By Richard Black
BBC science correspondent in Cologne
If a 3m-high inflatable maize cob can keep GM foods out of Europe, the biotech industry doesn't have a hope.
Swedish-brewed lager, using traditional ingredients as well as insect-resistant maize
For the duration of the Agricultural Biotechnology International Conference (ABIC) here in Cologne - one of the world's biggest annual gatherings of business people and scientists in the biotech field - a group of protestors have maintained a vigil outside under the shadow of their giant cob.
The group, led by the German NGO Misereor, say "no to GM in Europe" and "no to GM in the developing world".
"Large-scale farmers could benefit from such a technology for a time," said Misereor's Bernd Nilles. "But it will never be sustainable.
"There's a huge lack of acceptance of genetic engineering in politics and society, and it just isn't an effective tool to fight hunger and starvation."
Overwhelmingly, the 700-odd delegates inside the conference hall beg to differ.
Misereor's troops have been kept at a safe distance by a phalanx of extremely large security guards, many sporting pony-tails and unwise facial hair which would provoke ridicule if worn by gentlemen less physically imposing.
Lucky they were there, though, as one saved delegates from major calamity one morning by confiscating my plastic bottle of water.
"We have to take it; it is a security risk because you might hit someone over the head with it," he said, with no trace of a smile.
I suggested that my microphone, equally long and much more solid, was capable of causing considerably more damage if wielded aggressively (something which has come to mind during more than one rambling and un-editable interview).
"Yes but you need that for your work," he said.
I was tempted to say that my need for water was considerably more primal - but given the lavish conference hospitality, getting hold of another bottle inside was not likely to be an issue.
If there is a global food crisis which only GM agriculture can prevent, you wouldn't have guessed it from the laden tables of free food and drink.
This is the first time that the ABIC has been held in Europe - and it's no co-incidence that it's come in a year when the European Union has lifted its five-year moratorium on new GM foods, and, for the first time, approved a GM seed variety - a Monsanto maize - for planting throughout EU territory.
Biotech companies and the German state of Nord-Rhein Westphalia would not have spent 1.5m euros on the conference if they didn't scent business opportunities.
The ABIC is a showcase for GM technology
"Definitely there's a shift in public opinion within Europe," said Ashley O'Sullivan, president and CEO of the Canadian company Ag-West Bio, and a member of the ABIC foundation board.
"Europeans are looking, I think, at the North American experience and seeing that these things have been grown quite successfully for a number of years now and they're not causing damage to the environment, they're not causing any human health issues; in fact these technologies are safer."
Whether or not that's true - and whether the European public is following the lead of the European Commission in moving to embrace GM - what just about everyone here agreed on is that Europe's position may be crucial for Africa.
Many African countries export food to the EU, and if European consumers want their food GM-free, that sets limits on what African farmers can do.
Lovemore Simwanda, from the Environmental Conservation Association of Zambia, was quite happy for Europeans to remain sceptical. The United States, he said, was pushing genetically modified food on Africa before African governments could establish legislation and infrastructure to evaluate and monitor it.
"They want to dump the products of the technology on to Africa, and then say 'you can manage it by putting the laws in place'", he said.
A potato altered to produce a low-calorific carbohydrate
"But we think it should be the other way round. We need to know what the technology is, and then have the capacity to handle the technology, have the infrastructure in place, have the legal framework and policies in place, and then you have the right expertise to implement this."
Other African delegates, such as Florence Wambugu of the Kenya-based organisation Africa Harvest Biotech Foundation International, were more positive about the potential GM crops have for Africa.
"We need to look at what is going on in other developing countries like China and India and Brazil," she said.
Noting that GM crops are being used in some African countries, she commented: "Small-scale farmers are benefiting from better health because they are not inhaling the pesticides; there is money in their pockets; and they are benefiting because there are fewer toxins."
Genetic modification is, I would suggest, a uniquely polarising issue.
I can't think of another subject - with the possible exception of macro-economic theory - where intelligent and concerned people can look at the same set of facts and come up with such divergent conclusions.
And I say "concerned" deliberately, because there is a view that biotech researchers are uniformly Frankenstein-like scientists who want to inflict their evil creations on an unsuspecting world for their own financial gain.
Such people may exist in the biotech world - though I suspect they inhabit boardrooms rather than research laboratories.
But among scientists one chats to at a gathering like this - possibly over a bottle of Swedish GM beer - there are many who, rightly or wrongly, genuinely believe they are creating something which will benefit humankind.
Many admit that they were na´ve in believing the public would accept transgenic organisms without demur; "we got it wrong and need to listen more" was a common refrain.
And a trend that was clear here is that researchers are increasingly looking to step away from bringing novel genes into plants. Instead, they're working on ways of changing the plant's own genome, for example by introducing double copies of important genes, or changing the cues which switch a gene on and off.
Ten minutes into his talk, Misereor finally made their presence felt inside the conference hall, as two ladies leapt to their feet, produced a cassette-player and a lyric sheet and launched into an anti-GM song
Tony Connor, from the New Zealand Institute for Crop and Food Research, is working on ways of engineering plants which use DNA only from that plant.
"We want to overcome the requirement to use things like viruses or bacteria as vectors for gene transfer," he said.
"Now we can get everything we need from the host plant; this technology should overcome fears about moving genes from one species to another, and to be honest that was the main motivation behind this research."
Chris Somerville, from the Carnegie Institution, closed the conference with a talk on what new kinds of genetic modification we can expect in the near future.
"Most of the people who are dependent on rice are starving for iron," he said.
"The minimum number is eight hundred million; and the problem is compounded by the fact that many people with poor diets also have intestinal parasites that make the matter worse.
"I have reason to predict that there is going to be a major international effort to make transgenic plants for the developing world that have improved iron as a high priority."
But, as he acknowledged, this would be a different biotech world from the one we have now.
Of biotech varieties planted today, almost all are engineered for one of two traits - herbicide tolerance or insect resistance - the vast majority are cotton, soy and maize; and they're widely used in just a handful of counties.
He could have added that seeds are produced and distributed as a profit-making venture by big agribusiness companies, rather than by non-profit groups intent on helping the needy.
Big questions remain over who will pay to implement the vision Chris Somerville was putting forward, even if it were to be accepted as socially and environmentally desirable.
Ten minutes into his talk, Misereor finally made their presence felt inside the conference hall, as two ladies leapt to their feet, produced a cassette-player and a lyric sheet and launched into an anti-GM song.
"There is no future for the big polluters," they sang; then, changing person, "We've got the soya, we've got the lawyers, the politicians in our pocket."
The security guards finally had their moment in the sun, removing the two protestors, still chanting; as they left the hall, Chris Somerville commented "I don't think they could have been listening".
It could be a summary of the whole GM debate.