Monday, August 31, 2009

The evolutionary implications of our preference for the Maillard reaction

This is something that has been bugging me the last couple of days... As many of the foodies out there may know, the Maillard reaction (pronounced may-ARD) is that incredible magic chemistry that happens when you sear meat, roast coffee, or malt barley to make whiskey and beer. In a nutshell, heat applied to certain proteins causes them to get all jumbled up and rearrange themselves into literally hundreds of different complex flavor compounds. Okay, that was probably an imprecise lay explanation, but you get my point.

How can this delicious piece of seared meat help my genes to replicate themselves?
Make no mistake, the products of the Maillard reaction taste fucking good. In fact, it is so tasty that this is where the myth developed that searing meat helps to "hold in the juices". It doesn't, and in fact roasted meat that has not been seared will actually have very slightly higher moisture content than meat that has been properly seared. However, unseared meat will taste drier because the Maillard reaction is so (literally) mouth-wateringly good that it will actually make you salivate more while eating and make the seared meat taste tender and moister.

But here's the question: From an evolutionary perspective, why does it taste good?

I suppose its possible that a preference for cooked food was such a beneficial adaptation for us that we evolved a taste for charred meat in a relatively short amount of time, a hundred thousand years or so. I mean, our jaw structure definitely reflects the shift in selective pressures brought about by the advent of cooking, so it's not inconceivable. But I tend to doubt this explanation for a couple of reasons.

One is that there is a big difference between a modified jaw structure vs. the ability to detect and seek out a whole new class of flavor compounds. It seems the latter would take a lot longer to arise as a result of natural selection.

The other reason I doubt that this preference was selected due to cooking is because there doesn't seem to be any reproductive benefit to preferring charred meat over, say, boiled meat. I suppose our ancestors may just have used fire-roasting more than boiling -- but I have to imagine that the two techniques were invented around the same time, and if our ancestors did not already prefer the flavor of seared meat, I don't see why they wouldn't just boil it to save time, as well as to capture any rendered fat in a broth rather than letting it drip wastefully into the fire.

It seems most likely to me that we already had a taste for these flavor compounds prior to learning how to create them via cooking, and that it was a side effect of some other adaptation. But what?

The Wikipedia article talks about a similar reaction occurring naturally in our bodies... I wonder if that could have any bearing on it? I don't know, I am not an evolutionary biologist, or any kind of biologist for that matter. Anybody have any ideas?


  1. I think you're wrong about roasting and boiling originating at the same time. As soon as you have fire, you can roast. Boiling's hard, if you don't have pots, which are a lot more recent than fire.
    Without pottery, you can dig a hole, line it with leaves, fill it with water, throw your meat in, and then drop red-hot rocks in it. And people did do that, but I'll bet it took them a while to figure it out. And roasting's way easier.

  2. That's a good point... You don't need full-blown pottery skills do boil, you can do it if you can make a mostly water-tight basket (think about boiling water in a styrofoam cup... as long as the water level stays up, you can boil in otherwise flammable materials) but that's still requires a fair bit more technology than roasting over a spit.

    I suppose then the next question would be whether some of our primate cousins also enjoy the taste of charred meat...? If we are unique in liking it, then clearly it was a recent adaptation. But I don't know if that is the case or not..