When you marry,

usually you take on your partner's surname
or your parter takes on yours.

Two people with different surnames become

two people with the same.

One surname spreads, the other one goes...

...extinct? Usually not.

There might be siblings, cousins,

strangers who happen to share the surname,

to carry it on for the one who lost it.

But if one person fails to pass on the surname,

so might the others.

In fact, every now and then

entire surnames do go extinct

when its last bearer passes away

without passing it on.

According to the Daily Mail,

in England and Wales, 200,000 surnames

were lost since 1901.

You can find lists of endangered surnames

on websites such as Ancestry.com and myheritage.com

Ancestry counts surnames with less than

50 carriers left as endangered,

which in England and Wales,

would currently be names such as

Pober, Mirren, Febland (heh, Febland),

Nighy - N-Nighy?

While some of these names might be 
more of a loss than others,

it's sad to think that they might all 
cease to exist within a few generations.

Back in the days, new surnames 
were created as well

based on someone's job or father's given name or where they came from.

But that doesn't really happen anymore,

not on a large scale, anyway.

So more surnames are lost than
new ones are being born.

Keep this experiment going long enough,

and we will all end up with
the same surname eventually, won't we?

When we look at Earth's more ancient
civilizations - even more ancient-

intensive research reveals that most 
Chinese surnames in use today

were handed down from thousands of years ago.

While historically about 12,000 
Chinese surnames have been recorded,

only a bit over 3,000 are currently in use,

a reduction of 75 percent!

And only a fraction of those are taking 
over a majority of the entire population.

The three most common surnames in mainland
China are Li, Wang and Zhang,

which make up for more than 7 percent 
of the Chinese population each.

Together they belong to close to
300 million people

and are easily the most common surnames
in the world.

In China, the phrase "three Zhang, four Li"
is used to say just "anybody."

So after thousands of years, 
the Chinese people aren't down to

one all-dominating surname, but several.

What's going on here?

This effect can be shown in a simulation.

What you see here is the result of a 
Galton-Watson process,

which maps out how the distribution of
family names changes over time.

It starts out with a very large number
of unique family names

each represented by a different color, 
and after 40 generations,

or around a thousand years,
ends with the ones which are left.

When you look at the very end there,

what you see is very similar to the Chinese situation.

The top three names take over 20 percent
of the cake.

But the question is: 
if we keep the simulation going,

will we end up with only one surname?

Mathematically, the entire population does
converge to only one surname.

But in real life, if we start out with,
say, 10,000 surnames,

(and there are actually
much more than that)

after 40 generations we'd still be left
with over 400.

Okay, how about 200 generations?

Still 93 left.

While the less frequent names
are dying out quickly,

the more frequent ones
become so widely spread

that humans will probably cease to exist
before they do.

The probability of extinction of

a unique family name that is carried
by only one young couple

is 45 percent, at least in the West.

That's the average likelihood of them
having no children

or only children who won't pass
on the family name.

But the likelihood of a family name
which is held by multiple couples

going extinct within one generation
is 45 percent to the power of the number of couples.

So with a few more people sharing a surname
it becomes very unlikely very quickly

that this surname should disappear soon.

If you want to know how often your
family name is currently in use,

you can find that out on websites such as
Forebears.

According to the US Census Bureau,

the most common family names
in the US are currently

Smith, Johnson, and Williams,

which together make up for around
2 percent of the entire US population.

That's, of course, not very impressive
to China.

In a way, you could say that 
on this timeline, the US is somewhere here

while China is already over there.

As fewer family names
become more widely spread,

we might follow the Chinese feat and
become more creative about given names.

So instead of Tim Smith,

you might be called the
TalentedPeaceful Smith.

And, instead of Tom, I might be called
The Rest of Us.