Human evolution: the discipline that can save the biosphere

orangutan

Understanding where we fit into the natural world and how, rather than rising above it, we depend on it like every other species, is a sobering realisation achieved through archaeological and anthropological research.

I recently wrote two articles for the Nature blog ‘Eyes on Environment’ arguing that this psychological revolution could be the only way to save the biosphere and ultimately, ourselves:

Part I

http://www.nature.com/scitable/blog/eyes-on-environment/human_evolution_the_discipline_that

Part II

http://www.nature.com/scitable/blog/eyes-on-environment/human_evolution_the_discipline_that_228236

Comments encouraged

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Carpets of artefacts, mountains of baboons

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I must admit, I’ve slept in some pretty adventurous places…

And although I love spending the night on top of Mayan jungle temples and on Nicaraguan volcano-islands, I wouldn’t be the first to volunteer to sleep in the middle of a baboon hangout. But, for archaeology, anything….

I have arrived at my final few weeks in South Africa, but it has definitely not slowed down. It has in fact done the exact opposite. Since arriving back in January it has been almost non-stop excavations and surveying, from 500,000 year-old hominins on the shores looking out to Table Mountain, to rock-art searching in the beautiful Cederberg mountains, to Late Stone Age human burials in residential Cape Town, to trekking through the rivers and mountains of South Africa’s semi-desert: the Tankwa Karoo.

Here’s a brief impression of our time in the Tankwa Karoo in search of stone tools…

I was lucky enough to be invited to explore this incredibly beautiful yet very strange landscape in the hunt for tools made by humans both recent(ish) and ancient. Emily Hallinan, a PhD student with Cambridge, has been working in an area east of the Cederberg mountains for a little while now and recruited University of Cape Town collaborator Matt Shaw, as well as another UCT student and myself to venture through the never-ending valleys of the Tankwa to find artefacts.

The area that Emily has honed in on for this trip is a mid point between two sites of hers, one in the Cederberg mountains and the other further in the Karoo.

The team L-R: Matt Shaw, Candice Koopowitz and Emily Hallinan

The team L-R: Matt Shaw, Candice Koopowitz and Emily Hallinan

This is a really special place. Not only did we walk across landscapes so dense with Late Stone Age (~40,000 – 3,000 ya) stone tools that a ‘carpet’ is a accurate term, but they were lying right alongside those from the Middle Stone Age (~300,000 – 40,000 ya), as well as the Early Stone Age (~3.3m – 300,000 ya)! Unbelievable.

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A Middle Stone Age point

An Early Stone Age (ESA) hand-axe (1 million years old or older)

An Early Stone Age hand-axe (1 million years old or older)

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A Middle Stone Age radial core

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The artefacts Emily and Matt have found include stunning silcrete points made in a way not seen anywhere but north Africa…until now! (Have a read of their article for more details).

Surface scatters of lithics (stone tools) are rarely in their original archaeological context, however the bizarre intermingling geology of the Tankwa (sandstone, quarzite, diamictite and others) combined with a spectacularly low annual rainfall has created a ‘desert pavement'(as Emily has put it) restricting the movement of material.

The type of lithic you want to make is achieved by using certain types of rock, by knapping rocks together in very intricate ways, and by modifying the product further afterwards. The earliest lithics, now dated to ~3.3 millions years ago in Kenya, were very rudimentary involving smashing two rocks together. Over the following millions of years, techniques developed into much more precise and selective behaviours as a result of exploiting new environmental niches and the evolution of greater cognitive abilities. Over the two weeks of research, we saw this spectrum of technological development with our own eyes, coming across cruder Acheulean hand-axes (likely ~1m years old or more) up the valley from much more recently crafted blades and retouched points. We even found ostrich egg-shell beads and hunter-gatherer handprints on the cliff wall. Amazing.

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Most of the time we stayed in a stunning little house perched on the side of a river valley. We reached the start of our surveying hikes either through driving around the river or canoeing along it. The canoe trips were mind-blowingly beautiful, the river so glass-like that you could turn your head upside down and convince yourself you’re standing upright. In an unexpected, yet classic archaeology-fieldwork kind-of way, we discovered a hole in our canoe whilst paddling back one day, the boat filling up by the minute! In an act of self-sacrifice, I plugged the hole with my thumb, rewarded later with extra chocolate rations (thanks Emily!). The terrain of the surveying was incredible – vast valleys, endless rocky desert, or forests of stabbing 4-inch long acacias…DSCF8162DSCF806611110796_10153448525976874_5581473344415973029_o

To continue the craziness of the trip, we learned the house had been booked for the weekend. In the spirit of adventure, we thought it would be fun to camp on the porch of a derelict house in the middle of a dry river valley. The one small catch was that this happened to be the centre of baboon nighttime festivities.

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We woke up sometime in the early hours to loud baboon barks behind the house, and a large male replying down the front path. I’m unsure how familiar you are with baboon dental morphology, but lets just say the canines are of an unfriendly size.

Having survived the night (largely through Matt honking the car horn, flashing the lights repeatedly, and revving the engine – maybe we could have hafted lithics to spears if we had the know-how), we were looking forward to staying in a house the farm owners had allocated for us. Unfortunately for us, it turned out to be the most bone chillingly, death-horror-movie worthy, no-one-can-hear-you-scream dilapidated house imaginable. Saying that, we had a great game of carcassonne and slept like babies.

All this drama was only in addition to the catastrophe of the car nearly rolling over down a hill potentially crushing Matt underneath it as it rolled the week before… And yes, there were groups of baboons surrounding us there too.

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We even managed to head over to the insane South African version of Burning Man Festival – Afrikaburn. Think thousands of hippies running around in the middle of the desert, setting fire to gigantic wooden sculptures, wearing florescent everything.

What a two weeks! But next time, I’m not partaking without a machete.

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South Africa: a home more ancient than anyone thought

To an archaeologist, anthropologist or geneticist, South Africa is irresistible

And to tantalise the scientific tastebuds even further, two studies which came out this week and last have found that South Africa holds an even more ancient human history than anyone thought.

1. Little Foot

Australopithecus prometheus

In case you didn’t know, it is this country which has yielded some of the oldest and most significant fossil humans (hominins) found to date. The majority of these human relatives have been unearthed from the cave systems in Sterkfontein, Malapa, Taung and Swartkrans in Gauteng – including the famous ‘Mrs Ples’ and ‘Taung Child’ (Australopithecus africanus), Paranthropus robustus, and Australopithecus sediba.  These extinct South African human species date back to early days in human evolution; from ~3 to ~1.2 million years ago, though were unlikely our direct ancestors (as indicated by the recent find of a 2.8myo jaw bone in Ethiopia belonging to our genus Homo).

In the 1990’s, a new Australopithecus specimen was dug up in Sterkfontein which didn’t fit into any of the Australopithecus species already described. ‘Little Foot’ (Australopithecus prometheus) as it’s been affectionately known, was dated to ~2.2myo (million years old) based on the flowstones in which the fossil lay, though this dating was controversial. 9 years later, a team has re-dated Little Foot to 3.67mya, indicating that this species of hominin lived 1.47 million years earlier than thought, and at the same time as the famous East African species Australopithecus afarensis (‘Lucy’). Clearly the early players in human evolution (the early australopiths) were far more wide-ranging and diverse than we thought. Though the oldest of the oldest hominins belong to east and central Africa, the South African hominin record gets pushed back further in time.

2. The San

The San, or bushmen, are thought to be one of the oldest human lineages, still practising a hunter-gatherer existence in the Kalahari desert of Botswana and Namibia (though they’re being horribly repressed by the Botswanan government).

Mitochondrial DNA is an amazing piece of wizardry that evolutionary geneticists can use to track past population movements. Using mtDNA, previous studies have found that the San lineage broke off from that of every other human around 150,000 years ago, however a new study has re-analysed this date finding that the distinct San haplogroup (the unique mitochondrial DNA group that the San belong to) ‘L0d’ diverged from the main human line ~172,000 years ago. That’s incredibly old! Considering that our species (Homo sapiens) only evolved ~200,000 years ago, you can see how ancient the San lineage is. It is, in fact, the oldest offshoot from the main human lineage (of those analysed in this study).

And so although South Africa may not be the ancestral land of all modern humans, it has sure been a hospitable host to evolving hominins for at least 3,670,000 years

500,000 year-old humans and me

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This is what you will find 45 minutes up the west coast from Cape Town

As beautiful as this landscape is, its what’s under the sand that is truly valuable.

Dig down even only 20cm through the white dune sand and you’ll find the start of a deep red layer of sand. This is an ancient landscape of history frozen in time.

The site was originally discovered by workmen at the nearby nuclear power plant, who’s accidental unearthing of fossilised animal bones attracted Stanford archaeologist Richard Klein. After arriving on the scene and doing a fair bit of surveying and excavation, Klein et al. found that the find wasn’t an isolated stroke of luck – the site yielded wheelbarrows full of fossilised bones. Macro- and micromammals were present in their findings, ranging from the Egyptian mongoose (H. ichneumon), black rhino (D. bicornis), and the extinct long-horned African buffalo (Pelorovis antiquus), to the hairy-footed gerbil (G. paeba), Cape golden mole (C. asiatica), and Krebs’s fat mouse (S. krebsii), to name but a few. And that’s just the mammals! Bird species from the jackass penguin (S. demersus) to the spotted eagle owl (B. africanus) have appeared from the depths, as well as species of frogs and toads.

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P. antiquus (Image: E. Esterhuizen)

 

The incredible (and unexpected) biodiversity found in this stratigraphy is only really comparable to that in an Ace Ventura movie.

The abundance of bones from fresh water-dwelling animals (including hippos) reveal that this area, now vast dry sand dunes, was once a marshy wetland, with the high frequency of fauna that graze rather than browse (like buffalo), and fossilised pollen in hyena poo, indicating that the area was vast grasslands (full paper here).

However, the most exciting finds were those directly made by humans. Hundreds of stone tools have been gradually exposed in the form of flakes (and their debris), hammerstones and cores, showing that humans were living alongside this oasis of life. The Klein team conducted ‘optically stimulated luminescence dating’ on the sand surrounding the upper layer, arriving at a date of ~270,000 years ago. Tools have been found in lower layers too that go back even further in time – perhaps even ~500,000 years ago, or older. This would instantly get any archaeologist, anthropologist or biologist excited, as these humans were therefore pre-Homo sapiens (us). Most likely Homo erectus or Homo heidelbergensis, this realisation has transformed this site into a sought-after hominin site, allowing us to peer directly into the lives of our half a million year-old ancestors.

Cruz-Uribe et al., 2003

Cruz-Uribe et al., 2003

H. heidelbergensis

H. heidelbergensis

H. erectus

H. erectus

In a stroke of luck, I managed to get on board with a team carrying out new excavations at this same site, and what treasures we have found… Unfortunately I can’t reveal most of them, but I’ll provide a brief flavour to give you an idea.

The frequency of faunal finds only increased since we started, with a fossilised rhino tooth, antelope jaw, and possible extinct long-horned buffalo horn. Of greater significance in relation to humans, we’ve found lots of stone tools thereby confirming that hominins were hunting and living in this exact area.

What blew my mind after hours scraping away in a 1 x 1 meter hole however, was finding stone tools in situ myself. It’s hard to describe the feeling when you take it out of the sand, brush it off, hold it in your hand, and know that the last person to hold it was an extinct species of human living ~500,000 years ago. And boy are they incredibly beautiful! Flakes of silcrete, quartzite and quartz that I’d just pulled out of the sand after lying there for an unimaginable time-span were still sharp, and with a careful eye it’s easy to see where the maker had hit it off the stone core (and sometimes where they had missed), as well as where they had touched up the edges to make it as sharp as possible (a ‘retouched flake’). These materials are not available in the immediate area, and so, along with river pebble tools we’ve also found, these hominins were fetching specific lithic material, bringing it back to this site, and knapping away. Debitage and flake chips that have turned up in our excavation pits in abundance, confirm that these early humans were sitting exactly where I was, creating sharp tools, but ~500,000 years earlier.

I found, and still find this fact absolutely unfathomable.

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The lead researcher, Dr Deano Stynder’s, research interests in the site are centered on reconstructing the palaeoenvironment through faunal and floral proxy material in order to infer what the landscape in which Middle Pleistocene hominins were living was like (particularly whether the biome was C3 or C4 dominated). Through this, he hopes to gain a greater understanding of the environmental pressures which shaped the ecology and behaviour of these early humans.

In addition to the excavation (and bucket carrying, and endless sieving), Dr David Braun (Uni of Cape Town & George Washington Uni) turned up to carry out some aerial photography by literally attaching a camera to a kite. This is a nice technique to get a broader view of your site and a spatial context of where you’ve excavated…and more importantly where you haven’t.

Further excavations at this unique treasure trove of human evolution will take place through the hottest part of the summer, potentially leading to the faunal bones found 500,000 years from now being those of dehydrated archaeology students…