Did Humans Almost Go Extinct? | Random Thursday

for my mom's birthday this year I got her a genetic testing kit from National Geographic this wasn't like 23andme that kind of shows you what diseases you can expect to get throughout your life because I mean you know happy birthday now this traces your lineage back you know hundreds of thousands of years of show your place in the whole human ancestral tree and and the results are pretty interesting as it turns out I shared genetic markers with Abraham Lincoln Queen Victoria and Copernicus and probably like thousands of nobodies most of my lineages from northwestern Europe shocker and I'm about to percent neanderthal judging from my body here I would have thought that would be higher of course if we go back far enough we all descend from a single common ancestor what scientists call mitochondrial Eve but the vast majority of us actually have all of our DNA funneled through a population bottleneck that occurred about 70,000 years ago because according to genetic research very similar to this we almost went extinct and nobody really knows why genetic research showed that African populations actually have a very much higher genetic diversity than people who came out of Africa which kind of supports the theory that human you know life began in Africa and then traveled out from there but it also says that since the rest of the world's genetic population is a lot less diverse that means that it came from a smaller gene pool and the studies have shown that that gene pool went goes down to about a thousand to ten thousand breeding pairs more people will probably see this video than existed on our 70,000 years ago this is also supported by a study in 2008 that looked at the mitochondrial DNA of the koi and some people in South Africa mitochondrial DNA is obviously DNA that comes from the mitochondria the powerhouse of the cell but it's also only passed down from mothers this powerhouse DNA from mom studies showed that the koi and some people actually diverged from the rest of the population about anywhere from ninety thousand to one hundred and fifty thousand years ago so the idea is that humans kind of came up in Africa and then about a hundred thousand or so years ago began to spread out from there but then the population hits this huge bottleneck but why one of the more popular explanations through the years has been the Toba explosion tobin was a volcano in Indonesia that erupted around 74 thousand years ago and the reason why I'm saying that in the past tense that it was a volcano is because it's now because that ish blew up the Toba supervolcano is the largest explosion that has occurred since human beings have been on this planet just beating out on her the Giants parts the explosion dumped 15 centimeters or 6 inches of Ash across South Asia in the South China Sea and released 28,000 cubic kilometers of magma it rates an 8 in the volcano explosivity index which is the highest rating of any known explosion on earth you did not want to be near this thing by near I mean anywhere on the planet because according to the Toba catastrophe theory which was first posed by an gibbons in 1993 this is what caused the big human bottleneck that caused our genetic diversity to go down 70,000 years ago the explosion created a 10-year volcanic winter that lowered temperatures around the globe 3 to 5 degrees Celsius keep in mind we were already in an ice age at the time so yeah not good timing fitness a period of cooling lasting a thousand years may have followed this that wiped out food populations but not just for humans but for species around the world one argument that supporters of this theory point to is the explosion of Mount Tambora in 1815 the Mount Tambora eruption is the largest one in recorded human history measuring a seven on the volcano exposed to the index and it puts so much ash into the atmosphere that it caused what we became known as the year without a summer it was basically winter for an entire year's crops didn't grow people starve it was bad but the Tobin explosion was a hundred times stronger than the tambura explosion so the effects of it would have been equally so right so airtight case except this is science so of course not the Toba theory has come under scrutiny over the last few years because of research done by Chad Yost and his team where they took core samples from Lake Malawi that seems to disprove this entire thing mostly that these cores didn't show any proof of the volcanic winter also this bottleneck seems to have not affected the people living in Africa just those who left Africa so it's possible there might not have been a bottleneck at all that there was just a very small population of people that came out of Africa and then you know the population boomed after that so the real explosion might not have been Toba at all just us now a similar and far more dramatic bottleneck did occur in the America now we all know that Native Americans made their way into North America from Asia by crossing over a land bridge in the Bering Strait around 16 thousand years ago this was during the Ice Ages when the water level dropped and they exposed an underwater shelf that created a bridge about a thousand kilometers wide if scientists actually have a name for that area now they call it Beringia but what might surprise you is how many people apparently made this journey according to a 2005 study from Rutgers University doing genetic testing on Native American people they found that the pre 1492 population in the Americas all descended from 70 people 70 from only 70 people the Native Americans spread throughout North America and South America rising to a population level of around a hundred million people and then the Europeans came where there was a cataclysmic event that choked off our human population way back when or we had just all descended from a small group of brave explorers humans have made some pretty strong stuff it turns out we're a lot more close-knit family than we thought we were so thanks for watching fam this is an interesting topic I'll put some links down below that you can go check out some other videos that cover this subject really well t-shirts available at the store answers with joe comm slash shirts go there find some cool nerdy stuff they walk around and have people think wow this guy's really cool or a nerd or both whatever this your first time here I invite you to check out some of my other videos and if you like those please do hit subscribe because I keep coming back with stuff all the time you might like it oh and say hi to people down below we got a cool crowd watching this show alright that's it for today you guys go out have an eye-opening week and I'll see you next Monday love you guys take care

Channel: Joe Scott

Views: 217,963

Rating: 4.9438176 out of 5

Keywords: Answers With Joe, random thursdays, population bottleneck, toba explosion, toba catastrophe theory, DNA testing, National Geographic, Out of africa theory, Native americans, beringia, Mount Tambora, The year without a summer, Genetic diversity

Id: mVovCaJrjfw

Length: 6min 2sec (362 seconds)

Published: Thu Oct 11 2018