http://ap.google.com/article/ALeqM5i48rTo2rx21e6IQHCD6r-ZYc6eDwD908B0D00 Study says near extinction threatened people By RANDOLPH E. SCHMID WASHINGTON (AP) — Human beings may have had a brush with extinction 70,000 years ago, an extensive genetic study suggests. The human population at that time was reduced to small isolated groups in Africa, apparently because of drought, according to an analysis released Thursday. The report notes that a separate study by researchers at Stanford University estimated the number of early humans may have shrunk as low as 2,000 before numbers began to expand again in the early Stone Age. "This study illustrates the extraordinary power of genetics to reveal insights into some of the key events in our species' history," Spencer Wells, National Geographic Society explorer in residence, said in a statement. "Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA." Wells is director of the Genographic Project, launched in 2005 to study anthropology using genetics. The report was published in the American Journal of Human Genetics. Previous studies using mitochondrial DNA — which is passed down through mothers — have traced modern humans to a single "mitochondrial Eve," who lived in Africa about 200,000 years ago. The migrations of humans out of Africa to populate the rest of the world appear to have begun about 60,000 years ago, but little has been known about humans between Eve and that dispersal. The new study looks at the mitochondrial DNA of the Khoi and San people in South Africa which appear to have diverged from other people between 90,000 and 150,000 years ago. The researchers led by Doron Behar of Rambam Medical Center in Haifa, Israel and Saharon Rosset of IBM T.J. Watson Research Center in Yorktown Heights, N.Y., and Tel Aviv University concluded that humans separated into small populations prior to the Stone Age, when they came back together and began to increase in numbers and spread to other areas. Eastern Africa experienced a series of severe droughts between 135,000 and 90,000 years ago and the researchers said this climatological shift may have contributed to the population changes, dividing into small, isolated groups which developed independently. Paleontologist Meave Leakey, a Genographic adviser, commented: "Who would have thought that as recently as 70,000 years ago, extremes of climate had reduced our population to such small numbers that we were on the very edge of extinction." Today more than 6.6 billion people inhabit the globe, according to the U.S. Census Bureau. The research was funded by the National Geographic Society, IBM, the Waitt Family Foundation, the Seaver Family Foundation, Family Tree DNA and Arizona Research Labs.
So does anyone know the minimum amount of individuals that would be required to avoid inbreeding complications down the line that some of the endangered big cat species are encountering?
Sometimes I have this fantasy that I was the last living male on earth and I had to go around the block and impregnate evey female. Is that weird?
Y: The Last Man is one of the best comics I've read. Wasn't too thrilled about the final issue, but wasn't disappointed either.
The bottleneck effect they talk about could suggest that we are all r****ded! Ahhhh! Kinda! Thats a great question. I can only assume that any population thats small enough to result in disastrous deformities won't survive. I guess we'll find out pretty soon about the big cats... If we were left in the Stone Age with 2,000 people left, who is to say we didn't escape unscathed? In our genome you will find things like multiple copies of sections of DNA that could be the result of this level of inbreeding? Someone who has studied genetics could correct me if I'm off. It's been a couple years since my genetics class. Ironically though, it could be these multiple copies of genes that allow mutations to benignly create new versions of the gene. As long as we have multiple copies, it seems like there's some room for error if something goes wrong with one of 'em.
Apparently less than 2,000. As HAYJON noted I think there is a fair amount of give on that and I'm guessing different species have different levels of tolerance to it. For instance I've heard that some genetic studies indicate that Native Americans might have descended from as few as 200 individuals that made it into North America in a short span between when the Bering straight landbridge could be crossed while glaciers where no longer blocking the way. Also considering that mitochondrial DNA indicates all of us might've descended from a single "Eve" that would indicate a severe genetic bottleneck.
The next question though is would the world be better off if we had went extinct 70,000 years ago and would another species have become intelligent and started a civilization?
The thing is, we have no idea if there were intelligent life before us during the hundreds and hundreds of million years life has existed on earth. Give or take another 300 million years, and all the trash and junk will mostly be compacted and shredded by the earth. Radioactive decay and dust will have settled. Life would've evolved for its conditions by then. The major proofs of our existence would then be the junk in space or on the moon... maybe a teapot floating around Mars. Don't worry about harming the earth. The only harm comes from those are being harmed.
earth is ~4.6 Billion years old. people what 10-15 thousand years civilization less than 5 thousand. over population is going to be happening very soon which will lead to mass deaths. 7 billion people right now estimated human growth population will plateau around ~11 billion then mass deaths will happen. just look how fast the population has grown in the last 200 years. i dunno why i quoted invisibleFan and i didnt read the article. so yeah
The thing is that when people hear about planet Earth, they automatically think of it as a Human planet. But the truth of the matter is that Earth is truely a Dinosaur Planet. Before humans Dinosaurs ruled Earth for about 166 million years. Where as humans have only been on Earth for about 7 million years. Earth is a Dinosaur planet.
I think homo sapiens have only been around for a range that will vary anywhere between 250,000 and 100,000 depending on who you ask and what criteria of "species" you're using. Still, you're right about us being a drop in the bucket compared to dinos. I really don't think even most educated people really comprehend the scales of time we're talking about. We can only really grasp the time measurements we use: seconds, minutes, hours, years, decades, centuries. After that it gets too fuzzy for our primate brains to compute so anything from a millenium to an eon and upwards will just be computed as "a crap load". What we have trouble grasping is geologic or steller time periods, the very thing that makes concepts like evolution possible. Where else would we get questions like "so could I wake up a platypus tomorrow?" or the indignation you get with "I ain't no monkey".
