When Humans Almost Went Extinct

Around 1.2 million years ago, only 18,500 early humans were breeding on the planet. According to researchers, this is evidence that there was a real risk of extinction for our early ancestors. What's more, according to a new study it took at least a million years for humans to come back from the brink. It was not until the emergence of modern humans, Homo sapiens, around 160,000 years ago and their migration out of Africa that humanity's place on Earth was secured. Two factors helped humans to survive: an increasingly carnivorous diet and mastery of fire.

In an on online report in the Proceedings of the National Academy of Sciences (PNAS), “Mobile elements reveal small population size in the ancient ancestors of Homo sapiens,” researchers found that the ancient human effective population size 1.2 million years ago was about 18,500, and couldn't have been larger than 26,000. This means that the population of Homo erectus, an ancestor of modern humans, was small even at a time that the species was spreading around the world. This implies an “unusually small population size for a species spread across the entire Old World,” the authors write. “There's this history of a precarious existence not just for our species but for our ancestors,” says co-author Lynn Jorde, a human geneticist at the University of Utah in Salt Lake City.

On of the things that has long puzzled researchers is that modern humans lack the genetic variation found in other living primates. Compared with chimpanzees or gorillas, human genetic variation is remarkably small, even though our current population is so much larger than any species of great ape. One explanation for this lack of variation is that our species experienced events where a significant part of the human population were killed. Some researchers proposed that the lack of variation in our maternally inherited mitochondrial DNA suggested these events took place relatively recently, perhaps as our ancestors were migrating out of Africa.


Early humans migrated from Africa.

One possible indecent was the eruption of the Toba super-volcano, 70,000 years ago in Indonesia. Some scientists have speculated that the eruption could have triggered a “nuclear” winter that fewer than 15,000 individuals survived. Other genetic studies attributed our low genetic variation to chronically low numbers, with as few as 10,000 breeding humans at different times during the past 2 million years. To this point there have been technical problems with all these studies, making their conclusions uncertain.

For the PNAS study, a new method of studying markers across the entire genome is allowing geneticists to look back in time, to before the emergence of our species 200,000 years ago. Jorde and his colleagues used short lengths of DNA that randomly insert themselves into the genome, known as Alus, as probes to find ancient parts of the genome. This enabled the researchers to chart the population history of our really ancient ancestors, such as Homo erectus. According to the authors:

By comparing the likelihood of various demographic models, we estimate that the effective population size of human ancestors living before 1.2 million years ago was 18,500, and we can reject all models where the ancient effective population size was larger than 26,000. This result implies an unusually small population for a species spread across the entire Old World, particularly in light of the effective population sizes of chimpanzees (21,000) and gorillas (25,000), which each inhabit only one part of a single continent.

It is amazing to think how such a tiny population of humans managed to spread across the face of this planet, until today H. sapiens can be found living on every continent under all sorts of environmental conditions. From Arctic cold to tropical heat, from sodden rainforests to arid deserts, from sea level to mountain heights humans are literally everywhere on Earth. Humans spread across the world before civilization, before human technology rose above chipped flint knives and pointy sticks. What explains our ancestors' success?


Lunch was not easy to come by for our ancestors.

When viewed as wild animals, humans are singularly unimpressive. Poorly insulated, being mostly bereft of fur or hair, and noticeably weak—even an immature chimpanzee is stronger than an adult human. Our nails and teeth seem particularly unimpressive, unsuited for defense let alone hunting; try jumping on the back end of a buffalo and taking a bite with only the equipment nature has provided and you will see what I mean. Humans seem like an unlikely apex predator, yet somehow we managed to rise to the top of the planetary food chain and adapt to every environment on Earth.

Anthropologists will say that it was our ancestors' intelligence that was the key to humanity's success. From 1.9 million to 200,000 years ago, our ancestors tripled their brain size. Our large brains allowed us to develop weapons to augment nature's poor standard equipment. Intelligence also allowed us to develop language to better communicate, and to devise complex hunting strategies other pack hunters could only wish for. And make no mistake, hunting played an essential part in human development.

Despite the prattling by PETA and other radical vegetarian groups, our ancestors were meat eaters. The brain consumes 60% of the energy expended by a resting newborn baby. A resting adult's brain uses 25% of its energy, as opposed to 8% used on average by ape brains. Expanding the human brain demanded a new supply of energy. According to a longstanding body of evidence two things allowed humans to evolve bigger brains: meat and cooking.

About 2 million years ago, soon after the emergence of the genus Homo, our ancestors began to eat more meat, butchering animals with stone tools. The first stone tools appear in Ethiopia about 2.7 million years ago, along with evidence that hominids were using them to butcher scavenged carcasses and extract marrow from bones. Big changes in human anatomy don't appear in the fossil record until more than 1 million years later. According to paleoanthropologist Alan Walker of Pennsylvania State University in State College, a H. erectus skull dating to 1.6 million years ago indicates a brain twice the size of an older australopithecine's. Also about that time, archaeological sites show that H. erectus was moving carcasses to campsites for further butchering and sharing. The traditional explanation is that H. erectus was a better hunter and scavenger and ate more raw meat than its small-brained ancestors.

Harvard University primatologist Richard Wrangham thinks that in addition to going carnivore, our ancestors got cooking. Cooking in effect predigests food, allowing primitive humans to digest the same number of calories with less effort. “Even small differences in diet can have big effects on survival and reproductive success,” he maintains. But a diet of wildebeest tartar and antelope carne cruda alone isn't enough to account for these dramatic changes, says Wrangham. He notes that H. erectus had small teeth—smaller than those of its ancestors. Other carnivores adapted to eating raw meat by increasing tooth size. He argues that whereas earlier ancestors ate raw meat, H. erectus must have been roasting it, with root vegetables on the side or as a fallback when hunters didn't bring home the bacon. “Cooking produces soft, energy-rich foods,” he says (see “Food for Thought”).


A time-line of human events. Credit: J. Newfield/Science.

By the time modern humans arrived in Europe around 40,000 years ago, they were adept at hunting large game and had expanded their palates to dine regularly on small animals and freshwater fish. This according to Michael Richards of the University of British Columbia and Erik Trinkhaus of Washington University, reporting in PNAS (see “Isotopic evidence for the diets of European Neanderthals and early modern humans”). By studying the ratios of carbon and nitrogen isotopes from collagen in bones, they traced the main sources of dietary protein of 27 early Europeans and Neandertals. Richards and Trinkhaus found that the oldest known modern human in Europe—the 35,000-year-old jawbone from Pestera cu Oase cave in Romania—got much of his protein from fish. By 30,000 years ago, other modern humans got as much as 20% of their protein from fish. Compared with us, our ancestors ate “meat: more protein, less refined carbohydrates, and no milk,” according to exercise physiologist Loren Cordain of Colorado State University (see “What's for Dinner? Researchers Seek Our Ancestors' Answers”).

I find it interesting that the two things that made us human—eating meat and the use of fire—are now under attack by those who inhabit the lunatic fringe of rich societies. We are told that eating meat is a sin, atavistic behavior suitable only for savages, and that burning things produces CO2 that will surely bring our world to ruin. It seems like many of the modern world's oh-so-sophisticated thinkers have forgotten where we came from and just how cruel and uncaring nature can be. As comedian Jon Stewart said : “The one thing that brought human kind out the darkness was burning things. We rubbed two sticks together and suddenly we could eat cooked food.”


H. neanderthalensis, an extinct relative.

While interviewing noted global warming alarmist Al Gore, Stewart, the host of Comedy Central's The Daily Show, told the former US Vice-President, “you're fighting not just the industrial revolution age, you're fighting all the the years of human progress.” Stewart, an entertainer who is notably left leaning in his politics, managed to sum the situation up nicely: “It's a much more fundamental shift than I think environmentalists realize. It's the idea that the life that humans have carved out was created through a certain thing of burning things we found.” So light a fire, throw something on the barbie and thank our ancestors for eating meat and learning to cook. Without them we might have joined Homo erctus, Homo neanderthalensis and all the other members of the genus Homo in extinction.

Be safe, enjoy the interglacial and stay skeptical.


Our ancestors knew what was on the menu.

Vegetarian Caveman Update

In a new post, “Vegetarian Cavemen Died Out, Meat Eaters Thrived,” Dr. Hoffman reports on a pre-human species of man, who lived around 2.7 million to 1 million years ago, that many scientists think existed on a vegetarian diet. The dietary specialization of this vegan leaning branch of early hominin is thought to have contributed to its demise because it was unable to adapt to the changing environmental conditions that took place approximately 1 million years ago. Perhaps there is a message in this for today's vegetarians—eat meat or you too will become extinct.

The rise of humans.

This is about vegetarians and "US", I am so glad I read this on how we evolved by eating more meat, probably due to the fact we leant how to cook it! Great,
I once walked into a vegan pub, I did not know it was a vegan pub,not thinking that the pub only served VEGAN food. I ask could I please, notice that I said "please", may I have a HAM sandwich, WELL that look I got, well one would have thought I was a mass murderer?"?

I'm fairly certain no

I'm fairly certain no "radical" vegetarian group, especially one of the magnitude and influence of PETA, has ever asserted that our early ancestors were not omnivorous.

What a ridiculous thing for you to say.

Vegetarian Cavemen

Read what is written, not what you think was written. I never said that Peta claimed our ancestors were vegetarians. What I said was we are told that eating meat is a sin, atavistic behavior suitable only for savages. But now that you bring it up, there evidently was a pre-human species of vegan-eating man known as “Paranthropus robustus.” New research shows that the vegetarian branch of humans died off long ago, while their meat-eating cousins lived on and thrived. So science is fairly certain that there were “vegetarian” cavemen, but they didn't last. How ridiculous for you to doubt it.

More on ancient humans & Neanderthals

The affect climate change has had on human migration during the last glacial period is a matter of hot debate in some scientific circles. A study of ancient volcanic ash found at key archaeological sites across Europe suggests that early modern humans were more resilient to climate change and natural disasters than commonly thought. The study, which appeared in PNAS, analyzed volcanic ash from a major eruption that occurred in Europe around 40,000 years ago. Looks like our ancestors were more adaptable than some scientists think. If you are interested in more about ancient humans and Neanderthals check out “We're Still Standing.”


Humans almost went extinct

Humans almost went extinct when the worldwide flood occured.....8 survivers total.

Really? Well since you

Really? Well since you believe in 6000 year old mythology why don't you embrace 6000 year old medicine and culture too?

This is a scientific website, stupid

Please don't waste our time by citing to the Bible. It is a good book for entertainment and learning morals through parabals. It is not science.

well that is something new i

well that is something new i did not know. but i sure am glad we did survive that period and i am here today. lol thanks for the interesting post! i really enjoyed reading it.

We should have the mindset

We should have the mindset that a human population of 50 billion on planet Earth would be a good thing. And if you include the human population in the Solar system, then a total human population of trillions.

With a human populations exceeding a billion, we probably would need to depend upon various systems of farming as compared to being largely dependent any kind of system of hunting and gathering.

Today's fishing industry is still largely using a system of hunting and gathering rather than a system of farming. There is currently a lot of fishing farming, but potentially, it could be increased significantly.

Wiki:
"Salmon aquaculture is the major economic contributor to the world production of farmed fin-fish, representing over $1 billion US annually. Other commonly cultured fish species include: tilapia, catfish, sea bass, carp, bream, and trout. Salmon farming is very big in Chile, Norway, Scotland, Canada and the Faroe Islands, and is the source for most salmon consumed in America and Europe"
http://en.wikipedia.org/wiki/Salmon

Of course we are not going to get a total human population of 50 billion, anytime soon. But we shouldn't imagine that it's more optimal to have lower human population. If we see a future of human population in tens of billions, part of that vision must include higher population densities.

I also think an important thing is for there to be large areas which are wild. And I think we could a human population of more 50 billion on earth and at same time have more area which are wild than we do presently.
But have higher population densities we need more intelligence in the area of "city planning".

If your future includes our solar system, then we could have a exponential growth in "wild areas".
I would say you have to include the potential of human access to some area in order to "count it" as a wild area.
If you instead define wild space as area which inaccessible and in which humans never go to, then you have to include the entire universe as "wild areas" and have no reason to think there could be anything approaching a shortage in this regard.

So, as I define it, a wild area has to have a reasonable potential of humans visiting it- whether in person or say thru a mass media of seeing in film. So in this definition, we have actually had increase in wild areas in our modern world. For instance, we have visited small areas of the moon, we have visited some places in the deep ocean, etc.

Compare this to people living in a village 6 centuries ago in Europe or China. They might have never left the village in their lifetime, therefore the "exposure" to wild areas is somewhere around zero.
Or compared it to cave man living 1/2 million years ago. Now you could say everything this cave man experiences is "wild", including himself. Or could see it as a person or people "confined" to a certain "range"- the places they go could more diverse than most peasants living in some village, 1/2 million years into the future, but I don't see it as much of significant difference.
If you compare the cave man to someone living in 21 Century, the 21 century human has much more wild areas which are accessible- they watch it on TV, or they visit a park, or fly to Antarctic, climb Mt Everest, or even go into space.

But even if you limit wild areas to places on Earth, it's possible to increase wild areas- because vast areas of this planet can not be reasonable accessible at the present- such as, most of the Antarctic [a land area larger than the US], the most of the Ocean- both surface and underwater- which covers 70% of the planet.

Populations.

Well Doug, let's just suppose that we have a scenario where both Al Gore and Jon Stewart are equally correct. Wouldn't that make us a victim of our own success?

I've heard it said that 'half the people that ever lived are still alive today'. I don't know if there is any truth in that phrase, but it makes me think about current population levels.

Best regards, suricat.

I think you wronged it. It

I think you wronged it. It says that half of the people that ever lived are still alive but they mean the memories or the things that our ancestors ever did to make as humans.