[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:02.89,0:00:04.16,Default,,0000,0000,0000,,This is you.
Dialogue: 0,0:00:04.16,0:00:10.21,Default,,0000,0000,0000,,And these are your ancestors, a huge pyramid\Nstretching into the past and balancing right
Dialogue: 0,0:00:10.21,0:00:11.86,Default,,0000,0000,0000,,on your head.
Dialogue: 0,0:00:12.04,0:00:14.22,Default,,0000,0000,0000,,How many ancestors do you have?
Dialogue: 0,0:00:14.31,0:00:15.98,Default,,0000,0000,0000,,Well, you have two parents.
Dialogue: 0,0:00:16.02,0:00:17.02,Default,,0000,0000,0000,,Four grandparents.
Dialogue: 0,0:00:17.02,0:00:18.93,Default,,0000,0000,0000,,And eight great-grandparents.
Dialogue: 0,0:00:19.01,0:00:22.37,Default,,0000,0000,0000,,Four generations back, \Nyour direct ancestors total 30.
Dialogue: 0,0:00:22.43,0:00:27.07,Default,,0000,0000,0000,,If we continue down this line, doubling every\Nstep, just 40 generations ago we’d find
Dialogue: 0,0:00:27.07,0:00:31.02,Default,,0000,0000,0000,,a trillion ancestors, all living {\i1}at the same\Ntime{\i0}.
Dialogue: 0,0:00:31.06,0:00:32.10,Default,,0000,0000,0000,,Which is… ridiculous.
Dialogue: 0,0:00:33.00,0:00:37.09,Default,,0000,0000,0000,,That’s not only more people than have ever\Nbeen alive, it’s more stars than are in
Dialogue: 0,0:00:37.09,0:00:38.11,Default,,0000,0000,0000,,the Milky Way.
Dialogue: 0,0:00:39.01,0:00:44.01,Default,,0000,0000,0000,,Since our species came on the scene 200,000\Nyears ago, there’ve been maybe 7 or 8 {\i1}thousand{\i0}
Dialogue: 0,0:00:44.02,0:00:47.02,Default,,0000,0000,0000,,generations of humans leading up to… you.
Dialogue: 0,0:00:47.00,0:00:50.00,Default,,0000,0000,0000,,So where are all your missing ancestors?
Dialogue: 0,0:00:50.02,0:00:53.60,Default,,0000,0000,0000,,Clearly, there’s been some inbreeding.
Dialogue: 0,0:00:53.79,0:00:54.79,Default,,0000,0000,0000,,[OPEN]
Dialogue: 0,0:00:54.79,0:00:59.86,Default,,0000,0000,0000,,We’re not talking banjo-playing, King-of-Spain,\NCersei-Jamie inbreeding, but every family
Dialogue: 0,0:01:00.47,0:01:02.48,Default,,0000,0000,0000,,tree inevitably grows forks.
Dialogue: 0,0:01:02.61,0:01:07.66,Default,,0000,0000,0000,,Before Tinder, choices for mates were\Noften limited to as far as you could walk.
Dialogue: 0,0:01:07.07,0:01:10.12,Default,,0000,0000,0000,,Even people like Charles Darwin and Albert\NEinstein married their first cousins.
Dialogue: 0,0:01:14.02,0:01:18.12,Default,,0000,0000,0000,,Because so many people with shared ancestors\Nhave reproduced, our number of actual ancestors
Dialogue: 0,0:01:19.02,0:01:21.09,Default,,0000,0000,0000,,is much smaller than what simple math tells\Nus.
Dialogue: 0,0:01:21.09,0:01:26.18,Default,,0000,0000,0000,,If we replace that with fancy math, factoring\Nin how people moved and lived and paired up…
Dialogue: 0,0:01:27.08,0:01:33.10,Default,,0000,0000,0000,,life expectancy, trade, geography, Genghis\NKhan… we find something interesting: every
Dialogue: 0,0:01:34.00,0:01:38.01,Default,,0000,0000,0000,,human alive today shares a common ancestor\Nin their family tree, and this person lived
Dialogue: 0,0:01:38.05,0:01:40.05,Default,,0000,0000,0000,,only around 3,000 years ago.
Dialogue: 0,0:01:40.05,0:01:43.13,Default,,0000,0000,0000,,That’s right, next time you get in a fight\Nwith a stranger on the internet, just remember
Dialogue: 0,0:01:44.03,0:01:51.05,Default,,0000,0000,0000,,that you share the same great great great\Ngreat great (fast foward) great grandfather
Dialogue: 0,0:01:51.05,0:01:52.20,Default,,0000,0000,0000,,or grandmother.
Dialogue: 0,0:01:52.62,0:01:55.59,Default,,0000,0000,0000,,But we don’t know who that person was.
Dialogue: 0,0:01:55.06,0:01:58.14,Default,,0000,0000,0000,,The math tells us they must have existed,\Nbut they didn’t leave fossils or artifacts.
Dialogue: 0,0:01:59.04,0:02:01.56,Default,,0000,0000,0000,,Or like, a note or something.
Dialogue: 0,0:02:01.90,0:02:08.36,Default,,0000,0000,0000,,Though, writing birthday cards for each of\Ntheir 7.4 Billion great great great great
Dialogue: 0,0:02:08.04,0:02:10.63,Default,,0000,0000,0000,,great (fast forward) great grandchildren would\Nhave been nice gesture.
Dialogue: 0,0:02:10.96,0:02:14.95,Default,,0000,0000,0000,,But we all carry a record of our ancestors\Nin our genes.
Dialogue: 0,0:02:14.10,0:02:18.10,Default,,0000,0000,0000,,Because DNA is copied over and over, every\Nso often a mistake is written in.
Dialogue: 0,0:02:18.10,0:02:21.16,Default,,0000,0000,0000,,You know how when you make a copy of a copy,\Nit’s doesn't come out as sharp?
Dialogue: 0,0:02:22.06,0:02:26.09,Default,,0000,0000,0000,,Like that, but since most of our DNA can be\Nchanged without affecting how things work,
Dialogue: 0,0:02:26.09,0:02:29.16,Default,,0000,0000,0000,,many of these mutations slip through to the\Nnext generation.
Dialogue: 0,0:02:30.06,0:02:34.12,Default,,0000,0000,0000,,These genetic changes accumulate at a steady\Nrate through time, so scientists can read
Dialogue: 0,0:02:35.02,0:02:39.07,Default,,0000,0000,0000,,them like a molecular clock, and estimate\Nhow much time has passed.
Dialogue: 0,0:02:39.07,0:02:44.71,Default,,0000,0000,0000,,And which changes individuals share tell us\Nhow closely or distantly related they are.
Dialogue: 0,0:02:45.32,0:02:49.36,Default,,0000,0000,0000,,Humans {\i1}seem{\i0} really different, but on a DNA\Nlevel we’re remarkably similar.
Dialogue: 0,0:02:49.71,0:02:53.75,Default,,0000,0000,0000,,Groups of chimps in Central Africa, living\Nright next to each other, show more genetic
Dialogue: 0,0:02:54.16,0:02:58.33,Default,,0000,0000,0000,,variation than we find in the entire human\Npopulation.
Dialogue: 0,0:02:58.03,0:03:02.08,Default,,0000,0000,0000,,This genetic similarity tells us that our\Nspecies is new, in the big scheme of things,
Dialogue: 0,0:03:02.08,0:03:06.18,Default,,0000,0000,0000,,and that at one point our population was small,\Nmaybe as few as 10,000 of us.
Dialogue: 0,0:03:07.01,0:03:11.01,Default,,0000,0000,0000,,To put that in perspective, that’s only\Na third of your average Bruce Springsteen
Dialogue: 0,0:03:11.08,0:03:12.08,Default,,0000,0000,0000,,crowd.
Dialogue: 0,0:03:12.08,0:03:13.08,Default,,0000,0000,0000,,Sorry Boss.
Dialogue: 0,0:03:13.08,0:03:18.14,Default,,0000,0000,0000,,Today, any two humans only differ by about\N1 out of 1000 DNA base pairs.
Dialogue: 0,0:03:19.04,0:03:23.13,Default,,0000,0000,0000,,But our genome is so big, that’s still millions\Nof single letter differences, or SNPs, for
Dialogue: 0,0:03:24.00,0:03:26.05,Default,,0000,0000,0000,,“single nucleotide polymorphism”.
Dialogue: 0,0:03:26.08,0:03:30.10,Default,,0000,0000,0000,,We tend to see combinations of these changes,\Nchunks of SNPs, associated with different
Dialogue: 0,0:03:31.00,0:03:33.04,Default,,0000,0000,0000,,geographic locations.
Dialogue: 0,0:03:33.07,0:03:37.21,Default,,0000,0000,0000,,Companies that test your DNA ancestry read\Nthousands of these single letter changes in
Dialogue: 0,0:03:37.02,0:03:41.03,Default,,0000,0000,0000,,your genome, to make a sort of signature of\Nyour unique genetic variation.
Dialogue: 0,0:03:41.03,0:03:45.12,Default,,0000,0000,0000,,Then they compare your signature to thousands\Nof reference individuals from various parts
Dialogue: 0,0:03:46.02,0:03:50.04,Default,,0000,0000,0000,,of the world, and do a bunch of fancy math\Nto see which parts of your genome most likely
Dialogue: 0,0:03:50.04,0:03:52.07,Default,,0000,0000,0000,,came from certain geographic areas.
Dialogue: 0,0:03:52.07,0:03:55.12,Default,,0000,0000,0000,,My genetic results: Pretty much look like\Nthis.
Dialogue: 0,0:03:56.02,0:04:00.04,Default,,0000,0000,0000,,My ancNewsprestors, on both sides of my family,\Nare from Northern Europe and Scandinavia,
Dialogue: 0,0:04:00.04,0:04:05.82,Default,,0000,0000,0000,,which explains my last name, why I’m tall,\Nwhy I don’t tan, and also why I carry more
Dialogue: 0,0:04:06.19,0:04:09.29,Default,,0000,0000,0000,,Neanderthal DNA than 2/3rds of people.
Dialogue: 0,0:04:09.03,0:04:10.10,Default,,0000,0000,0000,,Confused why I have Neanderthal DNA?
Dialogue: 0,0:04:10.10,0:04:14.20,Default,,0000,0000,0000,,You should watch our last video. I didn’t\Nfind any surprises, but many people learn
Dialogue: 0,0:04:15.10,0:04:17.17,Default,,0000,0000,0000,,about ancestry they didn’t know they had.
Dialogue: 0,0:04:18.07,0:04:23.08,Default,,0000,0000,0000,,Where we come from isn’t always obvious\Non the outside, but DNA doesn’t lie.
Dialogue: 0,0:04:23.01,0:04:27.65,Default,,0000,0000,0000,,Before, using math, we identified an ancestor,\Nnot too long ago, that’s related to all
Dialogue: 0,0:04:28.44,0:04:29.44,Default,,0000,0000,0000,,of us.
Dialogue: 0,0:04:29.44,0:04:33.79,Default,,0000,0000,0000,,But that person’s genetic influence has\Nbeen shuffled so much it’s invisible in
Dialogue: 0,0:04:33.08,0:04:34.14,Default,,0000,0000,0000,,our DNA today.
Dialogue: 0,0:04:35.00,0:04:39.06,Default,,0000,0000,0000,,Is there someone whose genes have been passed\Non, unbroken, to today?
Dialogue: 0,0:04:39.10,0:04:42.19,Default,,0000,0000,0000,,Some leftover fingerprint from the mother\Nof everyone alive?
Dialogue: 0,0:04:43.09,0:04:44.10,Default,,0000,0000,0000,,There is.
Dialogue: 0,0:04:45.05,0:04:47.08,Default,,0000,0000,0000,,You have a 47th chromosome.
Dialogue: 0,0:04:47.08,0:04:54.17,Default,,0000,0000,0000,,It lives in mitochondria, the POWERHOUSE OF\NTHE CELL! – so we’re doing that again?
Dialogue: 0,0:04:55.07,0:04:57.07,Default,,0000,0000,0000,,Ok–mitochondria used to be free-swimming.
Dialogue: 0,0:04:57.07,0:04:58.17,Default,,0000,0000,0000,,They have their own genetic material.
Dialogue: 0,0:04:59.07,0:05:03.13,Default,,0000,0000,0000,,Unlike your other 46 chromosomes, there’s\Nno shuffling when it’s passed between generations.
Dialogue: 0,0:05:04.03,0:05:08.04,Default,,0000,0000,0000,,What’s more, all your mitochondria came\Nfrom your mother’s egg, not your father’s
Dialogue: 0,0:05:08.04,0:05:09.04,Default,,0000,0000,0000,,sperm.
Dialogue: 0,0:05:09.04,0:05:14.10,Default,,0000,0000,0000,,They trace an unbroken line of ancestors stretching\Nback through every female in your family tree.
Dialogue: 0,0:05:15.00,0:05:19.03,Default,,0000,0000,0000,,By comparing the changes that have accumulated\Nover the millennia, we find the most ancient
Dialogue: 0,0:05:19.03,0:05:24.04,Default,,0000,0000,0000,,human mitochondrial DNA comes from Africa,\Nwhere our species originated.
Dialogue: 0,0:05:24.04,0:05:28.13,Default,,0000,0000,0000,,We can even trace it back to one woman, about\N150,000 years ago.
Dialogue: 0,0:05:29.03,0:05:34.06,Default,,0000,0000,0000,,Other Homo sapiens females lived alongside\Nher, but only her lineage lives on today,
Dialogue: 0,0:05:34.06,0:05:36.14,Default,,0000,0000,0000,,all other Homo sapiens lineages are extinct.
Dialogue: 0,0:05:37.04,0:05:39.04,Default,,0000,0000,0000,,This is mitochondrial Eve.
Dialogue: 0,0:05:39.00,0:05:41.09,Default,,0000,0000,0000,,And every single one of us, descend from her.
Dialogue: 0,0:05:42.02,0:05:45.10,Default,,0000,0000,0000,,In the truest sense, we really are family.
Dialogue: 0,0:05:46.00,0:05:47.07,Default,,0000,0000,0000,,Even if we’re just hundredth cousins or\Nsomething.
Dialogue: 0,0:05:47.07,0:05:52.14,Default,,0000,0000,0000,,But our ancestry isn’t just branches stretching\Ninto the past, it’s also a tree that extends
Dialogue: 0,0:05:53.04,0:05:54.08,Default,,0000,0000,0000,,into the future.
Dialogue: 0,0:05:54.08,0:05:57.17,Default,,0000,0000,0000,,Today we have more power to mold that future,\Ndown to the genetic level, than we’ve ever
Dialogue: 0,0:05:58.07,0:05:59.08,Default,,0000,0000,0000,,had before.
Dialogue: 0,0:05:59.08,0:06:02.16,Default,,0000,0000,0000,,So what might our species’ future look like?
Dialogue: 0,0:06:03.06,0:06:04.10,Default,,0000,0000,0000,,Next time.
Dialogue: 0,0:06:05.00,0:06:06.08,Default,,0000,0000,0000,,Stay curious.
Dialogue: 0,0:06:06.08,0:06:10.08,Default,,0000,0000,0000,,This video is part of a special series we’re\Ndoing about the story of our species: Where
Dialogue: 0,0:06:10.84,0:06:14.24,Default,,0000,0000,0000,,we came from, how we’re all connected, and\Nwhere we’re going.
Dialogue: 0,0:06:14.02,0:06:18.09,Default,,0000,0000,0000,,If you haven’t already, check out part 1\Nand 2 to trace the fossils in our family tree
Dialogue: 0,0:06:18.09,0:06:20.10,Default,,0000,0000,0000,,and learn why we’re the only humans left.
Dialogue: 0,0:06:21.08,0:06:24.08,Default,,0000,0000,0000,,And be sure to subscribe so you don’t miss\Nany of our videos.