Hello viewers and we have reached a momentous milestone, I've been given a plastic chair
to sit on as a reward for a year of contributing to head squeeze and we now have a quarter
of a million subscribers, 250,000 people!
How about that!
And as a result we've themed some 250,000 related questions, experiments and what have
you and mine is Are humans really 250,000 years old?
Well possibly.
We can't be sure, because we've yet to find a neatly dated diary entry from the first
modern human: 'Tuesday, woke up.
Skinned a woolly mammoth and made underpants.'
In fact, all discussion for the exact date of humanity's arrival onto the planet is made
with a margin of error of several tens of thousands of years.
Let's start at the beginning.
Primates -- the biological order of which we're part -- started to evolve separately
from other mammals around 85 million years ago.
Hominini, our bit of the family tree, separated from chimpanzees -- our last common ancestor
of another species -- about five and a half million years ago.
The genus homo -- stop sniggering at the back -- which includes modern humans, first appeared
about 2.3 million years ago.
This marked the point at which our brains started to get significantly bigger, with
homo heidelbergensis -- who arrived between 1.3 million and 600,000 years ago - having
a cranial capacity similar to our own.
This was also when our distant ancestors evolved the ability to use tools, although -- to judge
from the number of stone age axe-heads left lying around the world -- not the ability
to tidy up after themselves.
Homo sapiens -- modern humans with the opposable thumb that was to become so useful for texting
-- first evolved in Africa between 250,000 and 200,000 years ago, and started to travel
around the world shortly afterwards.
That's short in evolutionary timescales, at least.
We arrived in Eurasia about 125,000 years ago, Australia about 40,000 years ago, the
Americas 15,000 years ago and New Zealand less than a thousand years ago: recently enough
that some early immigrants are still waiting for their luggage.
For a long time we lived alongside other members of the homo genus.
And, indeed, often seemed to do slightly more than that, with evidence that European Homo
Sapiens cross-bred with Neanderthals -- with whom we had diverged as a separate species
about 400,000 years ago.
But there was clearly as much violence as sex, with all other members of the homo family
apart from Homo Sapiens having died out by around 30,000 years ago.
This could well be because humans achieved what anthropologists refer to as behavioural
modernity around 50,000 years ago.
This meant that we were using more complex languages, building more advanced weapons
and then painting pictures in caves to show our awesome hunting skills, and how good we
looked in our underpants.
And our prey likely included the other types of early man.
We developed agriculture and learned animal husbandry about 12,000 years ago.
And the rest is just history.
Except it isn't, not quite.
Technically it's pre-history, the time before we had written records.
We only moved into what's generally regarded as being history, and gained the ability to
keep an accurate record, about 5700 years ago when the very first Cuneiform writing
appeared.
Or to put it another way, homo sapiens have been walking the planet for 0.15% of the earth's
4.54 billion year history.
And we've got some form of written record for less than one thousandth (0.085%) of mankind's
existence.
250,000 years?
In fact, it's just the twinkling of an eye.