Are tomatoes naturally unnatural?

The news GM Tomatoes are being grown in Canada broke on the BBC late last week. They also opened a com­ment sec­tion which, like com­ments sec­tions on any news site, is a mix of the thought­ful and bizarre.

One com­mon reac­tion is that the GM toma­toes aren’t nat­ural, and that this mat­ters because there’s an assump­tion that nat­ural is good. This might be a less pop­u­lar opin­ion if people lived for a month with nat­ural water sup­plies. More inter­est­ing is the other side of the argu­ment, that non-GM toma­toes are nat­ural, which makes a kind of sense, but is odd when you look closely.

The reason that toma­toes look nat­ural is that they’re an easy enough plant to cul­tiv­ate. You can grow toma­toes from seed without much trouble, and the tomato crop has seeds so it’s easy to see the cycle of life. It not stu­pid to think that looks natural.

A tiny wild tomato next to a massive cultivated tomato.

The large-fruited tomato ‘Giant Heirloom’ com­mon to mod­ern agri­cul­ture (right) and the typ­ical fruit of a related wild spe­cies (L. pimp­inel­li­fo­lium). Photo by Bai and Lindhout (2007)

We don’t see wild toma­toes in the shops and this photo from Bai and Lindhout shows why. The tomato on the right is the ‘Giant Heirloom’ tomato, grown by some farm­ers. The one on the left, you might need a mag­ni­fy­ing glass to see it, is a wild tomato. At that size, it wouldn’t be so sur­pris­ing to think of toma­toes as ber­ries. Bai and Lindhout point out that devel­op­ing tomato hybrids is an extremely com­pet­it­ive busi­ness with cul­tivars hav­ing a turnover of five years. It’s not just a mat­ter of keep­ing up with fash­ions, there are other advant­ages like res­ist­ance to dis­ease or longer shelf-life to breed for. This is innov­a­tion that com­pan­ies want to pro­tect so you get pat­ents for non-GM hybrids like this one.

Bai and Lindhout’s paper ‘Domestication and Breeding of Tomatoes: What have We Gained and What Can We Gain in the Future?’ is a bit dated now, as it was writ­ten in 2007. They men­tion using QTLs (quant­it­at­ive trait loci) and marker-assisted breed­ing in the future. This is now com­mer­cial prac­tice. Bai and Lindhout also anti­cip­ated the interest in the many wild Solanum as a source of genetic diversity for tomatoes.

Tracking the ori­gins of some spe­cies is dif­fi­cult, and espe­cially for tomato. The best archaeo­botan­ical remains in Mesoamerica found in places that aren’t suit­able for the wild crops to grow so the early domest­ic­ates appear divorced from their ori­gins (Pickersgill 2007). To make things more com­plic­ated, most genetic diversity for tomato is found in South America, but domest­ic­a­tion seems to have been in Mesoamerica. The domest­ic­a­tion of crops is inter­est­ing for his­tor­ical reas­ons, but Pickersgill notes that there are good prac­tical reas­ons for study­ing domest­ic­a­tion to improve mod­ern plant breed­ing. Genetic stud­ies effect­ively allows bot­an­ists to take plants apart to see how they work.

This intense exam­in­a­tion of plants poten­tially means a future of what Vaughan, Balázs and Heslop-Harrison (2007) call ‘super-domestication’. It com­bines both futur­istic genetic ana­lysis and a look back to the tra­di­tional meth­ods of farm­ing through eth­no­bot­any, but the reason it has prom­ise for the future is that it acknow­ledges the work that earlier gen­er­a­tions in cre­at­ing unnat­ural vari­et­ies of crops people would want to eat.

As for the GM Tomato, not every­one will wel­come it, but toma­toes have a his­tory of vili­fic­a­tion before accept­ance. In the long term it seems it’s the fact they’re unnat­ural that makes toma­toes so attractive.

If you fol­low the links, you’ll see they all come from the same journal. In 2007 Annals of Botany pub­lished a spe­cial issue on crop domest­ic­a­tion, which you can read with Open Access.


Wild tomato and heir­loom tomato by Bai and Lindhout.

Alun Salt. ORCID 0000-0002-1261-4283

When he's not the web developer for AoB Blog, Alun Salt researches something that could be mistaken for the archaeology of science. His current research is about whether there's such a thing as scientific heritage and if there is how would you recognise it?