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The National Research Council of the U.S. National Academy of Sciences issued a report on March 3, 2010, titled ‘Understanding Climate’s Influence on Human Evolution’ (see news release).
One of the report’s chief recommendations is to build a new scientific program for drilling ancient lake sediments in eastern Africa and other regions in order to obtain long climate records in the areas once inhabited by early hominins. This approach would be coupled with new lake and ocean drilling in order to understand worldwide, regional, and local climate dynamics relevant to the time periods and the regions where human evolutionary change took place.
Strategically-placed drill cores will capture the continuous, fine structure of the environmental record, which is vitally important in studying questions about changes in Earth’s climate, environment, and geological forces. The cores will allow sufficiently high resolution to study short-duration events and processes (e.g., seasonality, interannual change, volcanic episodes, tectonic events) and to see how these relate to environmental changes over evolutionary time scales that may have influenced the evolution of human adaptations.
The Smithsonian’s Human Origins Program is helping to lead this international effort to explore the parallels and connections between environmental change and human origins. Over the months to come, follow here the development of this new approach to studying human evolution.
Read the NRC report on the National Academy of Science's website.
A wire services report by ClimateWire summarized the NRC report in the following way:
A proposal to search the past for adaptation clues (Thursday, March 4, 2010)
Lauren Morello, E&E reporter
Research on climate change today focuses mostly on the future, taking stock of how humans have influenced the planet and using computer models to project unwanted changes like warming temperatures or rising seas and ways we might avoid them.
But a new report suggests that there's value in looking at not just how humans shape the climate, but how the climate shaped human development going back millions of years.
"How we get here is relevant to where we are going as a species," says the analysis released yesterday by the National Academy of Sciences. Written at the behest of the National Science Foundation, it lays out a 10- to 20-year plan for research that would improve understanding of the ancient climate and how that influenced human evolution.
Rick Potts, a Smithsonian Institution paleoanthropologist who helped write the report, said that until about 20 years ago, scientists had a simplistic view of how the environment shaped human history. They believed that a few major events, like the expansion of grasslands in Africa and later ice ages in Europe and Asia, signaled forks in the evolutionary path that led to Homo sapiens.
But with more data available now on ancient climate -- such as temperature records derived from sediment cores drilled from lake beds and ocean floors -- researchers now believe humans evolved amid "a great deal of instability and environmental fluctuation," said Potts, director of the Human Origins Program and curator of anthropology at the National Museum of Natural History.
"The human species today is a survivor of lots of different environmental changes," he said. "The possible implication is that we have, built into us, a certain degree of adaptability or resilience."
But history also shows there are limits.
"Look back to the fossil known as 'Lucy' -- her species, Australopithecus afarensis, lived back beyond 3 million years ago," Potts said. "Her species had a certain resilience to environmental change, but her species is no longer around."
A more recent example is the Classic Mayan civilization in southern Mexico and Central America, the report notes. Over a 400-year span between 750 and 1150, the Mayan population dropped by 70 percent or more.
'We're in an experiment that's never been tried'
Some archaeologists believe that a series of protracted droughts helped bring about the Mayans' downfall, basing their controversial theory on climate information gleaned from sediment cores.
Potts said he believes the research program outlined in the new report would help society look to its future, not just better understand its past.
The science academy panel is recommending an effort to broaden the collection of fossils to new geographic areas and across time periods, expand scientific drilling programs in lakes and oceans near sites where ancient humans evolved, and improve climate models to help scientists reconstruct the environment of the past.
That could help researchers understand how fast the environment changed at different points in human history -- and how that compares to conditions today.
"I think we need to look very closely at climate changes in the past and compare them to climate changes in the present and see where our sources of resilience will come from," Potts said. "What we're in now is an experiment that has never been tried. Homo erectus was never able to modify the landscape in the ways we do today."
"There's kind of a cautionary message there," he said, "but also a hopeful one."
The Olorgesailie Drilling Project
Advancing Understanding of Human Evolution over the Past 500,000 Years
The Smithsonian’s Human Origins Program team, led by Dr. Rick Potts in collaboration with the National Museums of Kenya, has obtained the first long climate core from an early human fossil site. The purpose in recovering the core is to investigate in greater detail than ever before the environments connected with the origin of our species in Africa, along with the events leading up to this benchmark in the history of life.
The goal was to obtain this climate core by drilling at the prehistoric site of Olorgesailie, located in the southern Kenya Rift Valley. Potts’s previous excavations there have documented fundamental changes in the behavior of our early human ancestors over the past 500,000 years. However, many tens of thousands of years of this period are missing due to the erosion of sediment layers visible above ground in the Olorgesailie region. The reason for drilling was to recover sediment layers underground that preserve a complete, high-precision record of rainfall, temperature, vegetation, and environmental stresses – and how these changed over time – during the critical transitions involved in the origin and evolution of Homo sapiens.
The drilling focused on a flat, grassy plain in the previously unexplored southern region of the Olorgesailie basin. Two decades of geological studies led our team to think that if the past 500,000 to 600,000 years of ancient lake deposits existed in the southern Kenya Rift Valley, they would occur under the flat plain where the layers could be accessed only by drilling.
Collaborations with the following partners were vital to the success of this project:
Drilling and Prospecting International, Ltd. (Kenya) DPI was responsible for carrying out the core drilling operation. Very special thanks to Mike Scarpellini, Natascha Sole and the rest of the DPI crew members.
Earthview Geoconsultants Ltd. (Kenya) Special thanks to Dr. Dan Olago and his team for the environmental impact study in the vicinity of the drilling site before, during, and after the project.
Oldoinyo Nyokie Group Ranch (Kenya) The Maasai landholders in the drilling area belong to a group ranch headed by Mr. Joseph Sakaya. The Olorgesailie project has enjoyed the support and friendship of the group ranch families and leaders. Several members of the community were employed by the project; they learned various aspects of the drilling work and core processing, and contributed to the safety of our field camps. These individuals included: Eliud Pussaren, Moses Saitoti, Keliya Lemparakwo, Taota, Jackson Keliya, Kishanto Kipampa, Tenge Ntinana, and Melita Samare. Electrical generators and other useful supplies were donated to the Nyokie community at the conclusion of the project.
The Olorgesailie Kenyan team: Under the leadership of Muteti Nume, our crew foreman, the following individuals contributed to our field camp and efforts during the drilling operation – Musyoka Kilonzi, Vincent Kimeu, George Mumo, Muthengi Kioko, Sina Muteti, King’ola Ndambuki, Mutuku King’oo, Nzioki Mativo, Kamula Kawaya, Kakai ole Mindo, Tima ole Kikanai, Bernard Mukilya, Katui Kasivo, Peter Asumani, Sila Nzivo, and Muthiani Makuu.
Drilling, Observation, and Sampling of Earth’s Continental Crust (DOSECC) and DOSECC Exploration Services (DES) (USA) DOSECC and DES advised the project on scientific drilling techniques, provided specialized coring equipment and shipped supplies for the project. With special thanks to Beau Marshall and Joe Bolin for their on-site supervision and coordination with DPI’s drilling crew.
University of Minnesota’s LacCore: National Lacustrine Core Facility (USA). Special thanks to Anders Noren, Kristina Brady, and René Dommain for processing and recording the cores on-site, training local assistants from the Oldoinyo Nyokie community, and preparing the cores for shipment to LacCore’s facility for scientific study and archival storage.
From September 2 to October 4, 2012, the effort to recover the core was successfully carried out. The core, lifted from two boreholes in segments 3-meters long, represents a detailed record of lake sedimentation. Through the plastic liners in which the core was recovered, fine laminations of diatomite and clay lake deposits can be seen, along with inputs of fine silts and sands – all of which we believe capture the environmental dynamics of this region of the East African Rift Valley over the past 500,000 years.
The cores extend down to 166m below the ground surface, and provide evidence of the ancient lake that had not previously been visible but that we suspected must have existed in the drilling area.
Unexpected challenges in recovering these cores occurred, but all were solved so that the project started and was completed on time. These challenges included initial difficulties in getting drilling rods, core liners, and other critical supplies into Kenya; a rupture in the water pipeline in the closest town of Magadi, which was to supply the drilling water at no cost to the project; and damage to the drilling rods by the Kenyan drilling company (Drilling and Prospecting International, Nairobi) during the first several days of drilling due to their team’s unfamiliarity with the specialized rods sent from the U.S. for this project. Project funding along with the expertise assembled at the drill site were instrumental in meeting and solving these challenges as they arose.
Future Study and Implications
The Olorgesailie team is excited about the results of the core drilling. Knowledge gained from our two-decades of study elsewhere in the Olorgesailie region imply that the layers of lake sediment in the cores represent the past 500,000 years in high-resolution. We will employ direct methods of dating the volcanic tephra in the core. If our current understanding of the age range is correct, the core will give us the most exact record of climatic stresses and ecological change in East Africa during four key chapters in human evolution:
- The earliest transition from handaxe technology to innovative technologies, including projectiles (i.e., being able to hunt at a distance); this transition is recorded at Olorgesailie between 500,000 and 300,000 years ago;
- The origin of the modern East African biota, which occurred in the same era;
- The origin of our species, around 200,000 years ago;
- A possible population crash of Homo sapiens in Africa 100,000 to 70,000 years ago, just prior to the global spread of our species.
Investigating the environmental challenges of these eras will allow us to test and determine as best as possible how evolutionary processes of survival helped shape the human species.
The first of two steps in this project have been completed. The ultimate goal is not only to recover the cores but to produce well-studied cores, which we believe will yield benchmark scientific papers in the study of human origins. In late April 2013, Potts will assemble an international team of 20 to 25 scientists to open the cores, which will be housed at the international lake core facility, LacCore, at the University of Minnesota, Minneapolis. At the week-long workshop, our scientific team will describe and sample the cores for detailed analysis, followed by 12-24 months of laboratory studies, project workshops, synthesis of results, and the writing of publications.
Support from the William H. Donner Foundation (New York); the Ruth and Vernon Taylor Foundation (Montana); and the Peter Buck Fund for Human Origins Research (Smithsonian) has been indispensible in enabling us to achieve the first step in this project. Projects are now being planned by other research teams to try to recover ancient lake cores from other famous fossil sites in East Africa.