Eyes on Environment: human evolution as the discipline that can save the biosphere

Part II: The Solution

This is a guest post by Simon Hoyte, a biology graduate fascinated by human evolution. Currently working as a research assistant at the Department of Archaeology, University of Cape Town, he integrates his evolutionary biology background with palaeolithic archaeology, anthropology, and genetics. He will be taking up a Master’s degree in human evolution at the University of Cambridge in October. His blog (simonhoyte.wordpress.com) follows his research in South Africa and he uses Twitter (@SimonHoyte) to share interesting ideas.  This post is reproduced from the original on Nature’s Eyes on Environment blog.

chimp

To all creatures still wild and free… The success of human evolution has not been kind to you.”1

This humbling dedication by Glenn Conroy and Herman Pontzer perfectly captures the overarching connection between human evolutionary science and the state of the natural world.

We’ve seen in Part I how, through artificially elevating ourselves ‘above’ Nature, we are allowing a gross over-exploitation of the biosphere and with it the very resources we need to survive. Millions of years of evolution and subsequent human development have produced an exemptionalist mind-set that we must dismantle by reconnecting with the world around us. What better way to mentally plug ourselves back into the biosphere than by studying evolution to reveal our place in it?

The birth of evolutionary thought began with Darwin, but in 1859 all he could mention of human evolution was simply that “light will be thrown on the origin of man and his history.”2 To put it modestly, Charles, you were right.

The science of human evolution is now exposing our humble origins, from arboreal African primates ~6 million years ago to the birth of our own species a mere ~190,000 years ago. 156 years since Darwin’s prediction, our understanding of how we fit into this picture has progressed at an incredible rate. Thousands of fossils from extinct species intermediate between us and our common chimpanzee ancestor have now been unearthed, ranging from the mysteriously ancient Sahelanthropus tchadensis to the 300+ fragmented individuals of Australopithecus afarensis (of which ‘Lucy’ is just one).

With the pace of human evolution research increasing faster than ever, discoveries are at a record high: in just the last few months new fossils have pushed back our genus to 2.8 million years old;3 a team has unearthed a whole new species of early human in Ethiopia;4 and the oldest stone tools have been found that push back the origins of this technology by 700,000 years!5

bones

Advances in evolutionary genetics, mastered in part by Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology, have revealed more than we could have ever imagined about our connection to the diversity of life around us. For example, all non-Africans are the love-children of a modern human-Neanderthal interbreeding which occurred 50-60,000 years ago,6 and chimpanzees and humans share a monumental 98.7% of our DNA.7 This genetic overlap is only 0.9% below the shared percentage of the two chimpanzee species to each other. This comparison would suggest that we are more closely related to chimps than, say, willow warblers are to chiffchaffs.8

This leap in our understanding of human evolution certainly gives us perspective of our place amongst Earth’s other species, and it doesn’t stop at bones and genes. Behavioural comparisons of modern humans to other great apes are closing the gap between ‘us’ and ‘them’ study by study. The very quality that many claim makes us human – culture – has been observed in other species. Specific groups of chimpanzees have been observed crafting wooden spears to hunt prey as well as teaching one another to use tools to extract food and water.9,10 These qualities add further to the list of traits no longer considered ‘uniquely human’. The line between us and chimps is in fact becoming so blurred that campaigns have been launched to award chimpanzees with human rights, a proposal currently under consideration by a New York court.

And don’t think that these behaviours are restricted just to the apes. The Behavioural Ecology Research Group at the University of Oxford has spent years studying a particularly remarkable bird, the New Caledonian Crow, revealing that this species is not only able to make tools, crafting sticks to access food sources, but also processes each tool specifically for a chosen task, even if it is completely new11. Evidence of ‘culture’ is increasingly recognised in a whole range of non-primate species, including the fascinating tendency of female bottlenose dolphins in Shark Bay, Australia, to break off marine sponges and parade them, seemingly pointlessly, on their nose through the ocean. This is considered the discovery of material culture in marine mammals12.

But there is still something special about the human brain, right? The evolutionary neuroscientist Suzana Herculano-Houzel hit the nail on the head in her 2013 TED talk in Edinburgh reminding us that: “The human brain may be remarkable yes, but it is not special. It is just a large primate brain. I think that is a very humbling and sobering thought that should remind us of our place in nature”.

Dissemination of this vast body of knowledge we are gathering about our evolutionary history and where we fit in this world is potentially a powerful driving force for the most important psychological revolution that’s ever been attempted. Such a possibility should be made known by all means necessary. Taught to every school child! Preached by every government! Heralded in every newspaper! Because until we wholeheartedly accept that the downfall of the biosphere is inseparable from our own downfall, Homo sapiens is destined to join the ranks of species we’ve forced to extinction.

References

  1. Conroy, G. C. & Pontzer, H. “Reconstructing human origins”. New York: Norton (2012)
  2. Darwin, C. “On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life”. London: John Murray (1859)
  3. Villmoare, B. et al. “Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia”. Science, 347(6228), 1352-1355 (2015)
  4. Haile-Selassie, Y. et al. “New species from Ethiopia further expands Middle Pliocene hominin diversity”. Nature, 521(7553), 483-488 (2015)
  5. Harmand, S. et al. “3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya”. Nature, 521(7552), 310-315 (2015)
  6. Fu, Q. et al. “Genome sequence of a 45,000 year-old modern human from western Siberia”. Nature, 514(7523), 445-449 (2014)
  7. Prüfer, K. et al. “The bonobo genome compared with the chimpanzee and human genomes”. Nature, 486(7404), 527-531 (2012)
  8. Diamond, J. “The Third Chimpanzee”. New York: Harper Perennial (1992)
  9. Pruetz, J. et al. “New evidence on the tool-assisted hunting exhibited by chimpanzees (Pan troglodytes verus) in a savannah habitat at Fongoli, Sénégal”. Royal Society Open Science, 2(4) (2015)
  10. Hobaiter, C. et al. “Social network analysis shows direct evidence for social transmission of tool use in wild chimpanzees”. PLoS Biology, 12(9), (2014)
  11. Bluff, L. A. et al. “Tool-related cognition in New Caledonian Crows”. Comparative Cognition & Behavior Reviews, 2, 1-25 (2007)
  12. Krützen, M. et al. “Cultural transmission of tool use in bottlenose dolphins”. PNAS, 102(25), 8939-8943 (2005)

Photo credit

Chimpanzee photo courtesy of Owen Booth on Flickr

Figure of jawbones and teeth of the newly discovered, ~3.4 million-year old human species (Australopithecus deyiremeda) courtesy of Reference 4

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