South Africa, 14,000 BC

Paleoecology is the study of how animals and their environments interacted in the distant past. While the basic idea has been around almost since we started the scientific investigation of fossils, it really only became a field in its own right around the 1950s. That's largely because it isn't easy, becoming harder the further back we go.

The basis of the field is to look, not at individual fossils, but at the whole array of fossils at some particular site, correlating them with what we can determine of the climate and environment at the time. Which, among other things, requires a good understanding of exactly what that time was and at least a reasonable confidence that the fossils in question are all around the same age. Often, it relies not just on good and plentiful fossils at a particular site, but on us being able to say what the animals' lifestyles were. Which is a lot harder for those that don't resemble the ones we have today - dinosaurs being an obvious case in point.

Fortunately, when it comes to mammals, especially those from the relatively recent times of the Ice Ages, we are on firmer ground.

The majority of paleoecological studies, at least in the English-language literature, relate to either Europe or North America. At the opposite end of the scale, as is the case with other branches of palaeontology, Africa is the least studied of the inhabited continents, leaving our knowledge of its past incomplete in comparison with its northern counterparts.

The Besaansklip fossil site is located on the southwest coast of South Africa. It was excavated in the 1990s, before making way for the cement quarry that is on the site today. The site consists of an assemblage of bones from two ancient animal dens that, judging from the amount of fossilised hyena dung found, must have been used by either spotted or brown hyenas. Such is the backlog and availability of suitable scientists, the fossils from it were only thoroughly examined in the last five years. The results of this analysis were recently published, and I am going to take a look at them here.

Perhaps the first question to ask is when the hyenas in question gathered the bones here. Fortunately, the site includes fragments of ostrich eggs, and it was possible to use radiocarbon techniques on them to date the site to between 16,790 and 15,278 cal. BP.

This stands for "calibrated years before present", and is the standard system used in radiocarbon dating. In order for this to remain consistent between papers published in different years, "present" for these purposes has to be defined as a specific date that never changes. So, when we say "BP" we mean years before that date, not before the literal present day. The date used is 1st January 1950, just nine months after the first-ever radiocarbon dates were published. So, in more familiar terms, the dens date to about 14,840 to 13,328 BC.

This, crucially, is far enough back to be during the Last Ice Age, which ended around 10,000 BC. Specifically, it is during a phase of the Last Ice Age referred to as the Oldest Dryas. This is the oldest of three periods during which the gradual warming of the world following the end of the Last Glacial Maximum around 20,000 BC was briefly interrupted by a cooling phase - in this case, one that lasted around 3,000 years. 

South Africa, of course, was not as heavily glaciated as Europe or North America, being closer to the equator. At the height of the Ice Ages, there would have been some good-sized glaciers around the peaks of the Drakensburg Mountains, but certainly nothing like that down by the coast. Nonetheless, even though the concept of the Oldest Dryas is largely based on data collected from the Alps in Europe, South Africa was significantly colder then than it is now.

The vegetation in the area today is described as 'fynbos', a type of scrubby or heathland vegetation found across much of South Africa. The warm semi-arid climate is too dry for most trees, so the terrain is dominated by drought-resistant shrubs such as Aloe and Euclea, and sparse grasses. Today, the site is just outside the town of Vredenburg, and only about 100 km (60 miles) from Cape Town, so wild animals are more limited than they used to be. 

Nonetheless, early European settlers reported large numbers of antelopes, including duikers, grysbok, and steenbok (the latter two of which I have covered in detail on this blog before). There were also smaller numbers of large antelopes, such as elands and hartebeest, as well as a few rhinos, elephants, lions, leopards, and, yes, hyenas. Most of these have gone now, but it is against these that we should compare what lived in the area 16,000 years ago.

In total, the researchers were able to look at 488 mammalian fossils. In addition to these, the site also provided numerous fragmentary mammalian remains that were essentially unidentifiable, as well as some other animals, such as the aforementioned ostriches, along with tortoises and lizards.

The majority of the fossils belonged to various kinds of antelope, following the usual rule that herbivores tend to be more common than carnivores and that, in this part of the world, antelopes are mostly what we'd expect. Some were of the kinds of antelope we would still find in the area today (or at least in the recent past), including all of those mentioned above. Others, while not native to the area today, are at least found in similar habitat nearby, including rhebok and bontebok. 

Some of the fossils, however, belong to animals we would not expect. 

For example, they found part of the horn of a wildebeest. Wildebeest are found in South Africa today, albeit mostly in nature preserves due to past overhunting, but even when they were free to roam wherever they wished, they only inhabited the eastern interior of the country, where the grasslands of the veldt are much thicker than the sparse fynbos around Besaansklip. Similarly, reedbuck were also present, despite being native to the well-watered floodplains of the east and certainly not to anywhere that could be described as "semi-arid".

These are all animals that we can see today, if no longer in this particular area, but 16,000 years ago, some species would have been less familiar. The bluebuck (Hippotragus leucophaeus) was a close relative of the modern roan antelope, which is found further north. It was native to the southern coast of South Africa, not far from Besaansklip and, from what we can tell, lived in habitats richer in grass. They survived into recent historical times, with the last known individual being shot in 1800, the first known African antelope to be hunted to extinction.

Remains of that most South African of animals, the springbok, were also found at the site. They were, however, incomplete, making it impossible to say whether they represented the springbok we know today or the southern springbok (Antidorcas australis), a close relative that went extinct around 5,000 BC. 

Another species was identified from its limb bones, which were larger than those of any antelope that lives in the area today. These are thought to represent the "giant wildebeest" (Megalotragus sp.) an unusually large relative of both wildebeest and hartebeest that stood around 140 cm (4' 7") at the shoulder. We know from stable isotope analysis of bones found elsewhere that it was a grazer, eating large quantities of grass. This is actually the youngest known fossil of the animal from the region, although they survived elsewhere until around 5,500 BC.

Other animals suggesting that the area around Besaansklip was grassier then than it is now include buffalo. In addition to the modern Cape buffalo, for which today's habitat would be marginal but just about tolerable, the site also revealed the partial jawbone of a giant buffalo (Syncerus antiquus). This was one of the largest bovids to have lived, standing around 185 cm (6 feet) at the shoulders, weighing an average of 1.2 tons (although some males would have been larger) and with almost implausibly long horns stretching up to 3 metres (9'10") from tip to tip. It is thought to have preferred habitats richer in grass than the modern species, although it was probably less keen on forests, not least because it's hard to see how it would have avoided catching its horns on trees as it went between them.

While we're on the subject of unusually large animals, the site was also home to the giant zebra (Equus capensis), which died out around 7,600 BC and stood around 150 cm (5 feet) high at the withers - large for a zebra, although common enough for a modern pony. It's likely that they were adaptable animals, not caring much about the specifics of the habitat, since modern zebras are very widespread.

Other herbivores from the site included warthogs, some kind of rhinoceros that was too fragmentary to narrow down, a baboon, and smaller animals such as hares and porcupines. Carnivore remains found at the site are largely those that we'd expect, including lions, leopards, honey badgers, jackals and, unsurprisingly, hyenas, although cheetahs, which were found there, are not known to have lived nearby in historical times. A more surprising finding was the discovery of the partial leg of a fur seal; hyenas do prey on seals, but they must have dragged it a fair distance for it to end up in a den a few miles inland.

What does all this tell us? Hyenas, especially brown hyenas, are known to scavenge on almost anything they can find so the contents of their dens are usually good markers for what was living in the area at the time, missing only the creatures that were too small for them to bother with. Furthermore, the fact that the radiocarbon dates at the site are all consistent indicates that the dens were not in use for a great length of time, so that the remains there would have been gathered together. What's notable about them is that they show a wider range of large herbivores living in the area than was even the case in pre-colonial times. This indicates a relatively fertile environment, with plenty of available food.

The identity of the herbivores suggests that the grass was richer and lusher then than it is now, allowing animals such as wildebeest to graze where they would do so no longer, even if humans weren't around to disturb them. The presence of reedbuck, which like pools of standing water, indicates that the environment must surely have been wetter than the semi-arid scrubland we have now.

There are probably a couple of reasons for this. For one, it may simply have rained more. The rain in the region now comes almost entirely in the winter, and it's thought that similar conditions prevailed towards the end of the Last Ice Age. However, the westerly winds that today largely pass to the south of Africa would have been closer to the equator, likely bringing more rain in winter than the area receives now.

The second reason may have been the cooler climate. Semi-arid climates are defined as those where water evaporates from the surface, or is transpired through leaves, faster than it can be deposited by rain (if it's more than twice as fast, then it's fully arid, or, in more common parlance, a "desert"). This is partly determined by the temperature, so simply being cooler reduces the rate at which water is lost, and can shift a climate from semi-arid to something moister, even if the rain remains seasonal.

From this, we can not only see what animals lived on the coast of western South Africa 16,000 years ago, but gain an insight into the weather, the plant life, and the general habitat. It was a richer, greener, place then than it is now, with lush grass and plentiful water allowing large antelope to graze as the lions and hyenas watched them, waiting for their next meal.

[Photo by Bernard Dupont, from Wikimedia Commons.]