Spring and summer, to many people, means barbecuing. This isn’t surprising, when you consider that the activity of cooking meat over an open flame has been indulged in by human beings for a very long time–a lot longer than anyone dreamed, according to recent research.
For a long time the earliest evidence of a human-controlled fire came from China and was dated to 500,000 years ago. However, evidence presented at the International Paleoanthropology Society’s annual meeting in Montreal suggests our hominid ancestors were using fire in a South African cave called Swartkrans1.5 million years ago.
Researchers from Transvaal Museum in Pretoria and Williams College in Williamstown, Pennsylvania, analyzed burnt bones found in the cave 20 years ago using a new technique called electron spin resonance, which told them just how hot the bones got.
They found that among the more than 250 bones (probably antelope) were some so thoroughly burned they must have been put in a wood campfire, because they’d been heated to 600 degrees Celsius. At the time the site was in the middle of a grassland, and temperatures in grass fires usually only reach 300 to 400 degrees Celsius.
Other bones were only slightly heated, which seems to indicate that the meat on them had been roasted–making Swartkrans the site of the world’s first known barbecue.
Francis Thackeray, one of the South African researchers, doesn’t think the hominids actually knew how to start a fire; he thinks they more likely collected it, bringing into the cave burning branches set afire by lightning strikes.
However, at a 790,000-year-old site called Gesher Benot Ya-aqov in Israel, researchers from Hebrew University’s Institute of Archaeology have found seeds, cut bones, wood, flint, numerous fruit specimens, and burned and unburned grains, all clustered together–just as you would expect if people built fires and tended them day after day.
The goal of putting meat over a fire, of course, is to make it easier to eat–and tastier.
Cooked meat is easier to eat because the heat alters the protein molecules in the meat. In raw meat, proteins molecules are wound up in coils, formed and held together by bonds. Heat breaks these bonds, allowing the protein molecules to unwind. Heat also causes the muscle fibers in the meat to shrink and shorten, by driving out water and causing the protein molecules to recombine or coagulate. This process of breaking, unwinding, and coagulating is called denaturing. (Not a term that has caught on among the barbecuing crowd. “Think I’ll go out to the deck and denature some animal protein” just doesn’t sound all that appetizing.)
Cooked meat is more flavorful for a couple of reasons. One is the Maillard reaction, which occurs when the denatured meat proteins recombine with the sugars that are also present. (“Instigating the Maillard reaction” is better known as “browning,” because this process changes the colour of the meat as well as creating that characteristic meaty flavour.) This reaction occurs most readily between around 185 and 300 degrees Celsius. Of course, the outside reaches this temperature faster than the inside, which is why the outside browns first and typically has the strongest flavours.
Fat also contributes to the flavour. Animals, like humans, are made up mostly of water, and so water is the most prevalent component of meat. Most of the flavour-carrying molecules are repelled by water. Instead, they dissolve in fat, so as the water is driven out and the fat melts, flavour is released into the meat. (This is also why well-marbled steak is tastier than very lean steak.)
Of course, we often add additional flavour to our grilled or barbecued meat with a special sauce or marinade.
Most marinades have three components: acid, oil and herbs. The acid helps to partially denature the proteins before the heat continues the process; this creates opening in the meat’s structure into which flavor can seep. This works best on meats such as chicken breast and fish, because the muscle structure isn’t as dense as in steak. Marinades work best on denser meat when it is first cut into smaller pieces.
Our ancient ancestors, alas, probably didn’t have any sauces or marinades to put on their antelope meat as they cooked it over their fires a million years ago.
But I’ll bet they would have used it if they could have got it.