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  • People use the internet for various reasons.

  • It turns out that one of the most popular categories of website

  • is something that people typically consume in private.

  • It involves curiosity,

  • non-insignificant levels of self-indulgence

  • and is centered around recording the reproductive activities

  • of other people.

  • (Laughter)

  • Of course, I'm talking about genealogy --

  • (Laughter)

  • the study of family history.

  • When it comes to detailing family history,

  • in every family, we have this person that is obsessed with genealogy.

  • Let's call him Uncle Bernie.

  • Uncle Bernie is exactly the last person you want to sit next to

  • in Thanksgiving dinner,

  • because he will bore you to death with peculiar details

  • about some ancient relatives.

  • But as you know,

  • there is a scientific side for everything,

  • and we found that Uncle Bernie's stories

  • have immense potential for biomedical research.

  • We let Uncle Bernie and his fellow genealogists

  • document their family trees through a genealogy website called geni.com.

  • When users upload their trees to the website,

  • it scans their relatives,

  • and if it finds matches to existing trees,

  • it merges the existing and the new tree together.

  • The result is that large family trees are created,

  • beyond the individual level of each genealogist.

  • Now, by repeating this process with millions of people

  • all over the world,

  • we can crowdsource the construction of a family tree of all humankind.

  • Using this website,

  • we were able to connect 125 million people

  • into a single family tree.

  • I cannot draw the tree on the screens over here

  • because they have less pixels

  • than the number of people in this tree.

  • But here is an example of a subset of 6,000 individuals.

  • Each green node is a person.

  • The red nodes represent marriages,

  • and the connections represent parenthood.

  • In the middle of this tree, you see the ancestors.

  • And as we go to the periphery, you see the descendants.

  • This tree has seven generations, approximately.

  • Now, this is what happens when we increase the number of individuals

  • to 70,000 people --

  • still a tiny subset of all the data that we have.

  • Despite that, you can already see the formation of gigantic family trees

  • with many very distant relatives.

  • Thanks to the hard work of our genealogists,

  • we can go back in time hundreds of years ago.

  • For example, here is Alexander Hamilton,

  • who was born in 1755.

  • Alexander was the first US Secretary of the Treasury,

  • but mostly known today due to a popular Broadway musical.

  • We found that Alexander has deeper connections in the showbiz industry.

  • In fact, he's a blood relative of ...

  • Kevin Bacon!

  • (Laughter)

  • Both of them are descendants of a lady from Scotland

  • who lived in the 13th century.

  • So you can say that Alexander Hamilton

  • is 35 degrees of Kevin Bacon genealogy.

  • (Laughter)

  • And our tree has millions of stories like that.

  • We invested significant efforts to validate the quality of our data.

  • Using DNA, we found that .3 percent of the mother-child connections in our data

  • are wrong,

  • which could match the adoption rate in the US pre-Second World War.

  • For the father's side,

  • the news is not as good:

  • 1.9 percent of the father-child connections in our data are wrong.

  • And I see some people smirk over here.

  • It is what you think --

  • there are many milkmen out there.

  • (Laughter)

  • However, this 1.9 percent error rate in patrilineal connections

  • is not unique to our data.

  • Previous studies found a similar error rate

  • using clinical-grade pedigrees.

  • So the quality of our data is good,

  • and that should not be a surprise.

  • Our genealogists have a profound, vested interest

  • in correctly documenting their family history.

  • We can leverage this data to learn quantitative information about humanity,

  • for example, questions about demography.

  • Here is a look at all our profiles on the map of the world.

  • Each pixel is a person that lived at some point.

  • And since we have so much data,

  • you can see the contours of many countries,

  • especially in the Western world.

  • In this clip, we stratified the map that I've showed you

  • based on the year of births of individuals from 1400 to 1900,

  • and we compared it to known migration events.

  • The clip is going to show you that the deepest lineages in our data

  • go all the way back to the UK,

  • where they had better record keeping,

  • and then they spread along the routes of Western colonialism.

  • Let's watch this.

  • (Music)

  • [Year of birth: ]

  • [1492 - Columbus sails the ocean blue]

  • [1620 - Mayflower lands in Massachusetts]

  • [1652 - Dutch settle in South Africa]

  • [1788 - Great Britain penal transportation to Australia starts]

  • [1836 - First migrants use Oregon Trail]

  • [all activity]

  • I love this movie.

  • Now, since these migration events are giving the context of families,

  • we can ask questions such as:

  • What is the typical distance between the birth locations

  • of husbands and wives?

  • This distance plays a pivotal role in demography,

  • because the patterns in which people migrate to form families

  • determine how genes spread in geographical areas.

  • We analyzed this distance using our data,

  • and we found that in the old days,

  • people had it easy.

  • They just married someone in the village nearby.

  • But the Industrial Revolution really complicated our love life.

  • And today, with affordable flights and online social media,

  • people typically migrate more than 100 kilometers from their place of birth

  • to find their soul mate.

  • So now you might ask:

  • OK, but who does the hard work of migrating from places to places

  • to form families?

  • Are these the males or the females?

  • We used our data to address this question,

  • and at least in the last 300 years,

  • we found that the ladies do the hard work

  • of migrating from places to places to form families.

  • Now, these results are statistically significant,

  • so you can take it as scientific fact that males are lazy.

  • (Laughter)

  • We can move from questions about demography

  • and ask questions about human health.

  • For example, we can ask

  • to what extent genetic variations account for differences in life span

  • between individuals.

  • Previous studies analyzed the correlation of longevity between twins

  • to address this question.

  • They estimated that the genetic variations account for

  • about a quarter of the differences in life span between individuals.

  • But twins can be correlated due to so many reasons,

  • including various environmental effects

  • or a shared household.

  • Large family trees give us the opportunity to analyze both close relatives,

  • such as twins,

  • all the way to distant relatives, even fourth cousins.

  • This way we can build robust models

  • that can tease apart the contribution of genetic variations

  • from environmental factors.

  • We conducted this analysis using our data,

  • and we found that genetic variations explain only 15 percent

  • of the differences in life span between individuals.

  • That is five years, on average.

  • So genes matter less than what we thought before to life span.

  • And I find it great news,

  • because it means that our actions can matter more.

  • Smoking, for example, determines 10 years of our life expectancy --

  • twice as much as what genetics determines.

  • We can even have more surprising findings

  • as we move from family trees

  • and we let our genealogists document and crowdsource DNA information.

  • And the results can be amazing.

  • It might be hard to imagine, but Uncle Bernie and his friends

  • can create DNA forensic capabilities

  • that even exceed what the FBI currently has.

  • When you place the DNA on a large family tree,

  • you effectively create a beacon

  • that illuminates the hundreds of distant relatives

  • that are all connected to the person that originated the DNA.

  • By placing multiple beacons on a large family tree,

  • you can now triangulate the DNA of an unknown person,

  • the same way that the GPS system uses multiple satellites

  • to find a location.

  • The prime example of the power of this technique

  • is capturing the Golden State Killer,

  • one of the most notorious criminals in the history of the US.

  • The FBI had been searching for this person for over 40 years.

  • They had his DNA,

  • but he never showed up in any police database.

  • About a year ago, the FBI consulted a genetic genealogist,

  • and she suggested that they submit his DNA to a genealogy service

  • that can locate distant relatives.

  • They did that,

  • and they found a third cousin of the Golden State Killer.

  • They built a large family tree,

  • scanned the different branches of that tree,

  • until they found a profile that exactly matched

  • what they knew about the Golden State Killer.

  • They obtained DNA from this person and found a perfect match

  • to the DNA they had in hand.

  • They arrested him and brought him to justice

  • after all these years.

  • Since then, genetic genealogists have started working with

  • local US law enforcement agencies

  • to use this technique in order to capture criminals.

  • And only in the past six months,

  • they were able to solve over 20 cold cases with this technique.

  • Luckily, we have people like Uncle Bernie and his fellow genealogists

  • These are not amateurs with a self-serving hobby.

  • These are citizen scientists with a deep passion to tell us who we are.

  • And they know that the past can hold a key to the future.

  • Thank you very much.

  • (Applause)

People use the internet for various reasons.

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【TED】How we're building the world's largest family tree | Yaniv Erlich

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    林宜悉   に公開 2019 年 10 月 18 日
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