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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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…

South Africans, be proud of the San!

“Whilst the Mayans were building temples, Egyptians constructing pyramids, and Babylonians designing ziggurats, why were our guys still rubbing two sticks together?”

Although this may seem like a perfectly decent question, the woman who asked me this at a charity dinner last week after discovering I work in the archaeology department, is greatly underestimating southern Africa’s indigenous population.

So, I’m going to enlighten her here, by exploring the ingenuity of this amazing indigenous group

Let’s start with a bang

All architectural designers have the San to thank

Cave art found in South Africa, though largely remaining undated, is not very old. It is unlikely that it compares in age to those of Chauvet Cave in France or the recently published hand stencils and animal drawings from Sulawesi in Indonesia, both dated up to ~40,000 years old. Granted, indigenous southern Africans probably weren’t the first to decorate cave walls. However, a prerequisite for art (that includes music, complex language, writing…) is thinking in an abstract and symbolic way, and the earliest evidence for this is from, you guessed it, South Africa.

Blombos cave on the south coast 300km from Cape Town has yielded ochre pieces with intentional patterns – showing the makers had symbolic intent. These have been dated from between 70 – 100,000 years old. 100,000 years old! That is doubly as old as the recently found Neanderthal engravings in Gibraltar! Engraved ostrich egg shell found in the Western Cape”s Diepkloof cave falls within the same time period.

Blombos

Blombos engraved ochre

Diepkloof ostrich eggshell

Diepkloof ostrich eggshell

We’re talking about the very emergence of key modern human behaviour here! Abstract and symbolic thought as evidenced here was the precursor for any sort of art, music and indeed architectural design…like that of the Egyptians. Recent genetics has established when the ancestors of the San headed south – around 150,000 years ago – so these engraving are remnants of the San and their ancestors.

No agriculture = No builders

As brilliantly conveyed by Jared Diamond in Guns, Germs and Steel, the advent of agriculture brought huge changes to almost every part of the human world. Suddenly, foraging and hunting for food didn’t have to dominate the daily lives of everyone; the ability to produce a greater quantity of food allowed for the stratification of society, leading to those specialising in writing, building, developing medicine and all the job specialisations you see around you today. Thus, no agriculture, no pyramids.

Why wasn’t agriculture developed in southern Africa as it was in the several other points of origin around the world? To cut short pretty much the whole of Diamond’s book, no plants or animals have proved suitable for domestication. Though southern Africa has far more than its fair share of indigenous floral and faunal species, it takes a rather unique species to pass the strict entrance requirements for domestication (i.e. zebra’s just don’t like being told what to do).

The isolated location of southern Africa, separated from the rest of the world by desert, ocean, and jungle, formed an impenetrable barrier to the movement of agricultural peoples from the ‘Fertile Crescent’ (now the Middle East), inhibiting the spread of agricultural knowledge. Livestock and crops domesticated in North/Central Africa and the Fertile Crescent couldn’t survive in the vastly different climate of southern Africa. And so agriculture only arrived here in full force ~1000 years ago.

The relevance of all this? Due to the geographical position of the San and their ancestors, agriculture did not arrive in southern Africa until much later than Egypt, Babylon and Mesoamerica, and so they were hunting and gathering away without growing a darn thing. If this were different, world history would have surely not played out the same; as Jared Diamond puts it…”Africans mounted on rhinos would have trampled any European invaders, but it never happened”

rhinoCAT_450x300

…or did it

Hunter-gatherers for 150,000 years (and counting)

Here’s an interesting idea for you: being a hunter-gatherer isn’t so bad.

Sure, a large proportion of your time is spent searching for food which restricts  time to do other things, but anthropologists experiencing the day-to-day life of the San have noted that they actually have quite a bit of spare time. This time is essential in groups without writing as a chance to pass stories, wisdom and techniques from one generation to the next. Perhaps the brilliantly abundant rock art all around South Africa is a testament to this spare time…

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Even after agriculture had become established in South Africa, most of the hunter-gatherers here didn’t enthusiastically grab the nearest shovel and start planting next year’s sorghum harvest. No, they continued living as hunter-gatherers.

As mentioned in Diamond’s The Third Chimpanzee, a San bushman said simply,

“Why should we plant, when there are so many mongongo nuts in the world?”

Despite European and Bantu colonialism, discrimination by contemporary African governments, and wide-scale environmental degradation of hunting lands by external forces, there are San living a hunting and gathering lifestyle in southern Africa to this day.

The Mayans were amazing; I’ve climbed up (and slept on) their temples in the middle of the Guatemalan rainforest myself. The downfall, however, of this complex civilization can be attributed to a whole host of factors, but as many archaeologists have speculated,  these were ultimately based on over-exploitation of their environment. As Dorothy Hosler, Jeremy Sabloff and Dale Runge originally proposed, the most likely scenario is that a steady increase in monument construction (to please the gods) necessitated ever more workers, which required ever more food but in less space and with fewer farmers; they were essentially trying to increasingly intensify agriculture in ever depleting productive land (see a nice review here). Over-intensification echoes through the decline of other great civilizations too…

So don’t get me wrong, I’m not attempting to discount the innovation, intelligence and architectural brilliance of ancient civilizations, I’m just trying to point out what seems rather obvious: throughout the rise and fall of these empires, San hunter-gatherers have been surviving perfectly well, as they and their ancestors have done for ~150,000 years, without over-exploiting their environment.

Maybe we should be asking them for some advice