ARCHÆOLOGY
A MONTHLY EXCAVATION OF ODDITIES AND ANTIQUITIES
PAUL DEVEREUX digs up the latest discoveries: a giant feline, Ice Age footprints and Denisovan DNA
PUSSYCAT, PUSSYCAT WHERE HAVE YOU BEEN?
Not to London to see the Queen, but rather lurking almost invisibly for about 2,000 years on the arid desert pampas of Peru, home of the so-called ‘Nazca Lines’: a cat-like geoglyph some 37m (120ft) long etched into the side of a small hill, possibly dating to early in the Paracas culture. The creature’s body is shown in profile but its head is fullface – a twist of perspective. Some people think it isn’t the depiction of a cat at all, but perhaps a mythical creature or other type of feline.
Why did it almost disappear? Because all the ground drawings on the Pampa, like the later lines, were created by removal of the dun topsoil to reveal a lighter coloured subsoil which darkens over time due to oxidation, so that they tend to visually merge back into the desert surface. This renders them generally hard to see at ground level, and they show up best from the air. Exceptionally well-drawn unicursal geoglyphs depicting, amongst numerous others, a giant spider, monkey and humming bird, have long been known about and photographed, but in recent years aerial survey has been greatly enhanced by the use of drones so that currently well over 100 previously unknown ground drawings have been spotted – this cat-like geoglyph being one of them. As we can see in the photograph here, it now stands out clearly, but that is only because a team of archæologists has freshened its lines, which vary between 12 and 15 inches (30-40cm) wide. Guardian, 18 Oct; phys.org 20 Oct, 2020.
A PERILOUS JOURNEY
An exceptional discovery of late Ice Age (Pleistocene era) human footprints tracking for 1.5km (almost a mile) have been made at White Sands National Park in New Mexico. Normally, tracks would not be preserved in the gypsum sands there, but in this case the extremely clear fossilised footprints must have been made during a long-ago muddy period. The more than 420 prints are those of an adolescent or young female, and intermittently among them those of a toddler.
Using visual and computer-modelled analysis of the depth variations, outlines and other properties of the footprints has enabled the Anglo-American researchers to determine that they mark an out-and-back journey conducted at a rapid walking pace. The young adult seems to have periodically carried the child on the left hip, every 100yds (90m) or so, putting the toddler down briefly on the ground.
Why the haste? Doubtless because potentially dangerous large mammals were roaming across the same tract of land. The prints of a mammoth and a giant sloth show on top of those of the humans on the northbound path, but below on the southbound, indicating that the humans had fitted their relatively speedy sortie of a few hours into a gap in the animals’ crossings. Never mind the mammoth, a giant sloth could weigh as much as 4 tons and grow to a length of 6m (20ft), so it is highly understandable that our scurrying humans wouldn’t want to encounter one. NY Times, 23 Oct, 2020. Original paper: Quaternary Science Reviews: https://doi.org/10.1016/j. quascirev.2020.106610.
IN A TIBETAN CAVE
When modern humans left Africa, they encountered various strains of now extinct archaic humans, among them the mysterious Denisovans, Asian cousins of the better-known Neanderthals. All that has been found of these shadowy hominins are bone fragments in a Siberian cave and more recently a jawbone in the Baishiya Karst Cave located at 3,280m (10,800ft) on a high plateau in Tibet. This latter fossil fragment has been controversial, though, with various experts questioning its Denisovan provenance. So a team of Australian researchers have revisited the Tibetan cave, which is now a Buddhist sanctuary, to see what more can be found. They were allowed in to conduct their research for only a few winter days, and at night, moreover, when the temperature drops to minus 18 degrees. The researchers had to dig into the frozen floor of the cave, where they unearthed hundreds of animal bone fragments and a few basic stone tools, though no further human fossils. But a paper in Science reports that they had a novel technique at their disposal – jokingly described as “DNA fishing”.
We shed DNA all over the place, in bodily fluids, skin flakes, fæces and so forth. In frozen ground, some DNA can survive for many thousands of years. Using this delicate new technique, the Australian researchers managed to extract Denisovan mitochondrial DNA from four sediment layers in the cave, dating between 100,000 and possibly 45,000 years ago. Denisovans obviously occupied the cave over long periods, but the findings also extended “the time of occupation of the Tibetan plateau by hominins”, according to the paper’s abstract. Furthermore, the suspect jawbone looks now to have pretty secure Denisovan provenance.
We know that the out-of-Africa modern humans were seemingly as randy as hell, having sex with just about all the archaic humans they encountered. Neanderthal DNA has infused itself into our genome, for example, and remnant elements of Denisovan DNA are found in Aboriginal and Tibetan populations. It seems that the Denisovans had a gene that enabled them to live at high altitudes, a characteristic found with some Tibetans. Sydney Morning Herald, 2 Nov, 2020. Original paper: Science, 30 Oct, 2020: vol.370, issue 6516.