Treezac

We are born of revolution: a revolution of ideas put into action. Sometimes new ideas are forced upon us by natural disasters or conflict, but sometimes they’re a result of change over time. The Neolithic Revolution was one such time. Approximately 12,000 years ago, our ancestors transitioned from a roaming life of hunting and gathering to a sedentary life of farming. Farming provided our ancestors with a reliable food source that eventually led to the development of cities, but there were consequences to these changes.

According to research led by Emory University anthropologist Amanda Mummert, health declined when a society adopted farming. Mummert and her team built on evidence that has been accumulating since 1984 with Mark Cohen and George Armelagos’ groundbreaking publication, Paleopathology at the Origins of Agriculture. Cohen and Armelagos’ research showed that populations who adopted farming experienced an increase in infectious diseases and a decrease in nutrition. Mummert and her team looked at reductions in stature and confirmed that the decline in health experienced by these populations negatively impacted their stature. They found that as farming increased stature decreased.

However, what originally shortened our ancestor’s lives may have provided future generations with an evolutionary advantage. Economists Oded Galor and Omer Moav from Brown University, investigated longevity in modern populations to determine if it is impacted by how long ago our ancestors adopted farming. Using mathematical models, the researchers demonstrated how the initial decrease in health experienced during the Neolithic Revolution resulted in an increase in health over following epochs. Galor and Moav attributed this improvement in health to an adaptive response to environmental hazards such as infectious diseases. The researchers suggest that approximately two years of life expectancy can be added to a population for every 1,000 years since their Neolithic Revolution. To put this in perspective, the first occurrence of the Neolithic Revolution was approximately 10,500 years ago (some estimates put the date at around 12,000 years ago as stated at the beginning) in the Middle East. However, according to Galor and Moav’s research, this time period varies for different populations around the world: 6,900 years ago in Asia, 6,300 in Europe, 3,800 in South America, 2,900 in Africa, and 2,300 years ago in North America. Although there is more to longevity than distance from the Neolithic Revolution, National Geographic’s Blue Zones initiative does provide support for Galor and Moav’s findings.

Fast-forward to modern city life and research showing that the health of people living in urban areas is dependent upon where they live. For example, in the United States urban dwellers live longer, healthier lives than their rural counterparts, but they have more mental health problems. Sandro Galea and his research team from the University of Michigan discovered that one specific mental health problem, depression, might be linked to the urban environment.

Galea’s research was conducted in 2002 to assess New Yorkers’ mental health following the 2001 terrorist attacks. The researchers conducted phone interviews with 1355 participants with an average age of 40 years (59 percent were female). They used the 1999 NYC housing and vacancy survey to obtain information on participant neighbourhoods. The researchers categorized poor quality neighbourhoods as areas with interior problems such as broken kitchens, poor heating, or peeling paint and exterior problems such as dilapidated buildings and several structural fires.

Galea and his team discovered that participants who lived in poor quality neighbourhoods were 29 to 58 percent more likely to report depression for the previous six months and 36 to 64 percent were more likely to report depression over their lifetime than participants who lived in better quality neighbourhoods. Galea and his team suggest that rather than one specific urban characteristic, it’s a combination of characteristics that influence depression. However, recent research from the UK and Slovakia suggest that trees might improve the mental health of urban residents.

Researchers from the universities of Exeter (UK) and Trnava (Slovakia) were led by Mark Taylor to investigate urban tree density and antidepressant prescription rates in London, UK. Antidepressant prescription and street tree data were collected from the Greater London Authority. After crunching the numbers, Taylor and his team discovered that areas with high street tree density had lower antidepressant prescription rates than areas with low street tree density. The team does caution against assuming that there is a direct correlation between the number of street trees and antidepressant rates. They emphasize that their results identify a potential relationship that opens the door for future research. Taylor concludes that his team’s research provides evidence that supports tree-planting campaigns in New York and the UK designed to improve mental health in urban areas.

The Neolithic Revolution was ground zero for all future revolutions the human species has experienced over the past 12,000 years. As a species, we have survived natural disasters, pestilence, and wars. At the centre of it all were cities: those places our ancestors called home and places we still call home. However, considering the Earth is 4.5 billion years old, we moved in a few seconds ago and there’s a lot we’re still learning about our new home: we’ve learned that it’s a complex place that can increase our lifespan; we’ve learned that it can cause mental health problems; and we’ve learned that the nature we’ve attempted to control and exclude from parts of our cities might be the key to our urban survival. A new revolution begins.

Rodney Steadman 19 May 2015

Lead Image Source: Flickr user GoShows

Works Cited

Galea S (2005). Urban built environment and depression: a multilevel analysis. Journal of Epidemiology & Community Health, 59 (10), 822-827 DOI: 10.1136/jech.2005.033084

Mummert A, Esche E, Robinson J, & Armelagos G (2011). Stature and robusticity during the agricultural transition: Evidence from the bioarchaeological record. Economics & Human Biology, 9 (3), 284-301 DOI: 10.1016/j.ehb.2011.03.004

Taylor M, Wheeler B, White M, Economou T, & Osborne N (2015). Research note: Urban street tree density and antidepressant prescription rates—A cross-sectional study in London, UK. Landscape and Urban Planning, 136, 174-179 DOI: 10.1016/j.landurbplan.2014.12.005

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