The k2p blog

There is much discussion about when to define the start of the Anthropocene  epoch “that begins when human activities started to have a significant global impact on Earth’s geology and ecosystem” . Scientists are looking for the parameters which could define the start of this geological age in the 4.5 billion year history of the Earth. There are suggestions that it should be 1945 when the first nuclear test was carried out or 1950 when radioactive particles began to be detected in the atmosphere. Others have argued for 1610 when “an unusual drop in atmospheric carbon dioxide and the irreversible exchange of species between the New and Old Worlds” began. Others still argue for 1964.

Homo timeline (Wikipedia)

But I find these arguments unconvincing. There is, in fact, a single development (whether it was a single event or a development, discovered and rediscovered, perhaps at many places and over a long period). That single development was the control of fire. I wrote a year or so ago “The Age of Man began when Homo Erectus learned to produce fire at will and to contain fire in a hearth.”

The one single capability which initiated the divergence of humans from all other animals and which has resulted in the inevitable development and domination of modern humans is the control of fire. And that was around 400,000 years ago. The Age of Man began when Homo Erectus learned to produce fire at will and to contain fire in a hearth. I would even speculate that without fire Homo Erectus would not have survived to evolve into Homo Sapiens. Without fire Homo Sapiens would not have thrived through the ice ages or left the tropics to colonise more northern climes.

When our ancestors came down from the trees and developed bipedalism, they did not have control of fire. There were just another primate species – one among many. The earliest stone tools were developed without fire possibly by homo habilis. It may well be that this tool making ability was a key survival attribute which allowed this species to become skillful hunters and shift to a diet containing much raw meat. The brains of homo habilis grew in size and the species continued evolving to become homo erectus and other bipedal primates died out. And then around 1.8 – 1.5 million years ago, homo erectus gained some control over fire. It is possible that it was the skill in stone cutting which itself led to the discovery that flint and iron pyrites struck together could create a spark. It may have been an ancient stone tool maker who, accidentally, first discovered a method of creating a spark and igniting a fire. While the earliest known hearths are only from around 400,000 years ago, hearths are relatively sophisticated technology. Primitive ignition techniques and a rudimentary control of fire must have been available earlier and was probably available to the common ancestors of both Neanderthals and AMH (anatomically modern humans). The size of the evolving homo erectus brain grew sharply as cooked meat dominated the diet and the biological energy resources available to an individual of the species took off. The – albeit primitive – control of light and heat from an external source would have been revolutionary. Though fire was not necessary for stone tools, the ability to make and hone stone tools, and fire-hardened wooden weapons, after the hunting day was done would have been a giant leap in the technological stakes.

There is a clear link between diet and energy availability and brain size evolution.

Smithsonian: Wherever humans have gone in the world, they have carried with them two things, language and fire. ….. Darwin himself considered these the two most significant achievements of humanity.

Harvard biologist Richard Wrangham, … believes that fire is needed to fuel the organ that makes possible all the other products of culture, language included: the human brain. Every animal on earth is constrained by its energy budget; the calories obtained from food will stretch only so far. And for most human beings, most of the time, these calories are burned …… in powering the heart, the digestive system and especially the brain, in the silent work of moving molecules around within and among its 100 billion cells. A human body at rest devotes roughly one-fifth of its energy to the brain, regardless of whether it is thinking anything useful, or even thinking at all. Thus, the unprecedented increase in brain size that hominids embarked on around 1.8 million years ago had to be paid for with added calories either taken in or diverted from some other function in the body. Many anthropologists think the key breakthrough was adding meat to the diet. But Wrangham and his Harvard colleague Rachel Carmody think that’s only a part of what was going on in evolution at the time. What matters, they say, is not just how many calories you can put into your mouth, but what happens to the food once it gets there. How much useful energy does it provide, after subtracting the calories spent in chewing, swallowing and digesting? The real breakthrough, they argue, was cooking.

……. Carmody explains that only a fraction of the calories in raw starch and protein are absorbed by the body directly via the small intestine. The remainder passes into the large bowel, where it is broken down by that organ’s ravenous population of microbes, which consume the lion’s share for themselves. Cooked food, by contrast, is mostly digested by the time it enters the colon; for the same amount of calories ingested, the body gets roughly 30 percent more energy from cooked oat, wheat or potato starch as compared to raw, and as much as 78 percent from the protein in an egg. …..

…..Fire detoxifies some foods that are poisonous when eaten raw, and it kills parasites and bacteria. Again, this comes down to the energy budget. Animals eat raw food without getting sick because their digestive and immune systems have evolved the appropriate defenses. Presumably the ancestors of Homo erectus—say, Australopithecus—did as well. But anything the body does, even on a molecular level, takes energy; by getting the same results from burning wood, human beings can put those calories to better use in their brains. Fire, by keeping people warm at night, made fur unnecessary, and without fur hominids could run farther and faster after prey without overheating. Fire brought hominids out of the trees; by frightening away nocturnal predators, it enabled Homo erectus to sleep safely on the ground, which was part of the process by which bipedalism (and perhaps mind-expanding dreaming) evolved. By bringing people together at one place and time to eat, fire laid the groundwork for pair bonding and, indeed, for human society.

I can see that once fire had been controlled and cooking developed, the sudden (relatively) advance of that species was inevitable. Both for evolution and for technology development. Within the individual it provided the elements necessary for the brain to grow. That in turn led – also inevitably – to speech (c. 200 kya) and language (c. 100 kya) and writing (c. 50 kya). Stone tools were sufficient – without fire – to lead to meat eating. But it was fire which gave cooking, which allowed an energy-rich diet containing cooked vegetable and animal proteins. But fire did not just give cooking. It provided the starting point for virtually all technology as we know it today. Fire provided safety. Hearths gave a focus for a cooperative society to develop. Hearths led to ovens and kilns and eventually to smelters. Light in the dark and heat in the bitter northern winters, probably gave rise to the first ever “leisure times”. The Stone Age, with fire, gave way to the Bronze Age. As the ability to control and contain even higher temperatures were developed, the Iron Age was born. Gods and alchemists and priests and shamans needed fire. The Sun in its avatar of fire paved the way for the first religions (though this may not be considered much of an advance). Temperature was recognised as being a critical parameter because of the control of fire. Blacksmiths and alchemists gave rise to Metallurgy and Chemistry and Physics. Sand and fire gave glass and Astronomy. The Steel Age and the Plastics Age and now the Semiconductor Age were all inevitable once fire had been controlled and harnessed. The species not only survived Ice Ages, it thrived through them. Our ancestors only expanded into the more northern climes because of the availability of fire. In due course, fire gave rise to electricity and then the dark, or the cold, or the heat, could all be banished at will.

The Age of Man has been, and is, the age of fire.

First came hominids and then came fire and the rest is history.

Homo sapiens is now with gravitation where ancient  homo erectus was with fire. As the magic of fire was understood and brought under control and harnessed, so the magic of gravitation, too, will be understood and controlled and harnessed to the service of homo superieur.

Related:

The Anthropocene began 400,000 years ago when fire was “controlled”