NAS Report on GE Crops has Overall Support of Leading Independent Scientists

Last May, the National Academies Press published a report entitled, Genetically Engineered Crops: Experiences and Prospects (available at https://www.nap.edu/download/23395).  Notable quotes from the report include:

  • “…no differences have been found that implicate a higher risk to human health safety from these GE foods than from their non-GE counterparts;”
  • “…no evidence [has been reported] of cause-and-effect relationships between GE crops and environmental problems;”
  • GE crops have “generally had favorable economic outcomes for producers who have adopted these crops, but there is high heterogeneity in outcomes;”
  • Whether GE crops “benefit intended stakeholders will depend on the social and economic contexts in which the technology is developed and diffused;”
  • “…it is the product, not the process, that should be regulated.”

 

Late in the year, the National Academy of Sciences (NAS) Board of Agriculture and Natural Resources convened a Forum of Scientific Society Leaders on Genetically-Engineered Crops:  Experiences and Prospects.  Invited participants were asked to consider future directions suggested by the findings of the report.  The participants represented a highly diverse body of scientific societies and other organizations with an interest in the science behind the agronomic, health, environmental, and socioeconomic dimensions of GE crops.  (I was invited to represent the American Phytopathological Society.)

 

One of the striking (though not surprising) aspects of my experience was how the distinguished participants in the forum generally agreed that the NAS report provided an authoritative, comprehensive, thoughtful review of peer-reviewed literature on highly diverse aspects of the subject of GE crops.  You can see this for yourself at http://dels.nas.edu/Past-Events/Forum-Scientific-Society-Leaders/AUTO-5-80-52-G?utm_source=Division+on+Earth+and+Life+Studies&utm_campaign=9804e0d620-EMAIL_CAMPAIGN_2016_12_21&utm_medium=email&utm_term=0_3c0b1ad5c8-9804e0d620-262640537&mc_cid=9804e0d620&mc_eid=9006ea2d48

 

In my prepared comments, I focused on aspects of how GE could contribute positively to crop production through more sustainable disease control (https://vimeo.com/album/4310385/video/195866079).  Of course, this is a complex topic and six minutes doesn’t do it justice, but I provided some science-based points for others to consider.  More on this can be found in my recent review paper: http://www.mdpi.com/2071-1050/8/5/495.

 

I also spoke (during the Closing Discussion) about we must engage science teachers, to help make them aware of key scientific findings on GE crops.  If we hope for a public that grounds its policy wishes on widely established scientific findings, along with its values, we must engage our science teachers on this topic.

 

The full report (nearly 600 pages) is available at the link provided above.  Although the report itself is massive, an abbreviated file, containing only findings and recommendations, is available at http://nas-sites.org/ge-crops/files/2016/05/All-Findings-and-Recommendations.pdf.  It is worth a look to see where consensus science lies, and where there are continuing scientific uncertainties.

Genetic Engineering and Plant Disruption

Be prepared to be surprised: Genetic engineering (GE) often causes less disruption to plant functioning than older breeding techniques.

This fact never fails to surprise people.  I suppose that is because most assume that GE is so far-fetched and unnatural that it must be terribly damaging to plants.  The reality is that the targeted DNA manipulations of GE are no more disruptive—and are commonly less disruptive—to a plant’s genes, its gene expression, its suite of proteins, and its chemical composition than more traditional methods of crop improvement.  Scientific support for this statement can be found in the following scholarly reports  [1-8].  This list of citations is actually incomplete since there are papers not listed that could be.

Hybridization between species is a common plant breeding practice.  Nevertheless, the title of this research paper gives me pause: “Hybridization as an Invasion of the Genome [9].”  Dr. Barbara McClintock, one of the most respected biologists of the 20th century, considered hybridization between species to be a cause of “genome shock.”  And this classic breeding technique generates no public protest.  Should it?  Should we be concerned about breeding techniques that cause “genome shock?”

One way I have learned to help people understand this phenomenon is through the following video:

 

These videos are not perfect metaphors for genetic processes, but there are adequate for communicating the fundamental fact that genetic changes due to GE are more targeted than those achieved by older techniques (which, by the way, are still very important for crop improvement).

If unanticipated health consequences from GE manipulations merit concern, what about the unanticipated health consequences of each new conventionally bred crop variety [10]?  One might say, “But breeding by human selection has been used for thousands of years old, so it must be safe, right?”  Yes, human selection of plants is an ancient practice, but every plant is an unprecedented genetic and epigenetic creation, unique onto itself. Without testing, no one knows whether a new non-GMO crop variety is safe.  Every new plant presents unknown risks due to its unique genetic and epigenetic heritage.

My understanding is that Canada requires safety evaluations of all new crop varieties, not simply those derived from GE.  From a scientific standpoint, it makes more sense to me to regulate new varieties based on the qualities the variety possesses, rather than how its genetic changes were made.  It is something for us in the USA to consider, particularly since GE commonly causes less disruption to the plant than conventional breeding.

Citations

  1. Ricroch, A. E., Assessment of GE food safety using ‘-omics’ techniques and long-term animal feeding studies. N Biotechnol, 2013, Vol. 30, p. 349-54, DOI: 10.1016/j.nbt.2012.12.001. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23253614
  2. Schnell, J., Steele, M., Bean, J., Neuspiel, M., Girard, C., Dormann, N., Pearson, C., Savoie, A., Bourbonniere, L. and Macdonald, P., A comparative analysis of insertional effects in genetically engineered plants: considerations for pre-market assessments. Transgenic Res, 2015, Vol. 24, p. 1-17, DOI: 10.1007/s11248-014-9843-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25344849
  3. Gao, L., Cao, Y., Xia, Z., Jiang, G., Liu, G., Zhang, W. and Zhai, W., Do transgenesis and marker-assisted backcross breeding produce substantially equivalent plants? A comparative study of transgenic and backcross rice carrying bacterial blight resistant gene Xa21. BMC Genomics, 2013, Vol. 14, p. 738, DOI: 10.1186/1471-2164-14-738. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24165682
  4. Batista, R., Saibo, N., Lourenco, T. and Oliveira, M. M., Microarray analyses reveal that plant mutagenesis may induce more transcriptomic changes than transgene insertion. Proc Natl Acad Sci U S A, 2008, Vol. 105, p. 3640-5, DOI: 10.1073/pnas.0707881105. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18303117
  5. Lehesranta, S. J., Davies, H. V., Shepherd, L. V., Nunan, N., McNicol, J. W., Auriola, S., Koistinen, K. M., Suomalainen, S., Kokko, H. I. and Karenlampi, S. O., Comparison of tuber proteomes of potato varieties, landraces, and genetically modified lines. Plant Physiol, 2005, Vol. 138, p. 1690-9, DOI: 10.1104/pp.105.060152. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15951487
  6. Ladics, G. S., Bartholomaeus, A., Bregitzer, P., Doerrer, N. G., Gray, A., Holzhauser, T., Jordan, M., Keese, P., Kok, E., Macdonald, P., Parrott, W., Privalle, L., Raybould, A., Rhee, S. Y., Rice, E., Romeis, J., Vaughn, J., Wal, J. M. and Glenn, K., Genetic basis and detection of unintended effects in genetically modified crop plants. Transgenic Res, 2015, Vol. 24, p. 587-603, DOI: 10.1007/s11248-015-9867-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25716164
  7. El Ouakfaoui, S. and Miki, B., The stability of the Arabidopsis transcriptome in transgenic plants expressing the marker genes nptII and uidA. Plant J, 2005, Vol. 41, p. 791-800, DOI: 10.1111/j.1365-313X.2005.02350.x. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15743445
  8. Herman, R. A. and Price, W. D., Unintended compositional changes in genetically modified (GM) crops: 20 years of research. J Agric Food Chem, 2013, Vol. 61, p. 11695-701, DOI: 10.1021/jf400135r. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23414177
  9. Mallet, J., Hybridization as an invasion of the genome. Trends Ecol Evol, 2005, Vol. 20, p. 229-37, DOI: 10.1016/j.tree.2005.02.010. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16701374
  10. Kok, E. J., Keijer, J., Kleter, G. A. and Kuiper, H. A., Comparative safety assessment of plant-derived foods. Regul Toxicol Pharmacol, 2008, Vol. 50, p. 98-113, DOI: 10.1016/j.yrtph.2007.09.007. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17983697

Are Biocontrols for Plant Diseases Safe to Humans?

I recently received a phone call from a citizen sounding quite frightened about an unusual bacterial infection she was experiencing.  Her physician had diagnosed the infection to be due to the bacterium, Pantoea agglomerans.  I did my best to answer her questions, primarily informing her how widespread and common this bacterium can be on plant surfaces and in soil.

As I thought about this case, the thing that most struck me was that P. agglomerans (which has been known by several scientific names) has been widely studied as a potential biocontrol agent for plant diseases.  As I dug into the scientific literature, I learned about many cases of P. agglomerans causing opportunistic infections in humans, often (though not always) associated with immunosuppression.

“Wait a minute!” I thought.  You mean, this natural biocontrol agent, which we commonly assume is nothing but beneficial, could actually cause harm to humans?  Most field plant pathologists are well-aware of the mistaken—but widely held—assumption that synthetic chemicals are harmful while natural chemicals are safe [1].  This isn’t the first time I have wondered about the safety of microbial biocontrol agents.  However, this was the first time I had ever “drilled down” into the scientific literature on this topic.

There was more there than I expected.  A number of bacterial species that can provide some biological control of plant disease have indeed been shown to be opportunistic human pathogens.  The ones I read about are listed below, with citations to some of the medical literature associating them with human infections:

  • P. agglomerans [2, 3];
  • Stenotrophomonas maltophilia [4];
  • Bacillus cereus [5];
  • Bacillus subtilis [6];
  • Lysobacter enzymogenes [7].

My literature search was not at all exhaustive.  Therefore, there could even be additional examples of biocontrol bacteria with “alter-egos” as opportunistic pathogens in humans.

There is a significant caveat.  Even though a bacterial species may be reported both in human infections and as a plant colonist, the human strains and the plant strains may not necessarily come from the same populations [8].  But I don’t take much comfort in that, for the following reasons:

  1. Relatively recent studies suggest that some of the human-infecting and plant-colonizing strains of P. agglomerans seem worryingly similar [9, 10].
  2. Even if they are from different populations, the classification of the human-infecting and plant-colonizing strains as the same species indicates that they have some phenotypic overlap.

To be honest, my discoveries concern me much more than traces of synthetic pesticides in my food.  And to think that farm workers sometimes apply biocontrol agents with no safety equipment!

So the take-away is, our concern for food safety should be in proportion to scientific risk, and not based on assumptions.  Biocontrol agents for plant disease control, sometimes assumed to be safe because they derive from Nature herself, may not be as safe as we think.  Likewise, pesticides—whether natural or synthetic—should not be assumed to be safe.

We do a good job evaluating pesticide safety in the USA, through intensive and increasingly sophisticated scientific and regulatory procedures.  Our pesticides undergo such extensive safety testing that, while I wash my produce well, I don’t concern myself with parts-per-billion—or parts-per-trillion—of pesticides in my food [11].  But my safety “radar” is up now on biocontrol agents.  Some questions worth asking:

  • What kind of safety testing do biocontrol agents undergo?
  • How good is our knowledge of exposure routes and doses?
  • Are they tested against immunocompromised mammals?
  • Are they tested for chronic effects?
  • What else do we need to know about biocontrol agents in order to assure the safety of our food supply, as we seek to reduce the use of synthetic pesticides by using alternative, “natural” materials?

 

Literature cited

  1. Ames, B. N., Profet, M. and Gold, L. S., Dietary pesticides (99% all natural). PNAS, 1990, Vol. 87, p. 7777-7781. Available from: http://www.pnas.org/content/87/19/7777.full.pdf
  2. Dutkiewicz, J., Mackiewicz, B., Lemieszek, M. K., Golec, M. and Milanowski, J., Pantoea agglomerans: a marvelous bacterium of evil and good .Part I. Deleterious effects: Dust-borne endotoxins and allergens – focus on cotton dust. Ann Agric Environ Med, 2015, Vol. 22, p. 576-88, DOI: 10.5604/12321966.1185757. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26706959
  3. Cruz, A. T., Cazacu, A. C. and Allen, C. H., Pantoea agglomerans, a plant pathogen causing human disease. J Clin Microbiol, 2007, Vol. 45, p. 1989-92, DOI: 10.1128/JCM.00632-07. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17442803
  4. Brooke, J. S., Stenotrophomonas maltophilia: an emerging global opportunistic pathogen. Clin Microbiol Rev, 2012, Vol. 25, p. 2-41, DOI: 10.1128/CMR.00019-11. Available from: http://www.ncbi.nlm.nih.gov/pubmed/22232370
  5. Bottone, E. J., Bacillus cereus, a volatile human pathogen. Clin Microbiol Rev, 2010, Vol. 23, p. 382-98, DOI: 10.1128/CMR.00073-09. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20375358
  6. Oggioni, M. R., Pozzi, G., Valensin, P. E., Galieni, P. and Bigazzi, C., Recurrent septicemia in an immunocompromised patient due to probiotic strains of Bacillus subtilis. Journal of Clinical Microbiology, 1998, Vol. 36, p. 325–326. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC124869/
  7. Dempsey, K. E., Riggio, M. P., Lennon, A., Hannah, V. E., Ramage, G., Allan, D. and Bagg, J., Identification of bacteria on the surface of clinically infected and non-infected prosthetic hip joints removed during revision arthroplasties by 16S rRNA gene sequencing and by microbiological culture. Arthritis Res Ther, 2007, Vol. 9, p. R46, DOI: 10.1186/ar2201. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17501992
  8. Bonaterra, A., Badosa, E., Rezzonico, F., Duffy, B. and Montesinos, E., Phenotypic comparison of clinical and plant-beneficial strains of Pantoea agglomerans. 2014, Vol. 17, p. 81-90, DOI: 10.2436/20.1501.01.210. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26418852
  9. Volksch, B., Thon, S., Jacobsen, I. D. and Gube, M., Polyphasic study of plant- and clinic-associated Pantoea agglomerans strains reveals indistinguishable virulence potential. Infect Genet Evol, 2009, Vol. 9, p. 1381-91, DOI: 10.1016/j.meegid.2009.09.016. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19800991
  10. Rezzonico, F., Smits, T. H., Montesinos, E., Frey, J. E. and Duffy, B., Genotypic comparison of Pantoea agglomerans plant and clinical strains. BMC Microbiol, 2009, Vol. 9, p. 204, DOI: 10.1186/1471-2180-9-204. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19772624
  11. Winter, C. K. and Katz, J. M., Dietary exposure to pesticide residues from commodities alleged to contain the highest contamination levels. J Toxicol, 2011, Vol. 2011, DOI: 10.1155/2011/589674. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21776262

 

Heartbreaking: GMO Goat Could Save Thousands of Children’s Lives

It was heartbreaking to read about GMO goats in this popular article.  In a nutshell, scientists at the University of California at Davis created goats engineered to express a human gene for lysozyme in their milk.  Lysozymes are natural antibacterial enzymes that degrade peptidoglycan, a major cell well component of gram-positive bacteria.  Lysozymes are found in human tears, saliva, and milk.

Over a half-million children around the world die each year from diarrhea.  One of the reasons for this is because water can be quite unsanitary in poor communities in developing countries (Figure 1).  Goats engineered to produce human lysozyme in their milk could be part of a solution to this problem.  But the project has been…well, read the article.

GMO-goat
Figure 1. Can you imagine having to utilize the water from this Central American stream? I did not photograph the woman, out of respect. However, after she left, I took this photograph.

I know the work of at least two of the scientists quoted in the article.  These are highly respected scientists.

Read the article.  It is really solid.  And it is heartbreaking, at least to me….

Crop Intensification and Carbon Emissions

In the scientific community, it is widely accepted that the global climate is changing, and that human activities are a principal cause.  Many human activities produce “greenhouse gases.”  These transparent gases are present at trace concentrations in the Earth’s lower atmosphere.  They have the unique quality of trapping heat there.  This trapped heat is driving many of the recent changes in the Earth’s climate, including rising global temperatures.

GHG emissions

Figure 1. USA greenhouse gas emissions, by sector. From Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2014, https://www3.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2016-Main-Text.pdf.  “MMT CO2 Eq” refers to million metric tons of carbon dioxide equivalents.

Figure 1 illustrates greenhouse gas emissions in the USA, by economic sector.  Sometimes, agriculture is unfairly blamed as a leading cause of global warming.  Certainly, agriculture is an important source of greenhouse gases.  However, Figure 1 illustrates how other sectors of our economy are even more important sources.  Ultimately, we must address emissions from all sources.

Policymakers worldwide are seeking ways to reduce emissions of greenhouse gases, so that we can reduce the disruptive impacts of climate change on water supplies, food production, human health, and extreme weather.  Since carbon dioxide is the most important greenhouse gas, policymakers often speak of reducing our “carbon footprint.”

U.S. producers have excelled at getting more yield from an acre of land.  This is called intensification.  For example, astonishing increases in grain yields have been achieved in the U.S. (Figure 2) and yields show no indication yet of slowing.  Remarkable yield increases have been achieved in horticultural crops, as well (Figure 3).

Corn yield trned

Figure 2. Trend-line for yield of field corn in the USA since 1900 (data source http://quickstats.nass.usda.gov/).

 

Tomato yield trend

Figure 3. Trend-line for yield of fresh-market tomato in the USA since 1960 (data source http://quickstats.nass.usda.gov/).

Here is how this crop intensification relates to greenhouse gas emissions.  Between 1980 and 2011:

  • U.S. corn producers emitted 36% less greenhouse gases to produce a bushel of corn (Field to Market, 2012).
  • Cotton producers emitted 22% less greenhouse gases to produce a bale of cotton.
  • A 22% reduction in greenhouse gases per hundredweight of potatoes was observed.
  • Rice and soybean producers achieved reductions of 38% and 49% in greenhouse gases per unit of production.
  • Over the study period, wheat production emitted 2% fewer greenhouse gases per bushel produced.

There is no question that U.S. crop production does emit significant amounts of greenhouse gases.  However, an important way to evaluate carbon emissions from crop production is to compare them to the unit of crop production, because the unit of production is what is traded and consumed.  By that standard, U.S. producers excel, because of efficiencies of scale and high-yield production.

Our high-production agriculture stands in contrast to the situation in many developing countries, where crop yields are quite a bit lower.  In such countries, the path to producing more food may include bringing more land under cultivation.  This can increase the carbon footprint per unit of production by as much as three times.

Pound-for-pound of food produced, U.S. farmers have significantly reduced the carbon footprint of food production.   However, crop production does emit greenhouse gases, and knowledgeable experts agree we must reduce our carbon footprint further.  Therefore, the challenge before us is, for every acre of land cultivated, we must grow as much food as is reasonably possible, with as little environmental impact as possible, including carbon emissions.

While U.S. agriculture has served us very well over the years in providing abundant, safe and wholesome food, more and more farm organizations recognize that we must do more to reduce the carbon emissions of producing the food we want and need.  It is a significant challenge, but one we must address in order to do right by our descendants.

Related literature

  1. Balmford et al. 2015. Land for Food & Land for Nature? Dædalus, the Journal of the American Academy of Arts & Sciences. doi:10.1162/DAED_a_00354
  2. Field to Market (2012). Environmental and Socioeconomic Indicators for Measuring Outcomes of On-Farm Agricultural Production in the United States: Second Report, (Version 2), December 2012. Available at: fieldtomarket.org
  3. Foley et al, 2011. Solutions for a cultivated planet. Nature, Volume 478, pages 337-342, http://bit.ly/MdA5yo.
  4. Grassini and Cassman, 2012. High-yield maize with large net energy yield and small global warming intensity, Proceedings of the National Academy of Sciences, Volume 109. Pages 1074-1079, http://bit.ly/KhTQCe.
  5. Stevenson et al, 2013. Green Revolution research saved an estimated 18 to 27 million hectares from being brought into agricultural production. Proceedings of the National Academy of Sciences, Volume 110, pages 8363-8368, http://bit.ly/12x7o3f
  6. Tilman et al, 2011. Global food demand and the sustainable intensification of agriculture. Proceedings of the National Academy of Sciences, Volume 108, pages 20260-20264, http://bit.ly/KfNC3L.
  7. West et al, 2010. Trading carbon for food: Global comparison of carbon stocks vs. crop yields on agricultural land. Proceedings of the National Academy of Sciences, Volume 107, pages 19645–19648, http://bit.ly/KcjEEu.

 

Selected content in this publication was originally published in the Extension publication, Intensification Has Reduced Carbon Footprint of U.S. Crop Production.

Conventional Breeding Creates Safer Foods Than Genetic Engineering: Fact or Assumption?

I am currently serving as Invited Lecturer at Jilin University (China), offering a college course entitled, Introduction to Genetically Engineered Crops: Risks and Benefits.  During this experience, it has dawned on me how commonly my students mistakenly believe that conventional breeding techniques creates foods that somehow are safer than those whose pedigree includes genetic engineering (GE).  During the course, I challenge them to understand that this is an assumption rather than established fact, and that this assumption can be challenged with scientific knowledge enumerated here.  (Note that this paragraph was edited post-publication for clarity.  Also, some of the text below was modified from my recent review paper [1]).

  1. Position statements of diverse, prestigious scientific organizations all support this conclusion [2-18].
  2. Scientific review papers supporting this position are readily found in the scholarly literature [19-26].
  3. As far as I can tell, when people express fears about food risks relating to GE, their predominant fear concerns recombinant DNA.  That being the case, it is noteworthy that recombinant DNA is a completely normal part of our diet.  Naturally produced recombinant DNA in our crops can result from diverse mechanisms, listed in my recent review paper [1].  In fact, all land plants are “natural GMOs,” as all contain genes acquired horizontally [27-43].  To my knowledge, there is no published, validated research showing any fundamental biochemical or biophysical difference between DNA recombined in a test tube vs. that recombined in a living cell.
  4. Compared to other breeding techniques, targeted DNA manipulations achieved during transgenesis, cisgenesis, intragenesis, or genome editing are no more disruptive—and are commonly less disruptive—to a plant’s genome, transcriptome, proteome, and composition than other methods of crop improvement [25, 26, 44-49].
  5. It seems logical to assume, since conventional breeding techniques can be centuries old, that the products derived from such must be safe.  However, every plant is a unique genetic and epigenetic creation.  Therefore, every new plant presents unknown risks as a result of its unique genetic and epigenetic heritage.
  6. Conventional breeding can produce plants with interactions of thousands of genes, which may create unintended outcomes and hazardous new products [3].

Scientists recognize that there is always the possibility of a GE plant that has some unintended, negative effect on a consuming animal or human.  However, the same risk applies to conventionally bred crops, for which harmful cases have been documented [50, 51].  Thus, what matters to food safety is not the process used to create a plant, but the properties of the resulting plant [11, 52-55].  In fact, instead of posing a routine food-safety risk, the reverse is true: GE traits can actually increase food safety as compared to conventional crops (see [56] and citations in [57]).

Comments are most welcome, but attempts to dispute my conclusion must include citations to relevant scholarly literature.

Literature Cited

  1. Vincelli, P., Genetic engineering and sustainable crop disease management: Opportunities for case-by-case decision-making. Sustainability, 2016, Vol. 8, p. 495, DOI: 10.3390/su8050495. Available from: http://www.mdpi.com/2071-1050/8/5/495/html
  2. American Medical Association. Genetically Modified Crops and Foods, Summaries and Recommendations of Council on Scientific Affairs Reports, 2000, AMA Interim Meeting. p. 18-19 Available from: http://www.ilsi.org/NorthAmerica/Documents/AMA_2000InterimMeeting.pdf
  3. The National Academies Press. Safety of Genetically Engineered Foods: Approaches to Assessing Unintended Health Effects. Washington, D.C. 256 pp. Available from: http://nap.edu/10977 Accessed 28 Feb 2016.
  4. European Academies Science Advisory Council. Planting the future: opportunities and challenges for using crop genetic improvement technologies for sustainable agriculture. 978-3-8047-3181-3. Halle/Saale, Germany. Available from: http://www.easac.eu/fileadmin/Reports/Planting_the_Future/EASAC_Planting_the_Future_FULL_REPORT.pdf Accessed 28 Feb 2016.
  5. The Royal Society. Genetically modified plants for food use and human health—an update. Report Number 0 85403 576 1. 20 pp. Available from: https://royalsociety.org/~/media/royal_society_content/policy/publications/2002/9960.pdf Accessed 28 Feb 2016.
  6. The Royal Society. Reaping the Benefits: Science and the Sustainable Intensification of Global Agriculture. ISBN 978-0-85403-784-1. Available from: https://books.google.com/books?id=qpQLkgEACAAJ Accessed 28 Feb 2016.
  7. Hollingworth, R. M., Bjeldanes, L. F., Bolger, M., Kimber, I., Meade, B. J., Taylor, S. L. and Wallace, K. B., Society of Toxicology position paper: the safety of genetically modified foods produced through biotechnology. Toxicological Sciences, 2003, Vol. 71, p. 2-8. Available from: http://toxsci.oxfordjournals.org/content/71/1/2.full.pdf+html
  8. American Association for the Advancement of Science. Statement by the AAAS Board of Directors On Labeling of Genetically Modified Foods. Available from: http://www.aaas.org/sites/default/files/AAAS_GM_statement.pdf Accessed 28 Feb 2016.
  9. American Phytopathological Society Council. Compulsory Labeling of Plants and Plant Products Derived from Biotechnology. St. Paul, MN. Available from: http://www.apsnet.org/members/outreach/ppb/positionstatements/pages/biotechnologypositionstatement.aspx Accessed 28 Feb 2016.
  10. International Union of Nutritional Sciences. Statement on Benefits and Risks of Genetically Modified Foods for Human Health and Nutrition. Available from: http://www.iuns.org/statement-on-benefits-and-risks-of-genetically-modified-foods-for-human-health-and-nutrition/ Accessed 28 Feb 2016.
  11. American Medical Association. H-480.958 Bioengineered (Genetically Engineered) Crops and Foods. Available from: https://www.ama-assn.org/ssl3/ecomm/PolicyFinderForm.pl?site=www.ama-assn.org&uri=/resources/html/PolicyFinder/policyfiles/HnE/H-480.958.HTM Accessed 28 Feb 2016.
  12. Britsh Medical Association, Board of Science and Education. Genetically modified foods and health: a second interim statement. Available from: http://www.argenbio.org/adc/uploads/pdf/bma.pdf Accessed 28 Feb 2016.
  13. Bruhn, C., Earl, R. and American Dietetic, A., Position of the American Dietetic Association: Agricultural and food biotechnology. J Am Diet Assoc, 2006, Vol. 106, p. 285-93, DOI: 10.1016/j.jada.2005.12.017. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16442880
  14. Biochemical Society. Genetically Modified Crops, Feed and Food: A Biochemical Society Position Statement. Available from: http://www.biochemistry.org/Portals/0/SciencePolicy/Docs/GM%20Position%20Statement%202011%20Final.pdf Accessed 28 Feb 2016.
  15. American Society for Microbiology. Statement of the American Society for Microbiology on Genetically Modified Organisms. Available from: http://www.asm.org/index.php?option=com_content&view=article&id=3656&Itemid=341 Accessed 28 Feb 2016.
  16. Crop Science Society of America. Researchers and farmers utilize GM technology to address society’s growing global food production, security, and safety needs. Available from: https://www.crops.org/files/science-policy/issues/reports/cssa-gmo-statement.pdf Accessed 28 Feb 2016.
  17. Federation of Animal Science Societies (FASS). FASS Facts: On Biotech Crops – Impact on Meat, Milk and Eggs. Savoy, IL. Available from: http://www.fass.org/geneticcrops.pdf Accessed 28 Feb 2016.
  18. National Academies Press. Genetically Engineered Crops: Experiences and Prospects. ISBN 978-0-309-43738-7. Washington DC. 420. Available from: http://www.nap.edu/23395 Accessed 18 May 2016.
  19. Key, S., Ma, J. K. and Drake, P. M., Genetically modified plants and human health. J R Soc Med, 2008, Vol. 101, p. 290-8, DOI: 10.1258/jrsm.2008.070372. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18515776
  20. Nicolia, A., Manzo, A., Veronesi, F. and Rosellini, D., An overview of the last 10 years of genetically engineered crop safety research. Crit Rev Biotechnol, 2014, Vol. 34, p. 77-88, DOI: 10.3109/07388551.2013.823595. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24041244
  21. European Union Publications Office. A Decade of EU-Funded GMO Research (2001-2010). ISBN 978-92-79-16344-9. Luxembourg. Available from: https://ec.europa.eu/research/biosociety/pdf/a_decade_of_eu-funded_gmo_research.pdf Accessed 28 Feb 2016.
  22. Van Eenennaam, A. L. and Young, A. E., Prevalence and impacts of genetically engineered feedstuffs on livestock populations. J Anim Sci, 2014, Vol. 92, p. 4255-78, DOI: 10.2527/jas.2014-8124. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25184846
  23. Delaney, B., Safety assessment of foods from genetically modified crops in countries with developing economies. Food Chem Toxicol, 2015, Vol. 86, p. 132-143, DOI: 10.1016/j.fct.2015.10.001. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26456807
  24. Snell, C., Bernheim, A., Berge, J. B., Kuntz, M., Pascal, G., Paris, A. and Ricroch, A. E., Assessment of the health impact of GM plant diets in long-term and multigenerational animal feeding trials: a literature review. Food Chem Toxicol, 2012, Vol. 50, p. 1134-48, DOI: 10.1016/j.fct.2011.11.048. Available from: http://www.ncbi.nlm.nih.gov/pubmed/22155268
  25. Ricroch, A. E., Assessment of GE food safety using ‘-omics’ techniques and long-term animal feeding studies. N Biotechnol, 2013, Vol. 30, p. 349-54, DOI: 10.1016/j.nbt.2012.12.001. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23253614
  26. Herman, R. A. and Price, W. D., Unintended compositional changes in genetically modified (GM) crops: 20 years of research. J Agric Food Chem, 2013, Vol. 61, p. 11695-701, DOI: 10.1021/jf400135r. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23414177
  27. Tarrio, R., Ayala, F. J. and Rodriguez-Trelles, F., The Vein Patterning 1 (VEP1) gene family laterally spread through an ecological network. PLoS One, 2011, Vol. 6, p. e22279, DOI: 10.1371/journal.pone.0022279. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21818306
  28. Yang, Z., Zhou, Y., Huang, J., Hu, Y., Zhang, E., Xie, Z., Ma, S., Gao, Y., Song, S., Xu, C. and Liang, G., Ancient horizontal transfer of transaldolase-like protein gene and its role in plant vascular development. New Phytol, 2015, Vol. 206, p. 807-16, DOI: 10.1111/nph.13183. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25420550
  29. Emiliani, G., Fondi, M., Fani, R. and Gribaldo, S., A horizontal gene transfer at the origin of phenylpropanoid metabolism: a key adaptation of plants to land. Biol Direct, 2009, Vol. 4, p. 7, DOI: 10.1186/1745-6150-4-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19220881
  30. Kyndt, T., Quispe, D., Zhai, H., Jarret, R., Ghislain, M., Liu, Q., Gheysen, G. and Kreuze, J. F., The genome of cultivated sweet potato contains Agrobacterium T-DNAs with expressed genes: An example of a naturally transgenic food crop. Proc Natl Acad Sci U S A, 2015, Vol. 112, p. 5844-9, DOI: 10.1073/pnas.1419685112. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25902487
  31. Bock, R., The give-and-take of DNA: horizontal gene transfer in plants. Trends Plant Sci, 2010, Vol. 15, p. 11-22, DOI: 10.1016/j.tplants.2009.10.001. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19910236
  32. Wang, Q., Sun, H. and Huang, J., The evolution of land plants: a perspective from horizontal gene transfer. Acta Societatis Botanicorum Poloniae, 2014, Vol. 83, p. 363-368, DOI: 10.5586/asbp.2014.043. Available from: https://pbsociety.org.pl/journals/index.php/asbp/article/view/asbp.2014.043
  33. El Baidouri, M., Carpentier, M. C., Cooke, R., Gao, D., Lasserre, E., Llauro, C., Mirouze, M., Picault, N., Jackson, S. A. and Panaud, O., Widespread and frequent horizontal transfers of transposable elements in plants. Genome Res, 2014, Vol. 24, p. 831-8, DOI: 10.1101/gr.164400.113. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24518071
  34. Fortune, P. M., Roulin, A. and Panaud, O., Horizontal transfer of transposable elements in plants. Communicative & Integrative Biology, 2008, Vol. 1, p. 74-77. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633806/
  35. Yue, J., Hu, X. and Huang, J., Horizontal gene transfer in the innovation and adaptation of land plants. Plant Signal Behav, 2013, Vol. 8, p. e24130, DOI: 10.4161/psb.24130. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23470724
  36. Bergthorsson, U., Richardson, A. O., Young, G. J., Goertzen, L. R. and Palmer, J. D., Massive horizontal transfer of mitochondrial genes from diverse land plant donors to the basal angiosperm Amborella. Proc Natl Acad Sci U S A, 2004, Vol. 101, p. 17747-52, DOI: 10.1073/pnas.0408336102. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15598737
  37. Geering, A. D., Maumus, F., Copetti, D., Choisne, N., Zwickl, D. J., Zytnicki, M., McTaggart, A. R., Scalabrin, S., Vezzulli, S., Wing, R. A., Quesneville, H. and Teycheney, P. Y., Endogenous florendoviruses are major components of plant genomes and hallmarks of virus evolution. Nat Commun, 2014, Vol. 5, p. 5269, DOI: 10.1038/ncomms6269. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25381880
  38. Yang, Z., Wang, Y., Zhou, Y., Gao, Q., Zhang, E., Zhu, L., Hu, Y. and Xu, C., Evolution of land plant genes encoding L-Ala-D/L-Glu epimerases (AEEs) via horizontal gene transfer and positive selection. BMC Plant Biol, 2013, Vol. 13, p. 34, DOI: 10.1186/1471-2229-13-34. Available from: http://www.ncbi.nlm.nih.gov/pubmed/23452519
  39. Matveeva, T. V. and Lutova, L. A., Horizontal gene transfer from Agrobacterium to plants. Front Plant Sci, 2014, Vol. 5, p. 326, DOI: 10.3389/fpls.2014.00326. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25157257
  40. Huang, J. and Yue, J., Horizontal gene transfer in the evolution of photosynthetic eukaryotes. Journal of Systematics and Evolution, 2013, Vol. 51, p. 13-29, DOI: 10.1111/j.1759-6831.2012.00237.x. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19271204
  41. Diao, X., Freeling, M. and Lisch, D., Horizontal transfer of a plant transposon. PLoS Biology, 2006, Vol. 4, p. e5. Available
  42. Stegemann, S., Keuthe, M., Greiner, S. and Bock, R., Horizontal transfer of chloroplast genomes between plant species. PNAS, 2012, Vol. 109, p. 2434–2438, DOI: 10.1073/pnas.1114076109. Available from: http://www.pnas.org/content/109/7/2434.abstract
  43. Markova, D. N. and Mason-Gamer, R. J., The role of vertical and horizontal transfer in the evolutionary dynamics of PIF-like transposable elements in Triticeae. PLoS One, 2015, Vol. 10, p. e0137648, DOI: 10.1371/journal.pone.0137648. Available from: http://www.ncbi.nlm.nih.gov/pubmed/26355747
  44. Schnell, J., Steele, M., Bean, J., Neuspiel, M., Girard, C., Dormann, N., Pearson, C., Savoie, A., Bourbonniere, L. and Macdonald, P., A comparative analysis of insertional effects in genetically engineered plants: considerations for pre-market assessments. Transgenic Res, 2015, Vol. 24, p. 1-17, DOI: 10.1007/s11248-014-9843-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25344849
  45. Gao, L., Cao, Y., Xia, Z., Jiang, G., Liu, G., Zhang, W. and Zhai, W., Do transgenesis and marker-assisted backcross breeding produce substantially equivalent plants? A comparative study of transgenic and backcross rice carrying bacterial blight resistant gene Xa21. BMC Genomics, 2013, Vol. 14, p. 738, DOI: 10.1186/1471-2164-14-738. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24165682
  46. Batista, R., Saibo, N., Lourenco, T. and Oliveira, M. M., Microarray analyses reveal that plant mutagenesis may induce more transcriptomic changes than transgene insertion. Proc Natl Acad Sci U S A, 2008, Vol. 105, p. 3640-5, DOI: 10.1073/pnas.0707881105. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18303117
  47. Lehesranta, S. J., Davies, H. V., Shepherd, L. V., Nunan, N., McNicol, J. W., Auriola, S., Koistinen, K. M., Suomalainen, S., Kokko, H. I. and Karenlampi, S. O., Comparison of tuber proteomes of potato varieties, landraces, and genetically modified lines. Plant Physiol, 2005, Vol. 138, p. 1690-9, DOI: 10.1104/pp.105.060152. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15951487
  48. Ladics, G. S., Bartholomaeus, A., Bregitzer, P., Doerrer, N. G., Gray, A., Holzhauser, T., Jordan, M., Keese, P., Kok, E., Macdonald, P., Parrott, W., Privalle, L., Raybould, A., Rhee, S. Y., Rice, E., Romeis, J., Vaughn, J., Wal, J. M. and Glenn, K., Genetic basis and detection of unintended effects in genetically modified crop plants. Transgenic Res, 2015, Vol. 24, p. 587-603, DOI: 10.1007/s11248-015-9867-7. Available from: http://www.ncbi.nlm.nih.gov/pubmed/25716164
  49. El Ouakfaoui, S. and Miki, B., The stability of the Arabidopsis transcriptome in transgenic plants expressing the marker genes nptII and uidA. Plant J, 2005, Vol. 41, p. 791-800, DOI: 10.1111/j.1365-313X.2005.02350.x. Available from: http://www.ncbi.nlm.nih.gov/pubmed/15743445
  50. Koerth-Baker, M., How the ‘Poison Potato’ impacted the GMO debate. 2013 [30 May 2016]; Available from: https://www.geneticliteracyproject.org/2013/10/04/potato-chips-dangerously-delicious/.
  51. Finkelstein, E., Afek, U., Gross, E., Aharoni, N., Rosenberg, L. and Halevy, S., An outbreak of phytophotodermatitis due to celery. International Journal of Dermatology, 1994, Vol. 33, p. 116-118. Available
  52. National Research Council, Committee on Genetically Modified Pest-Protected Plants. Genetically Modified Pest-Protected Plants, Science and Regulation. ISBN 0-309-50467-8. Washington, D.C. . 292 pp. Available from: http://www.nap.edu/catalog/9795/genetically-modified-pest-protected-plants-science-and-regulation Accessed 28 Feb 2016.
  53. Hartung, F. and Schiemann, J., Precise plant breeding using new genome editing techniques: opportunities, safety and regulation in the EU. Plant J, 2014, Vol. 78, p. 742-52, DOI: 10.1111/tpj.12413. Available from: http://www.ncbi.nlm.nih.gov/pubmed/24330272
  54. Kolseth, A.-K., D’Hertefeldt, T., Emmerich, M., Forabosco, F., Marklund, S., Cheeke, T. E., Hallin, S. and Weih, M., Influence of genetically modified organisms on agro-ecosystem processes. Agriculture, Ecosystems & Environment, 2015, Vol. 214, p. 96-106, DOI: 10.1016/j.agee.2015.08.021. Available from: http://www.sciencedirect.com/science/article/pii/S0167880915300657
  55. Conko, G., Kershen, D. L., Miller, H. and Parrott, W. A., A risk-based approach to the regulation of genetically engineered organisms. Nature Biotechnology, 2016, Vol. 34, p. 493-503, DOI: 10.1038/nbt.3568. Available from: http://www.nature.com/nbt/journal/v34/n5/full/nbt.3568.html
  56. Diaz-Gomez, J., Marin, S., Capell, T., Sanchis, V. and Ramos, A. J., The impact of Bacillus thuringiensis technology on the occurrence of fumonisins and other mycotoxins in maize. World Mycotoxin Journal, 2015, p. 1-12, DOI: 10.3920/WMJ2015.1960. Available from: http://www.wageningenacademic.com/doi/abs/10.3920/WMJ2015.1960
  57. Vincelli, P., GMOs and Corn Mycotoxins. Grain Crops Update 2013 [Accessed 28 Feb 2016]; Available from: http://graincrops.blogspot.com/2013/08/gmos-and-corn-mycotoxins.html.

 

Genetically Engineered Crops Can Help Reduce Pesticide Use

Ask just about anyone the question, “Are you in favor of reducing pesticide use on crops?” and you will almost certainly get the same answer: Yes!  We all want fewer pesticides on our foods.  So if we essentially all agree, how do we get there?

For infectious diseases, there are four general approaches to disease management, as follows:

  1. Genetic resistance: Basically we are taking advantage of the plant’s capacities to defend itself from microorganisms through its own biochemistry.
  2. Cultural practices: This means that we manage diseases through the way we grow the plant. Examples include crop rotation, using pathogen-free seed, careful management of fertilizer, etc.
  3. Biological control: This involves taking advantage of living organisms that suppress or destroy the infectious agent of concern.
  4. Pesticides.

 

cropped-dscn1558.jpg
Figure 1. Central American family living on the edge of rice field regularly treated with aerially applied pesticides.

 

 

 

 

 

We already agree we want to eliminate pesticides, so let’s remove that from the discussion.  Biological control is wonderful and is active in essentially all agricultural soils.  Unfortunately, destructive diseases still occur in cropping systems, so natural biological control is commonly not enough.  Cultural practices can be powerful tools for disease control, but like biological control, they are often insufficient.

That leaves genetics, by which I mean “genetic modification” in the broadest sense.  I am being highly inclusive, in that I am including the full range of genetic tools for crop improvement, from the most traditional breeding technique known—simple selection—to the most sophisticated, diverse strategies of genetic engineering (GE).  Genetic tools offer a wide spectrum of techniques that can provide pesticide-free disease control.

Just a few days ago, an invited review paper of mine was published in the open-access journal, Sustainability.  The title is, “Genetic Engineering and Sustainable Crop Disease Management: Opportunities for Case-By-Case Decision-Making.”  The content in the paper is quite solid scientifically.  It has gone through multiple rounds of peer review, including a university seminar on this topic, to take advantage of the opportunity for peer-review before the outstanding molecular biologists in my department.

The manuscript describes nearly a dozen distinct strategies for engineering disease resistance in plants.  Indeed, in preparing the review by reading the relevant scientific literature, I was astounded by the diversity of approaches molecular biologists have for engineering disease-resistant plants.  There are many opportunities already, with more coming with each year of rapidly advancing science.

Can genetic engineering really reduce pesticide use?  Yes.  We know this is true.  Bt crops, which are crops engineered to be resistant to certain insects, have consistently provided for reductions in insecticide use around the world.  The benefits of these pesticide reductions have included:

  • Lower production costs for farmers
  • Fewer pesticide poisonings in countries with developing economies
  • Increased insect biodiversity

It is important to keep in mind that no single tactic for controlling diseases is “the final answer.”  Disease-causing organisms always adapt to whatever we do in the agroecosystem.  Thus, we always need to continue to find ways to reduce selection pressure on these organisms, whether we are using GE or not.  (See Section 3 of my review paper for more on this topic.)  But I see GE as analogous to a cell phone.  Yes, there are risks, but there are many benefits.  Why not wisely take advantage of useful technologies?

For evidence-based citations in support of the statements made in this post, please see my review paper and the recent report by the National Academy of Science, Genetically Engineered Crops: Experiences and Prospects.

 

“20 points of broad scientific consensus on GE crops”

The title of this short post–20 points of broad scientific consensus on GE crops–seems rather accurate, based on my own extensive knowledge in this subject. The piece cites peer-reviewed studies or position papers from scientific societies. In fact, they list only a few of the position statements from scientific societies on the safety of consuming present-day GE crops. Others exist, including those from major European scientific societies.

The lead author, Pamela Ronald, is a highly respected molecular geneticist and her husband is an organic farmer.  Thus, as a pair, they bring a somewhat unique perspective to the topic of genetic engineering. (Just for clarity, Dr. Ronald’s husband is not a coauthor on this particular piece, but they do publish jointly.)

(Nearly) Sustainable Food Systems, Part II

While leading students on a University of Kentucky Education Abroad trip to Nicaragua last year, we had an enriching visit with Rama Indians near Bluefields. Meeting our Rama hosts—who live very simply and with appreciation for their forest—was indescribably special. For all of us, it was the most memorable part of the study tour, made especially so because we personally witnessed the suffering of the Rama at the hands of illegal deforestation.

The Rama taught us about their traditional, forest-based food system. They rely in significant measure on the forest for edible plants, medicinal plants, and wildlife (Figure 1). They also cultivate various well-recognized crops, including cassava, plantain, and beans (Figure 2).

Figure 1: Our Rama host explains the alimentary and cultural value of the ebu fruit, the trunk of which is in the background.
Figure 1: Our Rama host explains the alimentary and cultural value of the ebu fruit, the trunk of which is in the background.

One of the most common traditional farming systems in regions of tropical forest (and sometimes temperate forest) is called slash-and-burn. In slash-and burn-farming, plots of forest are cut, but most of the forest is left intact. The fallen vegetation is allowed to dry, then it is burned, thereby releasing nutrients for crop uptake. The people then grow crops for two to six years, eventually allowing the plot to revert to forest.

The Rama Indians we visited did not practice slash-and-burn, but rather, slash-mulch (Figure 3) (Thurston, 1992). In such a system, a parcel of forest is cut but not burned. Nutrients are released at a slower pace through natural decomposition of the fallen vegetation. Thus, nutrients would be less subject to runoff into waterways than in a slash-and-burn system.

Every time I ponder it, I reach the conclusion that this is the most sustainable farming system I have ever witnessed or studied. In a slash-mulch system, diverse forest covers most of the land at all times. Plots for crops are limited in size, temporary, and surrounded by forest, so there is an abundance of habitat for native wildlife, vegetation, and other biota. Furthermore, the soil surface in the plots is never completely bare, which would expose it to erosion. It is low-yield agriculture. They grow crops without external inputs, mechanization, and or irrigation. However, it serves the needs of the Rama Indians, with apparently quite modest environmental impact compared to the large-scale, highly productive farming systems that emerged in the 20th century.

We saw in Part I of this two-part series that the hunter-gatherer existence—sustainable though it is—would be woefully inadequate to feed our present population. But in contrast to a hunter-gather existence, a slash-mulch system incorporates crop production, and it does so in a way that seems environmentally sustainable. So how would that system perform as a food system for our present population of 7.3 billion people?

Thurston (1992) indicates that a slash and burn system requires 15-30 hectares per person. I’ll assume that a similar range applies to a slash-mulch system. The UN Food and Agriculture Organization reports that Earth has approximately 2.9 billion hectares of land suitable or very suitable for rain-fed crop production (UN-FAO. 2009). Dividing 2.9 billion hectares by the conservative figure of 15 hectares per person gives us about 193 million. One-hundred ninety three million people represents only 2.6% of our present population—nowhere near

Figure 2. Plot of cleared forest used for cultivation of bean, plantain, and other crops.
Figure 2. Plot of cleared forest used for cultivation of bean, plantain, and other crops.

all the humans presently living on our planet. If it turns out we need 30 hectares per person, instead of 15 hectares, we can feed a just a little over one percent of our present population.

The UN-FAO (2009) estimate indicates that a total of 4.2 billion hectares of Earth’s surface is suitable in some way for rain-fed agriculture, even if marginally so. Let’s be as optimistic as possible and assume that all of that land is available for a slash-mulch food system (leaving none for urban areas, forests, wetlands, and biofuels). Let’s also assume that we only need 15 hectares per person. Dividing 4.2 billion by 15 hectares per person gives us 280 million people that Earth can support. That’s less than four percent of our present population of 7.3 billion. In this food system, over 96% would have to starve ourselves out of existence.

And what about the ones yet to be born, as our global population continues to grow?

All of this is made even more challenging by climate change. Given the reality of a rapidly changing global climate (National Academies Press, 2014), making sure everyone has the food security and food sovereignty they deserve is a moving target.

The two food systems featured in this two-part series may provide for a noble life, possibly one of great freedom. But they are lives of great material simplicity, and in all my professional travel in four continents, I’ve never gotten the sense that the average citizen in countries with developed economies cares to forego the material lives some of us enjoy. In that sense, maybe the food systems described in this series are not actually sustainable after all, in that they are not socially acceptable—a fundamental pillar of agricultural sustainability.

One can fairly argue that neither of these traditional food systems represents modern farms with a sustainability focus, and that is a valid point. However, these food

Figure 3: Soil cover from residue of forest and of wild vegetation. This is conceptually very reminiscent of our no-till cropping systems.
Figure 3: Soil cover from residue of forest and of wild vegetation. This is conceptually very reminiscent of our no-till cropping systems.

systems remind me of how far we have come with agriculture, as well as how far we still need to go, when we consider both food security and sustainability. I often wonder how we will meet the challenges of:

  • Food security for over seven billion people today; and,
  • Food security for well over nine billion in a mere 35 years (Gerland et al, 2014); and,
  • The subsistence life experienced by many millions of farm families throughout the world; and,
  • The likely dietary choices of a global middle class that will more than double in two decades (MacLennan, 2015); and,
  • Sustainability, in the sense that our farms will be capable of feeding humans for many centuries with minimal negative impact on the Earth and on the social fabric of human societies.

Are there farming systems that can adequately address all these challenges? And if so, what are the costs and the unanticipated consequences of such a system? A thoughtful and balanced approach to such questions is critical because my work on four continents suggests to me that all farming approaches have good ideas, all have limitations, and all have costs and unanticipated consequences.

If you are reading this post, you and I undoubtedly agree that we need to improve the sustainability of our present food system. But a bigger question is not, “Whether,” but “How? “ How do we measure “sustainability”? More importantly, which costs are we personally willing to pay? And who decides which costs are imposed on the general public at large?

These calculations emphasize to me the depth of the challenges facing our children and grandchildren. One of the concepts I find useful is called sustainable intensification (FAO-UN, 2011; Godfray and Garnett, 2014; Pretty, 1997). Unfortunately, this phrase is used to defend whatever practice or technology one favors for producing food in the future. I think that is misguided. Basically, the simplest understanding of this phrase is that it is beneficial to humans and the environment to produce more crops per unit of land (=intensification) in sustainable ways. (And I am referring to sustainability in a broad sense.) I don’t see a flaw in this concept.

But even the concept of sustainable intensification is not a protocol, or even a road map—it is merely a useful way to think about ways to address some of our food-system challenges. I simply do not see easy answers. I see only tradeoffs. Global food system sustainability is like global energy sustainability: no one has found a “magic bullet,” because there is none.

Citations

  1. Diamond, J. 1997. Guns, Germs and Steel: The Fate of Human Societies. Norton and Company
  2. FAO-UN. 2011. Save and Grow: A Policymaker’s Guide to the Sustainable Intensification of Smallholder Crop Production.
  3. Gerland et al, 2014. World population stabilization unlikely this century. Science Express1126/science.1257469
  4. Godfray and Garnett. 2014. Food security and sustainable intensification. Phil. Trans. R. Soc. B 2014 369, 20120273.
  5. MacLennan, D. 2015. In 4 Charts: The Past, Present, and Future of Food Security. The Plate: National Geographic Daily Discussions on Food.
  6. National Academies Press. 2014. Climate Change: Evidence and Cause, An overview from the Royal Society and the US National Academy of Sciences
  7. Pretty, J. N. 1997. The sustainable intensification of agriculture. Natural Resources Forum 21(4):247-256.
  8. Thurston, D. 1992. Sustainable Practices for Plant Disease Management in Traditional Farming Systems. Oxford and IBH Publishing Co. 279 pp.
  9. UN-FAO. 2009. The Resource Outlook to 2050.

Out-of-the-Box: Science-Based Insights into Food System Sustainability, transitioning to new host

I am transitioning my blog, Out-of-the-Box: Science-Based Insights into Food System Sustainability, to wordpress.com.  My initial posts are listed below, with hotlinks.  More are forthcoming, as soon as my schedule permits…

Study: Genetically Modified Soybean Meal Associated With Reduced Growth of Goat Kids

Why Genome Editing is So Remarkable

Does Crop Insurance Influence Crop Diseases?

Disclosure Statement on Industry Relations

Why the Acronym “GMO” Can Provoke Deep-Seated Ange…

(Nearly) Sustainable Food Systems, Part I