look like a pussy cat.

Enormous holes in the pelvis of a Moa. Made by the gigantic talons of Harpagornis.

Enormous holes in the pelvis of a Moa. Made by the gigantic talons of Harpagornis. (Image from Holdaway & Worthy, 2008)

This bird got big quick. It evolved from smaller eagles around 1 million years ago. It’s a classic example of Island Gigantism, where animals isolated on islands have abundant food allowing them to grow to pretty big sizes. (The dodo is a good, if not often recognised, example of this.) With little competitors, and prey as huge as the Moa, these raptors were able to grow to extraordinary sizes.

Harpagornis was

Harpagornis was a massive eagle. Humans would have seen them in action.

What is truly fascinating, and is true for so many of our Twilight Beasts, is that humans saw them alive. The Maori may have watched in awe as Harpagornis took down a Moa: a true clash of the Titans. This magnificent bird was captured by the Maori in cave art, showing significance in their lives.

from ‘Cave of the Eagle’, in the Canterbury district.

Beautiful cave art from ‘Cave of the Eagle’, in the Canterbury district, New Zealand. (Image by Amanda Symon, Ngai Tahu Maori Rock Art Trust. Reproduced with permission.)

Even the name, Te Hōkioi, gives us a tantalising glimpse of what this extinct animal sounded like. It appears in Maori legend:

“Its rival was the hawk. The hawk said it could reach the heavens: the Hōkioi said it could reach the heavens to the hawk; there was contention between them.

The Hōkioi said to the hawk, “what shall be your sign?” The hawk replied “kei” (the peculiar cry of the hawk).

Then the hawk asked, “what shall be your sign?” The Hōkioi replied, “hokioi-hokioi-huu.” These were three words.” (Maori Legend)

Until just around 400 years ago, Harpagornis was swooping through the forests, like a gigantic sparrow hawk. It’s extinction is something familiar and obvious, but still something we fail to learn from today. As people began to settle on New Zealand, they expanded, altering the habitat as they went. The change in habitat hit the large flightless Moa hard, more so because they were also hunted by the Maori for food. The Moa became extinct around 1600. With their main food source gone, the Haarst Eagle vanished.

“They then flew and approached the heavens. The winds and the clouds came. The hawk called out “kei” and descended, it could go no further on account of the winds and the clouds, but the Hōkioi disappeared into the heavens.” (Maori Legend)

Around us the world is changing. Forests are vanishing. Habitats being destroyed. Oceans polluted. Climate is more erratic. Many species we know will be lost because of our lack of respect for nature. A species does not vanish alone. It is part of a complex web of life. When one species is gone, many, many more will sadly, silently, disappear into the heavens.

Written by Jan Freedman (@JanFreedman)

A special thank you to Amanda Symon at the Ngai Tahu Maori Rock Art Trust for allowing us to use the beautiful rock art painting. Please do have a look at their website for more information about New Zealand’s incredible rock art.

Further Reading:

Alcover, J. A & McMinn, M. (1994). ‘Predators of vertebrates on Islands.’ BioScience. 44 (1). pp. 12-18. [Abstract only]

Best, E. (1982), Maori Religion and Mythology. Part 2. P.D. Hasselberg, Wellington. pg. 563 [Full text]

Brathwaite, D. H. (1992).’ Notes on the weight, flying ability, habitat and prey of Haast’s Eagle (Harpagornis moorei)’. Notornis. Ornithological Society of New Zealand. 39 (4): 239–247. [Full article]

Bunce, M. et al. (2005). ‘Ancient DNA provides new insights into the evolutionary history of New Zealand’s giant eagle.’ PLoS Biology. 3 (1): e9. [Full article]

Haast, J. (1872). “Notes on Harpagornis Moorei, an Extinct Gigantic Bird of Prey, containing Discussion of Femur, Ungual Phalanges and Rib”. Transactions and Proceedings of the New Zealand Institute.  4. New Zealand Institute. pp. 193–196. [Full article]

Holdaway, R. N., M. E. Allentoft, C. Jacomb, C. L. Oskam, N. R. Beavan, and M. Bunce. (2014). “An Extremely Low-Density Human Population Exterminated New Zealand Moa.” Nat Commun 5. pp5436. [Abstract only]

Holdaway, R. N., & Worthy, T. H. (2008). ‘The Late Quaternary Avifauna’. In Winterbourne, M.J et al. ‘The natural history of Canterbury’. 3rd Edition. Canterbury University Press and Manaaki Whenua Press. Christchurch. [Book]

Perry, G. L. W., A. B. Wheeler, J. R. Wood, and J. M. Wilmshurst. (2014). “A High-Precision Chronology for the Rapid Extinction of the New Zealand Moa (Aves, Dinornithiformes).” Quaternary Science Reviews 105: pp.126-35. [Abstract only]

Rawlence, N. J., J. R. Wood, K. N. Armstrong, and A. Cooper. (2009). “DNA Content and Distribution in Ancient Feathers and Potential to Reconstruct the Plumage of Extinct Avian Taxa.” Proceedings of the Royal Society of London: Series B. [Full article]

Scofield, R. P. & Ashwell, W. S. (2009). ‘Rapid Somatic Expansion Causes the brain to lag behind: the case of the brain and behaviou of New Zealand’s Haast’s Eagle (Harpagornis moorei).’ Journal of Vertebrate Paleontology. 29 (3). Pp.637-649.

Tennyson, A.; Martinson, P. (2006). ‘Extinct Birds of New Zealand’. Wellington, New Zealand: Te Papa Press. [Book]

Wood, J. R., N. J. Rawlence, G. M. Rogers, J. J. Austin, T. H. Worthy, and A. Cooper. (2008). “Coprolite Deposits Reveal the Diet and Ecology of the Extinct New Zealand Megaherbivore Moa (Aves, Dinornithiformes).” Quaternary Science Reviews. [Abstract only]



Posted in Harpagornis, Terror Bird | Tagged , , , , , , , , , , , , , , | 1 Comment

Getting inside the bones

The European bison,or Wisent, (Bison bonasus) is Europe’s largest land mammal and the last surviving large grazer from a time of real giants. However, during most of the history of the species, it coexisted with other large bovines. One more familiar species was the Aurochs (Bos primigenius), the ancestor of modern domestic cattle, that went extinct in the 17th century. In Southern Scandinavia the two species coexisted for a brief period of time.

Both the Aurochs and the European bison colonized the area via a land bridge connecting southern Sweden, the Danish Isles and mainland Europe about 11,000 years ago. Remarkably, the European bison seem to have disappeared 9,600 years ago, possibly because the forests grew denser and they became isolated from the continental bison population when the land bridge was cut off due to rising sea levels. The aurochsen seem to have prevailed longer, disappearing from southern Sweden and Denmark about 7000 years ago and 3000 years ago, respectively.

The extent of the ice sheet at the Last Glacial Maximum

The extent of the ice sheet at the Last Glacial Maximum, around 20,000 years ago. Huge ice sheets covered much of northern Europe. With water trapped in the ice, sea levels were lower, and more land was connected. (Image Public Domain)

Remains of aurochsen are relatively abundant in bogs and at prehistoric human settlement sites, but only about 20 confirmed finds of European bison have been made in southern Scandinavia. This skewed ratio of finds between the two species has been proposed to reflect differences in choice of habitat due to competition or human disturbance as well as an actual difference in population sizes.

Photo taken in Réserve biologique des Monts d'Azur, Haut-Thorenc, France (Valène Aure)

The beautiful European Bison (Bison bonasus) in Réserve biologique des Monts d’Azur, Haut-Thorenc, France (Photo Valène Aure)

Although the animals looked quite different, the complete skulls are the only individual bone elements that can be positively identified as either aurochs or European bison. This means that the bones in archaeozoological assemblages, which usually are highly fragmented due to their exploitation by man as resources for food and raw materials, pose a particular challenge for species identification. As a consequence of this, one can suspect that some remains of European bison might have been misinterpreted as aurochs in previous analyses. This is common in museum collections across Europe: many specimens lay in drawers labelled as Bovine, because the post-cranial bones of the two species are so similar.

An almost complete skeleton of a European bison found at the end of the 18th century in southern Sweden. Photo by Lucas Gölén

An almost complete skeleton of a European bison found at the end of the 18th century in southern Sweden. (Photo by Lucas Gölén)

In a pilot study, researchers from Lund University, Sweden, and the Universities of York and Manchester (UK), plan to analyse bone powder from the skulls of one prehistoric European bison and one aurochs. The samples will be analysed for collagen-peptide sequencing using Zooarchaeology by Mass Spectrometry (ZooMS), a method previously used to successfully discern bone fragments from sheep (Ovis aries) and goats (Capra hircus) in archaeological assemblages. The bones of these two species are fairly similar in size and shape, and it has often proven very difficult to identify the individual species.

The purpose of the study is to investigate whether ZooMS is a feasible method for species identification of European bison and aurochs in various prehistoric bone assemblages. It is hoped that the species-specific peptide identified through the reference samples can then be used to distinguish fragments of uncertain taxonomic status. So many bone assemblages from sites contemporary with the known presence of bison in Scandinavia have previously identified as bovine and we’re aware it will need to be totally re-examined. It is hoped that the results will help to increase the number of European bison finds, increase our understanding of the species’ local history and its importance as a food source to prehistoric humans.

Written by Erika Rosengren (@RosengrenErika)

Edited by Rena Maguire (@JustRena)

For a description of the ZooMS method see: https://youtu.be/xBAXaLvGe5I

Contact: Erika Rosengren, Osteological Collections Curator. Lund University Historical Museum. Erika.Rosengren@luhm.lu.se

Further reading:
Benecke, N., (2005). ‘The Holocene distribution of European bison – the archaeozoological record’. Munibe (Anthropologia-Arkeologia) 57. pp. 421-428.

Buckley, M., Whitcher Kansa, A., Howard, S., Campbell, S., Thomas-Oates, J. & Collins, M. (2010). ‘Distinguishing between archaeological sheep and goat bones using a single collagen peptide’. Journal of Archaeological Science. 37. pp. 13–20.(http://www.sciencedirect.com/science/article/pii/S0305440309002854)

Ekström, J. (1993). ‘The late Quaternary history of the urus (Bos primigenius Bojanus 1827) in Sweden’. Lundqua Thesis 29.

Rosengren, E. (2014). ‘Sven Nilsson and the postglacial fauna of Scania’. Lund University Historical Museum. Lund.

Posted in Aurochs, Bison | 1 Comment

When life gives you lemmings…..

If I had a games console I wouldn’t get anything done. (Are they called ‘games consoles’ today?) Just like when I watch a film, I am completely captivated by the make-believe world: I am in that world. There is nothing around me. No one around me. Fortunately today, family, work, and late night blogging, prevent my loss of time. I am tempted by some of the incredibly realistic looking games on these futuristic looking consoles, but if I did, I would do nothing else. Nothing. Except finish the game.

When I was younger, we had a few PC games. Ghosts and Goblins on the Commodore 64 was good fun, and anyone remember Rider on the old BBC Micro PC? These were fun games. Addictive to finish the level. But nothing like the complexity and storytelling of games around today. In these games you really are the characters.

There was one game that got me. Totally got me. Completely hooked. Level after level. Lemming after lemming. I had to save them all. Or as many as I could. Sacrifice a couple, that’s fine: it would benefit the group. The classic early 90s game, Lemmings, was the game that told me I should never own a games console when I grow up. The game starts with around 100 lemmings falling from a trap door into a screen, and they all start to follow the leader. The leader walks, bumps into rocks and gets turned around: the aim of the game is to guide as many lemmings as you can to the ‘exit’. You can build bridges, dig under rocks or ‘freeze’ one, so it acts like a block to stop others from walking off the edge of a cliff, or into water, or lava.

A screen shot from the Amega version of Lemmins. (image Public Domain)

A screen shot from the Amega version of Lemmings. (image Public Domain)

As addictive as it was, this video game is based on lies. I know this now. We were lied to. All of us. All the tens of thousands, possibly even hundreds of thousands of children sat there trying frantically to stop these little green haired creatures follow each other to their deaths. We were made to believe that lemmings blindly followed a leader anywhere. Even over a cliff. We were made to believe that these gorgeous little critters were suicidal.

Lemmus lemmus

Fluffy, adorable, Norwegian Lemming (Lemmus lemmus) is just one species of lemming. (Image by Oma Kuva. Public Domain)

Lemmings are anything but suicidal. If an animal is suicidal, then it is intentionally wanting to die. In fact, suicidal animals in nature are very rare. Male spiders and mantids knowingly offering themselves to a female to be eaten are famous examples of suicide in animals (it makes sense that the male will be providing the nutrients for the eggs which he will have fertilised). If a male can leave his sperm and get out alive, it prefers this option (I completely understand why). But in lemmings? Do they really all follow each other knowingly to their deaths?

Lemmings are rodents, closely related to voles. First appearing in the fossil record around 4 million years ago, they live in the cold, icy Arctic tundra. And when food is abundant they breed fast. Their population doesn’t just boom, it explodes. With so many lemmings, all the available food is eaten super fast, so naturally the lemmings spread out looking for new places to live. Many die on this new pilgrimage across the desolate tundra. But some do find new food and set up new colonies. Those few survivors set up home for the next season, and so it goes on. So this ‘mass suicide’ is actually the lemmings trying to survive. Many die on this search for food, and perhaps early observations of their mass migration across the barren landscape, spawned the myth of suicidal lemmings.

They are a very successful group of rodents, with around 30 different species. Eating a variety of plants including moss, grasses, herbs, and lichen, these cold living creatures have a thick fur to help keep them warm in their cold homes. Because of their limited range due to their preferred temperature, they are excellent climatic indicators in the fossil record. They are found in deposits all over Europe, providing another insight into the erratic changes of climate in the past.

The temperatue

The temperature of the last 500,000 years (in blue) reconstructed from data from the Vostok Core, Antarctica. Note the see-saw pattern in the blue graph. Temperature rises rapidly, then there are periods of cooling which appear to be slower. (Image Public Domain)

We know the past has been a see-saw of warm and cold periods (we wrote about how we can measure the past climates through ocean sediments). Those warm interglacials allowing hippos to bask in English rivers, and those chilly, glacials which lacked snow but had huge ice sheets covering much of the northern hemisphere. Even these extremes were punctuated by cold and warm periods within them. And our little lemming fossils help us identify these cold periods.

Two species of Lemmings were present in Britain during the Pleistocene: the Norwegian Lemming (Lemmus lemmus) and the Collard Lemming (Disrostonyx sp.). As the great glaciers covered much of Britain, any exposed land was cold, dry, and hard. Here lemmings were in abundance. As the ice melted, and retreated north, so did the lemmings territory. So they are missing from fossil assemblages during warmer phases. But, they do pop back into some assemblages, showing us that the warm periods (the interglacials) were punctuated by cold periods (stadials).

Lemmings are small little critters, and as such, so are their teeth. Teeth survive pretty well in the fossil record. Especially in cave sites. Owls use the sites, and regurgitate the fur, teeth and bones that they cannot digest. These pellets accumulate and show us what animals were living within a few miles around the cave. Collections in museums hold lots of fossils from sites across Britain, opening a window into the past. Unfortunately many of the smaller teeth are not identified, mainly because there are so many of them. More evidence of lemmings may lie hidden within small jars filled with teeth of voles, mice, and rats.

Lemmings did, somehow, make it over to Ireland around 33,000 years ago: other species of vole living in Britain are absent in Ireland. It may have been the chance result of a mass dispersal of lemmings as they searched for new food. Some were lucky enough to have survived rafting across the Irish Sea.

Lemmings were extremely abundant in Britain towards the end of the Pleistocene. But as the  glaciers went through their final retreat, the last of the lemmings in Britain followed. For Now…..

Written by Jan Freedman (@JanFreedman)

Further Reading:

Current, A., & Jacobi, R. (2001). ‘A formal mammalian biostratigraphy for the Late Pleistocene of Britain’. Quaternary Science Reviews. 20. pp.1707-1716. [Abstract only]

Kurten, B. (1968), ‘Pleistocene mammals of Europe’, The World Naturalist. [Book]

Stuart, A. J. (1982), ‘Pleistocene Vertebrates in the British Isles’, Longman. [Book]

Sutcliffe, A. J. (1985), ‘On the track of Ice Age Mammals’, British Museum (Natural History). [Book]

Vendela K. et al. (2014). ‘On the origin of the Norwegian lemming.’ Molecular Ecology. [Abstract only]



Posted in Lemming | Tagged | 3 Comments

On the origins of our species

As families go ours is pretty amazing. You have ancient cousins who effortlessly chomped through the toughest of roots and hardest of seeds. Another relative was the first of our family to make it all the way to China around 1.7 million years ago. Each individual human alive today belongs to the same family as all of our extinct relatives, the Hominidae. Our kinship runs deeper than geographical boundaries.

What is truly spectacular is that we are still discovering incredible fossils today that are adding detail to our complex family history. Just last year, a new twig on the family tree was added with the remarkable discovery of Homo naledi. Recently, a strange structure was discovered at a Neanderthal site in France: our sister species was building things 170,000 years ago. Let’s not forget our quirky second cousin, the hobbit Homo florensiensis, with recent finds suggesting they evolved around 700,000 years ago from Homo erectus.

The several species of hominins through time (Image from Wiki Commons)

Our family is large! Hominins have a long hsitory, dating back to at least 7 million years ago. (Image from Wiki Commons)

We are learning more each year about our incredible family. But what about us: what can we say about the origins of our species?

Until relatively recently, our species, Homo sapiens was the only known species of human. In 1859 when Charles Darwin wrote his masterpiece On the Origin of Species, there was no solid evidence for any other human species. (Although Neanderthal fossils were known, they were thought to be remains of humans with disease. It wasn’t until 1864 until they were named as a separate species.) For such an important, ground shaking book, Darwin gave just one sentence to human evolution: “Light will be thrown on the origin of [hu]man[s] and [their] history.”

Some years later in The Descent of Man, Darwin writes a little more about how humans are related to other animals. With just the Neanderthal finds, there was little to include about evidence from the fossil record. Nevertheless, Darwin still made a prediction about where one should look for human ancestors:

“In each great region of the world the living mammals are closely related to the extinct species of the same region. It is, therefore, probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now [hu]man’s nearest allies, it is somewhat more probably that our early progenitors lived on the African continent than elsewhere.”

So by 1871 Darwin was advocating looking for our ancestors in Africa but this wasn’t the consensus view. The great German naturalist, Ernst Haekel, for example, argued strongly that human ancestors would be found in Indonesia (presumably because of the other great ape living there, the orang-utan). Remarkably hominin fossils were found there in 1891 by Eugène Dubois, which he saw as a species intermediate between apes and humans (though this ‘Java Man’ was later identified as Homo erectus). It wasn’t until 1924 that the first hominin fossil was found in Africa, with Raymond Dart’s discovery of the first Australopithecus africanus specimen. Since then, numerous hominin fossils have been found across Africa, Europe and Asia.

Original fossils of 'Java Man'. The thick broken skull at the back, with the (Image

Original fossils of ‘Java Man’. The thick broken skull at the back, with the big femur at teh front. (Image by Peter Mass, Public Domain)

We know hominins evolved in Africa, but with so many fossils being discovered across the continents, there have been huge debates about where our species, Homo sapiens, originated. Two main theories have dominated: the Out of Africa (or Recent African Origin) and the Multiregional origin. Out of Africa proposes that there was a single origin for anatomically modern humans. This theory says that the first modern humans arose on Africa soil around 100,000 years ago before spreading out to populate the rest of the world replacing existing human groups. The Multiregional theory instead suggests that rather than arising in Africa the modern form arose in multiple parts of the globe with constant gene flow between existing human species: so all modern humans alive today are a mixture of Homo sapiens, H. neanderthalensis, and H. erectus. (There is another theory, which often gets confused with the multiregional model. The Candelabra theory suggests that after leaving Africa and migrating to other regions of the world our very early ancestor H. erectus evolved modern features independently (without any gene flow between other species of Homo) and at multiple times.)

Are we a species that arose in Africa or in multiple regions round the globe? Did we leave Africa once and replace all other species of Homo, or did we bump into and have a little fun with other species we met on the way? Where did our species leave Africa from and what route did they take? A recent paper took a very detailed look at the publications on this subject to try to get a clearer picture. As well as fossils, climate and radiocarbon dates they advocate genetics as another tool in helping us to discover the true origins of Homo sapiens.

It turns out that by using genetic evidence we can disregard the Multireigonal and Candelabra theories rather quickly. Genetic studies using mitochondrial DNA, which traces genetic information down the female Homo sapiens line, point to all regions tracing their line back to Africa. Later Y chromosome studies, which looked at the male line, also suggested an African common ancestor. What is more, using information from our other 22 non-sex chromosomes genetic diversity was found to decrease predictably the further away you go from Africa. Given our ancestors must have been genetically more diverse than us this is pretty convincing evidence for an African origin.

These studies agree strikingly well with the fossil record. In 1967, Richard Leakey discovered the oldest anatomically modern human fossils in Ethiopia. Known as the Omo remains, these fossils date to between 200,000 and 190,000 years ago. Some more very old Homo sapiens fossils, known as the Herto skulls, were also found in Ethiopia in 2003, dating to between 160,000 and 154,000 years ago. The oldest fossils of our species have been found in Africa.

One of the earlierst Homo sapiens fossils, the

One of the Herto Skulls. One of the earlierst Homo sapiens fossils, around 160,000 years old. (Image Public Domain)

When and where our species left Africa is another hot topic for researchers. Outside of Africa, the oldest fossils of our species found so far are the Skhul/Qafzeh fossils in the Levant (where Israel is today), dating to around 100,000 years old. Originally thought of as a failed exodus, some believe the Skhul/Qafzeh fossils may represent a more successful distribution with stone tools on the Arabian Peninsula dating to between 100,000 and 80,000 years old. The location of these fossils falls in line with a Northern route out of Africa, through Egypt and Sinai. The other possible direction is a Southern route out of Africa through Ethiopia and the Bab el Mandeb strait across the Red Sea, following the coastline towards the Arabian Peninsular, heading to India.

Skhul/Quafzeh Skull number 5

The earliest anatomically modern humans out of Africa around 100,000 years ago, Skhul/Quafzeh Skull number 5. (Image Public Domain)

Given little in the way of archaeological evidence geneticists have attempted to track our ancestors African exit using DNA from people alive today. A number of studies have attempted to do this using different datasets and techniques but on the whole they run in to difficulties. It turns out people alive today are pretty bad representatives of those first humans leaving the African continent due to people having mixed extensively through history. Trying to figure out who mixed with whom, accounting for the mixed DNA in some way and then making any assumption that the DNA left looks anything like the DNA of those first ancestors is fraught with difficulties. This is particularly problematic in Africa where migrations of people ‘back to Africa’ have resulted in the DNA of modern day Africans being composed of high levels of non-African ancestry, muddying the signal further. One way around these problems is instead to analyse DNA extracted from people who lived many thousands of years ago (ancient DNA), allowing direct assessment of the genetic make up of past populations. With increasing improvements in the techniques used to recover DNA from human remains and account for damage as it has degraded through time, ancient DNA research is becoming a viable next option in answering these questions. However obtaining DNA from sufficient samples and in the right places (very tricky in Africa where the hot climate speeds up DNA damage) may be a limiting factor.

The fossils

The movement out (and back into) Africa based on the fossil and genetic evidence to date. (image from Lopez, van Dorp & Hellenthal, 2016)

The timing of when bands of Homo sapiens left Africa is also not easy to pinpoint. There are two main dates that are proposed based on DNA evidence, between 130, 000 and 100,000 years ago, or between 60,000 and 50,000 years ago. Many researchers support the later date but recent finds are shaking this idea up a bit. Last year fossil finds in China dated between 120,000 and 80,000 years old, showing that H. sapiens had made it to China much earlier than previously thought. Did these individuals just die out like has been suggested for Skhul and Qafzeh? Or did they make a contribution to the gene pool of humans alive today? Dating our African exit using DNA is not precise because it relies on having a good estimate of when mutations have occurred in the genome through time and often assumes clear splits between groups when the reality is likely somewhat noisier. One approach to mitigate these difficulties is using ancient DNA from different points in history as a genetic ruler to calibrate the speed at which mutations have occurred. Using timescales revised in this way genetic reconstructions date our African departure to fit the range of this more recent date: 95,000 – 62,000 years ago.

Exactly when and where we left Africa is proving to be a little difficult to determine. Maybe we will never pinpoint the exact date, or the exact place we left. Maybe there were a number of small groups leaving at different times and places. What we do know is that some of these groups met other species of humans. And we mated with them. Successfully. Some of the pioneering work on ancient DNA showed that modern humans share a detectable amount of DNA (1.5-4%) with Neanderthals, revising our idea of the Out of Africa model existing without any intermixing. And it’s not just the Neanderthals. Another species we had intimate relations with were the Denisovans, a mysterious species characterised solely from genetic material extracted from a sliver of finger bone. Even 40,000 year old secrets can be revealed.

The tiny fragment

A cast of a the tiny finger bone. The orginal was destroyed for DNA anaylsis. (Image Thilo Parg, Public Domain)

No field of science is more personal than the study of our own origins. With more finds every year, the details challenge what we know and often create more questions than answers. When we left Africa, where did we travel first and whom we met are all key questions, which we are beginning to answer by integrating archaeology, climatic and genetic evidence. Our species origins lie in Africa, illustrated by both the fossil record and genetic studies. We left Africa at least on two separate occasions, and travelled the world. We met, and slept with, other species of humans: the evidence of our promiscuity forever written in our DNA. The origins of us is a beautiful, but complicated story.

Written by Lucy van Dorp (@LucyvanDorp) and Jan Freedman (@JanFreedman)

This post is based on the following research:

Lopez, S, van Dorp, L, & Hellenthal, G. (2016). ‘Human Dispersal Out of Africa: A Lasting Debate.’ Evolutionary Bioinformatics. 11 (S2). pp.56-68. [Full article]

Further reading:

Blome MW, et al. (2012). ‘The environmental context for the origins of modern human diversity: a synthesis of regional variability in African climate 150,000–30,000 years ago.’ J Hum Evol. 62. pp.563–92. [Abstract only]

Cann, R. L, Stoneking, M, & Wilson, A. (1987), ‘Mitochondrial DNA and human evolution’, Nature. 325(6099). pp.31-36. [Abstract only]

Cooper, A & Stringer, C. B, (2013), ‘Did the Denisovans cross the Wallace line?’ Science. 342(6156). pp.321-323. [Abstract only]

Darwin, C. (1859). ‘On the origin of species by means of natural selection’. Murray. [Book]

Darwin C. (1871). ‘The Descent of Man, and Selection in Relation to Sex’. London: John Murray; 1871. [Book]

Gibbons, A. (2012), ‘Ancient DNA. A crystal-clear view of an extinct girl’s genome’, Science. 337(6098). pp.1028-1029. [Full article]

Goldstein D B, & Chikhi L. (2002) ‘Human migrations and population structure: what we know and why it matters.’ Annu Rev Genomics Hum Genet. 3. pp.129–152. [Abstract only]

Gunz P, et al. (2009). ‘Early modern human diversity suggests subdivided population structure and a complex out-of-Africa scenario.’ Proc Natl Acad Sci U S A. 106. pp.6094–6098. [Full article]

Krause, J, et al. (2010), ‘The complete mitochondrial DNA genome of an unknown hominin from southern Siberia’, Nature. 464(7290). pp.894-897. [Abstract only]

Lowery R. K, et al. (2013) ‘Neanderthal and Denisova genetic affinities with contemporary humans: introgression versus common ancestral polymorphisms.’ Gene. 530. pp.83–94. [Abstract only]

Pennisi, E, (2013), ‘More genomes from Denisova Cave show mixing of early human groups’, Science. 340(6134). pp.799. [Abstract only]

Prüfer, K, et al. (2013), ‘The complete genome sequence of a Neanderthal from the Altai Mountains’, Nature, 505(7481). pp.43-49. [Abstract only]

Reich, D, et al. (2011), ‘Denisova Admixture and the first modern human dispersals into Southeast Asia and Oceania’, The American Journal of Human Genetics. 89. pp.516-528. [Abstract only]

Roberts, A. (2009) ‘The Incredible Human Journey.’ Bloomsbury. [Book]

Sankararaman S, et al. (2014) ‘The genomic landscape of neanderthal ancestry in present-day humans.’ Nature. 507. pp.354–357. [Full article]

Stringer C. B, & Andrews, P. (1988) ‘Genetic and fossil evidence for the origin of modern humans.’ Science. 239. pp.1263–1268. [Abstract only]

Tattersall I. (2009) ‘Human origins: out of Africa.’ Proc Natl Acad Sci U S A. 106. pp.16018–16021. [Full article]

Templeton A. R. (2007) ‘Genetics and recent human evolution.’ Evolution. 61: pp.1507–1519. [Abstract only]

Thomson R, et al. (2000). ‘Recent common ancestry of human Y chromosomes: evidence from DNA sequence data.’ Proc Natl Acad Sci U S A. 97. pp.7360–7365. [Full article]

Wu X. (1981) ‘The well preserved cranium of an early Homo sapiens from Dali, Shanxi.’ Sciencia Sinica2 pp.200–206. [Full article]

Posted in Denisovan, Homo sapiens, Neanderthal | Tagged , , , , , , , , , , , , , , , , , , , , , , , , , , , , | 5 Comments