Last month, I got a question (reproduced with permission):

Dear Dr. Bonham,

I have seen your article in 2015 on Scientific American.

I am supporter of GMO, and wrote a popular science article about GMO. However these questions were directed at me and I don't have much information (nor the energy to research anymore, as I have other duties to do right now, this is not my subject and doing deep research on this subject takes my time) on these questions. I thought maybe you could help me with answering these with showing relevant studies. I would be glad if you could forward couple of relevant peer-reviewed papers.

1) Can we collect more seeds from GMO crops for next season? Or should we buy seeds each time we harvest?

2) How much yield in the world is done by small family farms? Is GMO a threat for biodiversity? If so, is making farmers dependent on buying seeds (to corporations) a solution?

3) 4th chapter in this report basically mentions that "there are no visible threat to environment".

This is comparing to what kind of yield method? What is the effect of chemicals and fertilizers used while growing these seeds? What is the effect on biodiversity? What is the effect of GMO's on soil quality?

Best Wishes,

- Bilgecan Dede

He managed to answer the first question for himself before I had a chance to respond. Short version: you can't collect seeds from GMOs to use next season, but you can't collect seeds year after year for other varieties of commercial crops either.

... By the 1930s, commercial hybrid crop varieties began to proliferate. When one replants second generation seeds from hybrids, one gets a mixture of inferior varieties, so it was in farmers’ best interest to buy new seeds each year. This was especially true for corn farmers, who had by and large been relying almost exclusively on hybrids for roughly a half a century before GE technology came along.

On to question 2. I'm no expert, but I found this site that seems to link to credible sources. 

The vast majority of the world’s farms are small or very small. Worldwide, farms of less than 1 hectare account for 72% of all farms, but control only 8% of all agricultural land. Farms between 1 and 2 hectares account for 12% of all farms and control 4% of the land. In contrast, only 1% of all farms in the world are larger than 50 hectares, but they control 65% of the world’s agricultural land

There are more than 570 million farms in the world. More than 90% of farms are run by an individual or a family and rely primarily on family labour. Family farms occupy a large share of the world’s agricultural land and produce about 80% of the world’s food.

It's also worth noting that productivity (that is, amount of calories produced per hectare of land) is significantly higher in large-scale farming operations, but also more costly in terms of CO2 footprint etc. And many "small-scale" or "Family" farms can be quite large, and often use industrial ag techniques including GMOs. It's not directly related, but I also just read this piece in The Economist last week that mentions how many small farms in Africa are being bought up by folks that have made money in cities - farming is big business apparently.

For the other questions, we need to separate GMO and industrial farming. Most farmers that are producing at scale, even those that don't use GMO, don't save seed to plant the next year, they buy every year. Industrial agriculture, even organic non-gmo agriculture relies on monoculture of a small number of cultivars and is a threat to biodiversity.

Genetic modification is a tool, and can be used for good or ill. I think it's too often linked to industrial agriculture because farmers seeking to maximize profits without regard for other considerations will use any tool at their disposal, including GM. But that doesn't make the tool a bad thing.

Regarding the third question, I'm not really an expert, so take what I say with a grain of salt. And also, I haven't read that book. In a lot of these studies that I read, they are trying to make direct comparisons looking at the same farming techniques +/- GMO. But the sorts of techniques used along with GMO are different from organic or biodynamic processes that do not use GMO. That said, if you used all of the organic farming methods, except used a GMO crop, the point is that there's not a difference.

In many cases, GMOs have led to decreased pesticide use and herbicide use. All of the complaints about Roundup for example are comparing Roundup to no herbicide, or to other farming techniques. This is not a fair comparison - it's not like farmers were all using organic farming methods and then roundup came along and displaced that - Roundup is actually far less toxic that what was used before, and could be used in much lower quantities. A lot of farmers are producing commodity crops and have low margins - there's a reason organic costs more. 

Broader studies are starting to look at things like soil quality and biodiversity, but it's a tricky scientific question, and again you have to be wary of people comparing industrial, unsustainable practices (that happen to also use GMO) with something like organic or biodynamic that doesn't. And let's say we determined that roundup ready was unambiguously bad for everything - that's an indictment of a single product, not GMOs as a whole.